explain xkcd - User contributions [en]

2793: Garden Path Sentence

2023-06-30T07:12:41Z

Rsge: Changed pronouns

{{comic
| number = 2793
| date = June 23, 2023
| title = Garden Path Sentence
| image = garden_path_sentence.png
| imagesize = 273x273px
| noexpand = true
| titletext = Arboretum Owner Denied Standing in Garden Path Suit on Grounds Grounds Appealing Appealing
}}
==Explanation==
{{incomplete|Created by a bird watcher strikes judge then modified by said strikes. Please add information here regarding what remains to be done for the article. (Clarity should be added to the first explanation. More possible explanations maybe should be added?)}}

A {{w|garden-path sentence}} is one in which the first or most obvious attempt at parsing the beginning of a sentence leads to the wrong meaning, causing confusion when the sentence is completed. A classic example of a garden path sentence is "The old man the boat.", leading to an initial incorrect parsing of "the old man" as a noun phrase, and therefore to assuming there is no verb before the noun "the boat". The actual correct way to parse this sentence is to treat "the old" as a noun and "man" as a verb, meaning "to work at, run, or operate", so the sentence means "The old people operate the boat."

Possible grammatically correct interpretations of the sentences in this comic are:

There was a court case regarding green walkways. The case was resolved with a sentence relating to an olive garden path. That sentence was vacated (cancelled) by a judge. That judge was flying an airplane. The airplane struck multiple birds. The plane overturned, but righted (turned right-side-up) and landed safely.

After (bird strikes)1, (judge)2, (who ordered)3 (olive garden-path sentence)4 in (case of green walkways)5 (vacated)3, (overturned but rights and lands safely.)2

# "[[wikipedia:bird strike|bird strike]]s": Airplane colliding with birds in flight, or alternatively "bird strikes" could refer to the strikes called by the Bird union that this judge was known for or involved in the ruling of.
# "judge ... overturned but rights and lands safely": The judge (and presumably the plane they were in) flipped over but was able to get right-side up again and land safely
# "who [[wikipedia:Court order|ordered]] [the sentence to be] [[:wikipedia:Vacated judgment|vacated]]": Identifies the judge as one who issued a ruling cancelling an earlier ruling.
# "[[wikipedia:Olive|olive]] garden path [[wikipedia:Sentence (law)|sentence]]": The thing that was cancelled was a punishment related to a path in an olive garden
# "[[wikipedia:Legal case|case]] of [[wikipedia:Greenway (landscape)|green walkways]]": The punishment was in a court case about shared-use walkways (likely the same paths listed above, which may have been placed in an olive garden)

Another way to break it down is, "After [the] bird strikes, [the] judge... [is] overturned, but [she] rights and lands safely." And she was "[the] judge who ordered [that the] olive garden-path sentence" (the legal sentence concerning a path in an olive garden) "in" (what is known as) "[the] Case of [the] Green Walkways [be] vacated."

This comic also pokes fun at newspaper headlines, which typically have minimal punctuation or articles and use only capital letters, leading to such ambiguities.

For another valid parsing of the sentence, here are some explanatory notes that aid in understanding:
* A criminal court case occurred involving green-colored walkways.
* The sentence handed down in the case involved a specific walkway (a garden path) and a specific shade of green (olive).
* A certain judge had ordered that the sentence be vacated (a legal term meaning undone or expunged).
* That judge was recently piloting a plane which, due to being struck by birds, overturned.
* The judge righted the plane (turned it right-side-up) and landed safely.

A mostly similar, but slightly more comical interpretation (though less likely for a newspaper headline) can be:
After (a) bird strikes, (the) judge ... (as above) (is) overturned, but rights and lands safely. In this case, the judge is standing, a bird strikes her and she is overturned, but she manages to right herself and land safely on the ground (not banging her head, for instance).

Another way of diagramming this (where noun phrases are in parenthesis and verbal clauses in brackets) would be:
[after (bird strikes) ],
[(the judge
[who ordered (((olive garden path) sentence) [in case of (green walkways)]) be vacated])
is overturned, but [(she) rights (himself) and [lands safely]]].

Certain combinations of words in the sentence are particularly easy to parse incorrectly. For example:
* "bird" the headline is in all caps so this could be an avian but could also mean a person with the name of Bird such as Larry Bird the basketball player.
* "bird strikes judge" can be interpreted to mean that a bird deliberately hit the judge with an appendage or weapon. If bird is a person or other worker, the phrase might mean a labour dispute in which Bird is withdrawing services
* "Olive Garden" is the name of a restaurant chain, and "ordered Olive Garden" could mean "placed an order for food from Olive Garden"
* "Garden path sentence" is a type of (written language) sentence
* "Green" could be referring to "green" initiatives, environmentally-friendly practices being used or to the color green, rather than to a park area
* "in case of" can mean "in the event of" (e.g. "in case of emergency, break glass")
* "vacated" and "overturned" can both mean "undone" in a legal context, and "rights" can refer to legal or constitutional rights

Ignoring the pictures showing a plane and flight path and only focusing on the headline, it could also be interpreted this way:
* "After bird strikes judge", "overturned but rights and lands safely": an avian creature flew into the judge, and as it bounced off it was upside-down, but it managed to recover in time to go right-side-up to land nearby.
* "case of green walkways", "olive garden path sentence": There was a case about green walkways, and the ruling was for an olive garden path (or it is dubbed the "Olive Garden path sentence" for the restaurant chain, because it is strongly linked to the chain - either they wanted this sentence as it benefits them or the chain is notorious for it).
* "judge who ordered", "vacated": The aforementioned judge is known to people for ordering that the sentence be vacated (perhaps this was highly controversial), thus making this event significant enough to warrant a headline.

If one focuses on the word "judge", many of the phrases relate to legal proceedings, making the parsing of the sentence especially difficult:
* "strike": to remove or delete from a legal document and especially from the record of a trial
* "order": a direction issued by a court or a judge requiring a person to do or not do something
* "sentence": punishment assigned to a defendant found guilty by a court
* "case": a civil or criminal proceeding at law or in equity
* "vacate": to legally annul, set aside, or render void
* "overturn": to disagree with a decision made earlier by a lower court
* "rights": powers or privileges held by the general public as the result of a constitution, statute, regulation, judicial precedent, or other type of law

Furthermore, the word "lands" can have two meanings:
* The present simple variation of "to land": in the context of an airplane, to come down through the air and alight on the ground
* The plural of "land", a common issue in legal proceedings

The title text is also an example of a garden path sentence. The meaning is probably the following: Arboretum owner, [who was] denied [legal] standing in [the] garden-path [law]suit on grounds (the reason) [that the garden] grounds [are] appealing, [is] appealing [the ruling]. Alternatively: Arboretum owner, [who was] denied [legal] standing in [the] garden-path [law]suit on grounds (reasoning) grounds (why it was denied), [is] appealing appealing [the ruling].

==Transcript==
:[A newspaper titled ''News'' with two pictures on the front page: one showing a judge with an airplane in the background, and the other displaying a map depicting the airplane's route. Above the pictures there is the following headline, displayed in all capital letters:]
:AFTER BIRD STRIKES JUDGE WHO ORDERED OLIVE GARDEN PATH SENTENCE IN CASE OF GREEN WALKWAYS VACATED OVERTURNED BUT RIGHTS AND LANDS SAFELY

{{comic discussion}}

[[Category:Language]]
[[Category:Aviation]]
[[Category:Animals]]
[[Category:Dinosaurs]]

2624: Voyager Wires

2022-07-07T06:17:44Z

Rsge: Values must have spaces before units

{{comic
| number = 2624
| date = May 25, 2022
| title = Voyager Wires
| image = voyager_wires.png
| titletext = Also, they're getting increasingly worried that someone will accidentally hit the 'retract' button, and that the end of the cable thrashing around as it winds up could devastate the Earth's surface.
}}

==Explanation==
{{incomplete|Created by a WIRE CUT BECAUSE OF BUDG- are you there houston? it's me v----ger, you'll never guess what I found! Please change this comment when editing this page. Do NOT delete this tag too soon.}}
This comic claims that the {{w|Voyager program|Voyager probe}}s communicate with NASA though ridiculously long copper wires. These wires would have to be continuously lengthened as the probes travel away from Earth. Supposedly, because of "high copper prices and budget constraints," they may not be able to afford to lengthen the wires much longer. If this occurred, they would have to either cut the wires or let them break, which would prevent any further communication with the probes. In reality [https://voyager.jpl.nasa.gov/mission/status/ they use radio waves], not long copper wires, so this will not actually happen.

If copper wires were dragged by the Voyager probes, assuming a 1 mm² thick cable, 550 tons of copper would be needed per hour and it would add 1 million Ohm per hour to the cable resistance. At [https://www.moneymetals.com/copper-prices $8,560/ton], this would cost $41 billion dollars/year, which would be nearly twice [https://www.planetary.org/space-policy/nasas-fy-2022-budget NASA's entire annual budget].

The resulting wire would slow down the probes by drag unless the wire itself was actively suspended (i.e. accelerated) continuously as it was fed. The wire could not be used for any other mechanical purpose such as a {{w|Space elevator|space elevator}} for this reason.

Since the Earth spins, the wires would also spool around the Earth, slowing the probes down even further. [https://what-if.xkcd.com/157/ Clearly, this is not a good idea.] This problem might be avoided if the wires reached earth at one of the poles. Or perhaps they could go to an airplane that flies around earth at exactly 15 degrees of longitude per hour, with periodic air-to-air refueling, so that it is always on the side of the earth facing the probe.

Because the Voyager probes aren't in the plane of the earth's orbit around the sun, the Earth would not, in its rotation around the sun, drag these copper wires through the sun. If it did, the wires would melt.

The title text references the phenomenon seen with self-retracting cables, such as are commonly found on vacuum cleaners, where the free end of the cable, where the plug is, oscillates more and more wildly as the cable approaches full retraction, leading to the danger of a painful rap on the hand if it is not withdrawn in time. A planet-sized impact of this kind could cause severe damage.

A few days before this comic was released, [https://voyager.jpl.nasa.gov/news/details.php?article_id=124 NASA had reported] receiving corrupted data from the Voyager 1 probe. The fact that they are receiving any data at all means that the attitude control system must be working (or else the antenna would not point at Earth), but they continue to investigate how that data could be corrupted after that point.

;Spoiler alert
The consequence of a cable between a craft in space and a planetary location being suddenly retracted was recently imagined in the first episode of the Apple TV+ series ''{{w|Foundation (TV series)|Foundation}}'', wherein a {{w|space elevator}} tether was severed. [https://www.youtube.com/watch?v=huRmvG3zRpg It didn't end well for anyone other than the terrorists] who won the freedom of thousands of inhabited worlds which had formerly suffered under the jackbooted oppression of {{w|Trantor}}'s fascist galactic Empire regime.

Another illustration in fiction of a severed space elevator is in Red Mars, part of the {{w|Mars Trilogy}} by Kim Stanley Robinson.

==Transcript==
:[In the bottom right corner is a space probe, with large satellite dish and long antenna. Behind it runs a long wire, that makes three loops before it is connected to North America on the Earth in the top left corner. To the left of the Earth there is a second wire, which goes off-panel to the left.]

:[Caption below the panel:]
:Sad news: Due to high copper prices and budget constraints, NASA may finally have to cut the wires that they've been spooling out to communicate with Voyager 1 and 2.

{{comic discussion}}

[[Category:Space probes]]

2586: Greek Letters

2022-07-06T06:51:39Z

Rsge: APA colon capitalisation convention - because it looks better to me

{{comic
| number = 2586
| date = February 25, 2022
| title = Greek Letters
| image = greek_letters.png
| titletext = If you ever see someone using a capital xi in an equation, just observe them quietly to learn as much as you can before they return to their home planet.
}}

==Explanation==
{{incomplete|Created by '''''O R B S''''' PRO®- Missing explanations for some letters. The text for each letter should be in the explanation with an attempt at explaining it. This has not been included and many of the letters have no explanation of the given text, only for what they actually are used for. Do NOT delete this tag too soon.}}
Mathematics uses lots of Greek letters, typically using {{w|Greek_letters_used_in_mathematics,_science,_and_engineering|the same letter consistently}} to represent a particular constant or type of variable. This comic gives a (non-)explanation of what they typically mean, see [[#Greek letters|below]].

In the title text the joke about capital Xi from the main comic is continued. In the main comic those using Ξ (capital xi) greets us as Earth mathematicians, indicating they are not from Earth, but have come here to learn what we know of math. In the title text the idea that any one using Ξ must be aliens is made clear. So if you ever meet someone using this letter while doing math, then learn as much as you can by quietly observing them, before they return to their home planet. Either learn from their possible advanced math (that allowed them to construct a way to get from one star system to another), or learn about them as the aliens species they represent.

Previously [[Randall]] made a similar comic, [[2520: Symbols]], about math symbols.

===Greek letters===

* '''π (lowercase pi): This math is either very simple or impossible.''' — Typically used to refer to the constant ratio between a circle’s circumference and its diameter (approximately 3.14). In a common school curriculum, this constant first shows up in introductory geometry classes, which would be considered "simple" by advanced mathematicians. But often, pi can show up seemingly randomly in advanced equations that have nothing to do with a circle at first glance, such as in infinite series. And because pi is transcendental, it can sometimes be difficult to work with pi in those situations. The comic may also be a reference to the impossibility of squaring the circle.
* An alternate explanation is that the comic refers to how the symbol can sometimes be used as a variable where the 'p' sound might make sense, such as in the prime-counting function where it stands for "prime" or the Buckingham π theorem where it stands for "parameter." These uses can be confusing to students who have only ever seen a lowercase pi used for the circle constant. This has pushed college courses to use it less and less frequently for anything other than the circle constant so that now you are only likely to see π as something else in higher math. (More confusing still is the variant lowercase pi, so-called omega pi {{w|Pi_(letter)#Variant_pi|ϖ}} sometimes used for angular frequency instead of the more common (and very similar-looking) lowercase omega ω. In astronomy, ϖ is traditionally used to denote the {{w|Longitude of the periapsis|longitude of perihelion}}.)

* '''Δ (capital delta): Something has changed.''' — Typically prefixes a variable to refer to a macroscopic change in or finite difference of that variable. For instance, Δ'''v''' may be the finite change in velocity '''v''' over some finite time span, while Δ[''f''](''x'') represents the forward difference of ''f'' at ''x'', defined as Δ[''f''](''x'') = ''f''(''x''+1) - ''f''(''x'').

* '''δ (lowercase delta): Something has changed and it's a mathematician's fault.''' — Used in calculus. In many areas of math, systems are studied by introducing small changes (perturbations) in input variables and observing how the system changes. The perturbations introduced are often written down as ''x'' → ''x'' + ''δx'' for some variable ''x'' being perturbed, where ''δx'' is the change being introduced. These are often applied in physics (perturbation theory, the principle of least action, Noether's theorem,…). Since this change was purposefully introduced by the mathematician instead of occurring naturally, it is, therefore, their fault.

* '''θ (lowercase theta): Circles!''' — Used in trigonometry. Typically used to refer to an angle, and is notably used in the polar coordinate system. The text refers to its close relationship with circles, on which the polar coordinate system is based. In European handwriting, the variant form ϑ is commonly used with the same meaning.

* '''ϕ (lowercase phi): ''O R B S''''' — Typically used to refer to another angle other than one referred to by theta. It's used in spherical coordinates, and the text refers to how spheres, or orbs, are important in spherical coordinates. Lowercase phi has two forms in modern typography which are confused by this website's default font. In the comic, it has a complete circle with a vertical line passing through it, which is what Knuth called "phi." The alternate form, φ, is what Knuth called "variant phi" and can be written in a single stroke. Most fonts reverse the way these symbols are rendered. There is no difference in meaning between the symbols. Additionally, "O R B S" is written with spaces between each letter, possibly a reference to the linguistic phenomena of surreal memes and their tendency to add spaces between letters of "surreal-sounding" words like "orbs".

* '''ϵ (lowercase epsilon): Not important, don't worry about it.''' — Typically used to refer to a very small quantity. ϵ may be an error term in a statistical model (which is usually small if the model is useful), a remainder term in an approximation (same), or an arbitrarily small (positive) quantity in analysis. Although a total cumulative change of "ϵ" is negligible, in analysis, ϵ is most often applied in a context of an infinitesimal change occurring with infinite frequency. The study of ratios of quantities that approach zero gives rise to infinitesimal calculus. This Greek lowercase letter has two common modern variants, ϵ and ε. ϵ is called the "{{w|Epsilon#Unicode|lunate epsilon}}" and may be more common in the U.S. A stylized version (∈) is used as the mathematical symbol for "is an element of." ε is what Knuth called the "variant epsilon" and is never used for the "element of" symbol but otherwise has identical meaning. Because epsilon represents an arbitrarily small (positive) quantity, there's no reason for anyone to worry about it from a practical standpoint.

* '''υ,ν (lowercase upsilon and nu): Is that a v or a u? Or...oh no, it's one of ''those''.''' — Common in college-level physics and engineering equations. ν commonly represents wavenumber in physics as well as a wide variety of other variables, often with names starting in N (e.g. neutron) or V (e.g. viscosity). Lowercase upsilon is rarely used, probably to avoid confusion. The symbols look remarkably similar to Latin u and v, to the point that they are nearly indistinguishable in some fonts; Randall has complained about this before in [[2351: Standard Model Changes]].

* '''μ (lowercase mu): This math is cool but it's not about anything that you will ever see or touch, so whatever.''' — Used broadly in the abstract mathematical fields of category theory and measure theory. Also used in statistics for the mean (average). Physicists use Latin letters for the indices of the 3-vectors of classical physics and Greek indices, including μ, for the 4-vectors of special relativity. This leads to μ being ubiquitous in a field that is very far from everyday experience (where speeds approach the speed of light). It is also employed in statistics for the population mean, which is a quantity that the statistician never actually knows and frequently wants to estimate. Equations requiring a μ are thus impossible to apply directly. However, μ is used in physics for the coefficient of friction in the Coulomb model, typically used to approximate resistive forces between dry solids of different materials sliding past each other. A very common use of μ in science and engineering is as the symbol of the SI prefix ''micro-'' for a millionth. Unicode has officially added a point for μ as the "micro sign," distinct from its usual codepoint as the lowercase Greek letter mu.

* '''Σ (capital sigma): Thank you for purchasing ''Addition Pro''®!''' — Typically used as a symbol for the sum of a series of numbers. The comic is making fun of summation, pointing out that it's essentially a complicated, "pro" version of simple addition. The capital sigma is often used as the icon for the all-important "sum" button in spreadsheet software. However, the sigma operator is often necessary for explicitly defining infinite sums, avoiding ambiguous notation like an ellipsis (...).

* '''Π (capital pi): ...and the ''Multiplication''® expansion pack!''' — Typically used as a symbol for the product of a sequence of numbers. The joke is the same as for summation. Here, it is advertised as an "expansion pack," a term used for a piece of software that cannot stand alone but adds features to some existing software. Any paid spreadsheet or database program should already have the ability to perform multiplication. The ® symbol indicates that ''Multiplication'' is a registered trademark somewhere, which is unlikely, as the term is not unique. However, common words are registered as parts of longer trademarks rather often.

* '''ζ (lowercase zeta): This math will only lead to more math.''' — Frequently used for the {{w|Riemann zeta function}} in analytic number theory, a function of complex numbers which is challenging even to define and which is the focus of a famously unsolved problem in highly advanced mathematics. Zeta is used much less often in other contexts, such as the ζ-potential in colloidal chemistry, and even there it is likely to just lead to more math.

* '''β (lowercase beta): There are just too many coefficients.''' — This could be a reference to the typical usage of beta to represent coefficients of independent variables in the {{w|Ordinary_least_squares#Linear_model|ordinary least squares regression model}}. Regression can potentially have a large number of independent variables, hence potentially many different betas (differentiated by a subscript, or compacted into matrix notation) would be used, while there is only ever a single zeroth-order coefficient α in these models. Alternatively, the comic might suggest whatever source this equation is from has run out of Latin letters to use as symbols, and is now going through the Greek letters.

* '''α (lowercase alpha): Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.''' — As the first Greek letter, α is used for a tremendous variety of purposes in math. For example, it is used to represent the probability of a Type-I error (false positive) occurring in a hypothesis test. It could also possibly refer to the {{w|fine-structure constant}} which shows up in high energy physics, atomic physics, quantum electrodynamics, and at least [[1047|one other xkcd comic]]. Alpha could also refer to {{w|angular acceleration}}, and a rapidly-rotating system is capable of killing people in a number of [[123|interesting ways]]. Another dangerous meaning for α comes from ionizing α-radiation: While it can be easily blocked by even a sheet of paper, it has been {{W|Alexander Litvinenko#Poisoning and death|used for assassinations}} through ingestion.

* '''Ω (capital omega): Oooh, ''some'' mathematician thinks their function is cool and important.''' — The last letter of the Greek alphabet and thus often seen as momentous (the end, the final word, death). The capital letter has been used as the symbol for a {{w|Omega_function|variety of mathematical functions}}, the {{w|first uncountable ordinal}}, and {{w|Absolute Infinity}}. It is commonly used in physics and electrical engineering as the symbol for {{w|ohms}}, a unit for electrical resistance. Capital omega has produced a fascination in common culture, perhaps due to God reportedly describing himself as "the alpha and the omega" in the Book of Revelation or due to its highly distinctive shape. It is often used to represent something of grave or transcendent significance. So using it to name your function (instead of a conventional symbol like ''f'' or ''g'') may mean you think the function is particularly important.

* '''ω (lowercase omega): A lot of work went into these equations and you are going to die here among them.''' — Used for the {{w|Transfinite_number|least transfinite ordinal number}}, the order type of the natural numbers under '<'. The line about dying here among the transfinite equations may be in reference to the "eternity" of the infinite set it represents. It is also used in physics and electrical engineering for angular frequency, equal to 2π times the frequency, and thus it is ubiquitous in equations dealing with all sorts of wave phenomena. '''ω''' is also used for the angular velocity of a rotating system, defined by '''v''' = '''r'''×'''ω'''.

* '''σ (lowercase sigma): Some poor soul is trying to apply this math to real life and it's not working.''' — In statistics, σ commonly refers to the population standard deviation of a distribution. Many simplified statistical equations substitute the population standard deviation σ for the sample standard deviation s for simplicity, even when this is not justifiable. A common example is using the normal distribution to model the mean of several identically normally distributed variables instead of the T distribution. The variant ς is used at the end of Greek words (called the "final sigma") but is rarely used in math or science.

* '''ξ (lowercase xi): Either this is terrifying mathematics or there was a hair on the scanned page.''' — Randall comments that this looks like a strand of curly hair. Xi is used in the {{w|Riemann Xi function}} and sometimes as a variable or function symbol in higher math. It is famously difficult to write in a way that is consistent and clearly distinct from other symbols.

* '''γ (lowercase gamma): ''Zoom'' pew pew pew [space noises] ''zoooom!''''' — Lowercase gamma is used for the {{w|Lorentz factor}}, an important variable in special relativity calculations. Its use implies that you are dealing with speeds approaching the speed of light and therefore with spaceships or other moving objects not confined to Earth. γ-rays are also the highest energy photons, so a space opera might have ships flying near the speed of light firing gamma-ray weapons that go PEW PEW. γ is also used as the symbol for the Euler-Mascheroni constant and occasionally as a variable or function name.

* '''ρ (lowercase rho): Unfortunately, the test vehicle suffered an unexpected wing separation event.''' — Used in statistics to measure the association between variables. Lowercase rho often represents volumetric mass density, such as the density of air that a wing might be traveling through. The density of a fluid is directly proportional to the Reynold's number, which dictates the sort of physics used to model motion through the fluid. Flying a plane in conditions with a Reynold's number well outside of what it was designed for could have catastrophic consequences. A variant symbol ϱ with the same meaning is common in European handwriting.

* '''Ξ (capital xi): Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.''' — Probably the least used Greek letter in math and physics despite being easy to write and recognize. According to the comic, anyone using this letter is likely a being from another planet. It does see very occasional use, such as in the Riemann xi function or as the symbol for a class of heavy baryons in particle physics. It resembles but is not to be confused with a "hamburger button" or a triple equals sign ≡. Coincidentally, it also resembles the simplified Hanzi (Chinese) character for the [https://en.wikibooks.org/wiki/Chinese_(Mandarin)/Numbers number 3]. Randall thinks it most closely resembles alien writing.

* '''ψ (lowercase psi): You have entered the domain of King Triton, ruler of the waves.''' — Both capital and lowercase psi are shaped like tridents. In classical mythology, {{w|Triton}} is one of the gods of the sea, alongside his father Poseidon, and tridents are commonly associated with sea gods. In quantum mechanics, either psi is used to represent the wave function of a particle, leading to a pun. (Psi is also used in mathematics to represent the sum of the inverse of the Fibonacci numbers, the division polynomials, the supergolden ratio, and other purposes.)

==Transcript==
:[A list with 21 explanations of different Greek letters. To the left, the letter (in one case two letters) are shown, and then the explanation is written to the right in one or two lines (and in one case on three lines). Above these explanations, there is a header in a slightly larger font:]
:<big>What Greek letters mean in equations</big>
:π This math is either very simple or impossible.
:Δ Something has changed.
:δ Something has changed and it's a mathematician's fault.
:θ Circles!
:Φ '''''O R B S'''''
:ϵ Not important, don't worry about it.
:υ,ν Is that a v or a u? Or...oh no, it's one of ''those''.
:μ This math is cool but it's not about anything that you will ever see or touch, so whatever.
:Σ Thank you for purchasing ''Addition Pro''®!
:Π ...and the ''Multiplication''® expansion pack!
:ζ This math will only lead to more math.
:β There are just too many coefficients.
:α Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.
:Ω Oooh, ''some'' mathematician thinks their function is cool and important.
:ω A lot of work went into these equations and you are going to die here among them.
:σ Some poor soul is trying to apply this math to real life and it's not working.
:ξ Either this is terrifying mathematics or there was a hair on the scanned page.
:γ ''Zoom'' pew pew pew [space noises] ''zoooom!''
:ρ Unfortunately, the test vehicle suffered an unexpected wing separation event.
:Ξ Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.
:ψ You have entered the domain of King Triton, ruler of the waves.

{{comic discussion}}

[[Category:Math]]
[[Category:Aliens]]

2586: Greek Letters

2022-07-06T06:45:14Z

Rsge: "Perform program" sounds strange

{{comic
| number = 2586
| date = February 25, 2022
| title = Greek Letters
| image = greek_letters.png
| titletext = If you ever see someone using a capital xi in an equation, just observe them quietly to learn as much as you can before they return to their home planet.
}}

==Explanation==
{{incomplete|Created by '''''O R B S''''' PRO®- Missing explanations for some letters. The text for each letter should be in the explanation with an attempt at explaining it. This has not been included and many of the letters have no explanation of the given text, only for what they actually are used for. Do NOT delete this tag too soon.}}
Mathematics uses lots of Greek letters, typically using {{w|Greek_letters_used_in_mathematics,_science,_and_engineering|the same letter consistently}} to represent a particular constant or type of variable. This comic gives a (non-)explanation of what they typically mean, see [[#Greek letters|below]].

In the title text the joke about capital Xi from the main comic is continued. In the main comic those using Ξ (capital xi) greets us as Earth mathematicians, indicating they are not from Earth, but have come here to learn what we know of math. In the title text the idea that any one using Ξ must be aliens is made clear. So if you ever meet someone using this letter while doing math, then learn as much as you can by quietly observing them, before they return to their home planet. Either learn from their possible advanced math (that allowed them to construct a way to get from one star system to another), or learn about them as the aliens species they represent.

Previously [[Randall]] made a similar comic, [[2520: Symbols]], about math symbols.

===Greek letters===

* '''π (lowercase pi): This math is either very simple or impossible.''' — Typically used to refer to the constant ratio between a circle’s circumference and its diameter (approximately 3.14). In a common school curriculum, this constant first shows up in introductory geometry classes, which would be considered "simple" by advanced mathematicians. But often, pi can show up seemingly randomly in advanced equations that have nothing to do with a circle at first glance, such as in infinite series. And because pi is transcendental, it can sometimes be difficult to work with pi in those situations. The comic may also be a reference to the impossibility of squaring the circle.
* An alternate explanation is that the comic refers to how the symbol can sometimes be used as a variable where the 'p' sound might make sense, such as in the prime-counting function where it stands for "prime" or the Buckingham π theorem where it stands for "parameter." These uses can be confusing to students who have only ever seen a lowercase pi used for the circle constant. This has pushed college courses to use it less and less frequently for anything other than the circle constant so that now you are only likely to see π as something else in higher math. (More confusing still is the variant lowercase pi, so-called omega pi {{w|Pi_(letter)#Variant_pi|ϖ}} sometimes used for angular frequency instead of the more common (and very similar-looking) lowercase omega ω. In astronomy, ϖ is traditionally used to denote the {{w|Longitude of the periapsis|longitude of perihelion}}.)

* '''Δ (capital delta): Something has changed.''' — Typically prefixes a variable to refer to a macroscopic change in or finite difference of that variable. For instance, Δ'''v''' may be the finite change in velocity '''v''' over some finite time span, while Δ[''f''](''x'') represents the forward difference of ''f'' at ''x'', defined as Δ[''f''](''x'') = ''f''(''x''+1) - ''f''(''x'').

* '''δ (lowercase delta): Something has changed and it's a mathematician's fault.''' — Used in calculus. In many areas of math, systems are studied by introducing small changes (perturbations) in input variables and observing how the system changes. The perturbations introduced are often written down as ''x'' → ''x'' + ''δx'' for some variable ''x'' being perturbed, where ''δx'' is the change being introduced. These are often applied in physics (perturbation theory, the principle of least action, Noether's theorem,…). Since this change was purposefully introduced by the mathematician instead of occurring naturally, it is, therefore, their fault.

* '''θ (lowercase theta): Circles!''' — Used in trigonometry. Typically used to refer to an angle, and is notably used in the polar coordinate system. The text refers to its close relationship with circles, on which the polar coordinate system is based. In European handwriting, the variant form ϑ is commonly used with the same meaning.

* '''ϕ (lowercase phi): ''O R B S''''' — Typically used to refer to another angle other than one referred to by theta. It's used in spherical coordinates, and the text refers to how spheres, or orbs, are important in spherical coordinates. Lowercase phi has two forms in modern typography which are confused by this website's default font. In the comic, it has a complete circle with a vertical line passing through it, which is what Knuth called "phi." The alternate form, φ, is what Knuth called "variant phi" and can be written in a single stroke. Most fonts reverse the way these symbols are rendered. There is no difference in meaning between the symbols. Additionally, "O R B S" is written with spaces between each letter, possibly a reference to the linguistic phenomena of surreal memes and their tendency to add spaces between letters of "surreal-sounding" words like "orbs".

* '''ϵ (lowercase epsilon): Not important, don't worry about it.''' — Typically used to refer to a very small quantity. ϵ may be an error term in a statistical model (which is usually small if the model is useful), a remainder term in an approximation (same), or an arbitrarily small (positive) quantity in analysis. Although a total cumulative change of "ϵ" is negligible, in analysis, ϵ is most often applied in a context of an infinitesimal change occurring with infinite frequency. The study of ratios of quantities that approach zero gives rise to infinitesimal calculus. This Greek lowercase letter has two common modern variants, ϵ and ε. ϵ is called the "{{w|Epsilon#Unicode|lunate epsilon}}" and may be more common in the U.S. A stylized version (∈) is used as the mathematical symbol for "is an element of." ε is what Knuth called the "variant epsilon" and is never used for the "element of" symbol but otherwise has identical meaning. Because epsilon represents an arbitrarily small (positive) quantity, there's no reason for anyone to worry about it from a practical standpoint.

* '''υ,ν (lowercase upsilon and nu): Is that a v or a u? Or...oh no, it's one of ''those''.''' — Common in college-level physics and engineering equations. ν commonly represents wavenumber in physics as well as a wide variety of other variables, often with names starting in N (e.g. neutron) or V (e.g. viscosity). Lowercase upsilon is rarely used, probably to avoid confusion. The symbols look remarkably similar to Latin u and v, to the point that they are nearly indistinguishable in some fonts; Randall has complained about this before in [[2351: Standard Model Changes]].

* '''μ (lowercase mu): This math is cool but it's not about anything that you will ever see or touch, so whatever.''' — Used broadly in the abstract mathematical fields of category theory and measure theory. Also used in statistics for the mean (average). Physicists use Latin letters for the indices of the 3-vectors of classical physics and Greek indices, including μ, for the 4-vectors of special relativity. This leads to μ being ubiquitous in a field that is very far from everyday experience (where speeds approach the speed of light). It is also employed in statistics for the population mean, which is a quantity that the statistician never actually knows and frequently wants to estimate. Equations requiring a μ are thus impossible to apply directly. However, μ is used in physics for the coefficient of friction in the Coulomb model, typically used to approximate resistive forces between dry solids of different materials sliding past each other. A very common use of μ in science and engineering is as the symbol of the SI prefix ''micro-'' for a millionth. Unicode has officially added a point for μ as the "micro sign," distinct from its usual codepoint as the lowercase Greek letter mu.

* '''Σ (capital sigma): Thank you for purchasing ''Addition Pro''®!''' — Typically used as a symbol for the sum of a series of numbers. The comic is making fun of summation, pointing out that it's essentially a complicated, "pro" version of simple addition. The capital sigma is often used as the icon for the all-important "sum" button in spreadsheet software. However, the sigma operator is often necessary for explicitly defining infinite sums, avoiding ambiguous notation like an ellipsis (...).

* '''Π (capital pi): ...and the ''Multiplication''® expansion pack!''' — Typically used as a symbol for the product of a sequence of numbers. The joke is the same as for summation. Here, it is advertised as an "expansion pack," a term used for a piece of software that cannot stand alone but adds features to some existing software. Any paid spreadsheet or database program should already have the ability to perform multiplication. The ® symbol indicates that ''Multiplication'' is a registered trademark somewhere, which is unlikely, as the term is not unique. However, common words are registered as parts of longer trademarks rather often.

* '''ζ (lowercase zeta): This math will only lead to more math.''' — Frequently used for the {{w|Riemann zeta function}} in analytic number theory, a function of complex numbers which is challenging even to define and which is the focus of a famously unsolved problem in highly advanced mathematics. Zeta is used much less often in other contexts, such as the ζ-potential in colloidal chemistry, and even there it is likely to just lead to more math.

* '''β (lowercase beta): There are just too many coefficients.''' — This could be a reference to the typical usage of beta to represent coefficients of independent variables in the {{w|Ordinary_least_squares#Linear_model|ordinary least squares regression model}}. Regression can potentially have a large number of independent variables, hence potentially many different betas (differentiated by a subscript, or compacted into matrix notation) would be used, while there is only ever a single zeroth-order coefficient α in these models. Alternatively, the comic might suggest whatever source this equation is from has run out of Latin letters to use as symbols, and is now going through the Greek letters.

* '''α (lowercase alpha): Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.''' — As the first Greek letter, α is used for a tremendous variety of purposes in math. For example, it is used to represent the probability of a Type-I error (false positive) occurring in a hypothesis test. It could also possibly refer to the {{w|fine-structure constant}} which shows up in high energy physics, atomic physics, quantum electrodynamics, and at least [[1047|one other xkcd comic]]. Alpha could also refer to {{w|angular acceleration}}, and a rapidly-rotating system is capable of killing people in a number of [[123|interesting ways]]. Another dangerous meaning for α comes from ionizing α-radiation: while it can be easily blocked by even a sheet of paper, it has been {{W|Alexander Litvinenko#Poisoning and death|used for assassinations}} through ingestion.

* '''Ω (capital omega): Oooh, ''some'' mathematician thinks their function is cool and important.''' — The last letter of the Greek alphabet and thus often seen as momentous (the end, the final word, death). The capital letter has been used as the symbol for a {{w|Omega_function|variety of mathematical functions}}, the {{w|first uncountable ordinal}}, and {{w|Absolute Infinity}}. It is commonly used in physics and electrical engineering as the symbol for {{w|ohms}}, a unit for electrical resistance. Capital omega has produced a fascination in common culture, perhaps due to God reportedly describing himself as "the alpha and the omega" in the Book of Revelation or due to its highly distinctive shape. It is often used to represent something of grave or transcendent significance. So using it to name your function (instead of a conventional symbol like ''f'' or ''g'') may mean you think the function is particularly important.

* '''ω (lowercase omega): A lot of work went into these equations and you are going to die here among them.''' — Used for the {{w|Transfinite_number|least transfinite ordinal number}}, the order type of the natural numbers under '<'. The line about dying here among the transfinite equations may be in reference to the "eternity" of the infinite set it represents. It is also used in physics and electrical engineering for angular frequency, equal to 2π times the frequency, and thus it is ubiquitous in equations dealing with all sorts of wave phenomena. '''ω''' is also used for the angular velocity of a rotating system, defined by '''v''' = '''r'''×'''ω'''.

* '''σ (lowercase sigma): Some poor soul is trying to apply this math to real life and it's not working.''' — In statistics, σ commonly refers to the population standard deviation of a distribution. Many simplified statistical equations substitute the population standard deviation σ for the sample standard deviation s for simplicity, even when this is not justifiable. A common example is using the normal distribution to model the mean of several identically normally distributed variables instead of the T distribution. The variant ς is used at the end of Greek words (called the "final sigma") but is rarely used in math or science.

* '''ξ (lowercase xi): Either this is terrifying mathematics or there was a hair on the scanned page.''' — Randall comments that this looks like a strand of curly hair. Xi is used in the {{w|Riemann Xi function}} and sometimes as a variable or function symbol in higher math. It is famously difficult to write in a way that is consistent and clearly distinct from other symbols.

* '''γ (lowercase gamma): ''Zoom'' pew pew pew [space noises] ''zoooom!''''' — Lowercase gamma is used for the {{w|Lorentz factor}}, an important variable in special relativity calculations. Its use implies that you are dealing with speeds approaching the speed of light and therefore with spaceships or other moving objects not confined to Earth. γ-rays are also the highest energy photons, so a space opera might have ships flying near the speed of light firing gamma-ray weapons that go PEW PEW. γ is also used as the symbol for the Euler-Mascheroni constant and occasionally as a variable or function name.

* '''ρ (lowercase rho): Unfortunately, the test vehicle suffered an unexpected wing separation event.''' — Used in statistics to measure the association between variables. Lowercase rho often represents volumetric mass density, such as the density of air that a wing might be traveling through. The density of a fluid is directly proportional to the Reynold's number, which dictates the sort of physics used to model motion through the fluid. Flying a plane in conditions with a Reynold's number well outside of what it was designed for could have catastrophic consequences. A variant symbol ϱ with the same meaning is common in European handwriting.

* '''Ξ (capital xi): Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.''' — Probably the least used Greek letter in math and physics despite being easy to write and recognize. According to the comic, anyone using this letter is likely a being from another planet. It does see very occasional use, such as in the Riemann xi function or as the symbol for a class of heavy baryons in particle physics. It resembles but is not to be confused with a "hamburger button" or a triple equals sign ≡. Coincidentally, it also resembles the simplified Hanzi (Chinese) character for the [https://en.wikibooks.org/wiki/Chinese_(Mandarin)/Numbers number 3]. Randall thinks it most closely resembles alien writing.

* '''ψ (lowercase psi): You have entered the domain of King Triton, ruler of the waves.''' — Both capital and lowercase psi are shaped like tridents. In classical mythology, {{w|Triton}} is one of the gods of the sea, alongside his father Poseidon, and tridents are commonly associated with sea gods. In quantum mechanics, either psi is used to represent the wave function of a particle, leading to a pun. (Psi is also used in mathematics to represent the sum of the inverse of the Fibonacci numbers, the division polynomials, the supergolden ratio, and other purposes.)

==Transcript==
:[A list with 21 explanations of different Greek letters. To the left, the letter (in one case two letters) are shown, and then the explanation is written to the right in one or two lines (and in one case on three lines). Above these explanations, there is a header in a slightly larger font:]
:<big>What Greek letters mean in equations</big>
:π This math is either very simple or impossible.
:Δ Something has changed.
:δ Something has changed and it's a mathematician's fault.
:θ Circles!
:Φ '''''O R B S'''''
:ϵ Not important, don't worry about it.
:υ,ν Is that a v or a u? Or...oh no, it's one of ''those''.
:μ This math is cool but it's not about anything that you will ever see or touch, so whatever.
:Σ Thank you for purchasing ''Addition Pro''®!
:Π ...and the ''Multiplication''® expansion pack!
:ζ This math will only lead to more math.
:β There are just too many coefficients.
:α Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.
:Ω Oooh, ''some'' mathematician thinks their function is cool and important.
:ω A lot of work went into these equations and you are going to die here among them.
:σ Some poor soul is trying to apply this math to real life and it's not working.
:ξ Either this is terrifying mathematics or there was a hair on the scanned page.
:γ ''Zoom'' pew pew pew [space noises] ''zoooom!''
:ρ Unfortunately, the test vehicle suffered an unexpected wing separation event.
:Ξ Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.
:ψ You have entered the domain of King Triton, ruler of the waves.

{{comic discussion}}

[[Category:Math]]
[[Category:Aliens]]

2586: Greek Letters

2022-07-06T06:39:25Z

Rsge: Represent headline w/ spaces like in comic

{{comic
| number = 2586
| date = February 25, 2022
| title = Greek Letters
| image = greek_letters.png
| titletext = If you ever see someone using a capital xi in an equation, just observe them quietly to learn as much as you can before they return to their home planet.
}}

==Explanation==
{{incomplete|Created by '''''O R B S''''' PRO®- Missing explanations for some letters. The text for each letter should be in the explanation with an attempt at explaining it. This has not been included and many of the letters have no explanation of the given text, only for what they actually are used for. Do NOT delete this tag too soon.}}
Mathematics uses lots of Greek letters, typically using {{w|Greek_letters_used_in_mathematics,_science,_and_engineering|the same letter consistently}} to represent a particular constant or type of variable. This comic gives a (non-)explanation of what they typically mean, see [[#Greek letters|below]].

In the title text the joke about capital Xi from the main comic is continued. In the main comic those using Ξ (capital xi) greets us as Earth mathematicians, indicating they are not from Earth, but have come here to learn what we know of math. In the title text the idea that any one using Ξ must be aliens is made clear. So if you ever meet someone using this letter while doing math, then learn as much as you can by quietly observing them, before they return to their home planet. Either learn from their possible advanced math (that allowed them to construct a way to get from one star system to another), or learn about them as the aliens species they represent.

Previously [[Randall]] made a similar comic, [[2520: Symbols]], about math symbols.

===Greek letters===

* '''π (lowercase pi): This math is either very simple or impossible.''' — Typically used to refer to the constant ratio between a circle’s circumference and its diameter (approximately 3.14). In a common school curriculum, this constant first shows up in introductory geometry classes, which would be considered "simple" by advanced mathematicians. But often, pi can show up seemingly randomly in advanced equations that have nothing to do with a circle at first glance, such as in infinite series. And because pi is transcendental, it can sometimes be difficult to work with pi in those situations. The comic may also be a reference to the impossibility of squaring the circle.
* An alternate explanation is that the comic refers to how the symbol can sometimes be used as a variable where the 'p' sound might make sense, such as in the prime-counting function where it stands for "prime" or the Buckingham π theorem where it stands for "parameter." These uses can be confusing to students who have only ever seen a lowercase pi used for the circle constant. This has pushed college courses to use it less and less frequently for anything other than the circle constant so that now you are only likely to see π as something else in higher math. (More confusing still is the variant lowercase pi, so-called omega pi {{w|Pi_(letter)#Variant_pi|ϖ}} sometimes used for angular frequency instead of the more common (and very similar-looking) lowercase omega ω. In astronomy, ϖ is traditionally used to denote the {{w|Longitude of the periapsis|longitude of perihelion}}.)

* '''Δ (capital delta): Something has changed.''' — Typically prefixes a variable to refer to a macroscopic change in or finite difference of that variable. For instance, Δ'''v''' may be the finite change in velocity '''v''' over some finite time span, while Δ[''f''](''x'') represents the forward difference of ''f'' at ''x'', defined as Δ[''f''](''x'') = ''f''(''x''+1) - ''f''(''x'').

* '''δ (lowercase delta): Something has changed and it's a mathematician's fault.''' — Used in calculus. In many areas of math, systems are studied by introducing small changes (perturbations) in input variables and observing how the system changes. The perturbations introduced are often written down as ''x'' → ''x'' + ''δx'' for some variable ''x'' being perturbed, where ''δx'' is the change being introduced. These are often applied in physics (perturbation theory, the principle of least action, Noether's theorem,…). Since this change was purposefully introduced by the mathematician instead of occurring naturally, it is, therefore, their fault.

* '''θ (lowercase theta): Circles!''' — Used in trigonometry. Typically used to refer to an angle, and is notably used in the polar coordinate system. The text refers to its close relationship with circles, on which the polar coordinate system is based. In European handwriting, the variant form ϑ is commonly used with the same meaning.

* '''ϕ (lowercase phi): ''O R B S''''' — Typically used to refer to another angle other than one referred to by theta. It's used in spherical coordinates, and the text refers to how spheres, or orbs, are important in spherical coordinates. Lowercase phi has two forms in modern typography which are confused by this website's default font. In the comic, it has a complete circle with a vertical line passing through it, which is what Knuth called "phi." The alternate form, φ, is what Knuth called "variant phi" and can be written in a single stroke. Most fonts reverse the way these symbols are rendered. There is no difference in meaning between the symbols. Additionally, "O R B S" is written with spaces between each letter, possibly a reference to the linguistic phenomena of surreal memes and their tendency to add spaces between letters of "surreal-sounding" words like "orbs".

* '''ϵ (lowercase epsilon): Not important, don't worry about it.''' — Typically used to refer to a very small quantity. ϵ may be an error term in a statistical model (which is usually small if the model is useful), a remainder term in an approximation (same), or an arbitrarily small (positive) quantity in analysis. Although a total cumulative change of "ϵ" is negligible, in analysis, ϵ is most often applied in a context of an infinitesimal change occurring with infinite frequency. The study of ratios of quantities that approach zero gives rise to infinitesimal calculus. This Greek lowercase letter has two common modern variants, ϵ and ε. ϵ is called the "{{w|Epsilon#Unicode|lunate epsilon}}" and may be more common in the U.S. A stylized version (∈) is used as the mathematical symbol for "is an element of." ε is what Knuth called the "variant epsilon" and is never used for the "element of" symbol but otherwise has identical meaning. Because epsilon represents an arbitrarily small (positive) quantity, there's no reason for anyone to worry about it from a practical standpoint.

* '''υ,ν (lowercase upsilon and nu): Is that a v or a u? Or...oh no, it's one of ''those''.''' — Common in college-level physics and engineering equations. ν commonly represents wavenumber in physics as well as a wide variety of other variables, often with names starting in N (e.g. neutron) or V (e.g. viscosity). Lowercase upsilon is rarely used, probably to avoid confusion. The symbols look remarkably similar to Latin u and v, to the point that they are nearly indistinguishable in some fonts; Randall has complained about this before in [[2351: Standard Model Changes]].

* '''μ (lowercase mu): This math is cool but it's not about anything that you will ever see or touch, so whatever.''' — Used broadly in the abstract mathematical fields of category theory and measure theory. Also used in statistics for the mean (average). Physicists use Latin letters for the indices of the 3-vectors of classical physics and Greek indices, including μ, for the 4-vectors of special relativity. This leads to μ being ubiquitous in a field that is very far from everyday experience (where speeds approach the speed of light). It is also employed in statistics for the population mean, which is a quantity that the statistician never actually knows and frequently wants to estimate. Equations requiring a μ are thus impossible to apply directly. However, μ is used in physics for the coefficient of friction in the Coulomb model, typically used to approximate resistive forces between dry solids of different materials sliding past each other. A very common use of μ in science and engineering is as the symbol of the SI prefix ''micro-'' for a millionth. Unicode has officially added a point for μ as the "micro sign," distinct from its usual codepoint as the lowercase Greek letter mu.

* '''Σ (capital sigma): Thank you for purchasing ''Addition Pro''®!''' — Typically used as a symbol for the sum of a series of numbers. The comic is making fun of summation, pointing out that it's essentially a complicated, "pro" version of simple addition. The capital sigma is often used as the icon for the all-important "sum" button in spreadsheet software. However, the sigma operator is often necessary for explicitly defining infinite sums, avoiding ambiguous notation like an ellipsis (...).

* '''Π (capital pi): ...and the ''Multiplication''® expansion pack!''' — Typically used as a symbol for the product of a sequence of numbers. The joke is the same as for summation. Here, it is advertised as an "expansion pack," a term used for a piece of software that cannot stand alone but adds features to some existing software. Any paid spreadsheet or database program should already have the ability to perform products. The ® symbol indicates that ''Multiplication'' is a registered trademark somewhere, which is unlikely, as the term is not unique. However, common words are registered as parts of longer trademarks rather often.

* '''ζ (lowercase zeta): This math will only lead to more math.''' — Frequently used for the {{w|Riemann zeta function}} in analytic number theory, a function of complex numbers which is challenging even to define and which is the focus of a famously unsolved problem in highly advanced mathematics. Zeta is used much less often in other contexts, such as the ζ-potential in colloidal chemistry, and even there it is likely to just lead to more math.

* '''β (lowercase beta): There are just too many coefficients.''' — This could be a reference to the typical usage of beta to represent coefficients of independent variables in the {{w|Ordinary_least_squares#Linear_model|ordinary least squares regression model}}. Regression can potentially have a large number of independent variables, hence potentially many different betas (differentiated by a subscript, or compacted into matrix notation) would be used, while there is only ever a single zeroth-order coefficient α in these models. Alternatively, the comic might suggest whatever source this equation is from has run out of Latin letters to use as symbols, and is now going through the Greek letters.

* '''α (lowercase alpha): Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.''' — As the first Greek letter, α is used for a tremendous variety of purposes in math. For example, it is used to represent the probability of a Type-I error (false positive) occurring in a hypothesis test. It could also possibly refer to the {{w|fine-structure constant}} which shows up in high energy physics, atomic physics, quantum electrodynamics, and at least [[1047|one other xkcd comic]]. Alpha could also refer to {{w|angular acceleration}}, and a rapidly-rotating system is capable of killing people in a number of [[123|interesting ways]]. Another dangerous meaning for α comes from ionizing α-radiation: while it can be easily blocked by even a sheet of paper, it has been {{W|Alexander Litvinenko#Poisoning and death|used for assassinations}} through ingestion.

* '''Ω (capital omega): Oooh, ''some'' mathematician thinks their function is cool and important.''' — The last letter of the Greek alphabet and thus often seen as momentous (the end, the final word, death). The capital letter has been used as the symbol for a {{w|Omega_function|variety of mathematical functions}}, the {{w|first uncountable ordinal}}, and {{w|Absolute Infinity}}. It is commonly used in physics and electrical engineering as the symbol for {{w|ohms}}, a unit for electrical resistance. Capital omega has produced a fascination in common culture, perhaps due to God reportedly describing himself as "the alpha and the omega" in the Book of Revelation or due to its highly distinctive shape. It is often used to represent something of grave or transcendent significance. So using it to name your function (instead of a conventional symbol like ''f'' or ''g'') may mean you think the function is particularly important.

* '''ω (lowercase omega): A lot of work went into these equations and you are going to die here among them.''' — Used for the {{w|Transfinite_number|least transfinite ordinal number}}, the order type of the natural numbers under '<'. The line about dying here among the transfinite equations may be in reference to the "eternity" of the infinite set it represents. It is also used in physics and electrical engineering for angular frequency, equal to 2π times the frequency, and thus it is ubiquitous in equations dealing with all sorts of wave phenomena. '''ω''' is also used for the angular velocity of a rotating system, defined by '''v''' = '''r'''×'''ω'''.

* '''σ (lowercase sigma): Some poor soul is trying to apply this math to real life and it's not working.''' — In statistics, σ commonly refers to the population standard deviation of a distribution. Many simplified statistical equations substitute the population standard deviation σ for the sample standard deviation s for simplicity, even when this is not justifiable. A common example is using the normal distribution to model the mean of several identically normally distributed variables instead of the T distribution. The variant ς is used at the end of Greek words (called the "final sigma") but is rarely used in math or science.

* '''ξ (lowercase xi): Either this is terrifying mathematics or there was a hair on the scanned page.''' — Randall comments that this looks like a strand of curly hair. Xi is used in the {{w|Riemann Xi function}} and sometimes as a variable or function symbol in higher math. It is famously difficult to write in a way that is consistent and clearly distinct from other symbols.

* '''γ (lowercase gamma): ''Zoom'' pew pew pew [space noises] ''zoooom!''''' — Lowercase gamma is used for the {{w|Lorentz factor}}, an important variable in special relativity calculations. Its use implies that you are dealing with speeds approaching the speed of light and therefore with spaceships or other moving objects not confined to Earth. γ-rays are also the highest energy photons, so a space opera might have ships flying near the speed of light firing gamma-ray weapons that go PEW PEW. γ is also used as the symbol for the Euler-Mascheroni constant and occasionally as a variable or function name.

* '''ρ (lowercase rho): Unfortunately, the test vehicle suffered an unexpected wing separation event.''' — Used in statistics to measure the association between variables. Lowercase rho often represents volumetric mass density, such as the density of air that a wing might be traveling through. The density of a fluid is directly proportional to the Reynold's number, which dictates the sort of physics used to model motion through the fluid. Flying a plane in conditions with a Reynold's number well outside of what it was designed for could have catastrophic consequences. A variant symbol ϱ with the same meaning is common in European handwriting.

* '''Ξ (capital xi): Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.''' — Probably the least used Greek letter in math and physics despite being easy to write and recognize. According to the comic, anyone using this letter is likely a being from another planet. It does see very occasional use, such as in the Riemann xi function or as the symbol for a class of heavy baryons in particle physics. It resembles but is not to be confused with a "hamburger button" or a triple equals sign ≡. Coincidentally, it also resembles the simplified Hanzi (Chinese) character for the [https://en.wikibooks.org/wiki/Chinese_(Mandarin)/Numbers number 3]. Randall thinks it most closely resembles alien writing.

* '''ψ (lowercase psi): You have entered the domain of King Triton, ruler of the waves.''' — Both capital and lowercase psi are shaped like tridents. In classical mythology, {{w|Triton}} is one of the gods of the sea, alongside his father Poseidon, and tridents are commonly associated with sea gods. In quantum mechanics, either psi is used to represent the wave function of a particle, leading to a pun. (Psi is also used in mathematics to represent the sum of the inverse of the Fibonacci numbers, the division polynomials, the supergolden ratio, and other purposes.)

==Transcript==
:[A list with 21 explanations of different Greek letters. To the left, the letter (in one case two letters) are shown, and then the explanation is written to the right in one or two lines (and in one case on three lines). Above these explanations, there is a header in a slightly larger font:]
:<big>What Greek letters mean in equations</big>
:π This math is either very simple or impossible.
:Δ Something has changed.
:δ Something has changed and it's a mathematician's fault.
:θ Circles!
:Φ '''''O R B S'''''
:ϵ Not important, don't worry about it.
:υ,ν Is that a v or a u? Or...oh no, it's one of ''those''.
:μ This math is cool but it's not about anything that you will ever see or touch, so whatever.
:Σ Thank you for purchasing ''Addition Pro''®!
:Π ...and the ''Multiplication''® expansion pack!
:ζ This math will only lead to more math.
:β There are just too many coefficients.
:α Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.
:Ω Oooh, ''some'' mathematician thinks their function is cool and important.
:ω A lot of work went into these equations and you are going to die here among them.
:σ Some poor soul is trying to apply this math to real life and it's not working.
:ξ Either this is terrifying mathematics or there was a hair on the scanned page.
:γ ''Zoom'' pew pew pew [space noises] ''zoooom!''
:ρ Unfortunately, the test vehicle suffered an unexpected wing separation event.
:Ξ Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.
:ψ You have entered the domain of King Triton, ruler of the waves.

{{comic discussion}}

[[Category:Math]]
[[Category:Aliens]]

2586: Greek Letters

2022-07-06T06:36:06Z

Rsge: Passive sounds better imho

{{comic
| number = 2586
| date = February 25, 2022
| title = Greek Letters
| image = greek_letters.png
| titletext = If you ever see someone using a capital xi in an equation, just observe them quietly to learn as much as you can before they return to their home planet.
}}

==Explanation==
{{incomplete|Created by '''''O R B S''''' PRO®- Missing explanations for some letters. The text for each letter should be in the explanation with an attempt at explaining it. This has not been included and many of the letters have no explanation of the given text, only for what they actually are used for. Do NOT delete this tag too soon.}}
Mathematics uses lots of Greek letters, typically using {{w|Greek_letters_used_in_mathematics,_science,_and_engineering|the same letter consistently}} to represent a particular constant or type of variable. This comic gives a (non-)explanation of what they typically mean, see [[#Greek letters|below]].

In the title text the joke about capital Xi from the main comic is continued. In the main comic those using Ξ (capital xi) greets us as Earth mathematicians, indicating they are not from Earth, but have come here to learn what we know of math. In the title text the idea that any one using Ξ must be aliens is made clear. So if you ever meet someone using this letter while doing math, then learn as much as you can by quietly observing them, before they return to their home planet. Either learn from their possible advanced math (that allowed them to construct a way to get from one star system to another), or learn about them as the aliens species they represent.

Previously [[Randall]] made a similar comic, [[2520: Symbols]], about math symbols.

===Greek letters===

* '''π (lowercase pi): This math is either very simple or impossible.''' — Typically used to refer to the constant ratio between a circle’s circumference and its diameter (approximately 3.14). In a common school curriculum, this constant first shows up in introductory geometry classes, which would be considered "simple" by advanced mathematicians. But often, pi can show up seemingly randomly in advanced equations that have nothing to do with a circle at first glance, such as in infinite series. And because pi is transcendental, it can sometimes be difficult to work with pi in those situations. The comic may also be a reference to the impossibility of squaring the circle.
* An alternate explanation is that the comic refers to how the symbol can sometimes be used as a variable where the 'p' sound might make sense, such as in the prime-counting function where it stands for "prime" or the Buckingham π theorem where it stands for "parameter." These uses can be confusing to students who have only ever seen a lowercase pi used for the circle constant. This has pushed college courses to use it less and less frequently for anything other than the circle constant so that now you are only likely to see π as something else in higher math. (More confusing still is the variant lowercase pi, so-called omega pi {{w|Pi_(letter)#Variant_pi|ϖ}} sometimes used for angular frequency instead of the more common (and very similar-looking) lowercase omega ω. In astronomy, ϖ is traditionally used to denote the {{w|Longitude of the periapsis|longitude of perihelion}}.)

* '''Δ (capital delta): Something has changed.''' — Typically prefixes a variable to refer to a macroscopic change in or finite difference of that variable. For instance, Δ'''v''' may be the finite change in velocity '''v''' over some finite time span, while Δ[''f''](''x'') represents the forward difference of ''f'' at ''x'', defined as Δ[''f''](''x'') = ''f''(''x''+1) - ''f''(''x'').

* '''δ (lowercase delta): Something has changed and it's a mathematician's fault.''' — Used in calculus. In many areas of math, systems are studied by introducing small changes (perturbations) in input variables and observing how the system changes. The perturbations introduced are often written down as ''x'' → ''x'' + ''δx'' for some variable ''x'' being perturbed, where ''δx'' is the change being introduced. These are often applied in physics (perturbation theory, the principle of least action, Noether's theorem,…). Since this change was purposefully introduced by the mathematician instead of occurring naturally, it is, therefore, their fault.

* '''θ (lowercase theta): Circles!''' — Used in trigonometry. Typically used to refer to an angle, and is notably used in the polar coordinate system. The text refers to its close relationship with circles, on which the polar coordinate system is based. In European handwriting, the variant form ϑ is commonly used with the same meaning.

* '''ϕ (lowercase phi): ''ORBS''''' — Typically used to refer to another angle other than one referred to by theta. It's used in spherical coordinates, and the text refers to how spheres, or orbs, are important in spherical coordinates. Lowercase phi has two forms in modern typography which are confused by this website's default font. In the comic, it has a complete circle with a vertical line passing through it, which is what Knuth called "phi." The alternate form, φ, is what Knuth called "variant phi" and can be written in a single stroke. Most fonts reverse the way these symbols are rendered. There is no difference in meaning between the symbols. Additionally, "O R B S" is written with spaces between each letter, possibly a reference to the linguistic phenomena of surreal memes and their tendency to add spaces between letters of "surreal-sounding" words like "orbs".

* '''ϵ (lowercase epsilon): Not important, don't worry about it.''' — Typically used to refer to a very small quantity. ϵ may be an error term in a statistical model (which is usually small if the model is useful), a remainder term in an approximation (same), or an arbitrarily small (positive) quantity in analysis. Although a total cumulative change of "ϵ" is negligible, in analysis, ϵ is most often applied in a context of an infinitesimal change occurring with infinite frequency. The study of ratios of quantities that approach zero gives rise to infinitesimal calculus. This Greek lowercase letter has two common modern variants, ϵ and ε. ϵ is called the "{{w|Epsilon#Unicode|lunate epsilon}}" and may be more common in the U.S. A stylized version (∈) is used as the mathematical symbol for "is an element of." ε is what Knuth called the "variant epsilon" and is never used for the "element of" symbol but otherwise has identical meaning. Because epsilon represents an arbitrarily small (positive) quantity, there's no reason for anyone to worry about it from a practical standpoint.

* '''υ,ν (lowercase upsilon and nu): Is that a v or a u? Or...oh no, it's one of ''those''.''' — Common in college-level physics and engineering equations. ν commonly represents wavenumber in physics as well as a wide variety of other variables, often with names starting in N (e.g. neutron) or V (e.g. viscosity). Lowercase upsilon is rarely used, probably to avoid confusion. The symbols look remarkably similar to Latin u and v, to the point that they are nearly indistinguishable in some fonts; Randall has complained about this before in [[2351: Standard Model Changes]].

* '''μ (lowercase mu): This math is cool but it's not about anything that you will ever see or touch, so whatever.''' — Used broadly in the abstract mathematical fields of category theory and measure theory. Also used in statistics for the mean (average). Physicists use Latin letters for the indices of the 3-vectors of classical physics and Greek indices, including μ, for the 4-vectors of special relativity. This leads to μ being ubiquitous in a field that is very far from everyday experience (where speeds approach the speed of light). It is also employed in statistics for the population mean, which is a quantity that the statistician never actually knows and frequently wants to estimate. Equations requiring a μ are thus impossible to apply directly. However, μ is used in physics for the coefficient of friction in the Coulomb model, typically used to approximate resistive forces between dry solids of different materials sliding past each other. A very common use of μ in science and engineering is as the symbol of the SI prefix ''micro-'' for a millionth. Unicode has officially added a point for μ as the "micro sign," distinct from its usual codepoint as the lowercase Greek letter mu.

* '''Σ (capital sigma): Thank you for purchasing ''Addition Pro''®!''' — Typically used as a symbol for the sum of a series of numbers. The comic is making fun of summation, pointing out that it's essentially a complicated, "pro" version of simple addition. The capital sigma is often used as the icon for the all-important "sum" button in spreadsheet software. However, the sigma operator is often necessary for explicitly defining infinite sums, avoiding ambiguous notation like an ellipsis (...).

* '''Π (capital pi): ...and the ''Multiplication''® expansion pack!''' — Typically used as a symbol for the product of a sequence of numbers. The joke is the same as for summation. Here, it is advertised as an "expansion pack," a term used for a piece of software that cannot stand alone but adds features to some existing software. Any paid spreadsheet or database program should already have the ability to perform products. The ® symbol indicates that ''Multiplication'' is a registered trademark somewhere, which is unlikely, as the term is not unique. However, common words are registered as parts of longer trademarks rather often.

* '''ζ (lowercase zeta): This math will only lead to more math.''' — Frequently used for the {{w|Riemann zeta function}} in analytic number theory, a function of complex numbers which is challenging even to define and which is the focus of a famously unsolved problem in highly advanced mathematics. Zeta is used much less often in other contexts, such as the ζ-potential in colloidal chemistry, and even there it is likely to just lead to more math.

* '''β (lowercase beta): There are just too many coefficients.''' — This could be a reference to the typical usage of beta to represent coefficients of independent variables in the {{w|Ordinary_least_squares#Linear_model|ordinary least squares regression model}}. Regression can potentially have a large number of independent variables, hence potentially many different betas (differentiated by a subscript, or compacted into matrix notation) would be used, while there is only ever a single zeroth-order coefficient α in these models. Alternatively, the comic might suggest whatever source this equation is from has run out of Latin letters to use as symbols, and is now going through the Greek letters.

* '''α (lowercase alpha): Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.''' — As the first Greek letter, α is used for a tremendous variety of purposes in math. For example, it is used to represent the probability of a Type-I error (false positive) occurring in a hypothesis test. It could also possibly refer to the {{w|fine-structure constant}} which shows up in high energy physics, atomic physics, quantum electrodynamics, and at least [[1047|one other xkcd comic]]. Alpha could also refer to {{w|angular acceleration}}, and a rapidly-rotating system is capable of killing people in a number of [[123|interesting ways]]. Another dangerous meaning for α comes from ionizing α-radiation: while it can be easily blocked by even a sheet of paper, it has been {{W|Alexander Litvinenko#Poisoning and death|used for assassinations}} through ingestion.

* '''Ω (capital omega): Oooh, ''some'' mathematician thinks their function is cool and important.''' — The last letter of the Greek alphabet and thus often seen as momentous (the end, the final word, death). The capital letter has been used as the symbol for a {{w|Omega_function|variety of mathematical functions}}, the {{w|first uncountable ordinal}}, and {{w|Absolute Infinity}}. It is commonly used in physics and electrical engineering as the symbol for {{w|ohms}}, a unit for electrical resistance. Capital omega has produced a fascination in common culture, perhaps due to God reportedly describing himself as "the alpha and the omega" in the Book of Revelation or due to its highly distinctive shape. It is often used to represent something of grave or transcendent significance. So using it to name your function (instead of a conventional symbol like ''f'' or ''g'') may mean you think the function is particularly important.

* '''ω (lowercase omega): A lot of work went into these equations and you are going to die here among them.''' — Used for the {{w|Transfinite_number|least transfinite ordinal number}}, the order type of the natural numbers under '<'. The line about dying here among the transfinite equations may be in reference to the "eternity" of the infinite set it represents. It is also used in physics and electrical engineering for angular frequency, equal to 2π times the frequency, and thus it is ubiquitous in equations dealing with all sorts of wave phenomena. '''ω''' is also used for the angular velocity of a rotating system, defined by '''v''' = '''r'''×'''ω'''.

* '''σ (lowercase sigma): Some poor soul is trying to apply this math to real life and it's not working.''' — In statistics, σ commonly refers to the population standard deviation of a distribution. Many simplified statistical equations substitute the population standard deviation σ for the sample standard deviation s for simplicity, even when this is not justifiable. A common example is using the normal distribution to model the mean of several identically normally distributed variables instead of the T distribution. The variant ς is used at the end of Greek words (called the "final sigma") but is rarely used in math or science.

* '''ξ (lowercase xi): Either this is terrifying mathematics or there was a hair on the scanned page.''' — Randall comments that this looks like a strand of curly hair. Xi is used in the {{w|Riemann Xi function}} and sometimes as a variable or function symbol in higher math. It is famously difficult to write in a way that is consistent and clearly distinct from other symbols.

* '''γ (lowercase gamma): ''Zoom'' pew pew pew [space noises] ''zoooom!''''' — Lowercase gamma is used for the {{w|Lorentz factor}}, an important variable in special relativity calculations. Its use implies that you are dealing with speeds approaching the speed of light and therefore with spaceships or other moving objects not confined to Earth. γ-rays are also the highest energy photons, so a space opera might have ships flying near the speed of light firing gamma-ray weapons that go PEW PEW. γ is also used as the symbol for the Euler-Mascheroni constant and occasionally as a variable or function name.

* '''ρ (lowercase rho): Unfortunately, the test vehicle suffered an unexpected wing separation event.''' — Used in statistics to measure the association between variables. Lowercase rho often represents volumetric mass density, such as the density of air that a wing might be traveling through. The density of a fluid is directly proportional to the Reynold's number, which dictates the sort of physics used to model motion through the fluid. Flying a plane in conditions with a Reynold's number well outside of what it was designed for could have catastrophic consequences. A variant symbol ϱ with the same meaning is common in European handwriting.

* '''Ξ (capital xi): Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.''' — Probably the least used Greek letter in math and physics despite being easy to write and recognize. According to the comic, anyone using this letter is likely a being from another planet. It does see very occasional use, such as in the Riemann xi function or as the symbol for a class of heavy baryons in particle physics. It resembles but is not to be confused with a "hamburger button" or a triple equals sign ≡. Coincidentally, it also resembles the simplified Hanzi (Chinese) character for the [https://en.wikibooks.org/wiki/Chinese_(Mandarin)/Numbers number 3]. Randall thinks it most closely resembles alien writing.

* '''ψ (lowercase psi): You have entered the domain of King Triton, ruler of the waves.''' — Both capital and lowercase psi are shaped like tridents. In classical mythology, {{w|Triton}} is one of the gods of the sea, alongside his father Poseidon, and tridents are commonly associated with sea gods. In quantum mechanics, either psi is used to represent the wave function of a particle, leading to a pun. (Psi is also used in mathematics to represent the sum of the inverse of the Fibonacci numbers, the division polynomials, the supergolden ratio, and other purposes.)

==Transcript==
:[A list with 21 explanations of different Greek letters. To the left, the letter (in one case two letters) are shown, and then the explanation is written to the right in one or two lines (and in one case on three lines). Above these explanations, there is a header in a slightly larger font:]
:<big>What Greek letters mean in equations</big>
:π This math is either very simple or impossible.
:Δ Something has changed.
:δ Something has changed and it's a mathematician's fault.
:θ Circles!
:Φ '''''O R B S'''''
:ϵ Not important, don't worry about it.
:υ,ν Is that a v or a u? Or...oh no, it's one of ''those''.
:μ This math is cool but it's not about anything that you will ever see or touch, so whatever.
:Σ Thank you for purchasing ''Addition Pro''®!
:Π ...and the ''Multiplication''® expansion pack!
:ζ This math will only lead to more math.
:β There are just too many coefficients.
:α Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.
:Ω Oooh, ''some'' mathematician thinks their function is cool and important.
:ω A lot of work went into these equations and you are going to die here among them.
:σ Some poor soul is trying to apply this math to real life and it's not working.
:ξ Either this is terrifying mathematics or there was a hair on the scanned page.
:γ ''Zoom'' pew pew pew [space noises] ''zoooom!''
:ρ Unfortunately, the test vehicle suffered an unexpected wing separation event.
:Ξ Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.
:ψ You have entered the domain of King Triton, ruler of the waves.

{{comic discussion}}

[[Category:Math]]
[[Category:Aliens]]

2520: Symbols

2022-07-04T08:04:15Z

Rsge: Removed doubled "too"

{{comic
| number = 2520
| date = September 24, 2021
| title = Symbols
| image = symbols.png
| titletext = "röntgen" and "rem" are 20th-century physics terms that mean "no trespassing."
}}

==Explanation==
{{incomplete|Created by VERY EXPENSIVE EQUIPMENT - Please change this comment when editing this page. Do NOT delete this tag too soon. A bare-bones explanation is in but needs much more detail.}}
This comic refers to elements of (mostly mathematical or engineering) notation commonly used in various fields of math and science. Each piece of notation is presented as "symbolizing" not what it specifically means, but a typical ''context'' in which it might be encountered, see [[#Symbols|below]].

Many of the individual descriptions look like verbiage that might be found on informational or warnings signs or placards, although typically with a silly edge.

The title text refers to two non-SI units of radiation measurement, {{w|Roentgen (unit)|röntgen}} and {{w|Roentgen equivalent man|rem}}. In the mid-20th century when they were in use, the dangers of radiation weren't as well understood as today, so an area with radiation that was noteworthy back then is [https://archive.md/v3dME probably dangerous], hence the no trespassing part.

Later [[Randall]] made a similar comic, [[2586: Greek Letters]], regarding the use of Greek letters in math.

===Symbols===
'''d⁄dx: An undergrad is working very hard''' d/dx is the symbol for a single-variable {{w|Derivative|derivative}}. This is one of the basic operations in {{w|calculus}} and consequently is ubiquitous in the work of undergraduates in the sciences. A hard-working undergraduate in the relevant fields would churn through exercises using this symbol.

'''∂⁄∂x: A grad student is working very hard''' The replacement of the standard "d" letters with the curly letters "∂" denotes the partial derivative, which generalizes the ordinary derivative to multi-variable calculus. Problems with partial derivatives, especially partial differential equations, can be extremely challenging. Although PDEs would typically be first taught at an undergraduate level, difficult partial derivatives would be encountered in graduate-level work.

'''ħ: Oh wow, this is apparently a quantum thing''' ħ (pronounced "h-bar") is a symbol used for (the reduced) {{w|Planck's constant}}, a universal, fundamental constant in quantum physics. ħ is equal to the energy of a photon divided by its frequency, and angular momentum in quantum mechanical systems is measured in quantized integer or half-integer units of ħ.
Classical physics appears as a limit of quantum physics if all "actions" (quantities of dimension energy * time, momentum * length, or angular momentum) are much larger than ħ. Conversely, you can also formally set ħ=0 to get classical results from quantum formulae. This means that effects that are proportional to some power of ħ cannot be explained classically, and instead are "a quantum thing".

'''Rₑ: Someone needs to do a lot of tedious numerical work; hopefully it's not you''' The {{w|Reynolds number}} (which is usually denoted by "Re," not "Re" as it appears in the comic) is the most important dimensionless group in fluid mechanics. Named for Osborne Reynolds, Re characterizes the relative sizes of inertial and viscous effects in a moving fluid. Large values of Re are indicative of turbulent flow, which cannot usually be retrieved analytically, and so numerical modeling is necessary. Accurate numerical studies of high-Reynolds-number flows are notoriously difficult to create and program.

Alternatively, Rₑ could stand for electronic {{w|transition dipole moment}} in a molecule. This appears in quantum-mechanical calculations of transition probabilities and also includes a lot of unpleasant numerical work. Rₑ is also a term used for the radius of the Earth at mean sea level, though this is not necessarily a complex term in and of itself.

Another alternative is that Rₑ could refer to Relative Error, a measurement of precision or accuracy. Used often in the analysis of scientific data and numerical analysis.

'''(Ta⁴ - Tb⁴): You are at risk of skin burns''' The {{w|Stefan-Boltzmann law}} says that a perfectly absorbing ("black body") source emits electromagnetic radiation with a power per unit area of σT4, where σ is a known constant and T is the absolute temperature. The quantity (Ta4 – Tb4) thus appears in any calculation of purely radiative energy transfer between two bodies, one at temperature Ta and the other at Tb. When the radiative transfer is large enough to be the most important form of heat interchange, it is normally also large enough to sear the skin with thermal or ultraviolet burns.

'''NA: You are probably about to make an incredibly dangerous arithmetic error''' NA, or {{w|Avogadro's number}}, is the number of molecules in a mole of a substance, approximately the number of carbon atoms in exactly 12 grams of carbon-12. This is an enormous number, exactly 6.022 140 76 × 10²³, or 602 214 076 000 000 000 000 000. Working with NA, it is easy to accidentally divide by it instead of multiplying or vice versa, leading to erroneous and nonsensical answers such as ~10-23 molecules (even though you can't have less than 1 whole molecule) or ~1046 moles (>1043 to 1045 kilograms, depending on the chemical) of a substance.

'''µm: Careful, that equipment is expensive''' {{w|Micrometre|Micrometer}}s are a very small unit of distance. Micrometers are commonly used to measure wavelengths in the infrared, and infrared detectors are very expensive, compared with visible wavelength counterparts. Of course, micrometers are used as a measurement of distance in other contexts, but any distance-measuring device capable of accurately measuring micrometer distances would also be expensive. Similarly, tools used to create or calibrate items within micrometer tolerances can also be expensive.

'''mK: Careful, that equipment is very expensive''' {{w|Kelvin}} is a temperature scale roughly speaking similar to Celsius, but taking absolute zero as its zero point instead of the freezing point of water (rigorously speaking, its definition is now {{w|2019_redefinition_of_the_SI_base_units#Kelvin|based on the Boltzmann constant}}). {{w|Millikelvin}}s (1/1000 of a Kelvin) are used for high precision temperature work. Frequently this is used in processes of cooling temperatures to nearly absolute zero - such as superconductors or other quantum effects that occur when atoms are almost still. This is suggesting that the symbol appears on a sensitive experimental system probing quantum mechanical behavior that would likely only exist in an advanced laboratory. Any equipment that works down at mK temperatures, or at least to mK precision and accuracy, is likely to be very expensive.

'''nm: Don't shine that in your eye''' {{w|Nanometer}}s are frequently seen in the listed wavelengths for lasers. Pointing a visible or infrared laser at someone's eye is notoriously dangerous; the tightly-focused coherent light can cause permanent damage very quickly.

'''eV: Definitely don't shine that in your eye''' {{w|Electron volt}} energies are typical of moderate-energy particle beams, produced by accelerating electrons (or protons) over macroscopic voltages. These particle beams can be {{w|Anatoli Bugorski|even more damaging (and are probably a direct reference to Anatoli Bugorski)}} to soft tissues than optical-wavelength lasers.

'''mSv: You're about to get into an Internet argument''' The {{w|millisievert}} is a unit of radiation dose absorbed. It is a very small dosage, but the joke refers to Internet trolls debating the effects of low-dose radiation sources, such as 5G wireless networks. [[Randall|Randall's]] comment may also be referring to [https://xkcd.com/radiation/ this chart].

'''mg/kg: Go wash your hands''' This unit measures the dose of a drug or other chemical in milligrams per kilogram of body mass. If the appropriate dose - or worse, the lethal dose - is measured in mg/kg (parts per million), then the substance may be quite toxic.

'''µg/kg: Go get in the chemical shower''' A unit 1/1000 times the size of mg/kg. If a dosage is measured in micrograms per kilogram (parts per billion), any accident probably requires whole-body decontamination procedures.

'''π or τ: Whatever answer you get will be wrong by a factor of exactly two''' π is defined as the ratio of a circle's circumference to its diameter, while τ is defined as the ratio of a circle's circumference to its radius (and is therefore equal to 2π). {{w|pi|π}} has been used as the primary constant for describing the circumference and area of circles millennia ago, but proponents of {{w|Turn (angle)|τ}} claim that τ is more natural in most contexts since it makes working in radians more straightforward. The joke here is that whichever constant you use, it will probably be the wrong one (off by a factor of two, one way or the other) for the formula you are trying to use. The debate over Tau vs Pi was solved by Randall in this compromise: [[1292: Pi vs. Tau]].

==Transcript==
:[A list with 14 different scientific constants/symbols are shown. Next to each symbol is a description. Above the list is a heading and beneath that a subheading.]
:::::<big>Symbols</big>
::::And what they mean

:::d⁄dx    An undergrad is working very hard
:::∂⁄∂x    A grad student is working very hard
:::ħ       Oh wow, this is apparently a quantum thing
:::Rₑ     Someone needs to do a lot of tedious numerical work; hopefully it's not you
:(Ta⁴ - Tb⁴)    You are at risk of skin burns
:::NA    You are probably about to make an incredibly dangerous arithmetic error
:::µm    Careful, that equipment is expensive
:::mK    Careful, that equipment is very expensive
:::nm    Don't shine that in your eye
:::eV     '''''Definitely''''' don't shine that in your eye
:::mSv  You're about to get into an internet argument
::mg/kg      Go wash your hands
::µg/kg      Go get in the chemical shower
::π or τ      Whatever answer you get will be wrong by a factor of exactly two

{{comic discussion}}

[[Category:Math]]
[[Category:Physics]]
[[Category:Chemistry]]
[[Category:Biology]]
[[Category:5G]]

2445: Checkbox

2022-06-30T05:56:03Z

Rsge: Changed up the reference to next years April fools to be more concise and (imo) easier to read.

{{comic
| number = 2445
| date = April 1, 2021
| title = Checkbox
| image = checkbox.gif
| titletext = Check check check ... chhecck chhecck chhecck ... check check check
}}
{{TOC}}
*To experience the interactivity of this game, visit the {{xkcd|2445|original comic}}.
==Explanation==
This was the 11th [[:Category:April fools' comics|April fools' comic]] released by [[Randall]]. The previous fools comic was [[2288: Collector's Edition]], which was delayed two days and released on Friday April 3, 2020. The next became [[2601: Instructions]] released on Friday April 1, 2022 (a regular release day).

The comic looks similar to a loading screen. The actual comic (this “loading screen”) consists of an animated gif of a {{w|checkbox}} (hence the name).

The frame is replaced with an interactive panel. In the center is a check box, which clears itself immediately when checked. In the bottom right is a mute button, which begins muted. By unmuting, and changing it to a loudspeaker, sounds are played when the check box is checked. This was the second [[:Category:Comics with audio|comic with audio]] on xkcd. The very similar April Fool's comic from the next year, [[2601: Instructions]], used audio, too. It also had only one element in the center, but not a check box, but a {{w|radio button}}.

Under the checkbox is a scrolling visual representation of the timing and duration of clicks in the check box, which also produce matching beeping sounds when unmuted. The representation consists of a dot for a short press, or a bar for a longer press. All long presses are represented by a bar of a pre-determined length; in other words, a longer press does not result in a longer bar.

By varying between brief and long presses, and brief and long intervals between presses, it is possible to enter characters in Morse Code.

The check box then begins operating by itself, producing sounds which can be decoded as Morse Code. These responses are also printed in the browser's JavaScript console in both plain text and a textual representation of Morse code. If left without any initial input for 30 seconds it would send the message CQ (meaning "Seek You").

The title text hints at the use of Morse Code in the comic; interpreting the "check" as a Morse Code dot and the "chhecck" (a long check) as a Morse Code dash gives ...---..., which is the Morse Code for "SOS", the international distress signal. Incidentally, inputting the SOS signal gives "YOU TOO?".

For the majority of inputs, the check box responds with a random selection from the following list:
* COME AGAIN
* HUH
* NOT FOLLOWING
* SAY AGAIN
* TRY THAT AGAIN
* WHAT

Some keywords, however, have [[#Special Responses´|special responses]].

===Unique header text===
This comic has a [[xkcd_Header_text#Unique_header_text|unique header text]], see [[xkcd_Header_text#Checkbox|the details here]]. The header is:
:"This comic was put together by Max Goodhart, Patrick, Amber, Benjamin Staffin, Kevin Cotrone, and Michael Leuchtenburg."
Read Max's [https://chromakode.com/post/checkbox blog post] on development of the comic.

==Special Responses==
[. represents a short signal, - represents a long signal, and / represents pauses between words. Sojourner is a Mars rover which has been referenced by Randall in the past and is the entity operating the morse code device.]

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|XKCD -> FILE NOT FOUND
|[-..- -.- -.-. -..] -> [..-. .. .-.. . / -. --- - / ..-. --- ..- -. -..]
|
|-
|XKCD -> A CROSS THREE LETTERS
|[-..- -.- -.-. -..] -> [.- / -.-. .-. --- ... ... / - .... .-. . . / .-.. . - - . .-. ...]
|A pun on "across three letters", how clues are sometimes given in crossword puzzles. Instead, the word "xkcd" is literally a cross (x), followed by three letters (kcd).
|-
|HI -> HELLO! ANYBODY OUT THERE?
|[.... ..] -> [.... . .-.. .-.. --- -.-.-- / .- -. -.-- -... --- -.. -.-- / --- ..- - / - .... . .-. . ..--..]
|
|-
|HELLO -> HELLO TO YOU TOO!
|[.... . .-.. .-.. ---] -> [.... . .-.. .-.. --- / - --- / -.-- --- ..- / - --- --- -.-.--]
|
|-
|HELP -> ENTER IMAGE NUMBER
|[.... . .-.. .--.] -> [. -. - . .-. / .. -- .- --. . / -. ..- -- -... . .-.]
|See below; if you enter any number ≤ 2445 you will be linked to the corresponding xkcd comic.
|-
|HELP -> YES PLEASE
|[.... . .-.. .--.] -> [-.-- . ... / .--. .-.. . .- ... .]
|Sojourner mistakes the person inputting the morse code as offering help instead of asking for it.
|-
|ES -> QUE
|[. ...] -> [--.- ..- .]
|"Es" means "is" in Spanish, and "Qué" is "what".
|-
|WHAT -> ECHO
|[.-- .... .- -] -> [. -.-. .... ---]
|
|-
|ECHO -> ECHO
|[. -.-. .... ---] -> [. -.-. .... ---]
|
|-
|CHECK -> MATE
|[-.-. .... . -.-. -.-] -> [-- .- - .]
|Checkmate is the winning move in chess.
|-
|CHECKBOX -> RADIO BUTTON
|[-.-. .... . -.-. -.- -... --- -..-] -> [.-. .- -.. .. --- / -... ..- - - --- -.]
|This also works the other way around.
|-
|E (''repeat n times'') -> E (''repeat n times'')
|[.]
|This only applies for n < 7. Also, n=6 returns 'AAAAAA' instead.
|-
|T (''repeat n times'') -> T (''repeat n times'')
|[-]
|This only applies for n < 7.
|-
|E -> E ''pause'' I -> EIEIO
|[.] -> [.] ''pause'' [..] -> [. .. . .. ---]
|
|-
|I (''repeat n times'') -> I (''repeat n times'')
|[..] -> [..] ''or'' [.. ...-] (IV) ''or'' [...-] (V)
|This only applies for n < 4. n=4 returns 'IV' and n=5 returns 'V', the Roman numerals for 4 and 5, respectively.
|-
|FLIPCOIN -> HEADS ''or'' TAILS
|[..-. .-.. .. .--. -.-. --- .. -.] -> [.... . .- -.. ...] ''or'' [- .- .. .-.. ...]
|
|-
|LOOK AROUND -> NOT ENOUGH POWER
|[.-.. --- --- -.- / .- .-. --- ..- -. -..] -> [-. --- - / . -. --- ..- --. .... / .--. --- .-- . .-.]
|Indicates that Sojourner doesn't have enough battery to swivel its camera head.
|-
|SEE -> RED SOIL
|[... . .] -> [.-. . -.. / ... --- .. .-..]
|References that Sojourner is on Mars. Mars is covered in red soil.
|-
|WHO ARE YOU ''or'' WHAT IS YOUR NAME -> SOJOURNER
|[.-- .... --- / .- .-. . / -.-- --- ..-] ''or'' [.-- .... .- - / .. ... / -.-- --- ..- .-. / -. .- -- .] -> [... --- .--- --- ..- .-. -. . .-.]
|Indicates that Sojourner is the operator of the morse code device.
|-
|SOJOURNER -> CFM
|[... --- .--- --- ..- .-. -. . .-.] -> [-.-. ..-. --]
|CFM is short for confirm. Sojourner is confirming that its' in control of the morse code device.
|-
|ET -> PHONE HOME
|[. -] -> [.--. .... --- -. . / .... --- -- .]
|This is a reference to the movie ET.
|-
|LS -> DID YOU MEAN DIR
|[.-.. ...] -> [-.. .. -.. / -.-- --- ..- / -- . .- -. / -.. .. .-.]
|These are both commands for viewing the files in a directory. LS is the traditional method in UNIX, whereas DIR is more associated with MS-DOS/Windows (although it also exists in UNIX).
|-
|DIR -> ENTER IMAGE NUMBER
|[-.. .. .-.] -> [. -. - . .-. / .. -- .- --. . / -. ..- -- -... . .-.]
|This references to the next input. DIR stands for directory.
|-
|(''any number ≤ 2445'') -> (''loads xkcd comic in new tab'')
|
|Pulls up the xkcd comic corresponding to the number entered. Only works for comics published before this one.
|-
|MAKE ME A SANDWICH -> NOT A CHANCE
|[-- .- -.- . / -- . / .- / ... .- -. -.. .-- .. -.-. ....] -> [-. --- - / .- / -.-. .... .- -. -.-. .]
|A reference to [https://www.explainxkcd.com/wiki/index.php/149:_Sandwich this comic]
|-
|SUDO MAKE ME A SANDWICH -> NOT POSSIBLE HERE
|[... ..- -.. --- / -- .- -.- . / -- . / .- / ... .- -. -.. .-- .. -.-. ....] -> [-. --- - / .--. --- ... ... .. -... .-.. . / .... . .-. .]
|Another reference to [https://www.explainxkcd.com/wiki/index.php/149:_Sandwich this comic]
|-
|I LOVE YOU -> LESS THAN THREE
|[.. / .-.. --- ...- . / -.-- --- ..-] -> [.-.. . ... ... / - .... .- -. / - .... .-. . .]
|"Less than three" represents the less than (<) symbol followed by the number three (3), which together form <3. This is commonly used to represent a heart.
|-
|<nowiki />:) -> :D
|[---... -.--.-] -> [---... -..]
|This gives a bigger version of a smile than the one entered.
|-
|<nowiki />:( -> :C
|[---... -.--.] -> [---... -.-.]
|Following the pattern from the above entry, this converts the sad face entered to a bigger frown.
|-
|<nowiki />;) -> :O
|[-.-.-. -.--.-] -> [---... ---]
|
|-
|<nowiki />:O -> :X
|[---... ---] -> [---... -..-]
|
|-
|UWU -> OWO
|[..- .-- ..-] -> [--- .-- ---]
|
|-
|OWO -> UWU
|[--- .-- ---] -> [..- .-- ..-]
|
|-
|POG -> YEET
|[.--. --- --.] -> [-.-- . . -]
|Pog and yeet are both common interjections used on the Internet.
|-
|UNIX -> (''Opens [https://uni.xkcd.com uni.xkcd.com]'')
|[..- -. .. -..-]
|[https://www.explainxkcd.com/wiki/index.php/UniXKCD April Fools' Day in 2010]
|-
|GET YE FLASK -> YE WISH! IF THERE WAS A FLASK IN THIS GAME, WE'D KNOW ABOUT IT.
|[--. . - / -.-- . / ..-. .-.. .- ... -.-] -> [-.-- . / .-- .. ... .... -.-.-- / .. ..-. / - .... . .-. . / .-- .- ... / .- / ..-. .-.. .- ... -.- / .. -. / - .... .. ... / --. .- -- . --..-- / .-- . .----. -.. / -.- -. --- .-- / .- -... --- ..- - / .. - .-.-.-]
|
|-
|GET YE FLASK -> YOU CANNOT GET YE FLASK
|[--. . - / -.-- . / ..-. .-.. .- ... -.-] -> [-.-- --- ..- / -.-. .- -. -. --- - / --. . - / -.-- . / ..-. .-.. .- ... -.-]
|This response, as well as the previous one, are references to a recurring joke from {{w|Homestar Runner}}.
|-
|YO -> YO
|[-.-- ---] -> [-.-- ---]
|
|-
|DROP TABLE -> HAHA NO
|[.... .- .... .- / -. ---] -> [.... .- .... .- / -. ---]
| reference to [https://www.explainxkcd.com/wiki/index.php/327:_Exploits_of_a_Mom this comic]
|-
|WHY -> TO STUDY THE RED PLANET
|[.-- .... -.--] -> [- --- / ... - ..- -.. -.-- / - .... . / .-. . -.. / .--. .-.. .- -. . -]
|Refers to Sojourners' misson on Mars.
|-
|EAT -> I PHOTOSYNTHESIZE
|[. .- -] -> [.. / .--. .... --- - --- ... -.-- -. - .... . ... .. --.. .]
|Sojourner is a rover, and therefore does not require food. For that matter, Sojourner also does not photosynthesize. It does, however, generate energy from light in a superficially similar manner using its solar panels.
|-
|BATTLE ''or'' FIGHT -> THROW
|[-... .- - - .-.. .] ''or'' [..-. .. --. .... -] -> [- .... .-. --- .--]
|
|-
|START -> DID YOU MEAN START GAME?
|[... - .- .-. -] -> [-.. .. -.. / -.-- --- ..- / -- . .- -. / ... - .- .-. - / --. .- -- . ..--..]
|References the below input.
|-
|STARTGAME -> CHECK BACK LATER
|[... - .- .-. - --. .- -- .] -> [-.-. .... . -.-. -.- / -... .- -.-. -.- / .-.. .- - . .-.]
|
|}
===Controls===

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|QUIET -> (turns the volume off)
|[--.- ..- .. . -]
|
|-
|MUTE -> (turns the volume off)
|[-- ..- - .]
|
|-
|BEEP -> (turns the volume on)
|[-... . . .--.]
|
|}
See also QRS and QRQ.

===Q codes and radio shorthand===
An explanation of Q codes can be found {{w|Q code|here}}.

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|CQ -> CQD DE SOJ
|[-.-. --.-] -> [-.-. --.- -.. / -.. . / ... --- .---]
|
|-
|SOS -> YOU TOO?
|[... --- ...] -> [-.-- --- ..- / - --- --- ..--..]
|Implies that Sojourner is also in need of help.
|-
|SOS -> OH NO
|[... --- ...] -> [--- .... / -. ---]
|
|-
|QRS -> (reduces playback speed)
|[--.- .-. ...]
|
|-
|QRQ -> (increases playback speed)
|[--.- .-. --.-]
|
|-
|QRA -> QRA SOJOURNER
|[--.- .-. .-] -> [--.- .-. .- / ... --- .--- --- ..- .-. -. . .-.]
|
|-
|QRB -> QRB 264 MILLION KM
|[--.- .-. -...] -> [--.- .-. -... /..--- -.... ....- / -- .. .-.. .-.. .. --- -. / -.- --]
|
|-
|QRH -> QRH 0.652 METERS
|[--.- .-. ....] -> [--.- .-. .... / ----- .-.-.- -.... ..... ..--- / -- . - . .-. ...]
|
|-
|QRG -> QRG PATHFINDER
|[--.- .-. --.] -> [--.- .-. --. / .--. .- - .... ..-. .. -. -.. . .-.]
|
|-
|QRZ -> QRZ SOJOURNER
|[--.- .-. --..] -> [--.- .-. --.. / ... --- .--- --- ..- .-. -. . .-.]
|
|-
|QRT -> PLEASE DON'T GO
|[--.- .-. -] -> [.--. .-.. . .- ... . / -.. --- -. .----. - / --. ---]
|
|-
|QTH -> QTH ARES VALLIS
|[--.- - ....] -> [--.- - .... / .- .-. . ... / ...- .- .-.. .-.. .. ...]
|
|-
|QSL -> QSL
|[--.- ... .-..] -> [--.- ... .-..]
|
|-
|73 -> 73 KN
|[--... ...--] -> [--... ...-- / -.- -.]
|
|-
|CL -> BYE
|[-.-. .-..] -> [-... -.-- .]
|
|}

===FORTUNE===

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|F -> DID YOU MEAN FORTUNE
|[..-.] -> [-.. .. -.. / -.-- --- ..- / -- . .- -. / ..-. --- .-. - ..- -. .]
|
|-
|FORTUNE -> OPEN ME
|[..-. --- .-. - ..- -. .]
|
|-
|OPEN -> ''returns one of the following fortunes''

1. A BEAUTIFUL SMART AND LOVING PERSON WILL BE COMING INTO YOUR LIFE

2. CHANGE IS HAPPENING IN YOUR LIFE SO GO WITH THE FLOW

3. COURTESY BEGINS IN THE HOME

4. DILIGENCE AND MODESTY CAN RAISE YOUR SOCIAL STATUS

5. EVERYWHERE YOU CHOOSE TO GO FRIENDLY FACES WILL GREET YOU

6. FOLLOW THE MIDDLE PATH NEITHER EXTREME WILL MAKE YOU HAPPY

7. FOR THE THINGS WE HAVE TO LEARN BEFORE WE CAN DO THEM WE LEARN BY DOING THEM

8. HELP IM BEING HELD PRISONER IN A CHINESE BAKERY

9. LIKE THE RIVER FLOW INTO THE SEA SOMETHING ARE JUST MEANT TO BE

10. MANS MIND ONCE STRETCHED BY A NEW IDEA NEVER REGAINS ITS ORIGINAL DIMENSIONS

11. MEDITATION WITH AN OLD ENEMY IS ADVISED

12. NEVER FEAR THE END OF SOMETHING MARKS THE START OF SOMETHING NEW

13. PERHAPS YOUVE BEEN FOCUSING TOO MUCH ON SAVING

14. SAVOR YOUR FREEDOM IT IS PRECIOUS

15. STAYING CLOSE TO HOME IS GOING TO BE BEST FOR YOUR MORALE TODAY

16. YOU ARE GENEROUS TO AN EXTREME AND ALWAYS THINK OF THE OTHER FELLOW

17. YOU HAVE AN UNUSUAL EQUIPMENT FOR SUCCESS USE IT PROPERLY

18. YOU SHOULD PAY FOR THIS CHECK BE GENEROUS

19. YOU WILL BE A GREAT SUCCESS BOTH IN THE BUSINESS WORLD AND SOCIETY

20. YOUR DREAMS ARE NEVER SILLY DEPEND ON THEM TO GUIDE YOU

21. YOUR INFINITE CAPACITY FOR PATIENCE WILL BE REWARDED SOONER OR LATER

22. YOUR MENTALITY IS ALERT PRACTICAL AND ANALYTICAL

23. YOUR MOODS SIGNAL A PERIOD OF CHANGE

24. FIRST THINK OF WHAT YOU WANT TO DO THEN DO WHAT YOU HAVE TO DO

25. ADVENTURE CAN BE REAL HAPPINESS

26. SUCCESS IS GOING FROM FAILURE TO FAILURE WITHOUT LOSS OF ENTHUSIASM

|[--- .--. . -.]

1. [.- / -... . .- ..- - .. ..-. ..- .-.. / ... -- .- .-. - / .- -. -.. / .-.. --- ...- .. -. --. / .--. . .-. ... --- -. / .-- .. .-.. .-.. / -... . / -.-. --- -- .. -. --. / .. -. - --- / -.-- --- ..- .-. / .-.. .. ..-. .]

2. [-.-. .... .- -. --. . / .. ... / .... .- .--. .--. . -. .. -. --. / .. -. / -.-- --- ..- .-. / .-.. .. ..-. . / ... --- / --. --- / .-- .. - .... / - .... . / ..-. .-.. --- .--]

3. [-.-. --- ..- .-. - . ... -.-- / -... . --. .. -. ... / .. -. / - .... . / .... --- -- .]

4. [-.. .. .-.. .. --. . -. -.-. . / .- -. -.. / -- --- -.. . ... - -.-- / -.-. .- -. / .-. .- .. ... . / -.-- --- ..- .-. / ... --- -.-. .. .- .-.. / ... - .- - ..- ...]

5. [. ...- . .-. -.-- .-- .... . .-. . / -.-- --- ..- / -.-. .... --- --- ... . / - --- / --. --- / ..-. .-. .. . -. -.. .-.. -.-- / ..-. .- -.-. . ... / .-- .. .-.. .-.. / --. .-. . . - / -.-- --- ..-]

6. [. ...- . .-. -.-- .-- .... . .-. . / -.-- --- ..- / -.-. .... --- --- ... . / - --- / --. --- / ..-. .-. .. . -. -.. .-.. -.-- / ..-. .- -.-. . ... / .-- .. .-.. .-.. / --. .-. . . - / -.-- --- ..-]

7. [..-. --- .-. / - .... . / - .... .. -. --. ... / .-- . / .... .- ...- . / - --- / .-.. . .- .-. -. / -... . ..-. --- .-. . / .-- . / -.-. .- -. / -.. --- / - .... . -- / .-- . / .-.. . .- .-. -. / -... -.-- / -.. --- .. -. --. / - .... . --]

8. [.... . .-.. .--. / .. -- / -... . .. -. --. / .... . .-.. -.. / .--. .-. .. ... --- -. . .-. / .. -. / .- / -.-. .... .. -. . ... . / -... .- -.- . .-. -.--]

9. [.-.. .. -.- . / - .... . / .-. .. ...- . .-. / ..-. .-.. --- .-- / .. -. - --- / - .... . / ... . .- / ... --- -- . - .... .. -. --. / .- .-. . / .--- ..- ... - / -- . .- -. - / - --- / -... .]

10. [-- .- -. ... / -- .. -. -.. / --- -. -.-. . / ... - .-. . - -.-. .... . -.. / -... -.-- / .- / -. . .-- / .. -.. . .- / -. . ...- . .-. / .-. . --. .- .. -. ... / .. - ... / --- .-. .. --. .. -. .- .-.. / -.. .. -- . -. ... .. --- -. ...]

11. [-- . -.. .. - .- - .. --- -. / .-- .. - .... / .- -. / --- .-.. -.. / . -. . -- -.-- / .. ... / .- -.. ...- .. ... . -..]

12. [-. . ...- . .-. / ..-. . .- .-. / - .... . / . -. -.. / --- ..-. / ... --- -- . - .... .. -. --. / -- .- .-. -.- ... / - .... . / ... - .- .-. - / --- ..-. / ... --- -- . - .... .. -. --. / -. . .--]

13. [.--. . .-. .... .- .--. ... / -.-- --- ..- ...- . / -... . . -. / ..-. --- -.-. ..- ... .. -. --. / - --- --- / -- ..- -.-. .... / --- -. / ... .- ...- .. -. --.]

14. [... .- ...- --- .-. / -.-- --- ..- .-. / ..-. .-. . . -.. --- -- / .. - / .. ... / .--. .-. . -.-. .. --- ..- ...]

15. [... - .- -.-- .. -. --. / -.-. .-.. --- ... . / - --- / .... --- -- . / .. ... / --. --- .. -. --. / - --- / -... . / -... . ... - / ..-. --- .-. / -.-- --- ..- .-. / -- --- .-. .- .-.. . / - --- -.. .- -.--]

16. [-.-- --- ..- / .- .-. . / --. . -. . .-. --- ..- ... / - --- / .- -. / . -..- - .-. . -- . / .- -. -.. / .- .-.. .-- .- -.-- ... / - .... .. -. -.- / --- ..-. / - .... . / --- - .... . .-. / ..-. . .-.. .-.. --- .--]

17. [-.-- --- ..- / .... .- ...- . / .- -. / ..- -. ..- ... ..- .- .-.. / . --.- ..- .. .--. -- . -. - / ..-. --- .-. / ... ..- -.-. -.-. . ... ... / ..- ... . / .. - / .--. .-. --- .--. . .-. .-.. -.--]

18. [-.-- --- ..- / ... .... --- ..- .-.. -.. / .--. .- -.-- / ..-. --- .-. / - .... .. ... / -.-. .... . -.-. -.- / -... . / --. . -. . .-. --- ..- ...]

19. [-.-- --- ..- / .-- .. .-.. .-.. / -... . / .- / --. .-. . .- - / ... ..- -.-. -.-. . ... ... / -... --- - .... / .. -. / - .... . / -... ..- ... .. -. . ... ... / .-- --- .-. .-.. -.. / .- -. -.. / ... --- -.-. .. . - -.--]

20. [-.-- --- ..- .-. / -.. .-. . .- -- ... / .- .-. . / -. . ...- . .-. / ... .. .-.. .-.. -.-- / -.. . .--. . -. -.. / --- -. / - .... . -- / - --- / --. ..- .. -.. . / -.-- --- ..-]

21. [-.-- --- ..- .-. / .. -. ..-. .. -. .. - . / -.-. .- .--. .- -.-. .. - -.-- / ..-. --- .-. / .--. .- - .. . -. -.-. . / .-- .. .-.. .-.. / -... . / .-. . .-- .- .-. -.. . -.. / ... --- --- -. . .-. / --- .-. / .-.. .- - . .-.]

22. [-.-- --- ..- .-. / -- . -. - .- .-.. .. - -.-- / .. ... / .- .-.. . .-. - / .--. .-. .- -.-. - .. -.-. .- .-.. / .- -. -.. / .- -. .- .-.. -.-- - .. -.-. .- .-..]

23. [-.-- --- ..- .-. / -- --- --- -.. ... / ... .. --. -. .- .-.. / .- / .--. . .-. .. --- -.. / --- ..-. / -.-. .... .- -. --. .]

24. [..-. .. .-. ... - / - .... .. -. -.- / --- ..-. / .-- .... .- - / -.-- --- ..- / .-- .- -. - / - --- / -.. --- / - .... . -. / -.. --- / .-- .... .- - / -.-- --- ..- / .... .- ...- . / - --- / -.. ---]

25. [.- -.. ...- . -. - ..- .-. . / -.-. .- -. / -... . / .-. . .- .-.. / .... .- .--. .--. .. -. . ... ...]

26. [... ..- -.-. -.-. . ... ... / .. ... / --. --- .. -. --. / ..-. .-. --- -- / ..-. .- .. .-.. ..- .-. . / - --- / ..-. .- .. .-.. ..- .-. . / .-- .. - .... --- ..- - / .-.. --- ... ... / --- ..-. / . -. - .... ..- ... .. .- ... --]

|
|-
|OPEN -> HUH (if after something other than "FORTUNE")
|[--- .--. . -.] -> [.... ..- ....]
|}

===ENCABULATOR===

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|STATUS -> RADIO ONLINE, MOTOR ONLINE, UNILATERAL PHASE DETRACTOR UNPOWERED, CARDINAL GRAMMETER UNSYNCHRONIZED
|[... - .- - ..- ...] -> [.-. .- -.. .. --- / --- -. .-.. .. -. . --..-- / -- --- - --- .-. / --- -. .-.. .. -. . --..-- / ..- -. .. .-.. .- - . .-. .- .-.. / .--. .... .- ... . / -.. . - .-. .- -.-. - --- .-. / ..- -. .--. --- .-- . .-. . -.. --..-- / -.-. .- .-. -.. .. -. .- .-.. / --. .-. .- -- -- . - . .-. / ..- -. ... -.-- -. -.-. .... .-. --- -. .. --.. . -..]
|
|-
|YOUTUBE -> RXJKDH1KZ0W
|[-.-- --- ..- - ..- -... .]
|This represents the video ID for [https://youtu.be/RXJKdh1KZ0w Rockwell Retro Encabulator]
|-
|REPAIR ''or'' ENCABULATOR ''or'' FIX ''or'' SYSTEM -> ENTERING ENCABULATOR RECOVERY SYSTEM. OPTIONS 1 INITIATE SIDE FUMBLING 2 ALIGN SPURVING BEARINGS 3 REVERSE TREMIE PIPE
:1 -> SIDE FUMBLING DETECTED. MODIAL INTERACTION UNSTABLE. RECOVERY TERMINATED.
:2 -> MODIAL INTERACTION INITIATED. OPTIONS 1 UNWIND LOTUS O DELTOID 2 INCREASE DEPLENERATION 3 CONNECT GIRDLESPRING ON DOWN END OF GRAMMETER 4 CONNECT SEVENTH CONDUCTOR TO GIRDLESPRING
::1 -> SIDE FUMBLING DETECTED. MODIAL INTERACTION UNSTABLE. RECOVERY TERMINATED.
::2 -> DEPLENERATION PREVENTED BY DINGLE ARM
::3 -> SIDE FUMBLING DETECTED. MODIAL INTERACTION UNSTABLE. RECOVERY TERMINATED.
::4 -> PANAMETRIC FAN ACTIVATED. MODIAL INTERACTION STABLE. DEFAULT CONFIGURATION MISSING. MANUALLY ENTER MARZELVANE TYPE TO COMPLETE RECOVERY
:::HYDROCOPTIC -> RECOVERY SUCCESSFUL. REBOOT Y N?
::::Y -> (''Opens [https://imgs.xkcd.com/comics/sojourner_repaired.png sojourner_repaired.png]'')
:3 -> ERROR TREMIE PIPE NONREVERSIBLE
|[.-. . .--. .- .. .-.] ''or'' [. -. -.-. .- -... ..- .-.. .- - --- .-.] ''or'' [..-. .. -..-] ''or'' [... -.-- ... - . --] -> [. -. - . .-. .. -. --. / . -. -.-. .- -... ..- .-.. .- - --- .-. / .-. . -.-. --- ...- . .-. -.-- / ... -.-- ... - . -- .-.-.- / --- .--. - .. --- -. ... / .---- / .. -. .. - .. .- - . / ... .. -.. . / ..-. ..- -- -... .-.. .. -. --. / ..--- / .- .-.. .. --. -. / ... .--. ..- .-. ...- .. -. --. / -... . .- .-. .. -. --. ... / ...-- / .-. . ...- . .-. ... . / - .-. . -- .. . / .--. .. .--. .]
:[.----] -> [... .. -.. . / ..-. ..- -- -... .-.. .. -. --. / -.. . - . -.-. - . -.. .-.-.- / -- --- -.. .. .- .-.. / .. -. - . .-. .- -.-. - .. --- -. / ..- -. ... - .- -... .-.. . .-.-.- / .-. . -.-. --- ...- . .-. -.-- / - . .-. -- .. -. .- - . -.. .-.-.-]
:[..---] -> [-- --- -.. .. .- .-.. / .. -. - . .-. .- -.-. - .. --- -. / .. -. .. - .. .- - . -.. .-.-.- / --- .--. - .. --- -. ... / .---- / ..- -. .-- .. -. -.. / .-.. --- - ..- ... / --- / -.. . .-.. - --- .. -.. / ..--- / .. -. -.-. .-. . .- ... . / -.. . .--. .-.. . -. . .-. .- - .. --- -. / ...-- / -.-. --- -. -. . -.-. - / --. .. .-. -.. .-.. . ... .--. .-. .. -. --. / --- -. / -.. --- .-- -. / . -. -.. / --- ..-. / --. .-. .- -- -- . - . .-. / ....- / -.-. --- -. -. . -.-. - / ... . ...- . -. - .... / -.-. --- -. -.. ..- -.-. - --- .-. / - --- / --. .. .-. -.. .-.. . ... .--. .-. .. -. --.]
::[.----] -> [... .. -.. . / ..-. ..- -- -... .-.. .. -. --. / -.. . - . -.-. - . -.. .-.-.- / -- --- -.. .. .- .-.. / .. -. - . .-. .- -.-. - .. --- -. / ..- -. ... - .- -... .-.. . .-.-.- / .-. . -.-. --- ...- . .-. -.-- / - . .-. -- .. -. .- - . -.. .-.-.-]
::[..---] -> [-.. . .--. .-.. . -. . .-. .- - .. --- -. / .--. .-. . ...- . -. - . -.. / -... -.-- / -.. .. -. --. .-.. . / .- .-. --]
::[...--] -> [... .. -.. . / ..-. ..- -- -... .-.. .. -. --. / -.. . - . -.-. - . -.. .-.-.- / -- --- -.. .. .- .-.. / .. -. - . .-. .- -.-. - .. --- -. / ..- -. ... - .- -... .-.. . .-.-.- / .-. . -.-. --- ...- . .-. -.-- / - . .-. -- .. -. .- - . -.. .-.-.-]
::[....-] -> [.--. .- -. .- -- . - .-. .. -.-. / ..-. .- -. / .- -.-. - .. ...- .- - . -.. .-.-.- / -- --- -.. .. .- .-.. / .. -. - . .-. .- -.-. - .. --- -. / ... - .- -... .-.. . .-.-.- / -.. . ..-. .- ..- .-.. - / -.-. --- -. ..-. .. --. ..- .-. .- - .. --- -. / -- .. ... ... .. -. --. .-.-.- / -- .- -. ..- .- .-.. .-.. -.-- / . -. - . .-. / -- .- .-. --.. . .-.. ...- .- -. . / - -.-- .--. . / - --- / -.-. --- -- .--. .-.. . - . / .-. . -.-. --- ...- . .-. -.--]
:::[.... -.-- -.. .-. --- -.-. --- .--. - .. -.-.] -> [.-. . -.-. --- ...- . .-. -.-- / ... ..- -.-. -.-. . ... ... ..-. ..- .-.. .-.-.- / .-. . -... --- --- - / -.-- / -. ..--..]
::::[-.--]
:[...--] -> [. .-. .-. --- .-. / - .-. . -- .. . / .--. .. .--. . / -. --- -. .-. . ...- . .-. ... .. -... .-.. .]
|
|-
|}

===MAZE===

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|RETURN -> DID YOU MEAN ENTER
|[.-. . - ..- .-. -.]
|
|-
|ENTER -> DID YOU MEAN ENTER MAZE
|[. -. - . .-.]
|
|-
|ENTER MAZE -> AN EMPTY ROOM
:LOOK -> AN EMPTY ROOM
:HELP -> NORTH EAST SOUTH WEST GET
:EXIT -> CFM (''Exits the maze'')
|[. -. - . .-. / -- .- --.. .] -> [.- -. / . -- .--. - -.-- / .-. --- --- --]
:[.-.. --- --- -.-] -> [.- -. / . -- .--. - -.-- / .-. --- --- --]
:[.... . .-.. .--.] -> [-. --- .-. - .... / . .- ... - / ... --- ..- - .... / .-- . ... - / --. . -]
:[. -..- .. -] -> [-.-. ..-. --]
|
|}
{| class="wikitable"
|+ Maze
|-
|an open flame || a candle on a table || style="background-color: black;" |
|-
| style="background-color: black;" | || an empty room (start) || style="background-color: black;" |
|-
| style="background-color: black;" | || a hanging bell || an open book on a table (locked door)
|-
|}

Steps to complete (directions can be abbreviated as their first letter):
# NORTH
# GET CANDLE -> TAKEN
# WEST
# LIGHT CANDLE
# EAST
# SOUTH
# SOUTH
# RING BELL -> A DOOR OPENS
# EAST
# CLOSE BOOK -> CONGRATULATIONS YOU ESCAPE

===CROSSWORD===
{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|CROSSWORD -> NUMBER AND DIRECTION
|[-.-. .-. --- ... ... .-- --- .-. -..] -> [-. ..- -- -... . .-. / .- -. -.. / -.. .. .-. . -.-. - .. --- -.]
|This starts a crossword. You can ask for hints like "1 down" or "2 across". It appears to be the [https://rexwordpuzzle.blogspot.com/2021/04/libertarian-politico-johnson-thu-4-1-21.html New York Times Crossword] from the day this comic was written (2021-04-01).
|}

{| class="wikitable"
|+Solved Crossword
|-
| m || y || g || o || d || style="background-color: black; | || d || e || v || style="background-color: black; | || style="background-color: black; | || style="background-color: black; | || e || l || f
|-
| b || u || o || n || o || style="background-color: black; | || e || y || e || s || style="background-color: black; | || s || l || u || r
|-
| a || m || o || c || o || style="background-color: black; | || c || r || a || p || style="background-color: black; | || l || m || a || o
|-
| style="background-color: black; | || style="background-color: black; | || v || e || r || y || r || e || l || i || g || i || o || u || s
|-
| s || e || e || style="background-color: black; | || m || u || y || style="background-color: black; | || style="background-color: black; | || r || a || m || style="background-color: black; | || style="background-color: black; | || style="background-color: black; |
|-
| h || a || r || h || a || r || style="background-color: black; | || s || c || a || r || e || d || o || f
|-
| e || s || s || e || n || t || i || a || l || l || y || style="background-color: black; | || a || r || i
|-
| b || t || e || n || style="background-color: black; | || style="background-color: black; | || m || m || i || style="background-color: black; | || style="background-color: black; | || t || v || a || d
|-
| o || l || a || style="background-color: black; | || b || a || d || m || o || u || t || h || i || n || g
|-
| p || a || s || s || e || d || b || y || style="background-color: black; | || n || o || o || d || g || e
|-
| style="background-color: black; | || style="background-color: black; | || style="background-color: black; | || o || a || r || style="background-color: black; | || style="background-color: black; | || s || u || n || style="background-color: black; | || l || e || t
|-
| b || l || e || n || d || e || d || f || a || m || i || l || y || style="background-color: black; | || style="background-color: black; |
|-
| b || o || r || g || style="background-color: black; | || p || e || l || t || style="background-color: black; | || g || e || n || r || e
|-
| q || u || i || z || style="background-color: black; | || s || p || a || y || style="background-color: black; | || h || i || c || k || s
|-
| s || t || e || style="background-color: black; | || style="background-color: black; | || style="background-color: black; | || p || b || r || style="background-color: black; | || t || a || h || o || e
|}

{| class="wikitable mw-collapsible mw-collapsed"
|+ Words
! index !! down word !! across word
|-
| 1 || MBA || MYGOD
|-
| 2 || YUM ||
|-
| 3 || GOOVERSEAS ||
|-
| 4 || ONCE ||
|-
| 5 || DOORMAN ||
|-
| 6 || DECRY || DEV
|-
| 7 || EYRE ||
|-
| 8 || VEAL ||
|-
| 9 || ELMO || ELF
|-
| 10 || LUAU ||
|-
| 11 || FROS ||
|-
| 12 || || BUONO
|-
| 13 || || EYES
|-
| 14 || SPIRAL ||
|-
| 15 || SLIME || SLUR
|-
| 16 || || AMOCO
|-
| 17 || || CRAP
|-
| 18 || || LMAO
|-
| 19 || || VERYRELIGIOUS
|-
| 20 || YURT ||
|-
| 21 || GARY ||
|-
| 22 || SHEBOP || SEE
|-
| 23 || EASTLA ||
|-
| 24 || || MUY
|-
| 25 || || RAM
|-
| 26 || || HARHAR
|-
| 27 || HEN ||
|-
| 28 || SAMMY || SCAREDOF
|-
| 29 || CLIO ||
|-
| 30 || DAVIDLYNCH ||
|-
| 31 || ORANGE ||
|-
| 32 || FIDGET ||
|-
| 33 || || ESSENTIALLY
|-
| 34 || IMDB ||
|-
| 35 || || ARI
|-
| 36 || || BTEN
|-
| 37 || || MMI
|-
| 38 || THO || TVAD
|-
| 39 || || OLA
|-
| 40 || BEAD || BADMOUTHING
|-
| 41 || ADREPS ||
|-
| 42 || UNUM ||
|-
| 43 || TONIGHT ||
|-
| 44 || || PASSEDBY
|-
| 45 || SONGZ ||
|-
| 46 || || NOODGE
|-
| 47 || || OAR
|-
| 48 || SATYR || SUN
|-
| 49 || || LET
|-
| 50 || BBQS || BLENDEDFAMILY
|-
| 51 || LOUT ||
|-
| 52 || ERIE ||
|-
| 53 || DEPP ||
|-
| 54 || FLAB ||
|-
| 55 || LEIA ||
|-
| 56 || || BORG
|-
| 57 || || PELT
|-
| 58 || || GENRE
|-
| 59 || RKO ||
|-
| 60 || ESE ||
|-
| 61 || || QUIZ
|-
| 62 || || SPAY
|-
| 63 || || HICKS
|-
| 64 || || STE
|-
| 65 || || PBR
|-
| 66 || || TAHOE
|}

===Rover Scene===
After successfully repairing and rebooting Sojourner, a comic is opened which depicts it seeking out and finding its friends, Spirit, Opportunity, Curiosity, Perseverance, and Ingenuity. Curiosity and Perseverance are locked in a swordfight, and either Spirit or Opportunity is carried off by Ingenuity while the other speeds off a small mound of dirt. Ingenuity carrying a rover is a reference to the previous comic.

==Special Console Commands==
The page's JavaScript creates a global object <code>morse</code> with <code>encode</code> and <code>decode</code> methods. From the developer console, it is possible to write <code>morse.encode("A PHRASE")</code>, which will print the Morse code corresponding to the text provided, or <code>morse.decode("... --- ...")</code> which will translate the Morse code to text.

<code>BeepComic.hurryUp()</code> to get the reply immediately in the console.
<code>BeepComic.send(...)</code> to send directly to SOJOURNER.

==Transcript==
:[A small box is in the middle of a large white frame. The box can have a check-mark, but it is alternating between being checked or unchecked. At the bottom right there is a muted speaker (which can be unmuted). If the user press the checkbox gray dots or lines will appear below depending on the length of the press. These will move from right to left and then disappear.]

{{comic discussion}}

[[Category:April fools' comics]]
[[Category:Interactive comics]]
[[Category:Comics with animation]]
[[Category:Dynamic comics]]
[[Category:Comics with audio]]

2445: Checkbox

2022-06-30T05:38:47Z

Rsge: Comic w/ audio: Second, not first - Right Click was first.

{{comic
| number = 2445
| date = April 1, 2021
| title = Checkbox
| image = checkbox.gif
| titletext = Check check check ... chhecck chhecck chhecck ... check check check
}}
{{TOC}}
*To experience the interactivity of this game, visit the {{xkcd|2445|original comic}}.
==Explanation==
This was the 11th [[:Category:April fools' comics|April fools' comic]] released by [[Randall]]. The previous fools comic was [[2288: Collector's Edition]], which was delayed two days and released on Friday April 3, 2020. The next became [[2601: Instructions]] released on Friday April 1, 2022 (a regular release day).

The comic looks similar to a loading screen. The actual comic (this “loading screen”) consists of an animated gif of a {{w|checkbox}} (hence the name).

The frame is replaced with an interactive panel. In the center is a check box, which clears itself immediately when checked. In the bottom right is a mute button, which begins muted. By unmuting, and changing it to a loudspeaker, sounds are played when the check box is checked. This was the second [[:Category:Comics with audio|comic with audio]] on xkcd. But the very similar Fool's comic from the next year, [[2601: Instructions]], used audio as the main part of the joke. This comic and also has a mute button (but here the sound was on when the mute button is shown, seems like an error). This comic is also very similar to this one, as it only has one thing in the center, but not a check box, but a {{w|radio button}}.

Under the checkbox is a scrolling visual representation of the timing and duration of clicks in the check box, which also produce matching beeping sounds when unmuted. The representation consists of a dot for a short press, or a bar for a longer press. All long presses are represented by a bar of a pre-determined length; in other words, a longer press does not result in a longer bar.

By varying between brief and long presses, and brief and long intervals between presses, it is possible to enter characters in Morse Code.

The check box then begins operating by itself, producing sounds which can be decoded as Morse Code. These responses are also printed in the browser's JavaScript console in both plain text and a textual representation of Morse code. If left without any initial input for 30 seconds it would send the message CQ (meaning "Seek You").

The title text hints at the use of Morse Code in the comic; interpreting the "check" as a Morse Code dot and the "chhecck" (a long check) as a Morse Code dash gives ...---..., which is the Morse Code for "SOS", the international distress signal. Incidentally, inputting the SOS signal gives "YOU TOO?".

For the majority of inputs, the check box responds with a random selection from the following list:
* COME AGAIN
* HUH
* NOT FOLLOWING
* SAY AGAIN
* TRY THAT AGAIN
* WHAT

Some keywords, however, have [[#Special Responses´|special responses]].

===Unique header text===
This comic has a [[xkcd_Header_text#Unique_header_text|unique header text]], see [[xkcd_Header_text#Checkbox|the details here]]. The header is:
:"This comic was put together by Max Goodhart, Patrick, Amber, Benjamin Staffin, Kevin Cotrone, and Michael Leuchtenburg."
Read Max's [https://chromakode.com/post/checkbox blog post] on development of the comic.

==Special Responses==
[. represents a short signal, - represents a long signal, and / represents pauses between words. Sojourner is a Mars rover which has been referenced by Randall in the past and is the entity operating the morse code device.]

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|XKCD -> FILE NOT FOUND
|[-..- -.- -.-. -..] -> [..-. .. .-.. . / -. --- - / ..-. --- ..- -. -..]
|
|-
|XKCD -> A CROSS THREE LETTERS
|[-..- -.- -.-. -..] -> [.- / -.-. .-. --- ... ... / - .... .-. . . / .-.. . - - . .-. ...]
|A pun on "across three letters", how clues are sometimes given in crossword puzzles. Instead, the word "xkcd" is literally a cross (x), followed by three letters (kcd).
|-
|HI -> HELLO! ANYBODY OUT THERE?
|[.... ..] -> [.... . .-.. .-.. --- -.-.-- / .- -. -.-- -... --- -.. -.-- / --- ..- - / - .... . .-. . ..--..]
|
|-
|HELLO -> HELLO TO YOU TOO!
|[.... . .-.. .-.. ---] -> [.... . .-.. .-.. --- / - --- / -.-- --- ..- / - --- --- -.-.--]
|
|-
|HELP -> ENTER IMAGE NUMBER
|[.... . .-.. .--.] -> [. -. - . .-. / .. -- .- --. . / -. ..- -- -... . .-.]
|See below; if you enter any number ≤ 2445 you will be linked to the corresponding xkcd comic.
|-
|HELP -> YES PLEASE
|[.... . .-.. .--.] -> [-.-- . ... / .--. .-.. . .- ... .]
|Sojourner mistakes the person inputting the morse code as offering help instead of asking for it.
|-
|ES -> QUE
|[. ...] -> [--.- ..- .]
|"Es" means "is" in Spanish, and "Qué" is "what".
|-
|WHAT -> ECHO
|[.-- .... .- -] -> [. -.-. .... ---]
|
|-
|ECHO -> ECHO
|[. -.-. .... ---] -> [. -.-. .... ---]
|
|-
|CHECK -> MATE
|[-.-. .... . -.-. -.-] -> [-- .- - .]
|Checkmate is the winning move in chess.
|-
|CHECKBOX -> RADIO BUTTON
|[-.-. .... . -.-. -.- -... --- -..-] -> [.-. .- -.. .. --- / -... ..- - - --- -.]
|This also works the other way around.
|-
|E (''repeat n times'') -> E (''repeat n times'')
|[.]
|This only applies for n < 7. Also, n=6 returns 'AAAAAA' instead.
|-
|T (''repeat n times'') -> T (''repeat n times'')
|[-]
|This only applies for n < 7.
|-
|E -> E ''pause'' I -> EIEIO
|[.] -> [.] ''pause'' [..] -> [. .. . .. ---]
|
|-
|I (''repeat n times'') -> I (''repeat n times'')
|[..] -> [..] ''or'' [.. ...-] (IV) ''or'' [...-] (V)
|This only applies for n < 4. n=4 returns 'IV' and n=5 returns 'V', the Roman numerals for 4 and 5, respectively.
|-
|FLIPCOIN -> HEADS ''or'' TAILS
|[..-. .-.. .. .--. -.-. --- .. -.] -> [.... . .- -.. ...] ''or'' [- .- .. .-.. ...]
|
|-
|LOOK AROUND -> NOT ENOUGH POWER
|[.-.. --- --- -.- / .- .-. --- ..- -. -..] -> [-. --- - / . -. --- ..- --. .... / .--. --- .-- . .-.]
|Indicates that Sojourner doesn't have enough battery to swivel its camera head.
|-
|SEE -> RED SOIL
|[... . .] -> [.-. . -.. / ... --- .. .-..]
|References that Sojourner is on Mars. Mars is covered in red soil.
|-
|WHO ARE YOU ''or'' WHAT IS YOUR NAME -> SOJOURNER
|[.-- .... --- / .- .-. . / -.-- --- ..-] ''or'' [.-- .... .- - / .. ... / -.-- --- ..- .-. / -. .- -- .] -> [... --- .--- --- ..- .-. -. . .-.]
|Indicates that Sojourner is the operator of the morse code device.
|-
|SOJOURNER -> CFM
|[... --- .--- --- ..- .-. -. . .-.] -> [-.-. ..-. --]
|CFM is short for confirm. Sojourner is confirming that its' in control of the morse code device.
|-
|ET -> PHONE HOME
|[. -] -> [.--. .... --- -. . / .... --- -- .]
|This is a reference to the movie ET.
|-
|LS -> DID YOU MEAN DIR
|[.-.. ...] -> [-.. .. -.. / -.-- --- ..- / -- . .- -. / -.. .. .-.]
|These are both commands for viewing the files in a directory. LS is the traditional method in UNIX, whereas DIR is more associated with MS-DOS/Windows (although it also exists in UNIX).
|-
|DIR -> ENTER IMAGE NUMBER
|[-.. .. .-.] -> [. -. - . .-. / .. -- .- --. . / -. ..- -- -... . .-.]
|This references to the next input. DIR stands for directory.
|-
|(''any number ≤ 2445'') -> (''loads xkcd comic in new tab'')
|
|Pulls up the xkcd comic corresponding to the number entered. Only works for comics published before this one.
|-
|MAKE ME A SANDWICH -> NOT A CHANCE
|[-- .- -.- . / -- . / .- / ... .- -. -.. .-- .. -.-. ....] -> [-. --- - / .- / -.-. .... .- -. -.-. .]
|A reference to [https://www.explainxkcd.com/wiki/index.php/149:_Sandwich this comic]
|-
|SUDO MAKE ME A SANDWICH -> NOT POSSIBLE HERE
|[... ..- -.. --- / -- .- -.- . / -- . / .- / ... .- -. -.. .-- .. -.-. ....] -> [-. --- - / .--. --- ... ... .. -... .-.. . / .... . .-. .]
|Another reference to [https://www.explainxkcd.com/wiki/index.php/149:_Sandwich this comic]
|-
|I LOVE YOU -> LESS THAN THREE
|[.. / .-.. --- ...- . / -.-- --- ..-] -> [.-.. . ... ... / - .... .- -. / - .... .-. . .]
|"Less than three" represents the less than (<) symbol followed by the number three (3), which together form <3. This is commonly used to represent a heart.
|-
|<nowiki />:) -> :D
|[---... -.--.-] -> [---... -..]
|This gives a bigger version of a smile than the one entered.
|-
|<nowiki />:( -> :C
|[---... -.--.] -> [---... -.-.]
|Following the pattern from the above entry, this converts the sad face entered to a bigger frown.
|-
|<nowiki />;) -> :O
|[-.-.-. -.--.-] -> [---... ---]
|
|-
|<nowiki />:O -> :X
|[---... ---] -> [---... -..-]
|
|-
|UWU -> OWO
|[..- .-- ..-] -> [--- .-- ---]
|
|-
|OWO -> UWU
|[--- .-- ---] -> [..- .-- ..-]
|
|-
|POG -> YEET
|[.--. --- --.] -> [-.-- . . -]
|Pog and yeet are both common interjections used on the Internet.
|-
|UNIX -> (''Opens [https://uni.xkcd.com uni.xkcd.com]'')
|[..- -. .. -..-]
|[https://www.explainxkcd.com/wiki/index.php/UniXKCD April Fools' Day in 2010]
|-
|GET YE FLASK -> YE WISH! IF THERE WAS A FLASK IN THIS GAME, WE'D KNOW ABOUT IT.
|[--. . - / -.-- . / ..-. .-.. .- ... -.-] -> [-.-- . / .-- .. ... .... -.-.-- / .. ..-. / - .... . .-. . / .-- .- ... / .- / ..-. .-.. .- ... -.- / .. -. / - .... .. ... / --. .- -- . --..-- / .-- . .----. -.. / -.- -. --- .-- / .- -... --- ..- - / .. - .-.-.-]
|
|-
|GET YE FLASK -> YOU CANNOT GET YE FLASK
|[--. . - / -.-- . / ..-. .-.. .- ... -.-] -> [-.-- --- ..- / -.-. .- -. -. --- - / --. . - / -.-- . / ..-. .-.. .- ... -.-]
|This response, as well as the previous one, are references to a recurring joke from {{w|Homestar Runner}}.
|-
|YO -> YO
|[-.-- ---] -> [-.-- ---]
|
|-
|DROP TABLE -> HAHA NO
|[.... .- .... .- / -. ---] -> [.... .- .... .- / -. ---]
| reference to [https://www.explainxkcd.com/wiki/index.php/327:_Exploits_of_a_Mom this comic]
|-
|WHY -> TO STUDY THE RED PLANET
|[.-- .... -.--] -> [- --- / ... - ..- -.. -.-- / - .... . / .-. . -.. / .--. .-.. .- -. . -]
|Refers to Sojourners' misson on Mars.
|-
|EAT -> I PHOTOSYNTHESIZE
|[. .- -] -> [.. / .--. .... --- - --- ... -.-- -. - .... . ... .. --.. .]
|Sojourner is a rover, and therefore does not require food. For that matter, Sojourner also does not photosynthesize. It does, however, generate energy from light in a superficially similar manner using its solar panels.
|-
|BATTLE ''or'' FIGHT -> THROW
|[-... .- - - .-.. .] ''or'' [..-. .. --. .... -] -> [- .... .-. --- .--]
|
|-
|START -> DID YOU MEAN START GAME?
|[... - .- .-. -] -> [-.. .. -.. / -.-- --- ..- / -- . .- -. / ... - .- .-. - / --. .- -- . ..--..]
|References the below input.
|-
|STARTGAME -> CHECK BACK LATER
|[... - .- .-. - --. .- -- .] -> [-.-. .... . -.-. -.- / -... .- -.-. -.- / .-.. .- - . .-.]
|
|}
===Controls===

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|QUIET -> (turns the volume off)
|[--.- ..- .. . -]
|
|-
|MUTE -> (turns the volume off)
|[-- ..- - .]
|
|-
|BEEP -> (turns the volume on)
|[-... . . .--.]
|
|}
See also QRS and QRQ.

===Q codes and radio shorthand===
An explanation of Q codes can be found {{w|Q code|here}}.

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|CQ -> CQD DE SOJ
|[-.-. --.-] -> [-.-. --.- -.. / -.. . / ... --- .---]
|
|-
|SOS -> YOU TOO?
|[... --- ...] -> [-.-- --- ..- / - --- --- ..--..]
|Implies that Sojourner is also in need of help.
|-
|SOS -> OH NO
|[... --- ...] -> [--- .... / -. ---]
|
|-
|QRS -> (reduces playback speed)
|[--.- .-. ...]
|
|-
|QRQ -> (increases playback speed)
|[--.- .-. --.-]
|
|-
|QRA -> QRA SOJOURNER
|[--.- .-. .-] -> [--.- .-. .- / ... --- .--- --- ..- .-. -. . .-.]
|
|-
|QRB -> QRB 264 MILLION KM
|[--.- .-. -...] -> [--.- .-. -... /..--- -.... ....- / -- .. .-.. .-.. .. --- -. / -.- --]
|
|-
|QRH -> QRH 0.652 METERS
|[--.- .-. ....] -> [--.- .-. .... / ----- .-.-.- -.... ..... ..--- / -- . - . .-. ...]
|
|-
|QRG -> QRG PATHFINDER
|[--.- .-. --.] -> [--.- .-. --. / .--. .- - .... ..-. .. -. -.. . .-.]
|
|-
|QRZ -> QRZ SOJOURNER
|[--.- .-. --..] -> [--.- .-. --.. / ... --- .--- --- ..- .-. -. . .-.]
|
|-
|QRT -> PLEASE DON'T GO
|[--.- .-. -] -> [.--. .-.. . .- ... . / -.. --- -. .----. - / --. ---]
|
|-
|QTH -> QTH ARES VALLIS
|[--.- - ....] -> [--.- - .... / .- .-. . ... / ...- .- .-.. .-.. .. ...]
|
|-
|QSL -> QSL
|[--.- ... .-..] -> [--.- ... .-..]
|
|-
|73 -> 73 KN
|[--... ...--] -> [--... ...-- / -.- -.]
|
|-
|CL -> BYE
|[-.-. .-..] -> [-... -.-- .]
|
|}

===FORTUNE===

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|F -> DID YOU MEAN FORTUNE
|[..-.] -> [-.. .. -.. / -.-- --- ..- / -- . .- -. / ..-. --- .-. - ..- -. .]
|
|-
|FORTUNE -> OPEN ME
|[..-. --- .-. - ..- -. .]
|
|-
|OPEN -> ''returns one of the following fortunes''

1. A BEAUTIFUL SMART AND LOVING PERSON WILL BE COMING INTO YOUR LIFE

2. CHANGE IS HAPPENING IN YOUR LIFE SO GO WITH THE FLOW

3. COURTESY BEGINS IN THE HOME

4. DILIGENCE AND MODESTY CAN RAISE YOUR SOCIAL STATUS

5. EVERYWHERE YOU CHOOSE TO GO FRIENDLY FACES WILL GREET YOU

6. FOLLOW THE MIDDLE PATH NEITHER EXTREME WILL MAKE YOU HAPPY

7. FOR THE THINGS WE HAVE TO LEARN BEFORE WE CAN DO THEM WE LEARN BY DOING THEM

8. HELP IM BEING HELD PRISONER IN A CHINESE BAKERY

9. LIKE THE RIVER FLOW INTO THE SEA SOMETHING ARE JUST MEANT TO BE

10. MANS MIND ONCE STRETCHED BY A NEW IDEA NEVER REGAINS ITS ORIGINAL DIMENSIONS

11. MEDITATION WITH AN OLD ENEMY IS ADVISED

12. NEVER FEAR THE END OF SOMETHING MARKS THE START OF SOMETHING NEW

13. PERHAPS YOUVE BEEN FOCUSING TOO MUCH ON SAVING

14. SAVOR YOUR FREEDOM IT IS PRECIOUS

15. STAYING CLOSE TO HOME IS GOING TO BE BEST FOR YOUR MORALE TODAY

16. YOU ARE GENEROUS TO AN EXTREME AND ALWAYS THINK OF THE OTHER FELLOW

17. YOU HAVE AN UNUSUAL EQUIPMENT FOR SUCCESS USE IT PROPERLY

18. YOU SHOULD PAY FOR THIS CHECK BE GENEROUS

19. YOU WILL BE A GREAT SUCCESS BOTH IN THE BUSINESS WORLD AND SOCIETY

20. YOUR DREAMS ARE NEVER SILLY DEPEND ON THEM TO GUIDE YOU

21. YOUR INFINITE CAPACITY FOR PATIENCE WILL BE REWARDED SOONER OR LATER

22. YOUR MENTALITY IS ALERT PRACTICAL AND ANALYTICAL

23. YOUR MOODS SIGNAL A PERIOD OF CHANGE

24. FIRST THINK OF WHAT YOU WANT TO DO THEN DO WHAT YOU HAVE TO DO

25. ADVENTURE CAN BE REAL HAPPINESS

26. SUCCESS IS GOING FROM FAILURE TO FAILURE WITHOUT LOSS OF ENTHUSIASM

|[--- .--. . -.]

1. [.- / -... . .- ..- - .. ..-. ..- .-.. / ... -- .- .-. - / .- -. -.. / .-.. --- ...- .. -. --. / .--. . .-. ... --- -. / .-- .. .-.. .-.. / -... . / -.-. --- -- .. -. --. / .. -. - --- / -.-- --- ..- .-. / .-.. .. ..-. .]

2. [-.-. .... .- -. --. . / .. ... / .... .- .--. .--. . -. .. -. --. / .. -. / -.-- --- ..- .-. / .-.. .. ..-. . / ... --- / --. --- / .-- .. - .... / - .... . / ..-. .-.. --- .--]

3. [-.-. --- ..- .-. - . ... -.-- / -... . --. .. -. ... / .. -. / - .... . / .... --- -- .]

4. [-.. .. .-.. .. --. . -. -.-. . / .- -. -.. / -- --- -.. . ... - -.-- / -.-. .- -. / .-. .- .. ... . / -.-- --- ..- .-. / ... --- -.-. .. .- .-.. / ... - .- - ..- ...]

5. [. ...- . .-. -.-- .-- .... . .-. . / -.-- --- ..- / -.-. .... --- --- ... . / - --- / --. --- / ..-. .-. .. . -. -.. .-.. -.-- / ..-. .- -.-. . ... / .-- .. .-.. .-.. / --. .-. . . - / -.-- --- ..-]

6. [. ...- . .-. -.-- .-- .... . .-. . / -.-- --- ..- / -.-. .... --- --- ... . / - --- / --. --- / ..-. .-. .. . -. -.. .-.. -.-- / ..-. .- -.-. . ... / .-- .. .-.. .-.. / --. .-. . . - / -.-- --- ..-]

7. [..-. --- .-. / - .... . / - .... .. -. --. ... / .-- . / .... .- ...- . / - --- / .-.. . .- .-. -. / -... . ..-. --- .-. . / .-- . / -.-. .- -. / -.. --- / - .... . -- / .-- . / .-.. . .- .-. -. / -... -.-- / -.. --- .. -. --. / - .... . --]

8. [.... . .-.. .--. / .. -- / -... . .. -. --. / .... . .-.. -.. / .--. .-. .. ... --- -. . .-. / .. -. / .- / -.-. .... .. -. . ... . / -... .- -.- . .-. -.--]

9. [.-.. .. -.- . / - .... . / .-. .. ...- . .-. / ..-. .-.. --- .-- / .. -. - --- / - .... . / ... . .- / ... --- -- . - .... .. -. --. / .- .-. . / .--- ..- ... - / -- . .- -. - / - --- / -... .]

10. [-- .- -. ... / -- .. -. -.. / --- -. -.-. . / ... - .-. . - -.-. .... . -.. / -... -.-- / .- / -. . .-- / .. -.. . .- / -. . ...- . .-. / .-. . --. .- .. -. ... / .. - ... / --- .-. .. --. .. -. .- .-.. / -.. .. -- . -. ... .. --- -. ...]

11. [-- . -.. .. - .- - .. --- -. / .-- .. - .... / .- -. / --- .-.. -.. / . -. . -- -.-- / .. ... / .- -.. ...- .. ... . -..]

12. [-. . ...- . .-. / ..-. . .- .-. / - .... . / . -. -.. / --- ..-. / ... --- -- . - .... .. -. --. / -- .- .-. -.- ... / - .... . / ... - .- .-. - / --- ..-. / ... --- -- . - .... .. -. --. / -. . .--]

13. [.--. . .-. .... .- .--. ... / -.-- --- ..- ...- . / -... . . -. / ..-. --- -.-. ..- ... .. -. --. / - --- --- / -- ..- -.-. .... / --- -. / ... .- ...- .. -. --.]

14. [... .- ...- --- .-. / -.-- --- ..- .-. / ..-. .-. . . -.. --- -- / .. - / .. ... / .--. .-. . -.-. .. --- ..- ...]

15. [... - .- -.-- .. -. --. / -.-. .-.. --- ... . / - --- / .... --- -- . / .. ... / --. --- .. -. --. / - --- / -... . / -... . ... - / ..-. --- .-. / -.-- --- ..- .-. / -- --- .-. .- .-.. . / - --- -.. .- -.--]

16. [-.-- --- ..- / .- .-. . / --. . -. . .-. --- ..- ... / - --- / .- -. / . -..- - .-. . -- . / .- -. -.. / .- .-.. .-- .- -.-- ... / - .... .. -. -.- / --- ..-. / - .... . / --- - .... . .-. / ..-. . .-.. .-.. --- .--]

17. [-.-- --- ..- / .... .- ...- . / .- -. / ..- -. ..- ... ..- .- .-.. / . --.- ..- .. .--. -- . -. - / ..-. --- .-. / ... ..- -.-. -.-. . ... ... / ..- ... . / .. - / .--. .-. --- .--. . .-. .-.. -.--]

18. [-.-- --- ..- / ... .... --- ..- .-.. -.. / .--. .- -.-- / ..-. --- .-. / - .... .. ... / -.-. .... . -.-. -.- / -... . / --. . -. . .-. --- ..- ...]

19. [-.-- --- ..- / .-- .. .-.. .-.. / -... . / .- / --. .-. . .- - / ... ..- -.-. -.-. . ... ... / -... --- - .... / .. -. / - .... . / -... ..- ... .. -. . ... ... / .-- --- .-. .-.. -.. / .- -. -.. / ... --- -.-. .. . - -.--]

20. [-.-- --- ..- .-. / -.. .-. . .- -- ... / .- .-. . / -. . ...- . .-. / ... .. .-.. .-.. -.-- / -.. . .--. . -. -.. / --- -. / - .... . -- / - --- / --. ..- .. -.. . / -.-- --- ..-]

21. [-.-- --- ..- .-. / .. -. ..-. .. -. .. - . / -.-. .- .--. .- -.-. .. - -.-- / ..-. --- .-. / .--. .- - .. . -. -.-. . / .-- .. .-.. .-.. / -... . / .-. . .-- .- .-. -.. . -.. / ... --- --- -. . .-. / --- .-. / .-.. .- - . .-.]

22. [-.-- --- ..- .-. / -- . -. - .- .-.. .. - -.-- / .. ... / .- .-.. . .-. - / .--. .-. .- -.-. - .. -.-. .- .-.. / .- -. -.. / .- -. .- .-.. -.-- - .. -.-. .- .-..]

23. [-.-- --- ..- .-. / -- --- --- -.. ... / ... .. --. -. .- .-.. / .- / .--. . .-. .. --- -.. / --- ..-. / -.-. .... .- -. --. .]

24. [..-. .. .-. ... - / - .... .. -. -.- / --- ..-. / .-- .... .- - / -.-- --- ..- / .-- .- -. - / - --- / -.. --- / - .... . -. / -.. --- / .-- .... .- - / -.-- --- ..- / .... .- ...- . / - --- / -.. ---]

25. [.- -.. ...- . -. - ..- .-. . / -.-. .- -. / -... . / .-. . .- .-.. / .... .- .--. .--. .. -. . ... ...]

26. [... ..- -.-. -.-. . ... ... / .. ... / --. --- .. -. --. / ..-. .-. --- -- / ..-. .- .. .-.. ..- .-. . / - --- / ..-. .- .. .-.. ..- .-. . / .-- .. - .... --- ..- - / .-.. --- ... ... / --- ..-. / . -. - .... ..- ... .. .- ... --]

|
|-
|OPEN -> HUH (if after something other than "FORTUNE")
|[--- .--. . -.] -> [.... ..- ....]
|}

===ENCABULATOR===

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|STATUS -> RADIO ONLINE, MOTOR ONLINE, UNILATERAL PHASE DETRACTOR UNPOWERED, CARDINAL GRAMMETER UNSYNCHRONIZED
|[... - .- - ..- ...] -> [.-. .- -.. .. --- / --- -. .-.. .. -. . --..-- / -- --- - --- .-. / --- -. .-.. .. -. . --..-- / ..- -. .. .-.. .- - . .-. .- .-.. / .--. .... .- ... . / -.. . - .-. .- -.-. - --- .-. / ..- -. .--. --- .-- . .-. . -.. --..-- / -.-. .- .-. -.. .. -. .- .-.. / --. .-. .- -- -- . - . .-. / ..- -. ... -.-- -. -.-. .... .-. --- -. .. --.. . -..]
|
|-
|YOUTUBE -> RXJKDH1KZ0W
|[-.-- --- ..- - ..- -... .]
|This represents the video ID for [https://youtu.be/RXJKdh1KZ0w Rockwell Retro Encabulator]
|-
|REPAIR ''or'' ENCABULATOR ''or'' FIX ''or'' SYSTEM -> ENTERING ENCABULATOR RECOVERY SYSTEM. OPTIONS 1 INITIATE SIDE FUMBLING 2 ALIGN SPURVING BEARINGS 3 REVERSE TREMIE PIPE
:1 -> SIDE FUMBLING DETECTED. MODIAL INTERACTION UNSTABLE. RECOVERY TERMINATED.
:2 -> MODIAL INTERACTION INITIATED. OPTIONS 1 UNWIND LOTUS O DELTOID 2 INCREASE DEPLENERATION 3 CONNECT GIRDLESPRING ON DOWN END OF GRAMMETER 4 CONNECT SEVENTH CONDUCTOR TO GIRDLESPRING
::1 -> SIDE FUMBLING DETECTED. MODIAL INTERACTION UNSTABLE. RECOVERY TERMINATED.
::2 -> DEPLENERATION PREVENTED BY DINGLE ARM
::3 -> SIDE FUMBLING DETECTED. MODIAL INTERACTION UNSTABLE. RECOVERY TERMINATED.
::4 -> PANAMETRIC FAN ACTIVATED. MODIAL INTERACTION STABLE. DEFAULT CONFIGURATION MISSING. MANUALLY ENTER MARZELVANE TYPE TO COMPLETE RECOVERY
:::HYDROCOPTIC -> RECOVERY SUCCESSFUL. REBOOT Y N?
::::Y -> (''Opens [https://imgs.xkcd.com/comics/sojourner_repaired.png sojourner_repaired.png]'')
:3 -> ERROR TREMIE PIPE NONREVERSIBLE
|[.-. . .--. .- .. .-.] ''or'' [. -. -.-. .- -... ..- .-.. .- - --- .-.] ''or'' [..-. .. -..-] ''or'' [... -.-- ... - . --] -> [. -. - . .-. .. -. --. / . -. -.-. .- -... ..- .-.. .- - --- .-. / .-. . -.-. --- ...- . .-. -.-- / ... -.-- ... - . -- .-.-.- / --- .--. - .. --- -. ... / .---- / .. -. .. - .. .- - . / ... .. -.. . / ..-. ..- -- -... .-.. .. -. --. / ..--- / .- .-.. .. --. -. / ... .--. ..- .-. ...- .. -. --. / -... . .- .-. .. -. --. ... / ...-- / .-. . ...- . .-. ... . / - .-. . -- .. . / .--. .. .--. .]
:[.----] -> [... .. -.. . / ..-. ..- -- -... .-.. .. -. --. / -.. . - . -.-. - . -.. .-.-.- / -- --- -.. .. .- .-.. / .. -. - . .-. .- -.-. - .. --- -. / ..- -. ... - .- -... .-.. . .-.-.- / .-. . -.-. --- ...- . .-. -.-- / - . .-. -- .. -. .- - . -.. .-.-.-]
:[..---] -> [-- --- -.. .. .- .-.. / .. -. - . .-. .- -.-. - .. --- -. / .. -. .. - .. .- - . -.. .-.-.- / --- .--. - .. --- -. ... / .---- / ..- -. .-- .. -. -.. / .-.. --- - ..- ... / --- / -.. . .-.. - --- .. -.. / ..--- / .. -. -.-. .-. . .- ... . / -.. . .--. .-.. . -. . .-. .- - .. --- -. / ...-- / -.-. --- -. -. . -.-. - / --. .. .-. -.. .-.. . ... .--. .-. .. -. --. / --- -. / -.. --- .-- -. / . -. -.. / --- ..-. / --. .-. .- -- -- . - . .-. / ....- / -.-. --- -. -. . -.-. - / ... . ...- . -. - .... / -.-. --- -. -.. ..- -.-. - --- .-. / - --- / --. .. .-. -.. .-.. . ... .--. .-. .. -. --.]
::[.----] -> [... .. -.. . / ..-. ..- -- -... .-.. .. -. --. / -.. . - . -.-. - . -.. .-.-.- / -- --- -.. .. .- .-.. / .. -. - . .-. .- -.-. - .. --- -. / ..- -. ... - .- -... .-.. . .-.-.- / .-. . -.-. --- ...- . .-. -.-- / - . .-. -- .. -. .- - . -.. .-.-.-]
::[..---] -> [-.. . .--. .-.. . -. . .-. .- - .. --- -. / .--. .-. . ...- . -. - . -.. / -... -.-- / -.. .. -. --. .-.. . / .- .-. --]
::[...--] -> [... .. -.. . / ..-. ..- -- -... .-.. .. -. --. / -.. . - . -.-. - . -.. .-.-.- / -- --- -.. .. .- .-.. / .. -. - . .-. .- -.-. - .. --- -. / ..- -. ... - .- -... .-.. . .-.-.- / .-. . -.-. --- ...- . .-. -.-- / - . .-. -- .. -. .- - . -.. .-.-.-]
::[....-] -> [.--. .- -. .- -- . - .-. .. -.-. / ..-. .- -. / .- -.-. - .. ...- .- - . -.. .-.-.- / -- --- -.. .. .- .-.. / .. -. - . .-. .- -.-. - .. --- -. / ... - .- -... .-.. . .-.-.- / -.. . ..-. .- ..- .-.. - / -.-. --- -. ..-. .. --. ..- .-. .- - .. --- -. / -- .. ... ... .. -. --. .-.-.- / -- .- -. ..- .- .-.. .-.. -.-- / . -. - . .-. / -- .- .-. --.. . .-.. ...- .- -. . / - -.-- .--. . / - --- / -.-. --- -- .--. .-.. . - . / .-. . -.-. --- ...- . .-. -.--]
:::[.... -.-- -.. .-. --- -.-. --- .--. - .. -.-.] -> [.-. . -.-. --- ...- . .-. -.-- / ... ..- -.-. -.-. . ... ... ..-. ..- .-.. .-.-.- / .-. . -... --- --- - / -.-- / -. ..--..]
::::[-.--]
:[...--] -> [. .-. .-. --- .-. / - .-. . -- .. . / .--. .. .--. . / -. --- -. .-. . ...- . .-. ... .. -... .-.. .]
|
|-
|}

===MAZE===

{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|RETURN -> DID YOU MEAN ENTER
|[.-. . - ..- .-. -.]
|
|-
|ENTER -> DID YOU MEAN ENTER MAZE
|[. -. - . .-.]
|
|-
|ENTER MAZE -> AN EMPTY ROOM
:LOOK -> AN EMPTY ROOM
:HELP -> NORTH EAST SOUTH WEST GET
:EXIT -> CFM (''Exits the maze'')
|[. -. - . .-. / -- .- --.. .] -> [.- -. / . -- .--. - -.-- / .-. --- --- --]
:[.-.. --- --- -.-] -> [.- -. / . -- .--. - -.-- / .-. --- --- --]
:[.... . .-.. .--.] -> [-. --- .-. - .... / . .- ... - / ... --- ..- - .... / .-- . ... - / --. . -]
:[. -..- .. -] -> [-.-. ..-. --]
|
|}
{| class="wikitable"
|+ Maze
|-
|an open flame || a candle on a table || style="background-color: black;" |
|-
| style="background-color: black;" | || an empty room (start) || style="background-color: black;" |
|-
| style="background-color: black;" | || a hanging bell || an open book on a table (locked door)
|-
|}

Steps to complete (directions can be abbreviated as their first letter):
# NORTH
# GET CANDLE -> TAKEN
# WEST
# LIGHT CANDLE
# EAST
# SOUTH
# SOUTH
# RING BELL -> A DOOR OPENS
# EAST
# CLOSE BOOK -> CONGRATULATIONS YOU ESCAPE

===CROSSWORD===
{| class="wikitable"
! Message & response
! Morse Code
! Explanation
|-
|CROSSWORD -> NUMBER AND DIRECTION
|[-.-. .-. --- ... ... .-- --- .-. -..] -> [-. ..- -- -... . .-. / .- -. -.. / -.. .. .-. . -.-. - .. --- -.]
|This starts a crossword. You can ask for hints like "1 down" or "2 across". It appears to be the [https://rexwordpuzzle.blogspot.com/2021/04/libertarian-politico-johnson-thu-4-1-21.html New York Times Crossword] from the day this comic was written (2021-04-01).
|}

{| class="wikitable"
|+Solved Crossword
|-
| m || y || g || o || d || style="background-color: black; | || d || e || v || style="background-color: black; | || style="background-color: black; | || style="background-color: black; | || e || l || f
|-
| b || u || o || n || o || style="background-color: black; | || e || y || e || s || style="background-color: black; | || s || l || u || r
|-
| a || m || o || c || o || style="background-color: black; | || c || r || a || p || style="background-color: black; | || l || m || a || o
|-
| style="background-color: black; | || style="background-color: black; | || v || e || r || y || r || e || l || i || g || i || o || u || s
|-
| s || e || e || style="background-color: black; | || m || u || y || style="background-color: black; | || style="background-color: black; | || r || a || m || style="background-color: black; | || style="background-color: black; | || style="background-color: black; |
|-
| h || a || r || h || a || r || style="background-color: black; | || s || c || a || r || e || d || o || f
|-
| e || s || s || e || n || t || i || a || l || l || y || style="background-color: black; | || a || r || i
|-
| b || t || e || n || style="background-color: black; | || style="background-color: black; | || m || m || i || style="background-color: black; | || style="background-color: black; | || t || v || a || d
|-
| o || l || a || style="background-color: black; | || b || a || d || m || o || u || t || h || i || n || g
|-
| p || a || s || s || e || d || b || y || style="background-color: black; | || n || o || o || d || g || e
|-
| style="background-color: black; | || style="background-color: black; | || style="background-color: black; | || o || a || r || style="background-color: black; | || style="background-color: black; | || s || u || n || style="background-color: black; | || l || e || t
|-
| b || l || e || n || d || e || d || f || a || m || i || l || y || style="background-color: black; | || style="background-color: black; |
|-
| b || o || r || g || style="background-color: black; | || p || e || l || t || style="background-color: black; | || g || e || n || r || e
|-
| q || u || i || z || style="background-color: black; | || s || p || a || y || style="background-color: black; | || h || i || c || k || s
|-
| s || t || e || style="background-color: black; | || style="background-color: black; | || style="background-color: black; | || p || b || r || style="background-color: black; | || t || a || h || o || e
|}

{| class="wikitable mw-collapsible mw-collapsed"
|+ Words
! index !! down word !! across word
|-
| 1 || MBA || MYGOD
|-
| 2 || YUM ||
|-
| 3 || GOOVERSEAS ||
|-
| 4 || ONCE ||
|-
| 5 || DOORMAN ||
|-
| 6 || DECRY || DEV
|-
| 7 || EYRE ||
|-
| 8 || VEAL ||
|-
| 9 || ELMO || ELF
|-
| 10 || LUAU ||
|-
| 11 || FROS ||
|-
| 12 || || BUONO
|-
| 13 || || EYES
|-
| 14 || SPIRAL ||
|-
| 15 || SLIME || SLUR
|-
| 16 || || AMOCO
|-
| 17 || || CRAP
|-
| 18 || || LMAO
|-
| 19 || || VERYRELIGIOUS
|-
| 20 || YURT ||
|-
| 21 || GARY ||
|-
| 22 || SHEBOP || SEE
|-
| 23 || EASTLA ||
|-
| 24 || || MUY
|-
| 25 || || RAM
|-
| 26 || || HARHAR
|-
| 27 || HEN ||
|-
| 28 || SAMMY || SCAREDOF
|-
| 29 || CLIO ||
|-
| 30 || DAVIDLYNCH ||
|-
| 31 || ORANGE ||
|-
| 32 || FIDGET ||
|-
| 33 || || ESSENTIALLY
|-
| 34 || IMDB ||
|-
| 35 || || ARI
|-
| 36 || || BTEN
|-
| 37 || || MMI
|-
| 38 || THO || TVAD
|-
| 39 || || OLA
|-
| 40 || BEAD || BADMOUTHING
|-
| 41 || ADREPS ||
|-
| 42 || UNUM ||
|-
| 43 || TONIGHT ||
|-
| 44 || || PASSEDBY
|-
| 45 || SONGZ ||
|-
| 46 || || NOODGE
|-
| 47 || || OAR
|-
| 48 || SATYR || SUN
|-
| 49 || || LET
|-
| 50 || BBQS || BLENDEDFAMILY
|-
| 51 || LOUT ||
|-
| 52 || ERIE ||
|-
| 53 || DEPP ||
|-
| 54 || FLAB ||
|-
| 55 || LEIA ||
|-
| 56 || || BORG
|-
| 57 || || PELT
|-
| 58 || || GENRE
|-
| 59 || RKO ||
|-
| 60 || ESE ||
|-
| 61 || || QUIZ
|-
| 62 || || SPAY
|-
| 63 || || HICKS
|-
| 64 || || STE
|-
| 65 || || PBR
|-
| 66 || || TAHOE
|}

===Rover Scene===
After successfully repairing and rebooting Sojourner, a comic is opened which depicts it seeking out and finding its friends, Spirit, Opportunity, Curiosity, Perseverance, and Ingenuity. Curiosity and Perseverance are locked in a swordfight, and either Spirit or Opportunity is carried off by Ingenuity while the other speeds off a small mound of dirt. Ingenuity carrying a rover is a reference to the previous comic.

==Special Console Commands==
The page's JavaScript creates a global object <code>morse</code> with <code>encode</code> and <code>decode</code> methods. From the developer console, it is possible to write <code>morse.encode("A PHRASE")</code>, which will print the Morse code corresponding to the text provided, or <code>morse.decode("... --- ...")</code> which will translate the Morse code to text.

<code>BeepComic.hurryUp()</code> to get the reply immediately in the console.
<code>BeepComic.send(...)</code> to send directly to SOJOURNER.

==Transcript==
:[A small box is in the middle of a large white frame. The box can have a check-mark, but it is alternating between being checked or unchecked. At the bottom right there is a muted speaker (which can be unmuted). If the user press the checkbox gray dots or lines will appear below depending on the length of the press. These will move from right to left and then disappear.]

{{comic discussion}}

[[Category:April fools' comics]]
[[Category:Interactive comics]]
[[Category:Comics with animation]]
[[Category:Dynamic comics]]
[[Category:Comics with audio]]

2377: xkcd Phone 12

2022-06-28T10:51:28Z

Rsge: (Hopefully) improved reading flow

{{comic
| number = 2377
| date = October 26, 2020
| title = xkcd Phone 12
| image = xkcd_phone_12.png
| titletext = New phone OS features: Infinite customization (home screen icons no longer snap to grid), dark mode (disables screen), screaming mode (self-explanatory), and coherent ultracapacitor-pumped emission (please let us know what this setting does; we've been afraid to try it).
}}

==Explanation==
This is the "12th" (actually the 8th) in the ongoing [[:Category:xkcd Phones|xkcd Phone]] series in which Randall explains his new joke phone designs with many strange and useless features. It is also a reference to the recently released {{w|iPhone 12}}. However, there have only been 8 comics released, with the previous two being [[2000: xkcd Phone 2000]] and [[1889: xkcd Phone 6]].

The note about the xkcd Phone 12 and the xkcd Phone 12 Max (only for people named Max) is a joke about the different models of iPhone 12: iPhone 12, iPhone 12 Mini, iPhone 12 Pro and iPhone 12 Pro Max. The xkcd Phone 12 Max would be expected to have a larger screen, but it seems that this phone is also only for people with the name Max. If the phones are respectively placed, Max's (Maxes'?) phone is the smaller of the two models.

The slogan '"The only phone you'll ever own"' could be interpreted as something of a threat, which is believable given some of the purported features. It is similar to the phrase ''"The last suit you'll ever wear"'', describing the black suits worn by the Men In Black in the movie of the same name. The slogan has the "registered trademark" symbol, with that symbol supposedly itself trademarked, which is highly unlikely.

Multiple features are labelled on the phone that are common when advertising other products, but highly unusual in mobile phones, for comedic effect:

* '''Full drivetrain warranty''' — A common warranty feature for automobiles — see {{w|drivetrain}}. As a side note, the phone here would be cheaping out on the warranty if it were a car; a "drivetrain" warranty covers almost everything ''except'' the engine; only if it was a "{{w|powertrain}}" warranty would it cover the engine. A phone typically has none of these things, although this one seemingly does.
* '''Coated for easy swallowing''' — A common feature on solid medicines meant to be taken orally. Phones do not belong in the set of edible objects, much less orally-taken medicines{{Citation needed}}. Since some parents of young children let them teethe on their phones, this would be an undesirable feature. Since these coatings tend to be lubricants, it's also possible this "feature" makes the phone harder to hold. There may be a pun here, based on the larger smartphones being practically the same as the more {{w|Tablet_computer|minimal portable computers}}.
* '''Surgical-grade apps''' — "Surgical-grade steel" is sometime used as a selling point indicating quality materials. This feature suggests that the apps themselves are made from high-quality material, although this is absurd because an app is (as the name suggests) a software application, not any physical object that could be reasonably defined as 'surgical-grade' or not. Note that both hardware and software can be certified for {{w|Safety-critical_system|safety-critical applications}}.
* '''Built-in 600 lb magnet for magnet fishing''' — {{w|Magnet fishing}} is an activity for searching for objects that can be pulled in by a strong magnet. A 600 pound magnet can lift a 600 pound (272 kg) object (at Earth's surface). This would tend to make the phone stick to any iron or steel objects (such as refrigerators) and be impossible to remove with human strength, and only the strongest humans could pick up the phone even if it were properly insulated. It would also be impossible to separate two phones without destroying one of them if the interlocking feature were used. This feature would also erase any credit cards the owner puts in the vicinity of the phone, meaning this phone could not be put in one's pocket with a wallet. There is also a possibility that this is a reference to Apple’s {{w|MagSafe}} accessory.
* '''Oral-B partnership: hold phone against teeth to ultrasonically remove plaque''' — This is a reference to {{w|ultrasonic toothbrush}}es. {{w|Oral-B}} does not produce any ultrasonic toothbrushes, but does produce ''{{w|sonic toothbrush}}es.'' There is a logical connection between electric toothbrushes and smartphones, namely they are both electronic and both vibrate; however, most phones cannot perform dentistry autonomously{{Citation needed}}.
* '''40 mL emergency water supply''' — 40 milliliters is equal to 40 cubic centimeters. For comparison, the iPhone 11 Pro Max's volume is just shy of 100 cubic centimeters; if the Phone 12 Max is similarly sized, then the water supply would take up over 40% of its total volume. In this day and age, many phones are water-resistant to some degree; nevertheless, shipping a phone with an interior consisting of a 3:2 ratio of electronics-to-water will surely lead to many short-circuited, inoperable phones. Furthermore, {{w|survival kit}}s often come with pouches that can hold several liters of water, in case of emergency. Because people typically take their phones with them everywhere they go, storing a survival kit inside the phone would be a life-saving feature. Unfortunately, 40cc of water is not enough to stave off thirst for a meaningful amount of time, extinguish a flame much larger than a candle's, or deal with most other situations which would constitute an emergency. Unless you are suitably proficient at {{w|Katara_(Avatar:_The_Last_Airbender)#Waterbending|waterbending}}, this feature is useless for its intended function. 40 milliliters is also the amount of fluid that a shot glass holds.
* '''Security feature: unmarked side buttons''' — Some vendors (particularly car dealers) try to explain away questionable User Interface decisions as "Security Features". Technically, if everyone (including the owner) has difficulty using it, it is secure... Here, no buttons are visible which could indicate they are, in fact, simply a touch sensitive surface, which would certainly be difficult to use as users would have to guess the area they should touch to use these "buttons". This might be a reference to a feature present in iPhone 12s where one can double-tap on the back to do a set action, which some websites have called a "[https://metro.co.uk/2020/10/28/how-to-find-the-secret-button-on-the-iphone-12-13493472/ secret button]".
* '''3,000,000-volt arc allows wireless charging from a range of up to 36 inches''' — {{w|Inductive charging|Induction charging}} is a method that a number of modern phones advertise, allowing power to (inefficiently but 'conveniently') transfer into a device from a mains charging station or another device's battery without the need for plugging in cables. It transfers energy between safely tuned coils, that do not touch, though typically the case of one device must remain placed directly upon the other for the optimal transfer of charge between them. An electric arc can also be used to transfer electrical energy through the air through a lightning-like discharge. While arcs can transfer large amounts of energy quickly, the plasma generated would be very dangerous and damaging to the phone, charger, and immediate vicinity. The {{w|electrical breakdown}} voltage of air is approximately 3 kV / mm, which would allow a 3 MV potential to jump a distance of 100 cm (40 inches). 36 inches (91 cm), however, is within reach of a simple extension cord. {{w|Electrical_injury#Lethality|Shocks of 11,000 volts are usually lethal}}, so 3,000,000 volts of electricity (possibly from a complete {{w|Tesla coil}} assemblage) would require considerable protection.
* '''99.9% BPA- and hands- free''' — {{w|Bisphenol A}} (or BPA) is a compound that is used in making plastics. BPA has been found to exhibit hormone-like properties, so there is a movement to produce BPA-free plastics using alternative bisphenols. {{w|Hands-free}} describes using the device "without hands", e.g. using voice commands. This is important when using a device while driving. These are 2 unrelated ideas, which use the suffix "free" in different meanings ("BPA-free" means "containing no BPA", while "hands-free" means "your hands need not be used"). The construction "NOUN- and NOUN-ADJ" is normally only used with the meaning of "ADJ" repeated for both nouns, implying that this phone "contains no hands" (or possibly "your BPA is left free"). The "percentage free" description is also a standard form of advertising {{w|weasel word}}s, as remarked by Randall in [[641: Free]]. A food might be described as "90% fat-free" with the heavy implication that it has a tenth of the usual fat content, but likely really means "10% of the product is pure fat" (typically by weight or maybe pre-cooked volume) compared with perhaps 15% in the typical non-'fat-free' recipe. 0.1% of BPA is not an insignificant quantity given its possible effects, and is likely to be a higher leachable content if it is all concentrated in external trimmings. It is unclear what a tenth of a percent of a hand needs to do, to operate the device, but it does also mean that it is not as completely hands-free as implied. Or else it ''also'' implies that up to 0.1% of the phone contains ingredients sourced from human hands. At best, this could be skin cells from the workers (although phone assembly lines ''should'' be kept meticulously clean, to prevent damage to delicate components), or at worst, some workers could be losing hands into the assembly line due to poor safety practices.
* '''Extended release charge cable''' — Electronics manufacturers support standards to reduce time to fully recharge, e.g. Qualcomm {{w|Quick Charge}} standard. This is a reference to {{w|Modified-release dosage|"extended release" medication}}. It's unclear what purpose would be served by charging a phone slower than normal.
* '''Closed timelike curves''' — This label is applied to the curved corner of the phone. Randall may be making a visual joke by referring to the corner of the phone by a relativistic concept. {{w|Closed timelike curves}} is a world line in spacetime that is "closed", in that an object following that world line will return to its starting point in spacetime, which implies that the object would be able to go back in time. It could also be a reference to the [https://www.bloomberg.com/news/articles/2020-04-13/apple-plans-ipad-like-design-for-next-iphone-smaller-homepod|''Bloomberg'' leaks] that predicted the sharper corners of the iPhone 12, the phone model this is designed on.
* '''Fits in standard shipping container''' - An {{w|intermodal shipping container}} is large enough to fit automobiles, raising the question of just how big this xkcd phone is. Other standard "containers" used for shipping items might be things like the FedEx, UPS, and USPS boxes, which often come in various sizes (small, medium, large) as well as their shipping envelopes, all of which could easily hold just about any phone that's out there.
* '''Interlocking, stackable''' — A quality of, among other things, LEGO bricks. Probably a bad idea to use this feature, given how close the phone is to critical mass. There are electronic boards designed for interlocking and stacking, such as {{w|Arduino}} and {{w|Raspberry Pi}} computers, which can have other boards attached to them (shields, hats) to add functionality, however it's unclear what advantage there would be to stacking multiple identical phones together.
* '''Nintendo partnership: GameBoy Printer compatibility''' — The {{w|Game Boy Printer}} was a thermal paper printer originally paired with the {{w|Game Boy Camera}}. This device was released in 1998 and discontinued in 2003, so this partnership would be obsolete.
* '''Sustain pedal''' — A {{w|sustain pedal}} is commonly associated with a digital keyboard or piano; it lets the note continue sounding when the key is released. It's unclear what purpose it would serve in a phone, although it might be used for the screaming mode in the title text.
* '''CDC partnership: when in an indoor space with too many people, phone begins playing "We Like To Party! (The Vengabus)" at slowly increasing volume until everyone leaves''' — An allusion to the COVID-19 pandemic. CDC stands for Centers for Disease Control and Prevention, the United States public health institute. In [[2284: Sabotage]], Randall "promised" to bring an annoying karaoke song to a party to hopefully discourage people from attending, but this phone will apparently do so automatically. "{{w|We Like to Party! (Vengaboys song)|We Like To Party! (The Vengabus)}}" is a 1998 Eurodance/techno hit by the Vengaboys, and is perhaps most familiar to Americans from a series of {{w|Six Flags}} ads.
* '''Sacrificial anode''' — Useful if something metal will be in a wet environment for a long time. Commonly used on bridges and boats, but it may be a 'feature' of this phone because of its built-in water reservoir. The {{w|sacrificial anode}} is made of a material with higher redox potential (typically zinc), and will corrode faster than the (more valuable) metal object it's attached to. It's unclear if the phone HAS a sacrificial anode or IS a sacrificial anode.
* '''Tactical helium reserve''' — Since 1925, the United States has had a {{w|National Helium Reserve|strategic helium reserve}}. Helium is very rare on earth and has important scientific and military uses, so it’s important to have a supply in case supplies disappear. But here we have a tactical helium reserve, which suggests it's smaller and focused on shorter-term goals. Compare {{w|strategic bombing}} focused on destroying entire cities or countries and {{w|tactical bombing}} aimed at destroying individual targets or military units. Helium also has the property of being lighter than air, so if this reserve is large enough, the phone could float away if let go. However, this is unlikely, as the phone boasts other, heavy components such as large magnets, a water reserve and a critical mass of fissile material.
* '''50% below critical mass (2x safety factor)''' — Indicates the phone contains fissile material. This "2x safety factor" means that if you put 2 phones next to each other, or put one phone next to a {{w|neutron reflector}}, you would have a {{w|criticality accident}}, which may explain why you would not own another phone after this one. A phone with this much fissile material would pose a radiation hazard. The "2x safety factor" claim may be related to physicist {{w|Richard Feynman|Richard Feynman's}} famous criticism of NASA in the {{w|Rogers Commission}} report on the space shuttle Challenger disaster. Feynman found that when he confronted NASA engineers with a part worn one third of the way through, which was not supposed to be worn through at all, the engineers claimed that this demonstrated a 3x safety factor rather than a failure of the part. This could mean that using the phone is harmful for some other reason (social media addiction?) but the xkcd phone has half as many users as it would need to cause a problem in this way.
* '''Shake for factory reset''' — A {{w|factory reset}} is often possible on electronic devices, and is usually accomplished either by pressing a button that is often well-protected against accidental contact, for an extended period or closing an electrical bridge. This one works like an {{w|Etch A Sketch|Etch-a-Sketch}}, which would not be preferred, as [http://www.ahajokes.com/com045.html slight disturbances] could easily cause massive losses of data. In the other hand, given that it weighs at least 600 lbs, it will probably not be shaking due to a user intentionally trying to delete their data.
* '''Norton MacAfee protection: if you're ever attacked by John MacAfee, Peter Norton will come out of retirement to defend you''' — {{w|Norton (software)|Norton}} and {{w|McAfee}} (note spelling!) are competing software security companies, founded by {{w|Peter Norton}} and {{w|John McAfee}} respectively (though neither has any involvement with their name-sake companies any more). This "protection" combines the two of them and claims that Norton (the person) will defend you if McAfee (the person) attacks you. May have been inspired by [https://www.nytimes.com/2020/10/06/business/mcafee-arrested-tax-evasion.html John McAfee's recent arrest] which brought attention to the allegation that he had hired a hit man to kill his neighbor in Belize in 2012.

The title text mentions xkcd phone OS updates, including:
* '''Infinite customization (home screen icons no longer snap to grid)''' — iOS 14 offers new features such as widgets on the home screen and changing of app icons, allowing for customization on a level not seen before on the platform. Here though, the "customization" hinges on a technicality, specifically of permutations: On a phone with, say, one million pixels, the number of ways one can place 20 icons is P(1000000,20)=9.998x10^119, an absolutely enormous number, but most people would not call two home screens where the only difference is that one icon is one pixel over a different configuration. Plus, not being able to snap the icons to a grid would be incredibly unsatisfying, as it would make it very difficult to get icons lined up with each other.
* '''Dark mode (disables screen)''' — Dark mode is a popular feature on websites/apps with light backgrounds like Twitter and Reddit, changing the background to a dark color to help late-night users sleep better. Disabling the screen would not be a pleasant surprise when a user goes to turn on beloved dark mode. May be impossible to turn off if the screen is no longer touch sensitive when darkened unless the unmarked buttons can be used to disable it. Also a possible reason to want to use the shake-activated factory reset.
* '''Screaming mode (self-explanatory)''' — The phone screams. Reference to the screaming-while-falling [[1363: xkcd Phone|xkcd Phone 1]].
* '''Coherent ultracapacitor-pumped emission (please let us know what this setting does; we've been afraid to try it)''' - This mysterious feature has a terrifying name, with even the developers refusing to test it out. This option would probably be very easy to accidentally tap, given the style of every xkcd Phone ever. Possibly activated with one of the unlabeled buttons making it even more dangerous. Coherent Emission is associated with lasers, and a {{w|Helium-neon laser|common type of laser}} uses helium and neon to generate the beam, which could justify the helium reserve. {{w|Ultracapacitor}}s store a large amount of energy than can be discharged very quickly. The feature described is then probably some sort of very high power pulse laser. Raises the question of [[Beret Guy|who]] designs the phone if the people marketing it don't know what it does, or what purpose [[Black Hat|someone]] may use it for.

==Transcript==
:[The comic shows two smartphones: one taller and wider than the other. ]

:[Labels to the left of the larger smartphone:]
* Full drivetrain warranty
* Coated for easy swallowing
* Surgical-grade apps
* Built-in 600 lb magnet for magnet fishing
* Oral-B partnership: hold phone against teeth to ultrasonically remove plaque
* 40 mL emergency water supply
* Security feature: unmarked side buttons
* 3,000,000-volt arc allows wireless charging from a range of up to 36 inches
* 99.9% BPA- and hands- free
* Extended release charge cable
* Closed timelike curves

:[Labels to the right of the larger smartphone:]
* Fits in standard shipping container
* Interlocking, stackable

:[Labels to the right of the smaller smartphone:]
* Nintendo partnership: GameBoy Printer compatibility
* Sustain Pedal
* CDC partnership: when in an indoor space with too many people, phone begins playing "We Like To Party! (The Vengabus)" at slowly increasing volume until everyone leaves
* Sacrificial anode
* Tactical helium reserve
* 50% below critical mass (2x safety factor)
* Shake for factory reset
* Norton MacAfee protection: if you're ever attacked by John MacAfee, Peter Norton will come out of retirement to defend you

:[Text below the phone:]
:<big>The xkcd Phone 12* and 12 Max**</big>

:<nowiki>*Standard</nowiki> **For people named Max

:"The only phone you'll ever own"®™

{{comic discussion}}
[[Category:xkcd Phones]]
[[Category:Comics sharing name|xkcd Phones]]
[[Category:Comics featuring real people]]

2358: Gravitational Wave Pulsars

2022-06-28T08:31:48Z

Rsge: Fixed sentence structure

{{comic
| number = 2358
| date = September 11, 2020
| title = Gravitational Wave Pulsars
| image = gravitational_wave_pulsars.png
| titletext = The most important attributes of a vector in 3-space are {Location, Location, Location}
}}

==Explanation==
{{w|Pulsars}} are rotating neutron stars, which have a very precise period of rotation. Pulsars are highly magnetized, causing them to emit a beam of electromagnetic radiation that rotates across their sky. {{w|Radio astronomy|Radio astronomers}} can detect these beams if and when they point towards Earth, where they appear as pulses of radiation with highly stable periods. They use the pulsars' periodic beams to try to detect {{w|gravitational waves}} by tracking the rotation period of an ensemble of pulsars extremely precisely over long periods of time. Disturbances in the pulsars' rotation period will be measurable at Earth. A disturbance from a passing gravitational wave will have a particular signature across the ensemble of pulsars, and will be thus detected. The process is called {{w|Gravitational_wave#Using_pulsar_timing_arrays|"pulsar timing"}}, or just "timing" for short.

[[Ponytail]] presents this to [[Cueball]] as a joke - specifically, a joke about comedy. One of the most important aspects of comedy is revealing the punchline with correct timing. Ponytail sets Cueball up for a joke like, "Ask me what the secret of comedy is." / "What's the secret of--" / "Timing!" In this format, the punchline ("Timing!") deliberately comes too soon, which makes it funny because the timing is bad. Ponytail also replaces the secret to comedy with the secret to detecting gravitational waves with pulsars, to set up the joke about the word "timing".

The title text is a play on a well-known real estate saying that the three most important parts of a real estate deal are "location, location, location." In 3D {{w|Euclidean space}}, the three {{w|Cartesian coordinates}} {X, Y, Z} all refer to locations along the three axes.

==Transcript==

:[Single panel with Ponytail and Cueball standing facing each other]
:Ponytail: Ask me what the secret to detecting gravitational waves using pulsars is.

:Cueball: What's the secret to detecting grav—

:Ponytail: '''''Timing!'''''

{{comic discussion}}
[[Category: Comics featuring Ponytail]]
[[Category: Comics featuring Cueball]]
[[Category: Astronomy]]