explain xkcd - User contributions [en]

2186: Dark Matter

2019-08-09T18:13:47Z

108.162.210.254: /* Explanation */

{{comic
| number = 2186
| date = August 7, 2019
| title = Dark Matter
| image = dark_matter.png
| titletext = To detect dark matter, we just need to build a bird feeder that spins two squirrels around the rim in opposite directions at relativistic speeds and collides them together.
}}

==Explanation==
{{incomplete|Created by a DARK MATTER SQUIRREL ON A SPINNING BIRD FEEDER. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

[[Megan]] and [[Cueball]] are talking about {{w|dark matter}}, the mysterious invisible mass observed indirectly by the rate at which galaxies rotate. Megan states that dark matter's density in the solar system is 0.3 GeV/cm3, as claimed, for example, by [https://arxiv.org/abs/1205.4033 Bovy and Tremaine (2012) "On the local dark matter density" in ''The Astrophysical Journal''.] Cueball does not understand what that means, so Megan explains that it equates to one squirrel's mass of dark matter in the volume of the {{w|Earth}}. In the final two panels, Cueball humorously misinterprets this as implying dark matter is actually one or more squirrels, and thereby provides the mass which causes [https://www.youtube.com/watch?v=PfHu-UJaK0Q squirrels to spin on bird feeders designed to deter them] while birds, with lower mass, do not. This enrages Megan.

The {{w|gigaelectronvolt}} (GeV) is a unit of energy that can be converted to a mass using {{w|Mass%E2%80%93energy_equivalence|Einstein's formula}} ''E'' = ''mc''2. It is typically used for subatomic particles, such as {{w|weakly interacting massive particles}} (WIMPs), one of {{w|Dark matter#Composition of dark matter: baryonic vs. nonbaryonic|several contending possibilities}} for the still-open question of the composition of dark matter, and one which Megan's uniform density figure implies constitutes most of it. For example, the mass of a proton is 0.938 GeV/''c''2. However, it is common to omit the ''c''2 denominator, representing masses as GeV or MeV. A mass represented as 0.3 GeV is equal to 5.35 × 10−25 grams [https://www.wolframalpha.com/input/?i=0.3+(GeV%2Fc%5E2)+in+grams]. Since the {{w|Figure_of_the_Earth#Volume|Earth's volume}} is 1.083 × 1027 cm3 Megan's figures imply that a {{w|squirrel}} has a mass of about 1.3 lb (1.083 x 5.35 × 1027−25 g = 580 g [https://www.wolframalpha.com/input/?i=(0.3+(GeV%2Fc%5E2)%2Fcm%5E3)+*+(volume+of+earth)+in+grams]), a typical weight for several species of common squirrels.

[[:Category:Squirrels|Squirrels]] are a recurring topic on xkcd, but are not a serious alternative to WIMPs as a scientific explanation for the composition of dark matter. Since the September 2015 detection by the {{w|LIGO|Laser Interferometer Gravitational-Wave Observatory}} (LIGO) and subsequent confirmation by the {{w|Virgo interferometer}} of gravitational waves from unexpectedly many merging {{w|black hole|black holes}} substantially more massive than those produced by stellar collapse, {{w|primordial black hole| primordial black holes}} (PBHs) have become a popular alternative explanation to WIMPs (or squirrels), attracting [https://arxiv.org/abs/1605.04023 proponents at NASA,] and [http://www.buchaltercosmologyprize.org/#announcements other cosmologists] for [https://arxiv.org/abs/1711.10458 several reasons.] But PBHs remain controversial, because if they constituted more than a very small portion of dark matter, [https://iopscience.iop.org/article/10.1088/2041-8205/720/1/L67 alternative explanations would be almost entirely excluded.]

Other alternative hypotheses for the observations suggesting dark matter, such as theories involving the {{w|Modified Newtonian dynamics|gravitational force varying over different distances}}, often upset cosmologists as much as Megan is shown to be, because they violate the {{w|cosmological principle}} among other issues. Part of this frustration may be due to the fact that even after many decades of careful, tremendously expensive, and often [http://www.allesfoen.de/artinscience/wordpress/?p=236 stunningly beautiful] experiments, none of the many explanations for dark matter or the observations suggesting it have as yet any support from direct empirical observations.

To help resolve this mystery, the title text imagines using a spinning bird feeder like a {{w|particle accelerator}}, colliding squirrels at relativistic speeds as if they were atomic nuclei, to detect dark matter particles like the CERN accelerator discovered the {{w|Higgs boson}}. (Note, however, that accelerating even [https://what-if.xkcd.com/1/ one squirrel] to relativistic velocities would destroy the feeder along with any nearby birds, not to mention the squirrels, and the surrounding city.)

==Transcript==
:[Megan walks with Cueball. She is holding a hand out while telling Cueball something.]
:Megan: Dark matter density in the solar system is around 0.3 GeV/cm3
:Cueball: Is... that a lot?

:[As they continue to walk and talk she spreads her arms out.]
:Megan: In terms of mass, it means the Earth contains one squirrel worth of dark matter at any given time.
:Cueball: Wow.

:[In a frame-less panel Cueball stops while Megan walks past him. Megan is face-palming herself while looking down.]
:Cueball: Is there any way to find out which squirrel it is?
:Megan: No, it's not literally-

:[Cueball holds his hand with one finger up in front of Megan, while she has turned towards him and is holding both arms up, possible with balled fist, as she shouts back at him, shown both with large fat letters and with small lines emanating above her head.]
:Cueball: Oh, that explains why they weigh enough to set off those spinning bird feeders!
:Megan: '''''Dark matter isn't squirrels!

{{comic discussion}}

[[Category:Comics featuring Megan]]
[[Category:Comics featuring Cueball]]
[[Category:Squirrels]]
[[Category:Astronomy]]
[[Category:Physics]]

1434: Where Do Birds Go

2014-10-15T12:07:54Z

108.162.210.254:

{{comic
| number = 1434
| date = October 15, 2014
| title = Where Do Birds Go
| image = where_do_birds_go.png
| titletext = Water/ice has a lot of weird phases. Maybe asking 'where do birds go when it rains' is like asking 'where does Clark Kent go whenever Superman shows up?'
}}

==Explanation==
{{incomplete|List websites shown in image. Decide on title text explanation. More detail on the actual joke.}}
Cueball searches [http://lmgtfy.com/?q=where+do+birds+go+when+it+rains%3F Google] to find out where birds go when it rains. He finds that the question is asked worldwide, across different languages and websites, and that everyone wants to know the answer. A variety of screenshots are shown of different websites and forums with users asking where birds go when it rains, with at least seven languages shown. The bottom of this panel fades to white, suggesting that the occurrence of these questions stretches on and on.

{| class="wikitable"
! Language
! Question
! Translation
|-
|French
|Oû se cachent les oiseaux quand il pleut?
|Where do the birds hide themselves when it rains?
|-
|rowspan="3"|German
|Was passiert jetzt eigentlich mit den vögeln, die bei dem wetter in den bäumen sitzen?
|What really happens with the birds that are sitting in the trees in this weather?
|-
|Was machen Vögel bei schlechtem Wetter?
|What do birds do in bad weather?
|-
|Wohin gehen Vögel?
|Where do birds go?
|-
|rowspan="2"|Spanish
|Qué pasa con las aves durante un huracán?
|What happens to the birds during a hurricane?
|-
|¿A donde se van los pajaritos cuando llueve?
|Where do the little birds go when it rains?
|-
|Dutch
|Waar blijven de vogels als het heel hard stormt?
|Where do birds stay when it is storming very hard?
|-
|Finnish
|Minne linnut menevät sateella?
|Where do the birds go when it rains?
|}

As it starts to rain around the bird in the lower panels, he flies down to a smartphone on the floor, and begins searching the same thing. This seems to imply that even birds don't know where to go when it rains, or that it was birds looking for shelter asking this question on the World Wide Web.

In reality birds, just like humans, seek shelter when it rains. Getting wet is not a problem for birds, but it does complicate flying. On a rainy day you can usually find birds in leafy trees, caves or other kinds of cover.

In the title text, the question itself is considered - In the {{w|Superman}} comics Clark Kent ''*is*'' Superman so you couldn't observe Clark Kent and Superman at the same time. Although the {{w|State_of_matter|common states}} of solid, liquid and gas are widely known, water is observed at multiple phases ({{w|Ice#Phases|low and high pressure ices}}, {{w|Supercritical_fluid|supercritical gases}} etc.) and Randall is theorizing that one of the hitherto undiscovered states of water is 'bird' which would explain why birds and rains are apparently never seen together.

==Transcript==
{{incomplete transcript}}

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Internet]]
[[Category:Comics featuring Cueball]]
[[Category:Animals]]

1363: xkcd Phone

2014-05-12T22:36:12Z

108.162.210.254: /* Explanation */

{{comic
| number = 1363
| date = May 2, 2014
| title = xkcd Phone
| image = xkcd_phone.png
| titletext = Presented in partnership with Qualcomm, Craigslist, Whirlpool, Hostess, LifeStyles, and the US Chamber of Commerce. Manufactured on equipment which also processes peanuts. Price includes 2-year Knicks contract. Phone may extinguish nearby birthday candles. If phone ships with Siri, return immediately; do not speak to her and ignore any instructions she gives. Do not remove lead casing. Phone may attract/trap insects; this is normal. Volume adjustable (requires root). If you experience sudden tingling, nausea, or vomiting, perform a factory reset immediately. Do not submerge in water; phone will drown. Exterior may be frictionless. Prolonged use can cause mood swings, short-term memory loss, and seizures. Avert eyes while replacing battery. Under certain circumstances, wireless transmitter may control God.
}}

==Explanation==
This comic is a parody of a multitude of mobile-technology related issues that, when brought together, create a general satire of smartphone advertising. The advertised features here either make previously useful capabilities useless or add features nobody wants. Except for "your mobile world (going) digital", which is old news.

From bottom left, going clockwise:

* '''FlightAware partnership:''' This is a reference to the [http://www.flightaware.com/ FlightAware] flight tracking service. This FlightAware partnership results in the phone playing airplane engine noise whenever a flight passes over the phone's current location, an annoying and arbitrary feature. It may also be superfluous, as such noise may be heard from the plane itself, depending on altitude.
* '''Realistic case:''' possibly a joke on various audiovisual devices like gaming consoles that advertise realistic sound, graphics, etc. Of course, applying "realistic" to an actual physical case is ridiculous. Either the case is actually real, or it doesn't actually function as a case. Possible reference to [[331: Photoshops]], where [[Cueball]] finds a physical object to not look realistic.
* '''Clear screen:''' This is a pointless descriptor from the perspective of the consumer. Of course the screen is clear. This joke works in tandem with the previous joke, as a play on "clear case, realistic screen," which are both hypothetically viable selling points.
* '''Side Facing Camera:''' There was a recent controversy surrounding an [https://www.indiegogo.com/projects/spy-cam-peek-i Indiegogo for a surreptitious, side-mounted camera device] for smartphones due to the advertisement of the device as a good way to take creep shots, which are illegal in many places. Widespread dissemination of these devices as a built-in feature would likely result in a sharp increase in delinquency of this nature. May also be an ''ad absurdum'' extension of devices with both forward and backward facing cameras.
* '''Custom blend OS:''' iOS and Android are offered by different conglomerates and run on different kernels. A "custom blend" would probably be a nightmare to work with.
* '''Simulates alternative speed of light:''' This renders the clock useful only as a learning aid. The {{w|speed of light}} is exactly 299,792,458 meters per second. Relativistic effects, such as {{w|time dilation}}, are only noticeable at significant fractions of the speed of light. Since the phone is simulating a much slower speed of light, driving at even highway speeds will cause a significant amount of time dilation. For example, driving at 90mph (90% of the default simulated speed of light) will give a time dilation factor of about 2.29, causing the clock to advance only 26 minutes for each hour; driving at exactly 100mph makes the dilation factor infinite and will stop the clock entirely. Driving beyond 100mph...would make the clock start advancing through imaginary/complex time rather than real time. Somehow. (Let's not go there.)
* '''Wireless:''' as in cordless phone. This is the bare minimum a phone has to have in order to be a mobile phone, so advertising it as a feature feels dated by decades.
* '''Accelerometer screams in free fall:''' A humorous function. Rather than having some sort of feature to prevent breakage or cracking when a drop is detected, the phone just makes you more aware of its potential imminent doom.
* '''When exposed to light, phone says "hi":''' Bait and switch, and also a build from the previous joke. The implied feature is that the screen or camera will automatically adjust, but instead the phone is weirdly anthropomorphized.

The ominous warnings and disclaimers in the title text are probably a reference to the ''Saturday Night Live'' parody ad for {{w|Happy Fun Ball}} ([http://www.rollingstone.com/movies/pictures/50-greatest-saturday-night-live-sketches-of-all-time-20140203/happy-fun-ball-0459912 original video hosted on rollingstone.com]).

* '''Presented in partnership with {{w|Qualcomm}}, {{w|Craigslist}}, Whirlpool, {{w|Hostess}}, LifeStyles, and the US Chamber of Commerce.''' Qualcomm is a semiconductor company that designs and produces chips for mobile phones. {{w|Whirlpool Corporation}} is a large American multinational manufacturer and marketer of home appliances, while {{w|Whirlpool (website)|Whirlpool}} is a prominent Australian tech forum website, originally created for discussion of Australian broadband providers but now extending to cover general tech topics, including mobile phones. The other companies mentioned here have no association with mobile phones, though there is a long history of unrelated companies attempting to leverage their respective brands to help promote each other.
* '''Manufactured on equipment which also processes peanuts.''' A warning often seen on candy and other foods for people with a peanut allergy. It is highly unlikely that equipment used to produce mobile phones would also process food.
* '''Price includes 2-year Knicks contract.''' Mobile phones are often sold by phone companies in combination with a cell phone plan, but a contract with the {{w|New_York_Knicks|Knicks}} would only appeal to pro basketball players.
* '''Phone may extinguish nearby birthday candles.''' A rather oddly specific capability, which might also be annoying for anyone attempting to host a birthday party. As to how it would do this, a very powerful directional speaker would be able to blow out a nearby candle, but the speakers in mobile phones aren't going to be that big.
* '''If phone ships with {{w|Siri}}, return immediately; do not speak to her and ignore any instructions she gives.''' {{w|Siri}} is a virtual personal assistant application for Apple devices. Not speaking to it and not following its instructions would defeat its purpose. It may suggest that a malevolent "Siri AI" has sneaked itself onto some devices, at the manufacturing stage, for some diabolical purpose. May be a reference to the Companion Cube in the game Portal, in which the player is instructed to disregard its advice if the cube appears to be animate.
* '''Do not remove lead casing.''' A mobile phone encased in lead would not function because it could not transmit or receive data. Devices that emit high levels of ionizing radiation are often encased in lead, but a phone that would emit that level of radiation would be unhealthy to carry around. If encased in sufficient lead to mitigate the danger, it would be uncomfortably heavy. This might be reference to [https://xkcd.com/925/ xkcd comic no 925: Cell phones] where Randall makes fun of the WHO claiming that cell phones might cause cancer despite huge studies showing the opposite. This could also mean the device is an actual bananaphone as regular phones emit no ionizing radiation ([http://xkcd.com/radiation xkcd Radiation Dose Chart]). Regrettably, the lead casing would render the phone inedible, although this somewhat mitigates the issues with having been manufactured on equipment that also processes peanuts.
* '''Phone may attract/trap insects; this is normal.''' Some plants, like the {{w|Venus_flytrap|Venus flytrap}}, attract and trap insects, but mobile phones are not known to exhibit this behaviour. May be a reference to [[Rasberry crazy ant]]s which are attracted to electronics.
* '''Volume adjustable (requires root).''' {{w|Android_rooting|Rooting}} is the method to gain privileged access on Android phones. Adjusting the volume should be available to any user and sould not be restricted to root access only.
* '''If you experience sudden tingling, nausea, or vomiting, perform a factory reset immediately.''' These symptoms are usually associated with chemical or radiation poisoning, or Cialis commercials. It is unclear why these would be cured by a {{w|Factory_reset|factory reset}}, though software apps could plausibly be used to display nauseating visual effects.
* '''Do not submerge in water; phone will drown.''' Most phones are not waterproof and will probably short-circuit when submerged. Drowning however, would imply that the phone breathes air (which actually would be possible if it had a {{w|Lithium–air battery|Li-air battery}}).
* '''Exterior may be frictionless.''' The front of a smartphone is usually made of glass and should have a surface with very low friction. The back of a phone is usually made from a material that has higher friction to make it pleasant to hold and to make sure it doesn't slide off objects it is placed on. A [[669: Experiment|completely frictionless surface]] would make it almost impossible to hold and would make it very susceptible to drops (at which point the phone will scream).
* '''Prolonged use can cause mood swings, short-term memory loss, and seizures.''' These are all side effects that are associated with certain kinds of medication or radiation treatment of the brain and would not be acceptable for mobile phones.
* '''Avert eyes while replacing battery.''' Actions that would warrant averting your eyes are usually associated with high-intensity light capable of causing eye damage. Depending on the specific energy source, this may be accompanied by high levels of other types of radiation (e.g. making an {{w|X-ray}} photo). This may hint that the phone might be powered by a radionuclide battery which would explain the lead casing and the possible radiation side effects. A phone that emits X-ray radiation would not be healthy to be around. Alternately, this may be a reference to the {{w|Ark_of_the_Covenant|Ark Of The Covenant}}, implying that gazing upon the battery or the compartment wall behind it is forbidden on pain of severe punishment. Or merely that with its back removed the phone would be naked, and the user should avert their eyes to preserve the phone's modesty.
* '''Under certain circumstances, wireless transmitter may control God.''' According to most religions, God (or Gods) are usually in control of us. God(s) are usually viewed as not directly controllable.

==Transcript==
:Runs custom blend on Android and iOS
:Side-facing camera
:Simulates alternate speeds of light (default: 100 miles per hour) and adjusts clock as phone accelerates
:Clear screen
:Realistic case
:Wireless
:Accelerometer detects when phone is in free fall and makes it scream
:Flightaware partnership: Makes airplane noise when flights pass overhead
:When exposed to light, phone says "hi!"

:''Introducing''
:'''The xkcd phone'''
:Your mobile world just went digital®

{{comic discussion}}

Talk:1330: Kola Borehole

2014-02-14T16:47:48Z

108.162.210.254:

Reminds me of the title text in #[[1218]]: Doors of Durin. [[User:Whimsye|Whimsye]] ([[User talk:Whimsye|talk]]) 06:21, 14 February 2014 (UTC)

Surely this is a Dwarf Fortress reference. The Soviets breached the Happy Fun Stuff! [[Special:Contributions/108.162.250.5|108.162.250.5]] 06:42, 14 February 2014 (UTC)

:Well, DF ''has'' that connotation, but both the [[wikipedia:Kola_Superdeep_Borehole|real thing]] and the [[wikipedia:Well_to_Hell_hoax|hoax]] are older than Toady's game, so perhaps not so much a reference to DF (although Black Hat does propose a typically DF-player solution... I hope he's prepared for [http://dwarffortresswiki.org/index.php/FPS FPS Hell] from the flowing liquids). Randall ''[[1223|knows]]'' about DF, of course.
:(BTW, from that (first, factual event) page: "In 1983, the drill passed 12,000 m (39,000 ft), and drilling was stopped for about a year to celebrate the event." ...Russians!) [[Special:Contributions/141.101.98.176|141.101.98.176]] 08:18, 14 February 2014 (UTC)

Lakes and Oceans #[[1040]] also mentions the Kola Borehole.[[Special:Contributions/199.27.128.70|199.27.128.70]] 09:03, 14 February 2014 (UTC)Nix

If Hell would be a physical place, I don't think {{w|Lucifer}} would still be ruling there. In next war between Heaven and Hell, the winners will be anime and/or computer games nerds. Both Heaven and Hell will lose. :-) -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 11:06, 14 February 2014 (UTC)

One may recall from the ''Divine Comedy'' that Dante's imagery of Hell is a negative-mountain-shaped abyss that starts widest at the surface of our allegorical planet and ends at a point far below the surface where Satan resides. The deeper you go, the narrower the abyss gets, like a cone, and the more heinous the sinners. On the other side of the planet there is a mountain made from all that earth God removed to dig the Inferno. The Saints (all those who are saved by faith from the other fate) progress up the mountain through Purgatory to reach Paradise. ''— [[User:Tbc|tbc]] ([[User talk:Tbc|talk]]) 14:01, 14 February 2014 (UTC)''

I remember reading about this in Dial the Truth ministries: http://www.av1611.org/hell.html
Either way, in the war between Earth and Hell, I shall be in Heaven. [[User:Greyson|Greyson]] ([[User talk:Greyson|talk]]) 14:51, 14 February 2014 (UTC)

In Dante's Inferno, Hell is depicted as being a cold place since it is far from the warmth of the Creator. The modern hot version of hell is a byproduct of the fire and brimstone of the reformation period. [[Special:Contributions/108.162.210.254|108.162.210.254]] 16:47, 14 February 2014 (UTC)

Talk:1321: Cold

2014-01-24T16:33:42Z

108.162.210.254:

I really hate when articles on science get a POV tag. Science isn't politics (hint: evolution and gravity aren't POV either). Related to the comic, I just had a similar rant on Facebook in the last week or two where I linked to [http://www.skepticalscience.com/print.php?r=54 this article] when someone said it was too cold for Global Warming. [[Special:Contributions/108.162.237.64|108.162.237.64]] 12:24, 24 January 2014 (UTC)

I really hate it when people think the global warming scam is science, when it really is nothing more than politics masquerading as science. The IPCC has been proven to be a bunch of liars, and really there's nothing left but a bunch of whining left-wing lunatics who are desperately clinging to their hope of continuing to use this lie to raise energy prices/taxes. [[Special:Contributions/108.162.219.17|108.162.219.17]] 12:55, 24 January 2014 (UTC)
:Well you're wrong, and apparently delusionally paranoid about what the political left wants, but the bigger question is why is this in a wiki discussion page? [[Special:Contributions/108.162.249.117|108.162.249.117]] 13:21, 24 January 2014 (UTC)

Although it doesn't directly mention it, this is partly related to people's confusion over the difference between 'weather' and 'climate' - the former being what the conditions are at a given moment in time, and the latter referring to long-term trends.[[Special:Contributions/141.101.98.228|141.101.98.228]] 14:52, 24 January 2014 (UTC)

I think the one with whit wolly hat is whitehat [[User:Halfhat|Halfhat]] ([[User talk:Halfhat|talk]]) 16:10, 24 January 2014 (UTC)

Randall has cherry picked data for his conclusion and the graph in the comic. The full history is available from the NWS. The one for my home town can be found here http://www.erh.noaa.gov/iln/climo/below0.php The 1970's were unusually cold, which makes the present seem warmer by comparison. --[[Special:Contributions/108.162.210.254|108.162.210.254]] 16:33, 24 January 2014 (UTC)

250: Snopes

2013-12-05T17:21:35Z

108.162.210.254: /* Explanation */ Corrected Grammar

{{comic
| number = 250
| date = April 18, 2007
| title = Snopes
| image = snopes.png
| titletext = The MythBusters are even more sinister.
}}
==Explanation==
{{w|Snopes}} is a popular website for checking the validity of {{w|Urban legend|urban legends}}. Snopes proves or disproves facts, but another urban legend is known that suggests Snopes runs a spam operations to create sources for their own benefit.

The title text suggests that {{w|MythBusters}}, another group which debunks myths, also participate in the practice of spreading misinformation for the opportunity to test it.

==Transcript==
:Cueball: Another urban legend? You should check out Snopes before sending me this stuff.
:Friend: Oops; yeah.
:Cueball: Man, Snopes is really great--independent fact-checkers trawling our collective discourse, filtering out misinformation.
:Friend: Yeah, but they have their dark side. The couple that runs snopes.com also runs a network of spam servers that start many of those forwarded stories in the first place, ensuring they'll always have business.
:Cueball: That's absurd. Plus, it's definitely not true--it was debunked by...
:Friend: Yes?
:Cueball: ...Oh my God.

{{comic discussion}}
[[Category:Internet]]
[[Category:Comics featuring Cueball]]