explain xkcd - User contributions [en]

202: YouTube

2018-10-26T18:36:03Z

141.101.105.42: /* Explanation */

{{comic
| number = 202
| date = December 27, 2006
| title = YouTube
| image = youtube.png
| titletext = I pray GunPistolMan never learns the word 'sheeple'.
}}

==Explanation==

This comic is pointing out the fact that many of the comments on {{w|YouTube}} videos are insipid and poorly informed, being pointless arguments over some minor topic or factually incorrect position. At the time of this comic, YouTube was fairly new, and the comic's observation about the inanity of YouTube comments was novel. Since then, this observation has become a widely accepted truism about the Internet. In this case, the {{w|Moon landing conspiracy theories|Moon landing hoaxers}} are at the receiving end of [[Randall]]'s pen.

* The comment by ''Rocckir'' just states that the video is obviously fake, with no evidence or explanation.

* The comment by ''BigMike133'' confuses the {{w|Space Shuttle}} (which was never capable of landing on the Moon) with the {{w|Apollo Lunar Module}}.

* The comment from ''GunPistolMan'' claims that the video is fake due to the mistaken belief that the Moon would have no {{w|Gravity|gravity}}, whereas in reality, every object in the universe made of matter has gravity, including the Moon, {{w|Comet|comets}}, {{w|Asteroid|asteroids}}, {{w|Natural satellite|moons of other planets}}, and so on. The gravity of the Moon is approximately 1/6 the gravity of {{w|Earth}}.

* The comment by ''CrackMonkey74'' names {{w|Louis Armstrong}}, a famous jazz musician, who may have [http://lyrics.wikia.com/Louis_Armstrong:Moon_Song waxed] [http://www.youtube.com/watch?v=A5x8HnyIYHE lyrical] about the moon, but never went there. The ill-informed commenter actually means {{w|Neil Armstrong}}, who was the first person to walk on the Moon. The dare to accuse Armstrong to his face may be a reference to an incident where moon-hoax conspiracy theorist {{w|Bart Sibrel}} confronted {{w|Buzz Aldrin}} and called him "a coward, and a liar, and a thief." Aldrin responded by punching Sibrel; Sibrel's attempt to bring charges was dismissed on the grounds that he had provoked Aldrin to the point where the punch was a justified response.

* The comment by ''SimplePlan2009'' presents, likely mocking the other commenters, the ludicrous position that the Moon shot was faked by suggesting that the footage was filmed by actors on {{w|Mars}}, a planet that at its closest approach to Earth is over a hundred times farther away than the Moon. Landing humans on Mars (much less landing enough people and equipment to set up a soundstage) is a feat that has still not been accomplished, and if it had been possible during the Apollo era, the landing on the Moon would have been a trivial task in comparison. In other words, why go through all the trouble of faking it, if doing it for real would have been no trouble at all? This may be a reference to the Futurama film Into the Wild Green Yonder, in which Richard Nixon states that he "really did stage the moon landing... ON VENUS!"

This comic was published in December 2006. In July 2009, [https://www.youtube.com/watch?v=Vml7pZJujF0 a restored video] showing Neil Armstrong's first moonwalk was uploaded to YouTube. User Michael Huang copied to that video's comments section all the sentences in this comic. Then, after some other users took some of his comments seriously, he later added another comment stating, "This entire comment chain is from the famous webcomic, xkcd." The comments are copied verbatim, including typos and grammar errors. The only mistake is in the first comment: Michael Huang included only one question mark when the comic has three of them.

The title text is the first reference to [[:Category:Sheeple|Sheeple]], which appeared a few more times in xkcd comics. The reputation of YouTube comment threads as cesspools of abject stupidity and blatant trolling is revisited in [[301: Limerick]] and [[481: Listen to Yourself]]. The username CrackMonkey74 appears again in [[406: Venting]] and [[574: Swine Flu]].

==Transcript==
:The Internet has always had loud dumb people, but I've never seen anything quite as bad as the people who comment on YouTube videos.
:[A YouTube comments page for a moon landing video.]
:Comments & Responses
:rocckir (48 minutes ago)
:this is so obviously faked its unbilevable, why r people so gullible??? morons
:bigmike133 (35 minutes ago)
:ive seen the space shuttle ass hole it definetly landed on the moon do some research...
:GunPistolMan (22 minutes ago)
:if it was real why is their gravity? americans r fucken sheep
:crackmonkey74 (17 minutes ago)
:u dont think we went to the moon why not tell louis armstrong to his face
:simpleplan2009 (5 minutes ago)
:it was a soundstage on mars

{{comic discussion}}
[[Category:Comics with color]]
[[Category:YouTube]]
[[Category:Sheeple]]

899: Number Line

2018-10-13T02:22:54Z

141.101.105.42: /* Explanation */

{{comic
| number = 899
| date = May 16, 2011
| title = Number Line
| image = number line.png
| titletext = The Wikipedia page List of Numbers opens with "This list is incomplete; you can help by expanding it."
}}

== Explanation ==

Once again, [[Randall]] seems to be just messing around, this time with a number line.

*'''Negative numbers''' have the same magnitude as positive numbers but can only be used to represent the removal of that same magnitude (hence the term "difference" being used for subtraction).

*'''0.99'''.... is {{w|0.999...|equal to 1}} because there is no number between 0.99.... and 1. 1 − '''0.0000000372''' is 1 bit less than the {{w|IEEE_floating_point|IEEE 754 32-bit floating-point representation}} of 1.

*The '''{{w|golden ratio}}''' or '''ϕ''' (phi) is the number <math>\tfrac{1+\sqrt{5}}{2}</math>, about 1.61803. It has many interesting mathematical properties, mostly relating to geometry, and has occasional appearances in nature, such as spirals formed by the seeds in sunflowers. It is also subject to many less credible claims, such as the belief that phi appears in {{w|Parthenon}} (a well-disputed claim) or that rectangles proportioned after phi are more aesthetically pleasing.

* The approximate range from 2.1 to 2.3 is marked as '''The Forbidden Region'''. Why Randall marked this range as forbidden is really anyone's guess; it seems to be an entirely arbitrary designation.

*'''{{w|e (mathematical constant)|e}}''' (Euler's number) is 2.71828... and '''π''' (pi) is 3.14159265...

*'''2.9299372''' is a {{w|President's Day}} reference. It is the average of e and π just as the American Presidents' Day is always observed on the 3rd Monday of February (between {{w|George Washington}} and {{w|Abraham Lincoln}}'s birthdays). Washington and Lincoln were the 1st and 16th Presidents of the USA, respectively. Each has a celebrated place in American history.

*'''{{w|Gird}}''', '''ᛟ''' is a purely fictional number. (The glyph that Randall uses seems to resemble an older shape of the digit 4, such as seen on [http://www.bl.uk/learning/images/mappinghist/large2296.html archaic maps].). Canon and orthodox are references to organised religions. Gird could be a reference to any or all of:
**[http://www.strangehorizons.com/2000/20001120/secret_number.shtml Bleem] - a fictional integer between 3 and 4
**iCarly's [http://icarly.wikia.com/wiki/Derf Derf] - a fictional integer between 5 and 6
**George Carlin's [http://www.urbandictionary.com/define.php?term=bleen Bleen] - a fictional integer between 6 and 7
**[http://www.scp-wiki.net/scp-033 SCP-033] - a fictional number that causes freaky things to happen
**Saturday Morning Breakfast Cereal's [http://www.smbc-comics.com/index.php?id=3913 Sorf] - a fictional integer between 2 and 3

*'''Site of the Battle of 4.108''' is another map joke, implying that 4.108 is an actual location, where an eponymous battle was previously fought. It may be a reference (or homage) to the {{w|Battle of Wolf 359}}, a famous military conflict in the fictional universe of Star Trek.

*An '''Unexplored''' region obscures the line approximately ranging all values from from 4.5 to 6.7. In the days when the Earth was still being mapped out, territories that had yet to be properly explored and charted were labelled in a similar manner. The placement of the '''Unexplored''' region on the number line indicates that all numbers in that range, including the integers 5 and 6, are completely unknown. This is, of course, patently ridiculous, and the humor seems to derive solely from how nonsensical and unbelievable it is.

*It is often the case in the media that "It has been 7 years..." or "In the last 7 years..." etc. It is made to seem like a believable statistic but cannot always be true. Alternatively, it is intended as an absurd joke that the number 7 is just "not to be believed".

*'''8''' is not the largest even {{w|prime number}}, nor is it a prime at all. The largest (and only) even prime is 2. A joke intended for those who clearly know that the claim is false.

*The last entry seems to be a reference to certain fields of {{w|pure mathematics}}, which focus less on performing calculations with numbers and more on understanding structures that may be described using logic. It finishes off the tone of the comic that seems to be shaping the number line terms of what is commonly useful to certain areas of applied mathematics, rather than a complete, accurate version of the number line.

The title text is a literalism joke, implying that Wikipedia would like its "{{w|List of numbers}}" page to include every number from negative infinity to infinity. It could also be a reference to {{w|Gödel's incompleteness theorems}}, which [[Randall]] has used as comic fodder before in [[468: Fetishes]]. Gödel's theorems roughly assert that a number theory could never be fully complete. The equivalent for a list of numbers is {{w|Cantor's diagonal argument}}, which is a proof that any list of real numbers can never be complete even if the list is infinitely long. Either way, any "true" Wikipedia article named "List of numbers" would perforce forever be incomplete, no matter how much it was expanded. Both Gödel's incompleteness theorems and Cantor's diagonal argument feature prominently in {{w|Gödel, Escher, Bach}} by {{w|Douglas Hofstadter}}, to whom Randall devoted later comic [[917: Hofstadter]]. It may also be referencing his previous statements about Wikipedia being the home of compulsive list-makers, who make the most astonishingly complete lists imaginable.

== Transcript ==
:[Number line ranging from −1 to 10.]
:[Arrow pointing left, towards negative numbers] Negative "imitator" numbers (do not use)
:[Line right before the number one] 0.99... (actually 0.0000000372 less than 1)
:[Line at the golden ratio.] Φ Parthenon; sunflowers; golden ratio; wait, come back, I have facts!
:[Line at a region between two and 2.2] forbidden region
:[Line at Euler's number.] e
:[Line a bit before 3] 2.9299372 (e and pi, observed)
:[Line at π.] π
:[Line at 3.5 with ᛟ as the numeral] Gird – accepted as canon by orthodox mathematicians
:[Line a bit after 4.] site of battle of 4.108
:[Blob between 4.5 and 6.5 labeled unexplored.]
:[Line at seven.] Number indicating a factoid is made up ("every 7 years...", "science says there are 7...", etc)
:[Line at eight.] Largest even prime
:[Line at 8.75.] If you encounter a number higher than this, you're not doing real math

{{comic discussion}}
[[Category:Math]]
[[Category:Wikipedia]]

Talk:239: Blagofaire

2018-09-15T23:56:08Z

141.101.105.42:

Offline would mean dead.
[[Special:Contributions/173.245.54.47|173.245.54.47]] 13:35, 24 November 2013 (UTC)

;Structuring and levels?

I still don't understand the title text. Structuring, levels? Can it be explained more thoroughly?[[Special:Contributions/141.101.81.220|141.101.81.220]] 15:52, 15 May 2014 (UTC)

I can't figure out how to word well enough to add it in, but my interpretation is that's it's a joke about the way that we organize time, with the Structuring and the Levels being like the Renaissance and the Age of Enlightenment. Someone living through both wouldn't notice a sudden difference between them, while someone looking at them as past events can think of things in terms of decades and centuries, and choose a point at the start, middle or end of the gradual changes which brought about the later time period. [[Special:Contributions/108.162.246.209|108.162.246.209]] 22:16, 31 August 2014 (UTC)

:I have no other explanation, yet I wonder if there was a time before people tended to simplify past events or things in general. The title text sounds like a reminescence, maybe of how Munroe perceived the early internet.

No-one else thought that Structuring and Levels referred to some kind of event that restructured the internet of the future? I mean, the future cosplayer speaks of the modern internet as some wild and adventurous place, free of rules and responsibility. The future internet could be strictly regulated, where bloggers can only speak to bloggers of their "level" and a talk thread digressing out of it's place in the Structure would be ruthlessly persecuted!

Or something like that. In fact, the "wizard" explanation is dumb, so I'm gonna change it. -Pennpenn [[Special:Contributions/162.158.2.221|162.158.2.221]] 03:51, 9 June 2015 (UTC)

Levels would be the amount companies are going to force people to pay to keep the same Internet that they have now with the end of Net Neutrality and the ability to go to any website without restriction because it does not help pad the pockets of today Government/Corporate overlords[[Special:Contributions/162.158.62.231|162.158.62.231]] 11:20, 6 July 2017 (UTC)

2034: Equations

2018-08-28T12:45:28Z

141.101.105.42:

{{comic
| number = 2034
| date = August 17, 2018
| title = Equations
| image = equations.png
| titletext = All electromagnetic equations: The same as all fluid dynamics equations, but with the 8 and 23 replaced with the permittivity and permeability of free space, respectively.
}}
==Explanation==
{{incomplete|Created by a mere human. Do NOT delete this tag too soon.}}

This comic gives a set of equations supposedly from different areas of science in mathematics, physics, and chemistry. To anyone not familiar with the field in question they look pretty similar to what you might find in research papers or on the relevant Wikipedia pages. To someone who knows even a little about the topic, they are clearly very wrong and only seem even worse the more you look at them. In many disciplines, the mathematical description of a large area is summed up in a small number of equations, such as Maxwell's equations for electromagnetism. In similar fashion, the equations here purport to encompass the whole of their given field.

===Simplified Explanations===

;All kinematics equations
Kinematics is the study of the motion of objects. More specifically, it describes how the location, velocity, and acceleration of an object vary over time. The equation shown contains two of these standard kinematic variables, velocity ''v'' and time ''t'', in addition to several quantities (''E'', ''K0'', and ''ρ'') that are completely unrelated to kinematics.

;All number theory equations
Number theory is a branch of mathematics concerned primarily with the study of integers. However, the equation shown contains the non-integer Euler's constant ''e'' (approximately 2.718). It also uses the Greek letter π as an integer-valued variable, even though the symbol π is used in mathematics almost exclusively to denote the well-known ''non''-integer circle constant (approximately 3.14159). Even with π treated as a variable here, one of its uses in the equation is still nonsensical. <math>\pi-\infty</math> uses ∞ as if it were a specific number, which it is not, thus giving an undefined result.

;All chemistry equations
Randall implies that all chemistry is just combustion of chemicals, demonstrated with an incorrect form of a common example chemistry equation of burning Methane and Oxygen (with added heat), to form water and carbon dioxide. However, in this form "HEAT" is an actual molecule, rather than simply indicating the presence of heat to start the reaction. Thus the equation is modified to incorporate the fictional "HEAT" into the reaction. While the H in "HEAT" is the chemical symbol of the element hydrogen, none of the letters E, A, or T are symbols of any actual elements. Also, to account for the second hydrogen in "H(2)EAT" on the products side, the oxygen gas on the reactants side has been altered to be hydroxide, a strong base that would not facilitate traditional combustion.

TODO: other simplified explanations.

===Technical Explanations===
;All kinematics equations
:<math>E = K_0t + \frac{1}{2}\rho vt^2</math>
{{w|Kinematics}} describes the motion of objects without considering mass or forces. The latter is described by {{w|Kinetics}}. The two fields get frequently confused by freshmen, due to the similarity of words.

This equation here literally states: "Energy equals a constant <math>K_0</math> multiplied by time, plus half of density multiplied by speed multiplied by time squared".

The first term here is hard to interpret: it could be correct if <math>K_0</math> is a constant power applied to the system, but this symbol would more normally be used to denote an initial energy, in which case multiplying by <math>t</math> would be wrong. Alternatively, the term is similar to <math>k_B T</math> (sometimes written as ''kT''), a term that often appears in {{w|Statistical_mechanics|statistical mechanics}} equations, where ''kB'' (or ''k'') is {{w|Boltzmann_constant|the Boltzmann constant}}, and ''T'' is the {{w|Thermodynamic_temperature|absolute temperature}}. In this latter case, the term would have units of energy, consistent with the left side of the equation.

The second term looks similar to the kinetic energy term <math> \frac{1}{2}\rho v^2 </math> in [http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html the Bernoulli equation] for fluids. (More properly, this is the kinetic energy ''density'' in the fluid).

The whole equation appears to be a play on the kinematics formula: <math>s = v_0t + \frac{1}{2}\ at^2</math>, where distance travelled (''s'') by a constantly accelerating object is determined by initial velocity (''v0''), time (''t''), and acceleration (''a'')

Kinematics is often one of the first topics covered in an introductory physics course, both at the high school and freshman college levels. As such, mixing in material from more advanced topics like statistical mechanics and the Bernoulli equation, even if done correctly, would be very confusing for a typical student learning kinematics.

;All number theory equations
:<math>K_n = \sum_{i=0}^{\infty}\sum_{\pi=0}^{\infty}(n-\pi)(i-e^{\pi-\infty})</math>
{{w|Number theory}} is a branch of mathematics primarily studying the properties of integers.

Said in English, the equation can be read: "The ''n''th K-number is equal to the sum for all ''i'' from 0 to infinity of the sum for all π from 0 to infinity of ''n'' minus π, multiplied by ''i'' minus ''e'' raised to the power of π minus infinity." (''i'' here is an iteration variable, not the imaginary number constant; ''e'' is Euler's number, approximately 2.718). A twofold misconception can be seen here. The first is the use of π as a variable instead of the circle constant (3.14...). This might be a jab at how in number theory letters and numbers are used interchangeably, but where some letters are suddenly fixed constants.

Further confusion comes from the use of unusual mathematical models. While the term <math>e^{\pi-\infty}</math> is meaningless when considered in standard ("high school") mathematics, it is valid when considered on the {{w|extended real number line}}, a concept unfamiliar to most non-mathematicians and uncommon in number theory. Naively, this would signify that (with the use of π as a variable) the exponent would range from negative infinity to zero. In fact, assuming ''e'' really does mean Euler's constant (or at least a real number strictly greater than 1) the term would be zero for every π < ∞. Ultimately, the sum diverges for every ''n''.

The close proximity of the letters i, e and π also evokes {{w|Euler's identity}} <math>e^{i\pi}+1=0</math> (also written <math>e^{i\pi}=-1</math>), without actually using it, especially since both π and i are used as variables here.

;All fluid dynamics equations
:<math>\frac{\partial}{\partial t}\nabla\cdot \rho = \frac{8}{23}
\int\!\!\!\!\!\!\!\!\!\;\;\bigcirc\!\!\!\!\!\!\!\!\!\;\;\int
\rho\,ds\,dt\cdot \rho\frac{\partial}{\partial\nabla}
</math>
{{w|Fluid dynamics}} describes the movement of non-solid material. In particular for gases, the density <math>\rho</math> is often the most interesting quantity (for liquids, this is often just constant). A unique feature of fluid-dynamic equations is the presence of {{w|Advection|advection terms}}, which take the form of often strange-looking spatial derivatives. This equation turns this up to a new level by differentiating with respect to a differential operator <math>\nabla</math>, which does not make any sense at all. Also it has a contour integral which seems reminiscent to a closed-circle process like in a piston engine, but this does not really fit in the context (differential description of a gas), and it has a pair of {{w|Magic number (programming)|unexplained numbers}} <math>8</math> and <math>23</math>, probably alluding to the {{w|Heat capacity ratio|specific heat ratio}} which is often written out as the fraction <math>\tfrac{7}{5}</math>, whereas most other physics equations [[899: Number Line|avoid including any plain numbers higher than 4]].

The title text stating that the electromagnetism equation is the same as the fluid dynamics equation, but with the arbitrary 8 and 23 replaced with the permittivity and permeability of free space is likely because electromagnetism equations often have relations to fluid dynamics, and because those two constants appear in the vast majority of electromagnetism equations.

;All quantum mechanics equations
:<math>|\psi_{x,y}\rangle = A(\psi) A(|x\rangle \otimes |y\rangle)</math>
{{w|Quantum mechanics}} is a fundamental theory in physics which describes nature at scales of atoms and below. It typically uses the {{w|Bra–ket notation|bra–ket notation}} in its formulae.

This equation takes a state psi in the dimensions of x and y and equates it to an operator A performed on psi multiplied by the same operator performed on the tensor product of x and y. Since the state psi is already the tensor product of the states x and y, this is equivalent to performing the same unknown operator twice on psi, and unless this operator is the identity or is its own inverse such as a bit-flip or Hermitian operator, this equation is therefore incorrect.

;All chemistry equations
:<math>\mathrm{CH}_4 + \mathrm{OH} + \mathrm{HEAT} \rightarrow \mathrm{H}_2\mathrm{O} + \mathrm{CH}_2 + \mathrm{H}_2 \mathrm{EAT}</math>
A {{w|Chemical equation|chemical equation}} represents a chemical reaction as a formula, with the reactant entities on the left-hand side, and the product entities on the right-hand side. The number of each element on the left side must match those on the right side. The energy produced or absorbed in this process is not included in that formula.

This is a modification of the combustion of methane. The correct form is often taught and a good example problem but obviously there are more chemistry problems.<math>\mathrm{HEAT}</math> is normally shorthand for {{w|activation energy}}, but in Randall's version it's jokingly used as a chemical ingredient and becomes <math>\mathrm{H}_2\mathrm{EAT}</math>, taking the hydrogen atom freed by the combustion equation shown. The proper methane combustion equation would be: <math>\mathrm{CH}_4 + 2 \mathrm{O}_2 \rightarrow 2 \mathrm{H}_2\mathrm{O} + \mathrm{CO}_2</math>

While <math>\mathrm{OH}</math> often appears in chemical equations in the form of a negatively charged hydroxide group (<math>\mathrm{OH}^-</math>), the left side of the equation involves a bare <math>\mathrm{OH}</math>, possibly the highly unstable hydroxyl radical (although this would typically be written with a leading dot, e.g. <math>\bullet\mathrm{OH}</math>). Similarly, the right side contains an unstable methylene radical which would generally only appear as an intermediate rather than a product.

;All quantum gravity equations
:<math>\mathrm{SU}(2)\mathrm{U}(1) \times \mathrm{SU}(\mathrm{U}(2))</math>
This is more similar to expressions which appear in {{w|Grand_Unified_Theory|Grand Unified Theory}} (GUT) than general quantum gravity. Unlike some of the other equations, this one has no interpretation which could make it mathematically correct. This is similar to the notations used to describe the symmetry group of a particular phenomena in terms of mathematical {{w|Lie_Group|Lie Groups}}. A real example would be the Standard Model of particle physics which has symmetry according to <math>\rm{SU(3)\times SU(2) \times U(1)}</math>. Here, <math>\rm{SU}</math> and <math>\rm{U}</math> denote the special unitary and unitary groups respectively with the numbers indicating the dimension of the group. Loosely, the three terms correspond to the symmetries of the strong force, weak force and electromagnetism although the exact correspondence is muddied by symmetry breaking and the Higgs mechanism.

Of course, an expression missing an "=" sign, is difficult to interpret as an "equation", because equations normally express an "equality" of some kind. Nobody knows whether Randal refers to a horse, zebra, donkey or other equine here.

Randall's version clearly involves some similar groups although without the <math>\times</math> symbol it is hard to work out what might be happening. A term like <math>\rm{SU(U(2))}</math> has no current interpretation in mathematics, if anyone thinks otherwise and possibly has a solution to the quantum gravity problem they should probably get in touch with someone about that.

;All gauge theory equations
:[[File:All gauge theory equations.png]]
In physics, a {{w|Gauge theory|gauge theory}} is a type of field theory which is invariant to local transformations. The term gauge refers to any specific mathematical formalism to regulate redundant degrees of freedom.

This equation looks broadly similar to the sorts of things which appear in gauge theory such as the equations which define {{w|Yang–Mills_theory#Quantization|Yang-Mills Theory}}. By the time physics has got this far in, people have normally run out of regular symbols making a lot of the equations look very daunting. The actual equations in this field rarely go far beyond the Greek alphabet though and no-one has yet to try putting hats on brackets. The appearance of many sub- and superscripts is normal (this links to the group theory origins of these equations) and for the layperson it can be impossible to determine which additions are labels on the symbols and which are indices for an {{w|Einstein_notation|Einstein Sum}}.

The left-hand side <math>S_g</math> is the symbol for some {{w|Action_(physics)|action}}, in Yang-Mills theory this is actually used for a so-called "ghost action". On the right-hand side we have a large number of terms, most of which are hard to interpret without knowing Randall's thought processes (this is why real research papers should all label their equations thoroughly). The <math>\frac{1}{2\bar{\varepsilon}}</math> looks like a constant of proportionality which often appears in gauge theories. The factor of <math>i = \sqrt{-1}</math> is not unusual as many of these equations use complex numbers. The <math>\eth</math> symbol looks similar to a <math>\partial</math> partial derivative symbol especially as the {{w|Dirac_equation#Covariant_form_and_relativistic_invariance|Dirac Equation}} uses a slashed version as a convenient shorthand.

The rest of the equation cannot be mathematically correct as the choice of indices used does not match that on the left-hand side (which has none). In particle physics subscripts (or superscripts) of greek letters (usually <math>\mu</math> or <math>\nu</math>) indicate terms which transform nicely under Lorentz transformations (special relativity). Roman indices from the beginning of the alphabet relate to various gauge transformation propetries, the triple index seen on <math>p^{abc}_v</math> would likely come from some <math>\rm{SU(3)}</math> transformation (related to the strong nuclear force). Since <math>S_g</math> has none of these (and is thus a scalar which remains constant under these operations), we would need the right-hand side to behave in the same way. Most of the indices which appear are unpaired and so will not result in a scalar making the equation very wrong. For those not familiar with this type of equation, this is similar to the mistake of messing up units, for instance setting a distance equal to a mass.

;All cosmology equations
:<math>H(t) + \Omega + G \cdot \Lambda \, \dots \begin{cases} \dots > 0 & \text{(Hubble model)} \\ \dots = 0 & \text{(Flat sphere model)} \\ \dots < 0 & \text{(Bright dark matter model)} \end{cases}
</math>
This is a parody of equations defining the {{w|Hubble's_law#Derivation_of_the_Hubble_parameter|Hubble Parameter}} <math>H(t)</math> although it looks like Randall has become bored and not bothered to finish his equation. Such equations usually have several <math>\Omega</math> terms representing the contributions of different substances to the energy-density of the Universe (matter, radiation, dark energy etc.). In this context <math>G</math> could be Newton's constant and <math>\Lambda</math> is the cosmological constant (energy density of empty space) although seeing them appear multiplied and on the same footing as <math>H</math> is unusual (the dot is entirely unnecessary). Choosing to make <math>H</math> a function of time <math>t</math> and not of redshift <math>z</math> is also unusual.

The second section looks like the inequalities used to show how the equation varies with the shape of the Universe, based on the value of the curvature parameter <math>\Omega_k</math>. A value of 0 indicates a flat Universe (this is more or less what we observe) while a positive /negative value indicates an open /closed curved Universe. Randall's choice of labels further makes fun of the field as both a flat sphere and bright dark matter are oxymoronic terms which would involve some rather strange model universes.

;All truly deep physics equations
:[[File:All truly deep physics equations.png]]
<math>\hat H</math> is the Hamiltonian operator, which when applied to a system returns the total energy. In this context, U would usually be the potential energy. However, there is also a subscript 0 and a diacritic marking indicating some other variable. Much of physics is based on Lagrangian and Hamiltonian mechanics. The Lagrangian is defined as <math>\hat L = \hat K - \hat U </math> with K being the kinetic energy and U the potential. Hamiltonian mechanics uses the equation <math>\hat H = \hat K + \hat U </math>. The Hamiltonian must be conserved so taking the time derivative and setting it equal to zero is a powerful tool. The "principle of least action" allows most modern physics to be derived by setting the time derivative of the Lagrangian to zero.

==Transcript==
:[Nine equations are listed, three in the top row and two in each of the next three rows. Below each equation there are labels:]

:E = K0t + 1/2 ρvt2
:All kinematics equations

:Kn = ∑i=0∞∑π=0∞(n-π)(i-eπ-∞)
:All number theory equations

:∂/∂t ∇ ⋅ ρ = 8/23 (∯ ρ ds dt ⋅ ρ ∂/∂∇)
:All fluid dynamics equations

:|ψx,y〉 = A(ψ) A(|x〉⊗ |y〉)
:All quantum mechanics equations

:CH4 + OH + HEAT → H2O + CH2 + H2EAT
:All chemistry equations

:SU(2)U(1) × SU(U(2))
:All quantum gravity equations

:Sg = (-1)/(2ε̄) i ð (̂ ξ0 +̊ pε ρvabc η0 )̂ f̵a0 λ(ʒ̆) ψ(0a)
:All gauge theory equations

:[There is a brace linking the three cases together.]
:H(t) + Ω + G⋅Λ ...
:... > 0 (Hubble model)
:... = 0 (Flat sphere model)
:... < 0 (Bright dark matter model)
:All cosmology equations

:Ĥ - u̧0 = 0
:All truly deep physics equations

{{comic discussion}}

[[Category:Science]]
[[Category:Physics]]
[[Category:Math]]
[[Category:Chemistry]]
[[Category:Astronomy]]

Talk:1825: 7 Eleven

2017-04-17T20:12:39Z

141.101.105.42:

I don't think the title-text references leap seconds, as it says that "many" are wrong, not "all". It seems more likely it refers to stores that claim to be open 365 days per year, and are hence wrong in leap years.
[[Special:Contributions/141.101.105.42|141.101.105.42]] 20:12, 17 April 2017 (UTC)