explain xkcd - User contributions [en]

Talk:1758: Astrophysics

2016-11-12T06:49:48Z

Theme: Add a comment

"''Two days before the release of this comic the YouTube channel Space Time from PBS Digital Studios released a new video with the title [https://www.youtube.com/watch?v=7UNLgPIiWAg Did Dark Energy Just Disappear?]. This was based on the press coverage the paper [http://www.nature.com/articles/srep35596 Marginal evidence for cosmic acceleration from Type Ia supernovae] got, which relates to the one referenced in this comic for dark matter.''" This doesn't seem relevant. Dark energy is totally unrelated to dark matter. [[User:Schroduck|Schroduck]] ([[User talk:Schroduck|talk]]) 14:33, 11 November 2016 (UTC)
:I agree. I don't see any connection here either.[[Special:Contributions/108.162.237.37|108.162.237.37]] 16:02, 11 November 2016 (UTC)
::It is the idea that a paper seems to prove a theory wrong and then the press goes out presenting it like a proof instead of asking someone to explain to them why it doesn't fit the data. That is what this comic is about - not dark matter. See the title text. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 18:06, 11 November 2016 (UTC)

"What is the flip the table over reference in title text. To make other do the same through mirror neruons? Still new explanation. Add more if you can" "The title text also uses Mirror neurons as a reference to a joke: it suggests to "flip this table", just as a mirror flips the image in front of it." I too want to think there is a joke here about mirror behavior or something but I just don't get it. Somebody's got to come up with a clearer, and funnier, example![[User:ExternalMonolog|ExternalMonolog]] ([[User talk:ExternalMonolog|talk]]) 16:31, 11 November 2016 (UTC)

Seems like awkward timing since https://arxiv.org/abs/1611.02269 was posted 3 days ago, a non-MOND non-dark matter theory coming from Prof. Erik Verlinde, and this particular theory starts from first principles yet matches behavior of galaxies. [[Anon]] 16:49, 11 November 2016 (UTC)
:The comic doesn't mention MOND that is only in the explanation here. It just say that all data fits with dark matter. The idea is that the department is tired of all the "proofs" that dark matter doesn't exist. Maybe Randall thinks that this new paper is just the next in line and note as explained above this paper has not been peer reviewed. So unless you're and expert and could peer review it then his theory may not fit the data and that is Randall's point. But I'm sure Randall [[955: Neutrinos|would get your]] dark matter is still on the table after this paper... --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 18:13, 11 November 2016 (UTC)

MOND is but one theory among [https://en.wikipedia.org/wiki/Category:Theories_of_gravitation many classical and quantum gravitational theories] with differing predictions for galactic rotation and lensing anomalies. There are [https://en.wikipedia.org/wiki/Dark_matter#Alternative_theories non-gravitation theories] as well. It might behoove some intrepid sole to make a table of theories and dark matter alternatives. [[User:Run, you clever boy|Run, you clever boy]] ([[User talk:Run, you clever boy|talk]])

Perhaps [[Randall]] is echoing his fellow cartoonist, {{w|Scott Adams}}, when he points out the [http://blog.dilbert.com/post/136818042136/trump-and-climate-science-master-persuader hypocrisy in science reporting]. Recently, [http://www.tau.ac.il/~kochin/ Michael S. Kochin] exposed government [http://amgreatness.com/2016/09/26/she-blinded-me-with-science/ meddling in science reportage] among other inconvenient truths. Anyone with an NSF, DoE or EPA grant knows the pressures, as [http://www.henrypayne.com/ Henry Payne], another cartoonist, [http://www.nationalreview.com/article/414359/global-warming-follow-money-henry-payne points out]. FWIW, I side with {{w|Bjorn Lomborg}}, who famously champions a [http://www.lomborg.com/ middle way] in climate science for the sake of [https://www.washingtonpost.com/news/in-theory/wp/2016/09/19/when-it-comes-to-climate-change-lets-get-our-priorities-straight/ downtrodden peoples around the world]. Additionally, [https://www.cato.org/ Cato] provides an [http://www.cgd.ucar.edu/cas/wigley/magicc/ IPCC MAGICC] [http://www.cgd.ucar.edu/cas/wigley/magicc/UserMan5.3.v2.pdf climate model] simulator for [https://www.cato.org/blog/current-wisdom-we-calculate-you-decide-handy-dandy-carbon-tax-temperature-savings-calculator anyone to examine]. Should we reconsider this explanation and the [http://www.explainxkcd.com/wiki/index.php/1732:_Earth_Temperature_Timeline#Explanation explanation] for Randall’s [https://www.xkcd.com/1732/ Earth Temperature Timeline] in this light? [[User:Run, you clever boy|Run, you clever boy]] ([[User talk:Run, you clever boy|talk]])

The current explanation doesn't cover the failure of previous experiments to detect dark matter, despite the investment of time, money and effort.  Absence of evidence may not be evidence of absence, but it's fair to say that dark matter as an explanation for observations does technically lack direct evidence/detection.  – [[Special:Contributions/141.101.98.215|141.101.98.215]] 20:44, 11 November 2016 (UTC)
:That's the rub, isn't it? Even [http://pos.sissa.it/archive/conferences/050/067/ACAT_067.pdf LHC] and [https://losc.ligo.org/tutorials/ LIGO] detections rely on theoretical templates to enhance event rates. [[User:Run, you clever boy|Run, you clever boy]] ([[User talk:Run, you clever boy|talk]])

"Of course phlogiston exists. We haven't any observational evidence for it but any idea that combustion works different doesn't fit the data."
"Of course Vulcan exists. We haven't any observational evidence for it but any idea that gravity works different doesn't fit the data."
And here we go again. [[Special:Contributions/198.41.239.32|198.41.239.32]] 23:46, 11 November 2016 (UTC)
:But this was the same way that led us to discover Neptune, Uranus, Pluto, and the Kuiper belt. [[User:Theme|Theme]] ([[User talk:Theme|talk]]) 06:49, 12 November 2016 (UTC)

1687: World War III+

2016-06-01T11:05:21Z

Theme: Remove "Incomplete" heading

{{comic
| number = 1687
| date = May 30, 2016
| title = World War III+
| image = world_war_iii.png
| titletext = I hate how the media only ever uses the first part of this quote, stripping it of its important context.
}}

==Explanation==
This comic takes a famous quote {{w|wikiquote:World War III |attributed}} to {{w|Albert Einstein}}, and expands upon it to absurd levels. The original quote is: "I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones." The basic premise of this quote is that World War III would be so devastating to the world that all humanity's progress would be wiped out and we would return to the technological level of the Stone Age.

This comic expands the original quote letting Einstein suggest what other weapons future World Wars will be fought with:
*V: {{w|Crossbow}}s. Crossbows are type of bow that is deadlier than a regular longbow, but is much more difficult to load. Most often used in medieval era.
** It's also notable that the crossbow was the only weapon to be banned by the Vatican, due to the comparative lack of skill required to operate.
*VI: {{w|Laser}}s. In science fiction, blasts of lasers are often used instead of conventional guns. This suggests that society would have managed to rebuild lasers by World War VI.
*VII: {{w|Blowgun}}s. A blowgun is a small tube loaded with a small dart or other projectile, fired by blowing into one end. Once again, the world has been devastated, and returned to a simpler technology.
*VIII-XI: Skipped over.
*XII: The same weapons as III, but in underground tunnels. This is a parody of saying that X is basically Y 'but in space/underwater/etc', and, if the quote's well-known meaning is accepted, this has terrifying implications for the state of the world. It could also be a reference to HG Well's {{w|The Time Machine}} where the {{w|Morlock}}'s are the master race of the future living in underground caves. Also the fact that he did not know which weapons were used in III makes it weird that he knows the same weapons will be used again later.
*XIII is completely unmentioned. This could be an error, but it makes some sense, considering that 13 is a number considered unlucky in many Western cultures and is sometimes skipped. For example, many tall buildings don't have a floor numbered 13, skipping straight from 12 to 14.
*Before Einstein can discuss World War XIV, the audience of his quote seems to be going away. Einstein claims to have 'a whole list', suggesting that he may know a lot about the future wars to come more so than he has already suggested.

In the title text [[Randall]] feigns annoyance about how the media only use the first part of the quote, thus taking it out of context. He implies that this is actually a full quote by Einstein and that all other occurrences using only the "original" version of this quote are misrepresenting it. In this particular case it is a much stronger quote than the long version from the comic, but it is often the case that quotes taken out of context seem to have an entirely different meaning than originally intended.

==Transcript==
:[A quote with white text on black background:]
:{| class="wikitable"
|style="background-color:black;"|"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. World War V will be fought with crossbows, World War VI will be lasers, and World War VII will be blowguns. I don't know about World Wars VIII through XI. World War XII will use the same weapons as III, but will be fought entirely within underground tunnels. World War XIV will—Hey, come back! I have a whole list!"                   —''Albert Einstein''
|}

{{comic discussion}}

[[Category:Comics featuring real people]]

Talk:1447: Meta-Analysis

2014-11-14T08:49:50Z

Theme: meta-meta-comment

What is this "Medline, Embase and Cochrane" ? Thanks. Dams.
- Databases of Medical Publications [[Special:Contributions/108.162.254.30|108.162.254.30]] 08:19, 14 November 2014 (UTC)
:Medline[http://www.medline.com/], Embase[http://www.elsevier.com/online-tools/embase/about] and Cochrane[http://www.cochrane.org/] are medical research databases. You can find there studies on various drug uses or treatment plans. A useful information source if you want to compare studies on use of Allopurinol for chronic gout or else. [[User:Jkotek|Jkotek]] ([[User talk:Jkotek|talk]]) 08:28, 14 November 2014 (UTC)

Would it be helpful to include a breakdown of the terms?
*Meta-Analysis = "We searched M, E, & C for [keyword]"
*Meta-Meta-Analysis = "We searched M, E, & C for 'We searched M, E, & C for [keyword]'"
*Meta-Meta-Meta-Analysis = "We searched M, E, & C for 'We searched M, E, & C for 'We searched M, E, & C for [keyword]''"
[[User:Smperron|Smperron]] ([[User talk:Smperron|talk]]) 08:46, 14 November 2014 (UTC)

Your paper is rejected. //"TOO META"--[[User:Theme|Theme]] ([[User talk:Theme|talk]]) 08:49, 14 November 2014 (UTC)

1376: Jump

2014-07-04T02:46:15Z

Theme: Put back "Newton's cannonball". Quoting the main page: "feel free to put multiple interpretations in the wiki page for each comic"

{{comic
| number = 1376
| date = June 2, 2014
| title = Jump
| image = jump.png
| titletext = Or that I'm at least following the curve of the Earth around to land ...
}}

==Explanation==
[[Cueball]] is presumably experiencing a common dream subject, flying or floating. As in [http://boards.straightdope.com/sdmb/showthread.php?t=382657 many varieties of such a dream], the ability to fly, float or glide only gradually manifests, going from longer and longer jumps to a sort of flight or hovering. In Cueball's case, his jumps become longer and 'lighter' until at last he is gliding just above the surface of the Earth. He has apparently had such a dream before, with just such a flight mechanic manifesting itself, as he indicates that he 'loves' these dreams.

In his presumed dream, Cueball finally achieves his gliding flight just as he reaches the shoreline, and his gliding carries him over the water's edge and out to sea. After a moment's reflection, he realizes that if he were really gliding out to sea without any real apparent means of control, his situation would presumably be rather perilous — death by starvation or thirst, gradually slowing down and becoming 'stuck' over the water with no way to land, the loss of his gliding ability as suddenly as it came, etc, all suggest themselves as possible perils he would now be subject to if, in fact, his 'dream' were actual reality. Thus he eventually indicates that he ''hopes'' it is a dream, in contrast to his feeling at the comic's opening.

The title text adds a further worry not immediately apparent unless one considers the possibility that Cueball's 'gliding' will continue in a straight line in relation to the Earth's surface. In that case he would continue moving straight while the Earth's surface would curve away beneath him, sending him out into space instead of the relatively preferable scenario of merely floating across the ocean to the opposite shore. After all, if the laws of physics had changed to permit hovering/flying, consequences would be unpredictable — i.e. there'd be no assurance one would maintain a constant hovering height rather than take leave of the planet as one flies forth. One thing about miracles is that all bets are off!

Also note that this situation is similar to the case of {{W|Newton's cannonball}}. However, that is actually in very-low-earth-orbit — and you would need to be going 7,300 m/s, or about 16,000 mph (26,000 km/h) to stay in orbit. At that speed, or course, air friction would quickly destroy the cannonball or person. This is clearly not the case in the dream.

Getting weightless and drifting around was a fantasy in [[226: Swingset]].

==Transcript==
:[In the first panel Cueball is seen as a stop motion cartoon jumping down a small hill — jumping longer and longer between sentences. Jump is written over the head of Cueball that perform the jump until he floats.]
:Cueball: I love these dreams
:''jump''
:Cueball: Each jump is a little longer
:''jump''
:Cueball: Each push off the ground a little softer
:''jump''
:Cueball: Until I
:''g l i d e''

:[In the second panel Cueball glides over a fence and the dunes before the beach — then he glides out over the sea.]

:[In the third panel Cueball glides across the open sea — birds circling, a fish splashing beneath the second.]
:''sploosh''
:Cueball: ...I ''hope'' this is a dream.

==Trivia==
*The comic [[417: The Man Who Fell Sideways]] has some resemblance to this one.
*The title text for this comic originally read "I hope I'm at least following the curve of the Earth around to land ..." but later it was changed to "Or that I'm at least following the curve of the Earth around to land ...".

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Dreams]]

681: Gravity Wells

2014-07-04T02:35:54Z

Theme: Mention the mistake already mentioned in the discussion page

{{comic
| number = 681
| date = December 28, 2009
| title = Gravity Wells
| image = gravity_wells.png
| titletext = This doesn't take into account the energy imparted by orbital motion (or gravity assists or the Oberth effect), all of which can make it easier to reach outer planets.
}}

The xkcd page links to [http://xkcd.com/681_large/ a much larger version].

==Explanation==
{{incomplete|Fix Grammar, explain title text and explain the mistake}}

The comic shows the relative strengths of the gravitational fields of each planet in the solar system as well as some of their satellites. Each well is scaled such that rising out of a physical well of that depth, in constant Earth surface gravity, would take the same energy as escaping from that planet's gravity in reality. Each planet is shown cut in half at the bottom of its well, with the depth of the well measured down to the planet's flat surface.

Take note, however, that the Earth's gravity well's depth in the inset and in the main part of the comic don't match. This is most likely a mistake by Randall.

This is a simplified method of comparing the escape velocities of the various planets and satellites. In reality, the strength of gravity decreases the further you get from the planet. However, a comparison of energy expended to escape the gravitational pull allows for a simpler comparison between the objects.

Moons shown in the chart are at the appropriate distance from their respective planets' gravity wells for their orbits. Those moons featured are: Earth's moon, Mars' tiny moons Phobos and Deimos (in an inset panel), Jupiter's moons Ganymede, Io, and Europa, and Saturn's moon Titan.

The {{w|Sun|Sun's}} gravity well is not shown in its entirety, but is just indicated on the far left as ''"Very very far down"''. Had it been shown in its full extent it would have made the rest of the drawing so small in comparison that it would have been unreadable.

==== Inner Planets ====

* Mercury — no facts listed

* Venus — no facts listed

* Earth & Moon — listed with the depth of the gravity well of 5,478 km for Earth and 288 km for the Moon. Calculations of depth is explained in the Saturn insert.

* Mars — listed with the depth of gravity well of 1286 km

==== Cut outs ====

* The Mars cutout shows how small Mars' moons really are, specifically in terms of gravity. {{w|Deimos (moon)|Deimos}} is so small that a bike jump would be sufficient to escape its gravity well and on {{w|Phobos (moon)|Phobos}} you could launch a baseball into space simply by throwing it.

* The drawing next to Jupiter is playing on the classic "Yo Mama" joke, combining the aspects of your mom being very fat (having a huge gravitational pull) and very slutty (having sex with the entire football team), represented by the football team being attracted to, and falling into, her gravity well. A "Yo Mama" joke also appears in comic [[89: Gravitational Mass]].

* The Earth/Moon cut out shows the significant difference in strength between the {{w|gravity well}} of the Earth and the Moon. Cueball comments on how the {{w|Apollo Lunar Module|Apollo Lunar Module}} could be so small and still return to Earth while the {{w|Saturn V}} rocket used to get the moon had to be so huge since it was escaping Earth's well while the Lunar Module only needed to escape the pull of the Moon. The cut out also shows that objects like the {{w|International_Space_Station|International Space Station}}, the {{w|Space shuttle|space shuttle}}, {{w|GPS satellite|GPS satellites}} and {{w|Geostationary orbit|geo-stationary satellites}} at their respective positions within Earth's gravity well.

==== Outer Planets ====

* {{w|Jupiter}} — is so massive and dense that it is comparable in mass to a {{w|Brown dwarf}} which is the smallest kind of star. Saturn, while similar in size, is composed of much lighter gas material. Hence Saturn's mass and therefore its gravitational pull are much smaller. Strong gravitational pull is a significant factor in igniting fusion. As gravity pulls matter together the pressure and temperature increase. With sufficient increase in pressure and temperature {{w|Nuclear fusion|nuclear fusion}} begins. Had that happen during creation of our solar system, i.e. had a few dozen times the mass of gasses contained in Jupiter condensed in that location, then we would had two {{w|Sun|Suns}} and our solar system would have been a {{w|Binary system (astronomy)|Binary system}}.

* {{w|Titan (moon)|Titan}} — The figures on Titan are sirens, a reference to Kurt Vonnegut's ''{{w|The Sirens of Titan}}''.

* {{w|Saturn}} & its rings — The "Rings" in Saturn's gravity well are {{w|Rings of Saturn|Saturn's rings}}. The farther you get from a planet, the weaker the effect of its gravity on you, so, at some point, when climbing out of Saturn's gravity well, you've reached the point equivalent to starting your climb from the rings of Saturn, or, in fact, from specific rings of Saturn. Saturn's rings start fairly near the planet and extend out quite far, therefore multiple stripes are shown in the figure. The rings are also shown in multiple colors and roughly match the observed colors from photos take by the {{w|Cassini–Huygens|Cassini spacecraft}} expedition as it passed Saturn. All of the colors of the planets and moons represent the predominant color of that object as observed from earth.

* {{w|Uranus}} — notably absent is any "your-anus" jokes.

* {{w|Neptune}} — Megan's quote is a paraphrase of {{w|Carl Sagan|Carl Sagan's}} quote, "...but from a planet orbiting a star in a distant globular cluster, a still more glorious dawn awaits, not a sun-rise, but a galaxy rise." [http://www.youtube.com/watch?v=zSgiXGELjbc Video here]

==== How to interpret gravity wells ====

To escape a planet's or moon's orbit, you need merely climb to the highest of the two peaks to ''either'' the left or right of the object. So, for example, to escape Venus, you need merely reach the peak left of it, the slope right of it is part of the Sun's gravity well, and shows how much further you'd need to climb out of the Sun's gravity well to get from Venus to Earth. Likewise, the peak left of Jupiter is slightly lower than the one to the right; this is because the rightmost peak includes the difficulty of moving away from the Sun to get to Saturn, the next planet along.

The text explains that the depth of the well is mass-of-planet over radius-of-planet with newtons constant and 9.81 m/s² as constants, where 9.81 m/s² is the acceleration of a free falling body at Earth's gravity.

The calculation for a gravity well is:
:depth = (G * Planet-mass ) / (9.81 m/s2 * Planet-radius)
::where G is {{w|Isaac_Newton|Newton}}'s {{w|Gravitational_constant|gravitational constant}}, and
::9.81 m/s2 is the {{w|Acceleration|acceleration}} rate of a {{w|Gravity_of_Earth|free falling body on earth}} at sea level (g).

==== Escape Velocities ====

The following table was adapted from the table in {{w|Escape velocity#List of escape velocities|Escape velocity}}, using ''h'' = ''V_e''^2 / 2''g'':
{| class="wikitable" border="1"
| Location || with respect to || Ve (km/s) || Well depth (km) ||
| Location || with respect to || Ve (km/s) || Solar well (Mm) || Total depth (Mm)
|-
| on the Sun, || the Sun's gravity: || 617.5 || 19,435,000 || || || || || || 19,435
|-
| on Mercury, || Mercury's gravity: || 4.3 || 942 ||
| at Mercury, || the Sun's gravity: || 67.7 || 233.6 || 235
|-
| on Venus, || Venus' gravity: || 10.3 || 5,407 ||
| at Venus, || the Sun's gravity: || 49.5 || 124.9 || 130
|-
| on Earth, || the Earth's gravity: || 11.2 || 6,393 ||
| at the Earth/Moon, || the Sun's gravity: || 42.1 || 90.3 || 97
|-
| on the Moon, || the Moon's gravity: || 2.4 || 294 ||
| at the Moon, || the Earth's gravity: || 1.4 || || 91
|-
| on Mars, || Mars' gravity: || 5 || 1,274 ||
| at Mars, || the Sun's gravity: || 34.1 || 59.3 || 61
|-
| on Jupiter, || Jupiter's gravity: || 59.5 || 180,400 ||
| at Jupiter, || the Sun's gravity: || 18.5 || 17.4 || 198
|-
| on Ganymede, || Ganymede's gravity: || 2.7 || 372 || || || || ||
|-
| on Saturn, || Saturn's gravity: || 35.6 || 64,600 ||
| at Saturn, || the Sun's gravity: || 13.6 || 9.43 || 74
|-
| on Uranus, || Uranus' gravity: || 21.2 || 22,907 ||
| at Uranus, || the Sun's gravity: || 9.6 || 4.7 || 28
|-
| on Neptune, || Neptune's gravity: || 23.6 || 28,400 ||
| at Neptune, || the Sun's gravity: || 7.7 || 3.02 || 31
|-
| on Pluto, || Pluto's gravity: || 1.2 || 73 || || || || ||
|-
|at Solar System galactic radius, || the Milky Way's gravity: || 525 || 14,000
|}

==Transcript==
:'''Main Text'''
:Gravity Wells scaled to Earth surface gravity
:This chart shows the "depth" of various solar system gravity wells.
:Each well is scaled such that rising out of a physical well of that depth — in constant Earth surface gravity — would take the same energy as escaping from that planet's gravity in reality.
:Each planet is shown cut in half at the bottom of its well, with the depth of the well measured down to the planet's ''flat'' surface.
:The planet sizes are to the same scale as the wells. Interplanetary distances are not to scale.
:Depth = (G × PlanetMass) / (g × PlanetRadius)
:G = Newton's constant
:g = 9.81 m/s2

:'''Planetary Descriptions'''
:To Sun, very very far down
:Mercury
:Venus
:Earth - 5,478 km
:Moon - 288 km
:Mars - 1,286 km
:Ganymede
:Io
:Jupiter
::[A drawing of a "very deep" gravity well, "Your mom" at the bottom, several member of "local football team" falling down towards her.]
::Jupiter is not much larger than Saturn, but much more massive. At its size, adding more mass just makes it denser due to the extra squeezing of gravity.
::If you dropped a few dozen more Jupiters into it, the pressure would ignite fusion and make it a star.
:Europa
:Titan
::Two figures: Weeoooeeoooeeooo
:Saturn
::Rings
:Uranus
:Neptune
::Megan: An even more glorious dawn awaits!

:'''Mars Inset'''
:[Mars gravity well, the Pathfinder probe on its surface, with its moons Deimos and Phobos as smaller gravity wells.]

:[Figure of a man (to scale) in Deimos's gravity well.]
:You could escape Deimos with a bike and a ramp.

:[Figure of a man (to scale) in Phobos's gravity well.]
:A thrown baseball could escape Phobos.

:'''Earth Inset'''
:[Zoomed-in view of Earth/moon gravity well, featuring the relative locations of the atmosphere, Low Earth Orbit, the International Space Station, the Space Shuttle, GPS satellites, and satellites in geosynchronous orbit.]
:Cueball: This is why it took a huge rocket to get to the moon but only a small one to get back.

:It takes the same amount of energy to launch something on an escape trajectory away from Earth as it would to launch it 6,000 km upward under constant 9.81 m/s2 Earth gravity.

:Hence, Earth's well is 6,000 km deep.

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Large drawings]]
[[Category:Your Mom]]

Talk:1389: Surface Area

2014-07-03T09:40:49Z

Theme: Mention coastline paradox

FYI to whoever writes this: the Seattle reference is the Space Needle. [[Special:Contributions/108.162.221.65|108.162.221.65]] 05:03, 2 July 2014 (UTC)

Uranus is larger than all of these combined. Of course, it isn't on this map because it is full of gas. [[Special:Contributions/173.245.62.62|173.245.62.62]] 05:50, 2 July 2014 (UTC)
: Just wondering... Does that mean, a spaceship could just fly trough Uranus? (No pun intended.) --[[Special:Contributions/141.101.75.20|141.101.75.20]] 07:16, 2 July 2014 (UTC)
::It'd probably hurt. As an ice-giant, the interior of Uranus is mainly composed of ices and rock. Jupiter and Saturn have cores of liquid metallic hydrogen. Also, the rock/ice isn't considered the surface of Uranus, because most of the planet's mass lies outside the solid inner layers.) [[Special:Contributions/103.22.201.239|103.22.201.239]] 09:28, 2 July 2014 (UTC) P.S. Even if it was only gas, a spaceship would probably find it hard to handle the temperature and pressure at the center of Uranus.
:::As the gas giants contain a solid core, why is it the surface of those cores not included in the drawing? Just like Earth, Mars and Venus, they are still just solid with a (very thick) atmosphere. [[User:GadgetViking|GadgetViking]] ([[User talk:GadgetViking|talk]]) 23:55, 2 July 2014 (UTC)
:If the spaceship has not braked enough down it would burn up in the atmosphere. If it has it would get stuck in the core of the planet, where it would eventually get crushed, as the pressure would be brutal way before reaching any rock or metallic hydrogen. Although I did like the first comment :-p [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 21:00, 2 July 2014 (UTC)

And of course the earth is not correctly displayed: we have water which - in most cases - is not solid. -- jesterchen [[Special:Contributions/141.101.75.19|141.101.75.19]] 07:23, 2 July 2014 (UTC)
: Water still has surface area. Edit: oh, I see what you mean now, from the title in the comic. I guess you have a point, but it's mainly there for comparison so it's not necessarily a mistake. --[[User:NeatNit|NeatNit]] ([[User talk:NeatNit|talk]]) 06:14, 2 July 2014 (UTC)
:: Under the water there is solid bottom --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 07:01, 2 July 2014 (UTC)
::: But then it is not "surface" anymore... but you two have a point. I focused mainly on the title, not the image text... So forget my comment :) -- jesterchen [[Special:Contributions/141.101.75.19|141.101.75.19]] 09:12, 2 July 2014 (UTC)
:::: Water indeed has a surface, while gas doesn't. [[Special:Contributions/141.101.104.47|141.101.104.47]] 11:13, 2 July 2014 (UTC)Martin
:See the current explain - just remove the water from earth, and the earth's surface area would still be almost as big. It is only 3-4 km (on both sides) out of 12,000 km in the diameter. There are also fluids on some of the rocky moons (Ice and then water beneath on Europe, Methane lakes on Titan etc.)[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 21:00, 2 July 2014 (UTC)

There is also small section named "''All human skin''" (between Earth and Titan)... if you think about thread and needle... ugh... --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 07:01, 2 July 2014 (UTC)
:This is exactly the same as seen from the planets perspective. [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 21:00, 2 July 2014 (UTC)

This seems to be an island floating on something, maybe it's floating on the sun's plasma? --[[User:BelgianAtheist|BelgianAtheist]] ([[User talk:BelgianAtheist|talk]]) 08:24, 2 July 2014 (UTC)
:Or a supercontinent with an ocean around (so not floating). As the whole thing is just 3-4 times larger than earth, it would not need a very big planet to support it - a surface area 9 times as big as the earth would be plenty of big enough to contain the entire map (including all the ocean in the square). So the radius would only need to be like 3 times as big as the Earth's. No need to use the Sun for this... ;-) [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 21:00, 2 July 2014 (UTC)

So, what's the area surrounding Earth's landmass? It's not named, or am I blind? [[Special:Contributions/141.101.99.218|141.101.99.218]] 09:46, 2 July 2014 (UTC)
:It is the rest of the Earth - that part which is covered by the Ocean [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 21:00, 2 July 2014 (UTC)

Don't think it is strictly accurate to say that earth is included 'for scale' -- surely it is included because it qualifies to be on the map. Otherwise it's a bit like saying that Belgium is included in maps of Europe 'for scale' (as 'the size of Belgium' is a well-known unit of land area as in 'Amazonian rainforest the size of Belgium is cut down every week') -- Devonian Earache
: The size of Belium is also famous for its reference in the Doctor Who mini-episode "Time Crash" (see http://www.chakoteya.net/doctorwho/CIN2007.htm) {{unsigned|Esp666}}

The map of Earth doesn't look like the Waterman Butterfly projection. If it did, the continents would be angled in toward each other, and Australia would be up in the corner. The only thing that is even similar is that Antarctica is shown in "normal" proportions rather than stretched across the bottom. [[User:Prometheusmmiv|Prometheusmmiv]] ([[User talk:Prometheusmmiv|talk]]) 11:41, 2 July 2014 (UTC)
:But the map projection reference is very relevant as it is indeed as the Waterman keeping the relative sizes of the continents. And Randall is very in to this obvious from the comic. Thus included again [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 21:00, 2 July 2014 (UTC)

What's the area on the coast between Asteroids (1km+) and Triton? [[Special:Contributions/108.162.222.50|108.162.222.50]] 11:44, 2 July 2014 (UTC)
:Good question. Did he forget it or...? It is way to big to be his own asteroid Asteroid 4942 Munroe ;) And much smaller even than Vesta [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 21:00, 2 July 2014 (UTC)

(My first contribution here!) About the Earth/water surface issue, I think Randall is talking about planets' surface, and then it counts both earth and water (like if it were a sphere) [[Special:Contributions/173.245.52.173|173.245.52.173]] 12:31, 2 July 2014 (UTC)

I changed the explanation of the title text. The previous explanation, "all the matter in the solar system converted to a string" cannot be correct. First, he said "first we'll need a gigantic spool of thread". The title text obviously refers back to the title itself, about "stitching" the solar system's solid surfaces together. [[Special:Contributions/108.162.221.79|108.162.221.79]] 13:17, 2 July 2014 (UTC)

Regarding the table, perhaps it would be better to make a separate "Surface area relative to Earth" column? Or may be just a numeric order according to size? The scientific notation of areas does not sort by ascending/descending order very well. [[Special:Contributions/173.245.62.62|173.245.62.62]] 14:09, 2 July 2014 (UTC)
Also, the average adult skin is around 1.73 square meters. For a newborn, it is 0.25.[http://en.wikipedia.org/wiki/Body_surface_area]. Very roughly estimating 1 sq. meter as the mean BSA, we get 7 billion sq. meters, or 7000 sq. km of human skin. That would be slightly larger than the area of either Palestine or Delaware.{{unsigned ip|173.245.62.62}}

Should there not be a pixel (or perhaps a slightly grey pixel) for Asteroid 4942 Monroe - area of about 1-3×102 Km2?? [[User:Esp666|Esp666]] ([[User talk:Esp666|talk]]) 16:34, 2 July 2014 (UTC)
:It would be included in the asteroids larger than 1 km as it is about 6-10 km [http://blog.xkcd.com/2013/09/30/asteroid-4942-munroe/ according to Randall]. [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 21:00, 2 July 2014 (UTC)

;Sedna and Quaoar

Why are Sedna and Quaoar not included? I mean, Sedna is so fantastically far away that I can sort of understand not including it. But Quaoar is only 10% further from the sun than Pluto or Haumea, and it's actualy closer than Makemake! [[Special:Contributions/108.162.238.165|108.162.238.165]] 13:33, 2 July 2014 (UTC)
:Probably because we do not yet know if they have a stable surface. They would thus be included in the Various or asteroids sections. [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 21:00, 2 July 2014 (UTC)

;Sorting
The numerical column needs to be rewritten (preferably as two columns) in order for sorting to be useful. - [[User:Frankie|Frankie]] ([[User talk:Frankie|talk]]) 14:27, 2 July 2014 (UTC)

----

Well the "blank" spot around the earth continents is obviously all the other "solid" stuff we know earth is made up of, the continents are all above sea level are displayed as we see them from space - the rest of the "blank" area is solid mass under the ocean we don't see from up above but know is there through the sciences! {{unsigned ip|173.245.52.181}}
: Perhaps this is the Earth's surface after all the bodies of water vanish? http://what-if.xkcd.com/103/
:[[User:Wwoods|Wwoods]] ([[User talk:Wwoods|talk]]) 21:07, 2 July 2014 (UTC)

----

;Hannibal Lecter

I think that should be Buffalo Bill. Hannibal ate his victims, Bill sewed their skins into "clothing". --[[Special:Contributions/173.245.52.153|173.245.52.153]] 01:41, 3 July 2014 (UTC)

----

;Coastline paradox

Doesn't this thing suffer from the {{w|Coastline paradox}}? If that paradox applies to suface areas of 3D objects, then the surface areas of planets and other objects would be infinite or very large. Even if that is not the case, I don't think the 4*pi*r formula would work properly. [[User:Theme|Theme]] ([[User talk:Theme|talk]]) 09:40, 3 July 2014 (UTC)

1376: Jump

2014-06-02T09:58:23Z

Theme: Mention the sun's gravity

{{comic
| number = 1376
| date = June 2, 2014
| title = Jump
| image = jump.png
| titletext = I hope I'm at least following the curve of the Earth around to land ...
}}

==Explanation==
Cueball is (presumably) experiencing a common dream subject, flying or floating. As in many varieties of such a dream, the ability to fly, float or glide only gradually manifests, going from longer and longer jumps to a sort of flight or hovering. In Cueball's case, his jumps become longer and 'lighter' until at last he is gliding just above the surface of the Earth. He has apparently had such a dream before, with just such a flight mechanic manifesting itself, as he indicates that he 'loves' these dreams.

In his (presumed) dream, Cueball finally achieves his gliding flight just as he reaches the shoreline, and his gliding carries him over the water's edge and out to sea. After a moment's reflection, he indicates that he HOPES it is a dream, as if he were really gliding out to sea without any real apparent means of control, his situation would presumably be rather perilous ... death by starvation or thirst, gradually slowing down and becoming 'stuck' over the water with no way to land, the loss of his gliding ability as suddenly as it came, etc, all suggest themselves as possible perils he would now be subject to if, in fact, his 'dream' were actual reality.

The title text adds a further worry not immediately apparent unless one considers the possibility that Cueball's 'gliding' is actually some sort of cessation of gravity acting upon his person, in which case he would (if his forward momentum were maintained) continue moving in a straight line while the Earth's surface would curve away beneath him, sending him out into space instead of the (relatively) preferable scenario of merely floating across the ocean to the opposite shore. Of course if gravity no longer affects him, the earth would very quickly move away from him, on its path around the sun, so this cannot be the case, as he is sliding straight over the ocean. However, it might be possible that only the earth's gravity doesn't affect Cueball, and the sun's gravity keeps him in almost the same orbit as the earth instead.

Also note that this situation is similar to the case of {{W|Newton's cannonball}}.

==Transcript==
{{incomplete transcript}}

Cueball is jumping in the open...

"I love these dreams... Each jump is a little longer... Each push off the ground a little softer... Until I...GLIDE"

Cueball jumps over a fence and floats in the air, over the sea

"...I ''hope'' this is a dream."

{{comic discussion}}

1376: Jump

2014-06-02T09:54:46Z

Theme: mention Newton's cannonball

{{comic
| number = 1376
| date = June 2, 2014
| title = Jump
| image = jump.png
| titletext = I hope I'm at least following the curve of the Earth around to land ...
}}

==Explanation==
Cueball is (presumably) experiencing a common dream subject, flying or floating. As in many varieties of such a dream, the ability to fly, float or glide only gradually manifests, going from longer and longer jumps to a sort of flight or hovering. In Cueball's case, his jumps become longer and 'lighter' until at last he is gliding just above the surface of the Earth. He has apparently had such a dream before, with just such a flight mechanic manifesting itself, as he indicates that he 'loves' these dreams.

In his (presumed) dream, Cueball finally achieves his gliding flight just as he reaches the shoreline, and his gliding carries him over the water's edge and out to sea. After a moment's reflection, he indicates that he HOPES it is a dream, as if he were really gliding out to sea without any real apparent means of control, his situation would presumably be rather perilous ... death by starvation or thirst, gradually slowing down and becoming 'stuck' over the water with no way to land, the loss of his gliding ability as suddenly as it came, etc, all suggest themselves as possible perils he would now be subject to if, in fact, his 'dream' were actual reality.

The title text adds a further worry not immediately apparent unless one considers the possibility that Cueball's 'gliding' is actually some sort of cessation of gravity acting upon his person, in which case he would (if his forward momentum were maintained) continue moving in a straight line while the Earth's surface would curve away beneath him, sending him out into space instead of the (relatively) preferable scenario of merely floating across the ocean to the opposite shore. Of course if gravity no longer affects him, the earth would very quickly move away from him, on its path around the sun, so this cannot be the case, as he is sliding straight over the ocean.

Also note that this situation is similar to the case of {{W|Newton's cannonball}}.

==Transcript==
{{incomplete transcript}}

Cueball is jumping in the open...

"I love these dreams... Each jump is a little longer... Each push off the ground a little softer... Until I...GLIDE"

Cueball jumps over a fence and floats in the air, over the sea

"...I ''hope'' this is a dream."

{{comic discussion}}

1376: Jump

2014-06-02T05:18:22Z

Theme: Add missing "Transcript" section and add "incomplete transcript" template

{{comic
| number = 1376
| date = June 2, 2014
| title = Jump
| image = jump.png
| titletext = I hope I'm at least following the curve of the Earth around to land ...
}}

==Explanation==
{{incomplete|Created by a BOT - Please change this comment when editing this page.}}

==Transcript==
{{incomplete transcript}}

Cueball is jumping in the open...

"I love these dreams... Each jump is a little longer... Each push off the ground a little softer... Until I...GLIDE"

Cueball jumps over a fence and floats in the air, over the sea

"...I hope this is a dream."

1372: Smartwatches

2014-05-23T07:25:10Z

Theme: joke edit. revert if this is lame

{{comic
| number = 1372
| date = May 23, 2014
| title = Smartwatches
| image = smartwatches.png
| titletext = This is even better than my previous smartphone casemod: an old Western Electric Model 2500 desk phone handset complete with a frayed, torn-off cord dangling from it.
}}

==Explanation==
{{incomplete|Created by a BOT - Please change this comment when editing this page. OK... comment changed, now what?}}

The phone referenced in the title text: [http://en.wikipedia.org/wiki/Model_500_telephone]

Case modding is the art of building (usually computers) into nicely shaped non-standard cases [http://en.wikipedia.org/wiki/Case_modding]

==Transcript==
{{incomplete transcript}}

{{comic discussion}}

1308: Christmas Lights

2013-12-25T10:48:52Z

Theme: mention LED

{{comic
| number = 1308
| date = December 25, 2013
| title = Christmas Lights
| image = christmas_lights.png
| titletext = Merry Christmas from xkcd!
}}

==Explanation==
{{incomplete|Check grammar and add details about the star spectrum}}
Understanding this comic requires knowing about electromagnetic spectrums.
In a nutshell, an electromagnetic spectrum is the scientific way of representing the amounts and type of radiation than a specific source emits. In this comic apears a subtype of these, a light spectrum, that shows the visible radiation, some infrarred and some ultraviolet. More detailed info on wikipedia({{w|Electromagnetic spectrum}}).

There are 4 graphs in this comic:

In the center of the image, between the couple Cueball and Megan and Beret Guy appears a light spectrum of a fire, notably because it emits a lot of energy in the infrared band (The left zone of the spectrum), and in the red and orange zone (typical colors of a fire)

In the right of the comic appears some spectrums shaped in the form of a Christmas tree. There are 3 different spectrums in this "Christmas tree":

In the top appears a complex spectrum, possibly even from a real star, or simply an LED (see http://led-brdf.wikispaces.com/Introduction+to+LEDs), representing the tradition of putting a star in the top of the Christmas tree, representing the Star that guided the Three Wise Men in Christianity.

In the "leaves" there are are two simpler spectrums, one with a peak in the green zone, representing a green bulb, and other with a peak in the red zone, representing a red bulb

==Transcript==
{{incomplete transcript}}

{{comic discussion}}
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Beret Guy]]
[[Category:Comics with color]]

1300: Galilean Moons

2013-12-06T06:43:47Z

Theme: Explain who says what and note that they actually never line up

{{comic
| number = 1300
| date = December 6, 2013
| title = Galilean Moons
| image = galilean_moons.png
| titletext = I'm SO glad I escaped. They almost had me caught in their weird ... thing.
}}

==Explanation==
{{incomplete|Needs further astronomical explanations}}

[[File:Galilean moon Laplace resonance animation.gif|thumb|365px|The 1:2:4 {{w|orbital resonance}} of {{w|Ganymede (moon)|Ganymede}}, {{w|Europa (moon)|Europa}}, and {{w|Io (moon)|Io}}]] 

The four {{w|Galilean moons}}—the largest of the 67 {{w|moons of Jupiter|moons orbiting Jupiter}}—have an unusual orbit, in that the three inner moons, {{w|Ganymede (moon)|Ganymede}}, {{w|Europa (moon)|Europa}}, and {{w|Io (moon)|Io}}, have an {{w|orbital resonance}} of 1:2:4, as illustrated in the picture to the right. This comic personifies the moons, with the "MOOOOOON!" interruptions representing the disruptions in their orbits created by the resonance. Io, Europa and Ganymede say "Hi!", "What's your name?" and "MOOOOON!" respectively, when facing Cueball. However, these three moons never actually line up on the same side, but only in the same line on opposite sides (see animation).

The title text describes one of the moons (most likely {{w|Callisto (moon)|Callisto}}, the outermost of the four) escaping from the rest. "Their weird ... thing" ascribes a vaguely sexual nature to the other three moons' relationship, which is extra relevant due to the fact that all four moons are named after lovers of {{w|Zeus}} (a.k.a. {{w|Jupiter (mythology)|Jupiter}}!!!), who often held them captive, much as Jupiter the planet holds the four moons captive.

==Transcript==



:[[[Megan]] approaches [[Cueball]], orbited by four small floating balls.]
:Megan: Check it out!
:Cueball: What?
:Megan: I've got {{w|Galilean moons}}!

:[The moons converse as {{w|Io (moon)|Io}} and {{w|Europa (moon)|Europa}} orbits synchronize.]
:Io: Hi!
:Europa: What's your name?

:[They are separated before Io can answer. Io stands alone now.]
:Io: Hi!

:[Europa returns to her position near Io, and {{w|Ganymede (moon)|Ganymede}} joins them.]
:Io: Hi!
:Europa: What's your—
:Ganymede: MOOOOOON!

:[Io is once again alone.]
:Io: Hi!

:[Europa and Io are together again, this time absent Ganymede.]
:Io: Hi!
:Europa: What's your name?
:{{w|Callisto (moon)|Callisto}}: Ugh.

:[Once more, Europa leaves Io alone before she can answer.]
:Io: Hi!
:Callisto: So annoying.

:[Europa and Ganymede re-join Io.]
:Io: Hi!
:Europa: What's y—
:Ganymede: MOOOOOON.

:[Io is on her own once again. Callisto nudges herself toward Cueball.]
:Io: Hi!
:Callisto: ...Almost...
:Callisto: ...Almoooost...

:[Io and Europa are reunited, Ganymede by himself on the opposite side of Megan. Callisto enters orbit around Cueball.]
:Io: Hi!
:Europa: What's your name?
:Callisto: Yessss!

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