explain xkcd - User contributions [en]

Talk:3067: SawStart

2025-03-24T16:52:40Z

172.69.33.194: Update on sawstop in general.

It's weird seeing a totally empty explanation, also whats the point of sawstop, don't they just use vibrating blades? [[Special:Contributions/104.23.190.110|104.23.190.110]] 12:40, 24 March 2025 (UTC)
:SawStop is for rotating blades, like you would use for sawing wood. I'm sure there's a good reason why they don't use vibrating blades there, the most likely is "wood is harder than a plaster cast". I could also imagine that vibrating blades don't create nice cuts, which doesn't matter with a plaster cast that will be disposed of, but very much matters with wood used for construction. --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 13:16, 24 March 2025 (UTC)

empty explanation is freaky woah [[Special:Contributions/172.69.194.204|172.69.194.204]] 12:42, 24 March 2025 (UTC)
:Every explanation is empty, at least for a short amount of time. And this is not the earliest that a comic went up (shortly after midday, UK time, when it's not unknown for them to not arrive until after the midnight at the end of the designated publication day), but it looks like you (both, including first-poster at the top) have had the good luck/fortune to be just casually checking for new changes to old articles on the site and instead get 'first look' at the newest addition to it. Of course, it'll be a few hours before most of the article gets fine-tuned into some form of 'completion'. [[Special:Contributions/172.70.86.157|172.70.86.157]] 13:23, 24 March 2025 (UTC)
sudo systemctl stop saw-start.service [[Special:Contributions/172.69.208.132|172.69.208.132]] 13:11, 24 March 2025 (UTC)
:yay you saved the world! --[[User:Bb777|hi]] ([[User talk:Bb777|talk]]) 14:08, 24 March 2025 (UTC)

I'm 99% sure that the system is designed to start a ''stopped'' blade up to full speed within milliseconds, not just increase the speed of a spinning blade. --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 13:22, 24 March 2025 (UTC)

WAITER, WAITER, MORE [[Black Hat]] PLEASE [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 13:31, 24 March 2025 (UTC)

Because of gyroscopic precession, a still spinning (unstoppable?) blade, removed from its axle and housing, would be /very/ difficult and dangerous to dispose of. I'm a woodworker and I think I'll be having nightmares tonight.
-DW [[Special:Contributions/172.69.23.176|172.69.23.176]] 13:36, 24 March 2025 (UTC)

: At least if it's unstoppable we can use it as a free source of energy! [[Special:Contributions/172.69.195.62|172.69.195.62]] 14:01, 24 March 2025 (UTC)

As a woodworker, one note I would like to make is that while the sawblade ''can'' be damaged by cartridge activation, it is not ''required'' that it be replaced. It is possible to have the blade inspected and potentially repaired and continue to use it. That is addressed in SawStop's FAQ https://www.sawstop.com/sawstop_faq/can-the-blade-be-reused-if-the-safety-system-brake-is-activated/ [[Special:Contributions/172.69.33.189|172.69.33.189]] 15:04, 24 March 2025 (UTC)

The [citation needed] for violating other laws probably means that law enforcement should issue a citation to the manufacturer. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 15:21, 24 March 2025 (UTC)

General observation from a s/w test engineer/woodworker: Original version of the Sawstop used a shotgun shell to fire a stopper into the sawblade which absolutely did destroy the blade. (and made enough noise to pretty much ensure a 'code brown' if you triggered the stop system.) Newer version uses a high tension spring along with a deformable aluminum stopper assembly to absorb the energy and bring the blade to a stop. The advantage of the deformable aluminum assembly is that you can remove it from the blade (with care) and as noted can put the sawblade back to work. However you need a new ($200-ish) stopper assembly before you can re-start the saw. Having a family member who is a retired emergency room doctor who would regularly email me 'stories from work' of woodworker injuries who came through her ER, I can assure you that a tablesaw is pretty much the most dangerous woodworking tool in a typical woodshop. That being said, its quite amusing to me that "SawStop" became XKCD worthy. SawStop is somewhat notorious in the woodworking community because of their highly obnoxious business practices with regards patent and legal attacks on business competitors who came up with alternative approaches to the 'saw brake' or 'saw safety' system. JC from Canada

2974: Storage Tanks

2024-08-19T23:45:15Z

172.69.33.194: /* Explanation */ actual citation sufficient

{{comic
| number = 2974
| date = August 19, 2024
| title = Storage Tanks
| image = storage_tanks_2x.png
| imagesize = 321x251px
| noexpand = true
| titletext = We're considering installing a pressurization system to keep the tanks at constant pressure solely to deter them.
}}

==Explanation==
{{incomplete|Created by AN OVERENTHUSIASTIC CORPORATE SPY HIDING AS A CALCULUS TEACHER - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
A common question in introductory calculus courses asks [https://www.haywardflowcontrol.com/media/contentmanager/content//downloads//VessTime.pdf how long it will take a tank to empty,] assuming the rate of flow through a hole at the base is proportional to the pressure at the base of the tank. Assuming the tank is shaped like a cylinder, as appears to be the case in this comic, the amount of fluid left in the tank will follow an exponential decay, as the rate of pressure decrease will be proportional to the instantaneous pressure at any given moment. Variations of this question may consider more complicated tank geometries too, in which case the pressure at the base will not be simply proportional to the volume of fluid remaining in the tank.

The joke in the comic is that calculus teachers will actually drill a hole in a storage tank to demonstrate this principle, making the factory station someone to keep a lookout for them. This does not usually happen because sneaking a teacher and their entire class full of loud students into a facility without permission is a bad idea{{Citation needed}} and not getting caught is virtually impossible. It is illegal and will get you charged with trespassing, destruction of property, and attempted robbery.

The title text jokingly alludes to the fact that by maintaining a constant pressure at the base, the rate of flow would itself become constant, which would simplify the problem greatly and therefore make it much less interesting, or useful, as an example in a calculus course.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Two characters wearing helmets are standing on scaffolding next to two large tanks labeled "Tank #3" and "Tank #4", with the person on the left talking. Miss Lenhart has drilled a hole into the base of Tank #4 with liquid pouring out of it and she is running away with the drill.]
:Left person with helmet: As head of security, your primary task is to monitor the storage tanks and watch for calculus teachers trying to drill holes in their bases.

{{comic discussion}}

[[Category:Characters with hats]]
[[Category:Comics featuring Miss Lenhart]]
[[Category:Math]]
[[Category:Physics]]

1862: Particle Properties

2024-05-30T01:23:19Z

172.69.33.194: works better this way

{{comic
| number = 1862
| date = July 12, 2017
| title = Particle Properties
| image = particle_properties.png
| titletext = Each particle also has a password which allows its properties to be changed, but the cosmic censorship hypothesis suggests we can never observe the password itself—only its secure hash.
}}

==Explanation==
A table is presented comparing the range (maximum and minimum value) and scale (how big number increments are) of several measures. The table begins by listing properties pertinent to {{w|particle physics}} as the title suggests, but quickly devolves to other domains such as role-playing games (such as D&D) and sports after failing to provide a good definition of {{w|Flavour (particle physics)|flavor}}.

{| class=wikitable
! Property
! Scale
! Explanation
|-
| Electric charge
| [-1,1]
| The {{w|electric charge}} is shown in increments of a third from -1 to +1 which are the only known charges of fundamental particles (leptons, quarks and gauge bosons); however there are some exotic composite particles with twice integer charge, e.g. the recently discovered {{w|Ξcc++|double charmed Xi baryon}} with a charge of +2.

Quarks are the only particles with charges of ± ⅓ or ± ⅔, but cannot exist individually; below the {{w|Hagedorn temperature}}, they are only found within hadrons. To date, all hadrons (particles composed of quarks), leptons, and bosons have integer charge, and current models indicate that this must be the case.
|-
| Mass
| [0,∞) in kg
| Mass (specifically {{w|rest mass}}) is the measure of an object or particle's resistance to force, as well as its ability to distort {{w|spacetime}} (its gravitational attraction).
Theoretically, any object's mass could approach infinity, but mass cannot be below 0 (as far as {{w|Negative mass|we know}}). The mass units shown (kilograms) are, however, far too large for particles. Some particles, such as photons, have zero rest mass and are therefore massless.

All particles with rest mass obtain it through confinement, either by the {{w|Higgs field}} (the quarks; leptons; and W, Z, and Higgs bosons) or the strong nuclear force (hadrons).
Particles with no rest mass (photons and gluons) can only move at lightspeed.
|-
| Spin number
| (-∞,∞) (Intervals of ½)
| {{w|Spin (physics)|Spin}} is an intrinsic property of particles, a relativistic form of angular momentum. The spin of a particle determines what statistics the particle follows, half odd integer spin particles are classified as fermions and integer spin particles are bosons.

Two fermions cannot have exactly the same state, an observation known as the Pauli exclusion principle. Thus, for fermions to exist in the same position, they must have opposite spins, of + ½ and - ½. It follows that a maximum of two fermions of the same flavor (e.g. two electrons) may exist in the same position.
|-
| Flavor
| Misc. quantum numbers
| Flavor is a series of {{w|quantum numbers}} that do not fit neatly onto a set of dimensional axes.

The most general theory breaks flavor down into four distinct conserved values, the electric charge, the weak isospin, the baryon number and the lepton number, but more specific models increase the number of distinct values. Quarks, for example, add five more flavor numbers: isospin (upness vs. downness), strangeness, charm, topness and bottomness (the last four are literally just the number of strange, charmed, top and bottom quarks, minus the corresponding anti-quarks).
|-
| Color charge
| Coordinate system with R, G and B axes
| The primary {{w|strong nuclear force}} has six mutually attractive charges, arranged in three perpendicular axes each analogous to electric charge. These charges are commonly referred to as "{{w|Color charge|color}}" and the three axes are given the names of the three primary colors of light: Red, Green and Blue. The black dots in the diagram represent the actual colors while the white dots are the anti-color charges: anti-Red (colored cyan in diagrams), anti-Green (magenta) and anti-Blue (yellow). To complete the analogy, a color charge of zero is referred to as "White". The names of these charges are purely allegorical, but they do make it convenient to refer to them, especially in diagrams.

The color of a particle not confined by the strong force must be White, either as the sum of a color and its anti-color (as in a meson), as the sum of RGB or anti-RGB (as in a baryon), or as a sum of those sums (As in tetra-, penta- or hexaquarks). The attraction of the strong nuclear force is so strong that attempting to separate two quarks from each other creates enough energy to create two new quarks, which then bind to the original quarks. This property is known as "confinement" and means that color charge can never be observed directly.

Randall is incorrect in stating "Quarks only", since {{w|gluon}}s (the particle that carries the color force) are themselves colored. However, the colors of gluons are much more complicated, with a total of eight distinct superpositions of every possible color-anticolor pair. The fact that gluons are subject to the force they mediate also means that the strong force has a defined radius of effect, unlike the electromagnetic force, whose gauge bosons (the photon) are uncharged.

This is the last entry currently used to describe particles by particle physicists.
|-
| Mood
| 5 emojis on a number line ranging from angry to joyful
| Particles are not considered to have mood, even in the allegorical way they have color or flavor, but Randall implies that there is a quantized 5 point scale (from "angry" to "ecstatic") which would have some effect on the properties of the particle. This would be more appropriate for measuring customer satisfaction. Charts such as this are also sometimes used in medicine to indicate levels of pain, and in some psychiatric treatments as a quick way to track changes in the patient's condition.

In grammar, {{w|Grammatical particles|particles}} are a nebulous class of words, usually defined by a lack of declension or conjugation (such as prepositions in English). Some languages use particles instead of or in addition to "standard" declension/conjugation, much like auxiliary verbs are used in English. These particles may well carry "{{w|Grammatical mood|mood}}" as an attribute, as well as tense and aspect.
|-
| Alignment
| 3x3 grid with varying shades (columns Good-Evil, rows Lawful-Chaotic)
| A reference to the tabletop RPG ''{{w|Dungeons & Dragons}}'', where characters have an {{w|Alignment (Dungeons & Dragons)|alignment}} that is either Good, Neutral, or Evil (describing whether they have a propensity to help or harm others) and either Lawful, Neutral, or Chaotic (describing how much they care about organizations, social norms, and the status quo). Common examples of these alignments include Darth Vader (Lawful Evil), Superman (Lawful Good), Robin Hood (Chaotic Good), and the Joker (Chaotic Evil). This may be a reference to the now defunct names of the two heaviest known quarks ("truth" and "beauty").
|-
| Hit points
| [0,∞)
| Games (videogames, board games, CCGs, RPGs, etc.) often have values for players and other entities that represent {{w|Health (video game)|health}} (also called hit points or HP). Generally there is not necessarily a limit on this value, but it does not often go below 0 as the zero value is considered "dead" (or some equivalent).
|-
| Rating
| 5-star scale
| The five-star rating system is often used to rate films, TV shows, restaurants, and hotels. Randall has previously criticized this system in [[937: TornadoGuard]] and [[1098: Star Ratings]].

Interestingly, unlike the "Heat" rating with the chili peppers below, this scale doesn't have a creatively labeled number line, merely a rating (3.5, in this case). Considering [[1098]], could Randall be subtly self-deprecating here?
|-
| String type
| Bytestring-Charstring
| In computer science, this denotes what type of data is stored subsequent set of elements or a {{w|String_(computing)|string}}. This is likely a pun on {{w|String_(physics)|string}} types that appear in {{w|string theory}} and particle physics, and may also be a reference to {{w|Python (programming language)|Python}}, in which the difference between a byte string and a (Unicode) character string is a cause of difficulties for some programmers.
|-
| Batting average
| [0,100] in %
| In {{w|baseball}}, a player's {{w|batting average}} is calculated by dividing their hits by their at-bats. Instead of using the percent sign (%), it is usually presented as a number between 0 and 1 (inclusive) expressed as three decimal places with no leading zero: [.000, 1.000]. It is pronounced as though it is multiplied by 1,000: A batter with a batting average of .342 (which is very good) is said to be "batting three forty-two." A perfect batting average (unattainable except in very small samples) gives rise to the expression "batting a thousand." The 0-100 scale would be a better match for the batting average statistic in {{w|cricket}}, although percents would still not be used.
|-
| Proof
| [0,200]
| This refers to {{w|alcohol proof}}, which is the measure of the amount of ethanol in a beverage by volume. In the United States, 100 proof correspond to 50% alcohol, so the proof of a beverage is two times the percentage of ethanol, so the maximum value is 200.
|-
| Heat
| No jalapeño icons - 3 jalapeño icons, increasing
| Spicy dishes are sometimes measured by the intensity of the spicy flavor, usually ranging from values like "mild" to "hot". The gray jalapeño likely represents negligible or no spicy taste in the food. However, as an objective scale it is largely meaningless, since there is no reliable consistency in how these ratings are applied - what may be considered a 3-chilli dish in one establishment may only be a 1-chilli dish in another (as restaurants rarely if ever intend their dishes to be rated on the {{w|Scoville scale}}). The scale being unlimited may be a reference to the practice of some restaurants where a fourth or fifth chilli may be added to exaggerate the heat of their dishes.
|-
| Street value
| [0,∞) in $
| The value of an illegal good or a legal/controlled good when bought or sold by illegal means usually by or to the end user.
|-
| Entropy
| ''This already has like 20 different confusing meanings, so it probably means something here, too.''
| The term "entropy", which {{w|History of entropy|began}} as a {{w|Entropy (classical thermodynamics)|thermodynamic measure}}, has since been adopted {{w|Entropy in thermodynamics and information theory|by analogy}} into {{w|Entropy (disambiguation)|multiple seemingly unrelated domains}} including, for example, information theory. The table allows that the term "entropy" must mean something in the context of particle physics, but isn't certain whether it's the classical, Gibbs' modern {{w|Entropy (statistical thermodynamics)|statistical mechanics}}, Von Neumann's {{w|Von Neumann entropy|quantum entropy}}, or some other meaning.

In classical thermodynamics, entropy is a macroscopic property describing the disorder or randomness of a system with many particles. However, in statistical mechanics and quantum mechanics, the concept of entropy can also be applied to single particles under certain conditions. If the particle's position is not precisely known and can be described by a probability distribution, this contributes to entropy. Similarly, if the particle's momentum is uncertain and described probabilistically, this also contributes to entropy. A single quantum particle in a pure state (e.g., an electron in a specific atomic orbital) has zero entropy. This is because there is no uncertainty about the state of the system. If the single particle's state is described by a density matrix representing a mixed state (a probabilistic mixture of several possible states), the Von Neumann entropy can quantify the degree of uncertainty or mixedness of the state.

Imagine two identical balloons filled with the same gas and heated from two opposite sides with identical heat sources, creating symmetric temperature gradients in both; because the distribution of temperatures is the same, the Gibbs statistical thermodynamic entropy 𝑆 of the gas molecule particles in each balloon will be the same. In contrast, if one balloon is heated by a low-power heat source and another from by an otherwise identical high-power heat source, the balloon next to the high-power heat source will have a steeper temperature gradient, increasing the number of accessible microstates, so the Gibbs entropy 𝑆low power < 𝑆high power. Now consider electrons in two atoms excited by absorbing identical photons to a mixed state; if the mixed states have the same probabilities for different energy levels, their Von Neumann quantum entropy 𝑆 values will be the same. Conversely, if one atom has electrons excited to a {{w|Purity_(quantum_mechanics)|pure state}} and another to a mixed state by photons of different energies, the mixed state will have higher entropy due to greater uncertainty, i.e., 𝑆pure = 0 and 𝑆mixed = ln(2).
|}

The title text says that in addition each particle has a password, but only hash of the password can be observed. This is a computer science reference. In computer science, properties (e.g. of an object or program) often can be changed with a single command. In physics as we observe it, properties can locally change with the environment. There are several {{w|Time-variation_of_fundamental_constants|experiments}}, whether physical constants are really time-const. Password hashing is the practice of hiding the password itself by storing only an irreversible representation of the password. Since the password itself is not stored, the password cannot ever be viewed by the user or a hacker (outside of the login page). This method is considered to be safest way of storing passwords. Password hashing using some {{w|key derivation function}} makes it impossible to steal passwords even if the server that stores hashes is cracked, unless the hash function is also broken, which should be a task which cannot be completed in any feasible time for sufficiently strong passwords. The title-text claims this is predicted by the {{w|cosmic censorship hypothesis}}, which in reality claims that a {{w|gravitational singularity}} must always be obscured by an event horizon (i.e.: there can't be a {{w|naked singularity}}). There is also a hint of quantum mechanics in the statement, as observation is one of the central concepts of the field, and {{w|Heisenberg's uncertainty principle}} actually states that it is impossible to observe (measure) some property of a particle with arbitrary precision when another one is known (e.g.: you can't determine the momentum and position of a particle). This makes the title text a mix of several domains, as was the above table.

==Transcript==
:<big>Particle Properties in Physics</big>
{| class=wikitable
! Property
! Type/scale
|-
| Electric charge
| [Scale with -1, 0 and +1 labeled and markings dividing the units in thirds. The endpoints are both dots.]
|-
| Mass
| [Scale with 0, 1kg and 2kg labeled and markings dividing the units into thirds. The endpoints are a dot on the zero end and an arrow on the other end.]
|-
| Spin number
| [Scale with -1, -½, 0, ½ and 1 labeled and no additional markings. The endpoints are both arrows, pointing out.]
|-
| Flavor
| (Misc. quantum numbers)
|-
| Color charge
| [Coordinate system of three axes labeled R, G and B clockwise from the 10 o'clock position. Endpoints are arrow-dots on all ends, with black dots for the labeled ends and white dots for the unlabeled ends.] (Quarks only)
|-
| Mood
| [Scale labeled with 5 emoticons, from angry to happy, and markings dividing the units in thirds. Endpoints are both arrows, pointing out.]
|-
| Alignment
| [3x3 grid with varying shades] Good-Evil, Lawful-Chaotic
|-
| Hit points
| [Scale starting from 0, markings but no labels other than zero. Endpoints are a dot at zero end and an arrow at the other end.]
|-
| Rating
| [Star rating of 3.5/5 stars.]
|-
| String type
| Bytestring-Charstring
|-
| Batting average
| [Scale from 0% to 100%. Endpoints are dot at 0% end and arrow-dot at 100% end.]
|-
| Proof
| [Scale from 0 to 200. Endpoints are dot at 0 end and arrow-dot at 200 end.]
|-
| Heat
| [Scale labeled with pepper icons, from 0 (a grayed-out pepper) to 3 black peppers. Endpoints are a dot at zero end and an arrow at the other end.]
|-
| Street value
| [Scale with $0, $100 and $200 labeled. Endpoints are a dot at zero end and an arrow at the other end.]
|-
| Entropy
| (This already has like 20 different confusing meanings, so it probably means something here, too.)
|}

{{comic discussion}}

[[Category:Charts]]
[[Category:Physics]]
[[Category:Baseball]]