explain xkcd - User contributions [en]

Talk:2776: Crystal Ball

2023-05-18T03:34:33Z

162.158.154.18: Spherical aberration vs coma

I added an explanation of spherical aberration and the tendency of light to distort around spherical objects, as well as the idea of how fisheye lenses use this principle to do their thing. [[User:Darkwolf0218|Darkwolf0218]] ([[User talk:Darkwolf0218|talk]]) 01:01, 16 May 2023 (UTC)

I can't seem to find the citation toolbar while editing on mobile. So dropping this here for a reference to ball lenses on fiber optic cables. {{Cite web}} https://www.edmundoptics.com/knowledge-center/application-notes/optics/understanding-ball-lenses/ [[User:Iggynelix|Iggynelix]] ([[User talk:Iggynelix|talk]]) 12:37, 16 May 2023 (UTC)
:We ''very rarely'' use Cites on this site. Just add a link (in alternate-word form to flow with the sentence, ideally).
:I've never really used toolbar stuff (simple enough to tap in {s, }s, [s and ]s, as well as any <s and >s needed for HTML, etc), and it's simple to (eventually, perhaps checking via Preview that it's not ''totally'' messed up on the first go or two) work out what others did to add references and copy the style of the right kinds of them.
:So if you want to mention a link to [https://www.edmundoptics.com/knowledge-center/application-notes/optics/understanding-ball-lenses/ ball lenses], just do something like this. (PS., use the full <nowiki>~~~~</nowiki> when signing Talk contributions, I fixed yours without using the {{template|unsigned}} 'reminder'..) [[Special:Contributions/172.70.86.31|172.70.86.31]] 14:28, 16 May 2023 (UTC)

Why am I now ear-wormed by "Beware of the Beautiful Stranger" by Clive James and Pete Atkin?
"That ball needs a re-gun" I said, shelling out
The future you see there has all come about"
https://genius.com/Pete-atkin-beware-of-the-beautiful-stranger-lyrics
https://www.youtube.com/watch?v=MeOYHZQqWao
[[Special:Contributions/172.71.242.202|172.71.242.202]] 17:56, 16 May 2023 (UTC)

I’m going to edit the part on the title text to be more broad, as Google isn’t the exclusive way to receive any kind of information on the internet [[Special:Contributions/172.69.58.42|172.69.58.42]] 19:35, 16 May 2023 (UTC)

While we can all applaud the connection of spherical aberration to crystal balls, unfortunately the off-axis part of joke misses the mark as spherical aberration is an aberration that is generally uniform across the frame. [[Special:Contributions/172.70.210.190|172.70.210.190]] 19:52, 16 May 2023 (UTC)

: Yes, the comic seems to be confusing spherical aberration with coma, which makes it hard to produce a good explanation. I think the current reference to fisheye lenses, and distorted shapes, is a red herring. Spherical aberration rather appears as a lack of sharpness. [[Special:Contributions/162.158.154.18|162.158.154.18]] 03:34, 18 May 2023 (UTC)

I'm new to the whole xkcd's websites and comic strips and I desire to meet some other xkcd fans as well![[User:ArchaRaid|ArchaRaid]] ([[User talk:ArchaRaid|talk]]) 23:29, 16 May 2023 (UTC)

2775: Siphon

2023-05-12T17:43:06Z

162.158.154.18: Grammar nitpick

{{comic
| number = 2775
| date = May 12, 2023
| title = Siphon
| image = siphon_2x.png
| imagesize = 310x378px
| noexpand = true
| titletext = ADDITIONAL NOTES: Fixed a bug that caused some rocks to generate virtually infinite heat while just sitting there.
}}

==Explanation==
{{incomplete|Created by a SIPHONIC WINDS - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
Cueball and Megan have a demonstration of a {{w|Siphon}}, by which the gravitational force on an upper reservoir of liquid and molecular cohesion move a liquid upward through a tube, traversing a higher peak to reach a lower exit. Randall has also mentioned siphons in his book, "how to," section "how to make a pool."

Siphons are commonly used in modern society (e.g., toilets are flushed by siphon action).

Siphons are separate from a similarly counterintuitive phenomenon of {{w|capillary action}}, where a liquid flows through narrow spaces, usually upwards (against gravity) in that a siphon can be of much larger diameter and capillary action can move liquid up an initially empty channel.

Apparently, even though Cueball and Megan have probably set up the experiment correctly, the water no longer demonstrates a siphon by flowing from the upper bucket to the lower. Cueball observes in surprise that "it's true," meaning that this is a very recent development, and Megan remarks that it was honestly weird in retrospect that scientists had ever tried to rationalise this admittedly counterintuitive phenomenon in the first place.

The punchline of the comic is in the caption, which delivers a piece of physics news that the "2023 update to the universe" finally fixed capillary action, dubbed "the siphon bug" in this caption. The joke here is that the entire complex and multifaceted system of {{w|physics}} in and of itself is treated as though it's simply the logic (or perhaps the [[1620: Christmas Settings|officially maintained configuration]]) to a video game, and that capillary action (rather than being an interesting physical phenomenon worth studying) was nothing more than a bug unintentionally created by the "devs" (whoever that may be). In reality, capillary action still very much exists in our universe,{{citation needed}} though {{w|simulation hypothesis|the idea that we live in a computer simulation}} is also prevalent in {{w|the matrix|our modern pop culture}}.

The title text is a reference to [[2115: Plutonium]]. It expands on the joke surrounding the idea of an "Earth dev log" by referencing {{w|nuclear power}}, and how it's apparently another bug that some nuclear elements (notably {{w|uranium}} and {{w|plutonium}}, among others) can be and have been harnessed by humanity in order to generate virtually infinite amounts of energy, all while the elements themselves are simply sitting there in the core of some {{w|nuclear reactor}}.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:Cueball: Wow, it's true—the water doesn't flow up the tube anymore.
:Megan: Honestly, it's weird that it ever did.
:Megan: Why did we think that was normal?

:[Caption below the panel:]
:Physics news: The 2023 update to the universe finally fixed the "siphon" bug.

{{comic discussion}}

2770: Tapetum Lucidum

2023-05-02T01:13:05Z

162.158.154.18: Undo revision 312144 by 172.71.147.153 (talk)

{{comic
| number = 2770
| date = May 1, 2023
| title = Tapetum Lucidum
| image = tapetum_lucidum_2x.png
| imagesize = 412x492px
| noexpand = true
| titletext = Using a reflective wall in a game to give one shot two chances to hit is called a double-tapetum lucidum.
}}

==Explanation==
{{incomplete|Created by BILL NYE'S CAT - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

{{w|Bill Nye}}, known for his children's educational series ''Bill Nye the Science Guy'', wearing the same lab coat as in [[200: Bill Nye]], beats an unseen player (presumably [[Randall]]) in an online multiplayer game resembling {{w|XPilot}}, in which players pilot spaceships using simulated rocket physics and attempt to shoot and kill each other. During a laser battle, Bill Nye provides a scientific explanation for the {{w|tapetum lucidum}}, the layer behind the {{w|retina}} of a cat's eye. He explains that the layer reflects back some of the light that bounces off the retina, giving it a second chance to hit the retina again. This allows a cat's eye to capture more light than it otherwise would, and thus improves their night vision. It's also why [https://carnegiemnh.org/meowfest-why-do-cat-eyes-glow-in-the-dark/ cat's eyes appear to glow in the dark].

At the same time, Bill Nye's battle tactic in the online game perfectly analogizes the point he is making. His spaceship is firing energy pulses into the path of an approaching ship in an attempt to destroy it. Due to the difficulty of hitting a small, fast-moving target, it's likely that most or all of these shots will miss. However, because Bill Nye is firing at a reflective wall, each shot that misses bounces back into the path of the opponent's ship, giving it a second chance to hit the target and effectively doubling the density of the firepower. With double the number of shots to avoid, the opponent's ship is hit and explodes.

In the analogy, the weapon shots fired by Bill Nye's ship are the light photons entering the cat's eye, the reflective wall is the tapetum lucidum, and the opponent's ship is a retinal cell. Destroying the opponent's ship with a shot is analogous to a light photon being absorbed by the cat's retina (and therefore seen). If the reflective wall hadn't been there, the ship might have survived, which means the retina would never have seen that photon.

Randall presumably considers this "extra infuriating" because Bill Nye is showing off his scientific knowledge in some other field while also beating him in the game.

The title text refers to "tapetum lucidum" and uses "double tap" in the way that online games, memes, and films refer to shooting something twice in rapid succession to ensure its demise. This phrase is famously{{Actual citation needed}} used in the film "Zombieland," and is the subtitle of the 2019 "Zombieland: Double Tap" sequel.

==Transcript==
:[Two triangles with two long sides of equal length (isosceles triangles) but with the short side curving a bit in, are moving inside a black structure, their movement indicated with three and two curved lines below the left and above the right triangle. Both triangles shoots green lasers out of their sharp tip, indicating they represents space ships. They are flying inside a black structure, maybe a maze. There is nothing above the left ship. but below the ships are a black segment making a triangle in the lower left corner. The right ship is inside an opening created by this triangle below it, and another black triangle above it, that centers on the middle of the right side of the panel. The left ship has shot three green laser beams, one of them hits inside the opening on the right triangle and the beam bounces off this wall. But it is not close to the right ship. The right ship has only fires one green laser, which bounces off the left wall also far from the left ship. A voice emanates from the left ship, via a star burst at the top corner. And there are sounds because of the shots it has fired.]
:Left ship: Cats have a shiny layer behind their retina called the tapetum lucidum.
:Laser shots: Pew pew pew

:[Same setting but the scene has panned a bit to the left and up so less of the black walls can be seen. The left ship has moved closer to the right wall and has turned so it's sharp tip points almost straight down, still with three curved lines to indicate movement, probably turning movement. It again fires green lasers at the other ship, four this time, with sounds coming from the shooting. The right spaceship is accelerating forward as indicated with three wavy lines behind it's short side moving in to the line of fire. It seems as though all four lasers might miss it, but one of those that already has passed it, is being reflected up against it from below the left black wall. Again a voice emanates from the left ship via a starburst in the left corner:]
:Left ship: After light passes through the retina, this layer reflects it back through a second time.
:Laser shots: Pew pew

:[Same setting but the scene has again panned a bit to show a different segments of the black walls. The ship originally to the left is now above and a bit to the right of where the right ship originally was, and it is even closer to the right wall. It is not firing any more shots, because the reflected shot from the previous panel has hit the right ship which explodes in large green cloud with the black pieces of the ship inside it, and a huge sound. The tail of the laser shot that hits it can be seen entering the explosion. Three other laser shots from before are still moving down, but might all have missed the ship. There are no movement lines now but again the voice emanates from the left ship via a starburst in the left corner:]
:Left ship: This extra bounce gives photons another chance to interact with the retinal cells...
:Explosion: Boom!

:[A man with short black hair wearing a labcoat is sitting in an office chair typing on his computer while speaking. Below him is a frame with a caption, from which it becomes clear that the man, and the owner of the voice from the left ship, is Bill Nye.]
:Bill Nye: ...Improving their night vision! Isn't science cool?
:Caption: There's something extra infuriating about losing online games to Bill Nye.

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Comics featuring real people]]
[[Category:Video games]]
[[Category:Biology]]
[[Category:Cats]]

2768: Definition of e

2023-04-27T04:26:15Z

162.158.154.18:

{{comic
| number = 2768
| date = April 26, 2023
| title = Definition of e
| image = definition_of_e_2x.png
| imagesize = 571x186px
| noexpand = true
| titletext = Yeah, my math teacher back in high school set up the system to try to teach us something or other, but the 100% rate was unbelievably good, so I engineered a hostile takeover of his bank and now use it to make extra cash on the side.
}}

==Explanation==
{{incomplete|Created by 2.718 BANKERS - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
e (Euler's constant) is typically demonstrated in terms of compound interest. Here, Miss Lenhart seems to be setting up such an example, but is actually asking her student to deposit money.

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

:[Hairy is seated at a classroom desk, with Miss Lenhart standing in front of him, and a chalkboard behind her.]
:Hairy: Can you explain what the constant ''e'' actually ''means''?
:Miss Lenhart: Sure.

:Miss Lenhart: I have a bank account that pays 100% annual interest, compounded every minute.

:Miss Lenhart: If you deposit $1 now,

:Miss Lenhart: I will answer your question.

[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Miss Lenhart]]
[[Category:Math]]

{{comic discussion}}