explain xkcd - User contributions [en]

2780: Physical Quantities

2023-05-25T15:40:32Z

162.158.90.30: [citation needed]

{{comic
| number = 2780
| date = May 24, 2023
| title = Physical Quantities
| image = physical_quantities_2x.png
| imagesize = 338x183px
| noexpand = true
| titletext = The Hubble length is about 1.9 meters lying down; Edwin Hubble was a tall guy.
}}

==Explanation==
{{incomplete|Created by a TALL SCIENTIST - Do NOT delete this tag too soon.}}

This comic plays on the name of various established physical definitions by simply taking them overly literally. Each one is treated as being a bodily measure of the scientist after which they are named, rather than describing/estimating the objective feature within the scientist's field of study.

;Hubble volume
In cosmology, a {{w|Hubble volume}} (named for the astronomer {{w|Edwin Hubble}}) is a spherical region of the observable universe.
The Hubble volume is approximately equal to 1031 cubic light years (or about 1079 cubic meters).
The value given in the comic is the volume of Edwin Hubble's body.

;Schwarzschild radius
The {{w|Schwarzschild radius}} of a black hole refers to the event horizon: the radius beyond which light cannot escape. Curling up in a ball tends to reduce people's radii, so {{w|Karl Schwarzschild}}'s is given as 0.34 m, corresponding to a black hole of about 40 times the mass of Earth.

;Broca's area
{{w|Broca's area}} is part of the brain. It is not a measurement of area in the sense of length times width. The measurement shown here purports to be the area of {{w|Paul Broca}} (which might refer to the {{w|Body surface area|surface area of his body}}, or the area his body takes up), but it is given in cubic meters (a measure of volume) rather than square meters (a measure of area). (The surface area of an adult human is about two square meters.) This area was recently mentioned in the title text of [[2732: Bursa of Fabricius]].

;Fermi temperature
The concept of Fermi Temperature is {{w|Fermi energy#Related quantities|related to the Fermi Energy}}, a quantum value inherent to very cold substances. The {{w|Human body temperature|temperature of an average human}} is about 37 degrees Celsius, so it makes sense that {{w|Enrico Fermi}}’s temperature was 37 degrees Celsius, when he was alive. Today we can no longer test this, as he died in 1954. {{citation needed}}

;Planck length
{{w|Planck units}} are naturally-derived measurements invented by {{w|Max Planck}}; the Planck length (approximately 1.6×10-35 m) is one of the smallest meaningful distances. However, Randall measures the length of Max Planck, not the units. It is specifically when Planck was lying down (as to not decrease his height from a days exposure to gravity which may shorten a human by a centimeter or so, and also because lying down turns a human’s height into a length).

;Hubble length (title text)
A {{w|Hubble's_law#Hubble_length|Hubble length}} is 14.4 billion light years. This is a joke similar to the above play on the Planck length. The Hubble distance would be the distance between the Earth and the galaxies which are currently receding from us at the speed of light. The joke is that the Hubble length is 14 cm longer than the Planck length because Hubble was a tall man. Another joke by comparing these two are that these two distances are about as far from each other as possible on scales that make sense. The smallest distance to something on the order of the size of the visible universe.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[A centered header appears above a list.]
:Reference Physical Quantities
:Hubble volume: 96L
:Schwarzchild radius: 0.34m (curled up)
:Broca's area: 1.7m3
:Fermi temperature: 37°C
:Planck length: 1.76m (lying down)

{{comic discussion}}
[[Category:Comics featuring real people]]
[[Category:Comics with lowercase text]]
[[Category:Astronomy]]
[[Category:Physics]]
[[Category:Biology]]
[[Category:Science]]

Talk:1958: Self-Driving Issues

2018-02-21T09:46:05Z

162.158.90.30:

I assume the ''off-panel speaker'' is [[Megan]], based on their positioning, but not sure what the ruling on the ambiguity is. [[User:PvOberstein|PvOberstein]] ([[User talk:PvOberstein|talk]]) 05:47, 21 February 2018 (UTC)

I made a note about the typo in the title text. Also, weird question, does the "created by a BOT" tag mean that the explanation was written by an AI? Or is it a joke I'm missing for some reason? Sorry, kind of a dumb question I guess. 09:04, 21 February 2018 (UTC)

Could the firmware update be for the humans, because they are obviously malfunctioning in the scenario? Sebastian --[[Special:Contributions/162.158.90.30|162.158.90.30]] 09:46, 21 February 2018 (UTC)

1682: Bun

2017-08-02T18:27:54Z

162.158.90.30: /* Explanation */ If a fact is false, it is not a fact. The cartoon opens with a false statement, not with a fact.

{{comic
| number = 1682
| date = May 18, 2016
| title = Bun
| image = bun.png
| titletext = If a wild bun is sighted, a nice gesture of respect is to send a 'BUN ALERT' message to friends and family, with photographs documenting the bun's location and rank. If no photographs are possible, emoji may be substituted.
}}

==Explanation==
In this comic, [[Ponytail]] is teaching a class about an animal referred to as a "bun". The word "bun" is short for {{w|bunny}}, an informal term used for a {{w|rabbit}}. The comic depicts a childish response to seeing a cute animal, except coming from an adult. The humor in the comic comes from a tone of absurdity in a classroom situation where lectures are expected to be serious.

The lecture opens with the statement that smaller buns are superior in rank, which is plainly false. Instead, the teacher clearly thinks that smaller bunnies are just cuter. She mentions that "king buns" may be seen around this time of year, which refers to rabbit kittens being born in the spring. Kittens would be smaller and cuter than any other rabbits because of their age. There is no mention of a "queen bun", but the gender of the kitten can be difficult to determine without a close examination. A prime example of a king bun can be seen [https://imgur.com/gallery/HicMr/ here].

[[Megan]], who attends this biology class, expected to learn about rabbits and hares which are both {{w|Lagomorpha|lagomorphs}}, a mammalian {{w|Order (biology)|order}} that also includes the {{w|pika}}s. Megan thus clearly has the correct understanding of what a "bun" is. Ponytail then claims that the word ''bun'' is the scientific term, and states that rabbit, hare, and lagomorph are informal ways to describe these animals, again being completely wrong as in reality ''bun'' is the most contracted and informal name for a rabbit.

Two students are then legitimately doubting that they're in the correct class and decide to check online (either the crude theories that Ponytail expressed, or their course schedule). A third student however appears to believe the lecturer uncritically, reminding the fellow students that they're looking upon the image of a king (i.e. a cute bunny).

The title text refers to photographing a rabbit and, for example, posting it on social media - something which would typically be done today if someone sees a cute rabbit in the wild. If the poster had failed to photograph the rabbit before it ran away, they may typically post a message saying something like "I saw a really cute bunny today!" with an {{w|emoji}} depiction of a rabbit (probably 🐇 or [http://www.amazon.com/WEP-Emoticon-Cushion-Stuffed-Colorful/dp/B01EMBET4A 🐰]). This is especially common in the area where [[Randall]] lives, as the urban rabbit population in the Cambridge/Somerville area has exploded, putting a large human population with relatively little previous experience with rabbit-sightings suddenly in the position of encountering them very frequently.{{Citation needed}} Emoji has become a [[:Category:Emoji|recurrent theme]] on xkcd.

Ponytail tells that buns have a hierarchy in which the smaller the bun, the higher its ranking is - a rank-size distribution. A "king bun" can be seen as an instance of the king effect, the phenomenon where the top one or two members of a ranked set show up as outliers. An interesting linguistic note is that in several Slavic languages (including Russian, Czech and Polish), the word for Rabbit literally means "Little King".

[[231: Cat Proximity]] also shows an adult human reacting childishly to cute animals, though in a casual setting. A teacher teaching complete nonsense is depicted in [[1519: Venus]], though intentionally false. Another educator who is excited about their field is in [[1644: Stargazing]], but there the facts are true while being presented absurdly. These comics also show someone who should be acting maturely but fail to, and can be considered to be funny in the same way because of that. The bun joke is continued in [[1871: Bun Alert]].

==Transcript==
:[Ponytail is a teacher and she holds a pointer to a picture of a rabbit on a board behind her.]
:Ponytail: Good morning class! Today, we will be learning about the bun.

:[Two rabbits are shown, one slightly smaller, and a greater than symbol indicates that the smaller one is "greater than" the larger one. Ponytail is talking off panel to the left.]
:Ponytail (off panel): Buns have a hierarchy.
:Ponytail (off panel): A bun's rank is determined by its size. Smaller buns are higher-ranking.

:[Two normal sized rabbits are sitting left and right of a very small rabbit. The smaller rabbit appears to give off a radiant light indicated with gray and white alternating rays going through the image. It is indicated that is shines on the larger rabbits as they are gray on the side turned away from the smaller rabbit and white on the front turned towards it. Ponytail narrates above the frame of this half sized panel:]
:Ponytail (narrating): Most buns you see are relatively low-ranking.
:Ponytail (narrating): But this time of year, a lucky few may catch a glimpse of a ''king bun''.

:[A student represented by Megan is sitting at a desk with a few books on it, pencil in hand.]
:Megan: OK, hang on.
:Megan: We're talking about rabbits and hares, right? Lagomorphs?

:[Ponytail is holding her finger up on her left hand, and is holding her pointer at her side with the other. Students reply to her off panel to the right.]
:Ponytail: Informally, yes. But in this course, we use the ''scientific'' term, "bun".
:Student #1 (off-panel): Are we sure this is the right room for ''introductory mammalogy?''
:Student #2 (off-panel): I'll check online.
:Student #3 (off-panel): ''Shh!'' Show respect! We look upon the image of a king!

==Trivia==
*In the [http://www.explainxkcd.com/wiki/images/archive/2/2c/20160518175345!bun.png original version] the word "hierarchy" in the 2nd panel was misspelled as "h'''ei'''rarchy". This led to speculation regarding the near-homonyms "heir" and "hare", but the spelling was later corrected.
*In [[1663: Garden]], the rabbit image had the filename "[http://xkcd.com/1663/art/2x-important-bun.png important-bun.png]":
::[[File:Garden Important bun.png]]

{{comic discussion}}

[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Megan]]
[[Category:Animals]]
[[Category:Emoji]]