explain xkcd - User contributions [en]

2967: Matter

2024-08-05T23:23:18Z

108.162.245.236: /* Explanation */ change a repeated which to that

{{comic
| number = 2967
| date = August 2, 2024
| title = Matter
| image = matter_2x.png
| imagesize = 234x341px
| noexpand = true
| titletext = He was the first person to land a 900, which is especially impressive because pulling off a half-integer spin requires obeying Fermi-Dirac statistics.
}}

==Explanation==
{{incomplete|Created by a GOOFY FRONTSIDE WIKI GRIND TO SECRET PHYSICS DEMO TAPE - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

In {{w|skateboarding}}, the term "goofy" means to push with the left foot, using the {{w|Footedness#Goofy_stance|opposite stance}} to the supposedly standard stance of pushing with one's right foot. The comic uses those stances as an analogy for {{w|antimatter}} in particle physics, which has the opposite electrical charge of corresponding matter particles that will annihilate each other upon collision, releasing energy proportional to their combined mass. In this comic, famed professional skateboarder {{w|Tony Hawk}} has obtained a professorship in physics and is teaching this very non-standard concept. As Tony Hawk does not have a degree in physics,{{Citation needed}} teaching inaccurate lessons could be a likely pitfall of his gaining a professorship in real life.

Hawk's presence here could in part be inspired by professor {{w|Stephen Hawking}}, a famous astrophysicist at the University of Cambridge who died in 2018. Hawk is also the subject of [[296: Tony Hawk]].

Unlike other distributions of handedness in the natural world (chemical {{w|chirality}}, or the {{w|skewness}} of {{w|Multimodal distribution|bimodal statistics}} describing asymmetries in nature called {{w|homochirality}}), 'goofy-footed' skateboarders are about as common as those using standard footing. The analogy indirectly raises the issue of {{w|baryon asymmetry}}, the observation that ordinary matter is very much more common than antimatter because there is so little evidence of annihilation throughout the universe. Baryon asymmetry is often thought to have resulted from fluctuations during {{w|Inflation (cosmology)|cosmological inflation}} between 10<sup>−33</sup> and 10<sup>−32</sup> seconds [https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.251301 after the Big Bang], although there are several other candidate explanations of varying falsifiability.

The title text describes Hawk as the first person to "land a 900," meaning the [https://www.youtube.com/watch?v=4YYTNkAdDD8&t=1m30s successful completion] of {{w|900 (skateboarding)|a skateboarding trick}} that involves two and a half rotations, i.e. nine hundred degrees (2.5 × 360° = 900°). In physics, {{w|Spin (physics)|spin}} is a {{w|quantum number}} describing subatomic particles (see [[1862: Particle Properties]]), named in reference to the vaguely analogous ''but crucially distinct'' concept of {{w|angular momentum}} in classical physics. Obeying {{w|Fermi–Dirac statistics}} requires that the particles involved are {{w|fermion}}s, which include all of the electrons, protons and neutrons that comprise the entirety of everyone's body and electrochemical state. Fermions all have {{w|half-integer}} (i.e., ...–1½, –½, ½, 1½...) {{w|spin quantum number}}s which do indeed include 2½, but only [https://physics.aps.org/articles/v7/s137 extremely rare particles] have a spin of 5/2. However, it's very important to remember that [https://www.youtube.com/watch?v=pYeRS5a3HbE&ab_channel=ScienceClicEnglish quantum mechanical spin is ''not'' rotation, but instead how quickly the corresponding particle changes state when rotated.]

While everyone (and almost everything we ordinarily interact with except light and cosmic rays) is comprised entirely of fermions, {{w|Boson#Composite bosons|any composite particle made of an even number of fermions, including entire atoms and their nuclei, are not fermions}} but {{w|boson}}s, which do ''not'' obey Fermi–Dirac statistics. Luckily, landing a 900 does not actually require obedience to Fermi–Dirac statistics because a skateboarder comprised entirely of bosonic atoms would still have fermionic electrons in the orbitals of those atoms and thus would still obey the far more macroscopically fundamental and consequential {{w|Pauli exclusion principle}}. That principle gives mostly empty atoms the property of substance, allowing you to hold things, walk, make sound waves with your voice and employ any mechanical property of matter, and allowing a sufficiently skilled skateboarder to land a 900.

==Transcript==
:[Tony Hawk (drawn with short hair) is gesturing at a narrow whiteboard on which illegible things are marked, what may be a Feynman diagram with one of the particle/antiparticle pair going into a circle (possibly representing a black hole, and thus depicting the popularized (incorrect) analogy for {{w|Hawking radiation}}), and at the bottom, a 2x3 table of illegible values.]
:Tony Hawk: In the standard model, regular matter will annihilate if it comes in contact with oppositely-charged ''goofy'' matter.

:[Caption below the panel:]
:Tony Hawk becomes a physics professor

{{comic discussion}}

[[Category:Comics featuring real people]]
[[Category:Skateboard]]
[[Category:Physics]]
[[Category:Statistics]]

2941: Cell Organelles

2024-06-04T21:38:22Z

108.162.245.236:

{{comic
| number = 2941
| date = June 3, 2024
| title = Cell Organelles
| image = cell_organelles_2x.png
| imagesize = 563x451px
| noexpand = true
| titletext = It's believed that Golgi was originally an independent organism who was eventually absorbed into our cells, where he began work on his Apparatus.
}}

==Explanation==
{{incomplete|Created by a GOLGI ENDOPLASMIC RETICULUM. Do NOT delete this tag too soon.}}

This comic shows a {{w|Cell (biology)|biological cell}} diagram with a mix of real and fictional {{w|organelle}}s, giving both accurate {{w|Cell biology|cell biology}} terms and humorous ones. Actual cell components include the nucleus, mitochondria, and Golgi apparatus, while unrelated concepts come from geology, engineering, anitvirus software, and even Star Wars. Labels like "evil endoplasmic reticulum" and "sticky endoplasmic reticulum" are variations of real cellular organelles. Other labels like "pith," "mantle," and "Vitreous humor," are amusingly borrowed from other types of circular cross-sectional diagrams (i.e., of fruit, planets, and eyeballs).

The title text is a fictional backstory to the {{w|Golgi apparatus}}, an essential cell organelle involved in processing and packaging proteins. It suggests that {{w|Camillo Golgi}}, the scientist who discovered the Golgi apparatus, was originally an independent organism. This organism was supposedly absorbed into our cells, where it then started working on what is now known as the Golgi apparatus. The joke is a satirical take on {{w|Symbiogenesis|endosymbiotic theory}}, which posits that certain organelles within {{w|Eukaryote|eukaryotic}} cells, like {{w|mitochondria}} and {{w|chloroplasts}}, originated from independent symbiotic {{w|Prokaryote|prokaryotic organisms}} that were absorbed by a host {{w|germ cell}}. Golgi is drawn in the comic as a cute little alien.

{| class="wikitable sortable"
|-
! Label
! Meaning
! Real?
! Cell organelle?
! Explanation
|-
| {{w|Smooth endoplasmic reticulum}}
| A network of tubular membranes within the cytoplasm of the cell, involved in the transport of materials.
| Yes
| Yes
| A standard term for the smooth (i.e., not ribosome-covered) portion of the {{w|endoplasmic reticulum}}.
|-
| {{w|Lithosphere}}
| The rigid outer part of the earth, consisting of the crust and upper mantle.
| Yes
| No
| Term from geology; part of the Earth's crust. Labeled cross-sectional diagrams of cells and of the layers of the Earth are commonly found in science textbooks.
|-
| {{w|O-ring}}
| A mechanical gasket in the shape of a torus; used to seal connections.
| Yes
| No
| Engineering term. Both the o-ring and pith are drawn connected to the inner cell membrane. Made famous in pop culture for being the root cause of the {{w|Space Shuttle Challenger disaster}}.
|-
| {{w|Pith}}
| The central tissue in plants, used for nutrient transport.
| Yes
| No
| Botanical term. Both the pith and o-ring are drawn connected to the inner cell membrane.
|-
| {{w|Cell nucleus|Nucleus}}
| The central and most important part of an object, forming the basis for its activity and growth.
| Yes
| Yes
| The cell nucleus is an actual cell organelle which houses {{w|DNA}}.
|-
| {{w|Nucleolus}}
| A small dense spherical structure in the nucleus of a cell during {{w|interphase}}.
| Yes
| Yes
| Actual cell organelle, involved in {{w|ribosome}} production.
|-
| Nucleoloulous
| Not a real term.
| No
| No
| A humorous continuation of the terms "nucleus" and "nucleolus."
|-
| {{w|Nucleon}}s
| Protons and neutrons in the nucleus of an atom.
| Yes
| No
| While cells contain nucleons, the depicted circles are far larger than actual nucleons.
|-
| Drain plug
| A stopper for a drain.
| Yes
| No
| A plumbing term, which could refer to a {{w|porosome}}. Even small, temporary damage to the integrity of the {{w|cell membrane}} puts the cell at immediate and great risk of death.
|-
| Evil endoplasmic reticulum
| Not a real term.
| No
| No
| A humorous twist on the different types of actual {{w|endoplasmic reticulum|endoplasmic reticula}}, implying a malevolent version.
|-
| {{w|Hypoallergenic}} filling
| Materials that cause relatively fewer allergic reactions.
| Yes
| Technically not incorrect
| Consumer product term, used e.g. for pillows and mattresses. If the {{w|cytoplasm}} doesn't cause allergic reactions within the cell, it is hypoallergenic.
|-
| Weak spot
| A vulnerable point.
| Yes
| Conceivably
| {{w|Cell membrane}} surfaces do indeed vary in strength, often due to the presence of organelles such as {{w|ion channel pore}}s or {{w|porosome}}s, both of which can be leveraged by viruses to enter cells.
|-
| {{w|Mitochondria}}
| Organelles that generate energy for the cell.
| Yes
| Yes
| Actual cell organelles. Mitochondria are widely known as the "powerhouse of the cell," a phrase originally coined in 1957 by biologist {{w|Philip Siekevitz}}[https://www.scientificamerican.com/article/powerhouse-of-the-cell/] which came to prominence online in the mid-2010s.{{acn}}
|-
| {{w|Midichlorians}}
| Fictional microorganisms in the {{w|Star Wars}} universe, which confer Force sensitivity and thereby {{w|Jedi}} associated powers.
| No
| Fictional
| It's unclear whether {{w|George Lucas}} intended for "midi-chlorians" to be {{w|Symbiogenesis|endosymbiotic organelles}} or internal {{w|Symbiosis|symbionts}}.
|-
| {{w|Chloroplast}}s if you're lucky
| Organelles in plant cells responsible for {{w|photosynthesis}}.
| Yes
| Yes, but in plants and plantlike organisms
| Actual cell organelles, found in plant cells and those of several different lineages of non-plant microorganisms and seaweeds. The phrase "if you're lucky" alludes to the good fortune that an organism, be it plant, animal, or microbe, gains by being able to photosynthesize, getting energy from sunlight, rather than have to run around all the time chasing energy. This benefit makes chloroplasts [https://en.wikipedia.org/wiki/Kleptoplasty worth stealing].
|-
| Human skin
| The outer covering of the human body.
| Yes
| No
| Skin cells aren't normally inside other cells, but dead skin cell fragments can be inside {{w|phagocyte}}s. The label, however, is drawn connected to the outer {{w|cell membrane}} or the {{w|extracellular matrix}}.
|-
| {{w|Carbonation}}
| {{w|Carbon dioxide}} dissolved in a liquid.
| Yes
| No
| Carbonation causes soda pop and similar liquids to bubble, fizz, foam, and {{w|effervesce}}. The little dots depicted in the comic look like carbonation bubbles.
|-
| Golgi
| {{w|Camillo Golgi}} (1843–1926) was an Italian biologist and {{w|pathologist}} who discovered the Golgi apparatus; known also for his works on the central nervous system.
| Yes
| No
| The real Golgi was not and is not a tiny alien being who merged with our cells, as the comic and title text imply.{{Citation needed}}
|-
| {{w|Golgi apparatus}}
| A complex of {{w|vesicles}} and folded membranes involved in secretion and intracellular transport.
| Yes
| Yes
| Actual cell organelle, which takes {{w|polypeptide}} chains from the rough endoplasmic reticulum via transport vesicles and processes them into their protein structure before sending them (again via vesicles) to their destination such as an organelle or outside of the cell.
|-
| {{w|Norton AntiVirus}}
| A software product designed to protect computers from malware.
| Yes
| No
| Computer viruses and biological viruses are completely different, and systems designed to counter one generally don't work for the other. Many cell types do have antiviral mechanisms, notably the {{w|CRISPR}} (Clustered Regularly Interspaced Short Palindromic Repeats) DNA sequences in prokaryotes, which resist viral (bacteriophage) infection. However, the cell shown is not prokaryotic, since it contains a nucleus.
|-
| Sticky endoplasmic reticulum
| Not a real term, although parts of the reticula have sticky pockets.[https://www.frontiersin.org/articles/10.3389/fcell.2023.1156152/full]
| No
| No
| Another humorous twist on the actual types of endoplasmic reticula.
|-
| {{w|Pleiades}}
| A cluster of stars in the constellation Taurus.
| Yes
| No
| Even a single star is far too big to fit in a cell. The labled cluster in the comic looks like the actual constellation, as if this were a depiction of the night sky.
|-
| Natural flavor
| Flavoring derived from natural sources.
| Yes
| Conceivably
| A common ingredient on labels, usually meaning any substance to add flavor, aroma, or both, other than synthetic chemicals which are referred to as artificial flavors.
|-
| {{w|Cellophane}}
| A thin, transparent sheet made of regenerated {{w|cellulose}}.
| Yes
| No
| A type of packaging material. A {{w|cell wall}} is indeed made of cellulose, though not in the form of cellophane. Also, this drawing looks more like an animal cell, which unlike plants and fungi, do not usually have a cell wall.
|-
| {{w|Rough endoplasmic reticulum}}
| Endoplasmic reticulum with {{w|ribosomes}} attached, involved in protein synthesis.
| Yes
| Yes
| Actual cell organelle. "Rough" refers to the presence of ribosomes covering its membrane, which translate {{w|messenger RNA}} into polypeptide chains. Normally the endoplasmic reticulum would wrap around the cell nucleus.
|-
| {{w|Ventricle}}
| A chamber of the heart that pumps blood out.
| Yes
| No
| Ventricles are actually part of the body, and they are composed of many cells. Possibly a pun on {{w|vesicle}} (or {{w|vacuole}}), a small membrane-enclosed vessel, such as the transport vesicles that carry polypeptides from the rough endoplasmic reticulum to the Golgi apparatus for processing.
|-
| {{w|Mantle}} 
| The layer of the earth between the crust and the core.
| Yes
| No
| Misplaced geological term with many other meanings.
|-
| {{w|Slime}}
| A moist, soft, and slippery substance, or a {{w|Slime_(toy)|goopy substance sold as a toy}}.
| Yes
| No
| Could refer to the slimy texture and appearance of {{w|cytoplasm}}, but not specific to cells. Slime was a frequent appearance on the Nickelodeon TV kids channel during [[Randall]]'s youth in the 90s.{{acn}}
|-
| {{w|Vitreous humour}}
| The clear gel that fills the space between the lens and the retina in the eyeball.
| Yes
| No
| The vitreous humour is in the eyes' {{w|extracellular matrix}}, not inside cells.
|-
| {{w|Seed}}s
| Plant embryos used for reproduction.
| Yes
| No
| Seeds are multicellular, and sometimes contain small proportions of non-cellular tissue. Cells are found in seeds, not the other way around. Seeds would be labled on a cross-sectional diagram of a fruit, not a cell.
|}

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

Cell Organelles

[A cell is shown with the following structures and areas labeled, counter-clockwise from upper left:]

* Smooth endoplasmic reticulum
* Lithosphere
* O-Ring
* Pith
* Nucleus
* Nucleolus
* Nucleoloulous
* Nucleons
* Drain plug
* Evil endoplasmic reticulum
* Hypoallergenic filling
* Weak spot
* Mitochondria
* Midichlorians
* Chloroplasts if you're lucky
* Human skin
* Carbonation
* Golgi
* Golgi apparatus
* Norton AntiVirus
* Sticky endoplasmic reticulum
* Pleiades
* Natural flavor
* Cellophane
* Rough endoplasmic reticulum

[These labels are inside the cell:]

* Ventricle
* Mantle
* Slime
* Vitreous humour
* Seeds

{{comic discussion}}

[[Category:Biology]]

2941: Cell Organelles

2024-06-03T21:22:33Z

108.162.245.236: Undo revision 343629 by 172.69.71.72 (talk)

2941: Cell Organelles

2024-06-03T20:16:28Z

108.162.245.236: /* Explanation */ replace column

2941: Cell Organelles

2024-06-03T20:10:34Z

108.162.245.236: edit conflict, will resolve....

Talk:2486: Board Game Party Schedule

2021-07-08T00:27:42Z

108.162.245.236:

I've done the best I can starting this out. Since it's been years since I did gatherings like this, if someone can suggest more modern examples of complicated tabletop simulation games than the ones I suggested (Squad Leader and SFB started in the late 1970s, for heaven's sake), please do so. [[Special:Contributions/108.162.245.236|108.162.245.236]] 00:27, 8 July 2021 (UTC)

2486: Board Game Party Schedule

2021-07-07T23:38:30Z

108.162.245.236: /* Explanation */

{{comic
| number = 2486
| date = July 8, 2021
| title = Board Game Party Schedule
| image = board_game_party_schedule.png
| titletext = Several of the guests are secretly playing Meta Board Game Party. Every minute of parallel debate in the breakaway faction earns double victory points!
}}

==Explanation==
{{incomplete|Created by a BOT. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

This comic shows a timeline of a gathering to play some sort of fairly complex tabletop or roleplaying game, such as Dungeons and Dragons, Star Fleet Battles, or Squad Leader (please edit with more recent games). These games often have many pages of rules, forms to fill out, and in the case of many battle simulation games can have dozens or even hundreds of counters to position. Often the very complex rules must be explained in detail, which is often extremely dull in a group environment.

Conversely, "just beginning" without explanation often leads to new player frustration that, had they had a complete understanding, they would have made different choices and had a more reasonable chance at victory, or even worse, avoided constantly being informed of "illegal moves".

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

{{comic discussion}}