explain xkcd - User contributions [en]

2478: Alien Visitors 2

2021-06-18T23:56:02Z

173.245.54.227: base transscript

{{comic
| number = 2478
| date = June 18, 2021
| title = Alien Visitors 2
| image = alien_visitors_2.png
| titletext = "Although fresh juice DOES sound--" "NO! For humanity to survive we must learn from the mistakes of the past."
}}

==Explanation==
{{incomplete|Created by a 1920s ELIXIR. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
In the return of the aliens from the [[2477: Alien Visitors|previous comic]], they show more "advanced" inventions that are less efficient or more harmful than their current forms, and most have been invented by humans and replaced.

{{w|Biplane}}s are planes with two sets of wings, which have more drag than a {{w|monoplane}}.

A {{w|blimp}} is a lighter than air aircraft with no internal structure. The point raised about hydrogen would be because it is highly flammable and dangerous. The {{w|Hindenburg_disaster|Hindenburg}} was a famous explosion of a hydrogen airship (although zeppelin airships are not blimps because they have an internal structural framework and they're called rigid airships in contrast to blimps, that just rely on the internal pressure of their lifting gas to maintain their shape).

{{w|Tetraethyllead}} is a chemical added to gasoline (mostly from the 1920s to the 1990s — although some countries [https://web.archive.org/web/20171115235249/http://wedocs.unep.org/bitstream/handle/20.500.11822/17542/MapWorldLead_March2017.pdf?sequence=1&isAllowed=y still use it to this day]) to prevent {{w|Engine_knocking|Engine Knock}}, until it was revealed to have highly toxic effects. The aliens seem unaware of these toxic effects (it is unclear whether the chemical hurts aliens as well, or whether it doesn't hurt them but they don't realize the toxic effects on humans), and indeed quite concerned by them, implying they might be using leaded gasoline themselves.

{{w|Juicero}} was a juicer known for its absurd inefficiency and greedy business model {{Citation needed}}: the machine would only work on the company's proprietary branded single-serving bags of pulped fruit sold for $7-10 each, and more juice could be extracted from the bags by hand than by the press. Basically, they were selling $10 bags of chopped fruit and a $700 machine to squeeze them into a cup for you.

After the latest showing of unimpressive "inventions", the humans start questioning how "advanced" the aliens really are, asking if they built the flying saucer themselves and suggesting that it might be wise to avoid standing directly beneath it in case it suddenly crashes to earth.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
UFO: Greetings, humans. We have returned. - Since you already have pyramids, we've brought you more advanced wonders.

UFO: These machines will let you conquer the sky!

Hat: A biplane? Aren't monoplanes more efficient?

Cueball: Does that blimp use hydrogen?

UFO: [(CH3 CH2)4 Pb]

UFO: Add this elixir of lead to your gasoline and your engines will run smooth.

Hat: Lead? Isn't that stuff toxic?

UFO: Is it? Oh no.

UFO: Okay, uh. - This device's electric press can squeeze fresh fruit juice from bags of pulp!

Hair: ... Just curious, did you build that saucer?

Cueball: Maybe we shouldn't stand right under it.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category: Comics featuring Megan]]
[[Category:Aliens]]

2471: Hippo Attacks

2021-06-02T23:59:43Z

173.245.54.227:

{{comic
| number = 2471
| date = June 2, 2021
| title = Hippo Attacks
| image = hippo_attacks.png
| titletext = It's cool how, when there's a number lots of people are curious about, but which isn't easy to measure, some random guess will get cited everywhere and become the universally quoted value. Unrelatedly, did you know there are 850 trillion waves in the ocean?
}}

==Explanation==
{{incomplete|Created by a HIPAA-VIOLATING HIPPO. I think we have managed to capture the broad strokes of the comic, but it could use some copy-editing (especially my words), and I am not confident I am not missing some finer details. Do NOT delete this tag too soon.}}

The first part of this comic deals with unreliable sources on the internet. Neither "viral posts" or "random listicles" are usually very reliable sources of information. They rarely cite their sources, and they are often published without much fact-checking, as published volume and impressive-sounding numbers are far more important for ad-revenue than actual facts.

The Health Insurance Portability and Accountability Act ({{w|HIPAA}}, pronounced ''HIP-uh'') is an American healthcare law enacted in 1996. One of the most commonly cited provisions from HIPAA is the HIPAA Privacy Rule, which regulates the use and disclosure of protected health information.

In this comic, Cueball and Megan are discussing the number of {{w|hippopotamus}} attacks, which are unverified. They propose an alternative explanation as to why this particular number is hard to come by: it would be violating the patients' privacy to create statistics of a very specific and unusual cause of death. The punchline comes with the pun of "hippo violation" to "HIPAA violation".

The title text provides further explanation to the criticism of listicles. They sometimes provide factoids with regards to ill-defined, hard-to-measure numbers, and these factoids might end up in common circulation between such articles. One extreme example such would be the number of waves in the ocean. Some problems with this definition would be:

* In which ocean/oceans?
* Over what time frame?
* What is the smallest ripple that counts as a wave?
* When does one count two interacting waves as separate, and when does one count them as one?

With different answers to these questions, wildly different answers could be reached.

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

:[Cueball sits at his computer desk, facing left. Megan stands behind him.]
:Cueball: I hate unsourced statistics.
:Cueball: ''This'' viral post says hippos kill 2,900 people a year, but ''this'' random listicle says 500.
:Megan: Makes sense.
:Megan: Publishing the real number would be a hippo violation.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Animals]]
[[Category:Statistics]]
[[Category:Puns]]

Talk:2463: Astrophotography

2021-05-14T22:47:04Z

173.245.54.227:

So are any of those "balls" actually sunspots or the transit of Venus or something?
[[Special:Contributions/173.245.54.227|173.245.54.227]] 22:47, 14 May 2021 (UTC)

Talk:2377: xkcd Phone 12

2020-10-26T22:44:28Z

173.245.54.227:

Is there any way to install the Vengaboys feature on my own phone? It's pure genius

1249: Meteor Showers

2020-10-21T15:44:26Z

173.245.54.227: /* Explanation */ Removed incomplete explanation relating to the constellation of Orion

{{comic
| number = 1249
| date = August 9, 2013
| title = Meteor Showers
| image = meteor showers.png
| titletext = Remember, meteors always hit the tallest object around.
}}

==Explanation==
This comic spoofs the way that astronomical events are often reported in the mass media — events are often tagged with undeserved superlatives or described as being more dramatic than they actually are. In some cases, outright misinformation is spread. This phenomenon occurs in part by the result of over-eager scientists, but mostly because of journalists with no deeper knowledge on the subject they write about.

Meteor showers typically occur regularly each year. It always happens at the same days because the Earth is crossing the dust path of a particular {{w|comet}}. Sometimes meteor showers are in fact likely to be relatively spectacular when the peak of the shower occurs while your part of the world is in darkness and there is little moonlight. However, even in these cases it must be understood that there is nothing unusual about the meteor shower itself. The shower just consist of small particles at a size about roughly one millimeter, only the high speed is the reason that is can be seen from Earth's surface. The names of the showers refer to the star {{w|constellation}} where they visually belong to.

Most of the meteor showers listed in the comic are real, but some are made up (and indicated as such below).

*''{{w|Quadrantids}} - January 4th - Bring pets inside during peak activity''
:While keeping pets inside may be reasonable on days when fireworks are let off in the beginning of a new year, no regular meteor shower poses much danger to pets.
*(made-up) ''Tricuspids - January 21st - Not viewable in region 2 countries''
:Apparently a play on the {{w|tricuspid valve}} in mammalian hearts, or possibly on bicuspid teeth. The mention of "Region 2" is a reference to {{w|region locking}}, a digital rights management (DRM) scheme intended to restrict media to certain areas. DRM of course does not apply to natural events. However, meteor showers are also geographically restricted, and the visible area might roughly coincide with a DRM region (Though Region 2 covers a large and scattered area, not being strictly geographical).
*({{w|Alpha Centaurids|Alpha}} / {{w|Theta Centaurids|Theta}}) ''Centaurids - February 6th - Too faint to see without going outside''
:Since indoor lights and window glass make them harder to see, it would take a ''very'' bright meteor (like the Chelyabids two entries below) to be visible without going outside.
*(made-up) ''Beta Aquariids - February 10th - Inverted shower converges toward Aquarius instead of radiating away''
:This fictional shower would collect shooting stars into the origin to prepare for the real {{w|Eta Aquariids}} meteor shower associated with Halley's comet and ''diverging'' from {{w|Eta Aquarii}} in Aquarius; the real shower peaks around May 6th.
:Due to perspective, meteor showers appear to radiate outwards from a certain point in the sky. Meteor showers may be seen to converge on a point on the opposite side of the sky, but with the earth in the way there would only be a few visible going past the edge, seen as nearly parallel streaks overhead, so the convergence point would hardly be notable.
*(made-up) ''Chelyabids - February 15th - Only one meteor per shower, but it's big.''
:A reference to the February 15, 2013, {{w|Chelyabinsk meteor}} whose explosion shattered windows within a large radius.
*''{{w|Lyrids}} - April 22nd - Meteors sometimes scream''
:A meteor large enough to reach the lower atmosphere could produce sound audible to observers on the ground, but this is very unusual.
*''Daytime {{w|Zeta Perseids}} - June 9th - Likely a NASA hoax''
:This shower is mostly observed via its effects on radio and TV signals, and therefore a good target for conspiracy theorists responding to [http://science1.nasa.gov/science-news/science-at-nasa/2000/ast06jun_1m/ June's Invisible Meteors - NASA Science].
*''{{w|June Bootids|June Boötids}} - June 27th - 50/50 mix of meteors and shooting stars''
:The "50/50 mix of meteors and shooting stars" is a joke, as "meteor" and "shooting star" are synonymous.
*''{{w|Southern Delta Aquariids}} - July 19th - Meteors very bright, but stationary''
:This is saying that they are indistinguishable from stars, or that the stars themselves are actually meteors.
*(made-up) ''Dromaeosaurids - July 22nd - Fast, highly intelligent, can open doors''
:{{w|Dromaeosauridae|Dromaeosaurids}} are a family of dinosaurs containing the genus ''Velociraptor'', well-known from the movie Jurassic Park in which they are presented as a deadly menace, fast and especially intelligent to the point of understanding how to open a door; this representation of Velociraptors is a [[:Category:Velociraptors|recurrent topic in xkcd]].
*''{{w|Perseids}} - August 12th - Instead of falling from sky, meteors erupt from ground''
:Erupting from the ground is the funny inverse of falling from the sky, what meteors always do.
*(made-up) ''Tau Pyramids - August 15th - Visible even when eyes are closed''
:Probably a reference to {{w|Pyramidal cells}}, a type of neuron. The "tau" reference has two possibilities. The "visible even when eyes are closed" could refer to the Tau particle, a heavy sibling of the electron. When they traveled outside of Earth's magnetosphere on their way to the Moon, Apollo astronauts saw flashes of light about every three minutes even with their eyes closed; these were caused by high energy particles (cosmic rays) penetrating their eyes and brain. The other possibility is that it refers to {{w|Tau protein}}, a normal structural protein within brain neurons. In Alzheimer's Disease, abnormal Tau proteins can aggregate within pyramidal cells to form insoluble skeins. The number of these "{{w|Neurofibrillary tangle|neurofibrillary tangles}}" roughly correlate with the severity of cognitive impairment.
*''{{w|Draconids}} - October 8th - Very slow, but follow you if you run''
:This may have something to do with the fact that "draconids" etymologically means "of the dragon", which could make for a fearsome meteor shower. And if you run it will track you down, albeit slowly. This may also be a reference to {{w|Boo (character)|Boo}}, a character in the Mario series of video games that is slow but follows you if you turn your back on them. In the game Terraria, meteors (or rather, "meteor heads") follow this exact behavior.
*''{{w|Orionids}} - October 21st - Entire shower happens at once''
:Rather than taking place over the course of a week, all the meteors in the shower happen at the same time. This would involve about 3000 meteors appearing simultaneously, which would be quite an impressive sight.
*''{{w|Leonids}} - November 17th - In 1966, unusually active Leonid shower killed God''
:There ''was'' a very active Leonid shower (a "meteor storm") in 1966, and a precursor to it in 1965. The article ''{{w|Is God Dead?}}'' was published in ''Time Magazine'' on April 8 of 1966. Perhaps this suggests that the meteors killed God earlier in the year when they and He were further out in the solar system?
*''{{w|Geminids}} - December 13th - Can be deflected with tennis rackets''

The title text refers to the folk wisdom that ''lightning'' strikes the tallest thing around, but this has never been applied to meteors, where it is basically the size (area) that determines the likelihood of an impact with a given object. [[Randall]] expressed frustration over how "maddeningly inexact" the lightning statement is, and elaborated on the problem mathematically, in the [[what if?]] ''{{what if|16|Today's topic: Lightning}}''.

==Transcript==
:[A list of 16 meteor showers, with a caption above, labels on the three columns and then every other row in gray, beginning with a gray row beneath the line below the column labels.]
:{| border="1" cellpadding="1" cellspacing="1" class="wikitable" style="width: 60%; text-align: left;"
!colspan="3"|The <big><big>xkcd guide</big></big> to <big><big>meteor showers</big></big>
|-
|'''Name'''
|'''Peak'''
|'''Notes'''
|-
|Quadrantids
|January 4th
|Bring pets inside during peak activity
|-
|Tricuspids
|January 21st
|Not viewable in region 2 countries
|-
|Centaurids
|February 6th
|Too faint to see without going outside
|-
|Beta Aquariids
|February 10th
|Inverted shower converges toward Aquarius instead of radiating away
|-
|Chelyabids
|February 15th
|Only one meteor per shower, but it's big.
|-
|Lyrids
|April 22nd
|Meteors sometimes scream
|-
|Daytime Zeta Perseids
|June 9th
|Likely a NASA hoax
|-
|June Boötids
|June 27th
|50/50 mix of meteors and shooting stars
|-
|Southern Delta Aquariids
|July 19th
|Meteors very bright, but stationary
|-
|Dromaeosaurids
|July 22nd
|Fast, highly intelligent, can open doors
|-
|Perseids
|August 12th
|Instead of falling from sky, meteors erupt from ground
|-
|Tau Pyramids
|August 15th
|Visible even when eyes are closed
|-
|Draconids
|October 8th
|Very slow, but follow you if you run
|-
|Orionids
|October 21st
|Entire shower happens at once
|-
|Leonids
|November 17th
|In 1966, unusually active Leonid shower killed God
|-
|Geminids
|December 13th
|Can be deflected with tennis rackets
|}

==Trivia==
*In the [http://www.explainxkcd.com/wiki/images/archive/8/8a/20130809215612!meteor_showers.png original] version of this comic the date beneath the Dromaeosaurids shower was June 12th, the date of the velociraptor attacks in the Jurassic Park movie. To get the order of the dates correct it was probably easier to change just the date rather than move the Dromaeosaurids to the entry below June 9th.

{{comic discussion}}

[[Category:Charts]]
[[Category:Astronomy]]
[[Category:Velociraptors]]
[[Category:Jurassic Park]]
[[Category:Animals]] 
[[Category:Sport]] 
[[Category:Religion]]