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	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3103:_Exoplanet_System&amp;diff=379815</id>
		<title>3103: Exoplanet System</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3103:_Exoplanet_System&amp;diff=379815"/>
				<updated>2025-06-18T09:14:30Z</updated>
		
		<summary type="html">&lt;p&gt;MindTheGap: Added explanation on Potentially Habitable Void&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 3103&lt;br /&gt;
| date      = June 16, 2025&lt;br /&gt;
| title     = Exoplanet System&lt;br /&gt;
| image     = exoplanet_system_2x.png&lt;br /&gt;
| imagesize = 623x447px&lt;br /&gt;
| noexpand  = true&lt;br /&gt;
| titletext = Sure, this exoplanet we discovered may seem hostile to life, but our calculations suggest it's actually in the accretion disc's habitable zone.&lt;br /&gt;
}}&lt;br /&gt;
&lt;br /&gt;
==Explanation==&lt;br /&gt;
{{incomplete|Explanations for the planets are incomplete and some categories are missing. [[explain xkcd:Editor FAQ#table|Do NOT create a table]], unless it is impossible to convey that information without it.}}&lt;br /&gt;
{{w|Exoplanet}}s are planets outside the Sun's {{w|Solar System}}. Astronomers are constantly on the lookout for planets that might be habitable, particularly those with {{w|Earth-like_planet|Earth-like}} conditions. This gets prime attention, both because it suggests a higher potential for finding extraterrestrial life of a form we might more easily recognise, and because such planets might potentially be examined as candidates for future {{w|space colonization}}. Unfortunately, for many hopefuls, there are a number of specific conditions required for Earth life to survive, and there are many possible ways for space to be inhospitable to life. As a result, most exoplanets that have been discovered have conditions that make it nearly impossible for humans to survive, and difficult for any life form as we know it to exist. [[Randall]] draws a hypothetical star system containing many exoplanets that describe (in an exaggerated fashion) the many frustrations astronomers face when analyzing planets and getting their hopes up, only to discover the planets they found are, sadly, nothing like Earth.&lt;br /&gt;
&lt;br /&gt;
There are a total of 19 planets in the comic. Here are the explanations for each planet, in order of how far they are from the star:&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!-- 50px from the star--&amp;gt;  Giant planet orbiting so close that it's actually rolling on the star's surface&lt;br /&gt;
: {{w|Giant planet}}s are often gravitationally pulled close to their star. Here, the planet is literally touching the star, which, given both bodies' gaseous makeup, should cause them to merge.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!-- 80pxfrom the star--&amp;gt;  Hot Jupiter&lt;br /&gt;
: A {{w|Hot Jupiter}} is typical terminology used in analyzing exoplanets, generally depicting a {{w|gas giant}} (of a size similar to our {{w|Jupiter}} or {{w|Saturn}}) which orbits in a much closer/hotter orbit than our own. Hot Jupiters are easier to detect than many other types of exoplanets, due to their gravitational effect on their stars.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--115px from the star--&amp;gt;  Planet that may actually be in the habitable zone, according to a very optimistic modeling paper by some desperate postdocs&lt;br /&gt;
: The {{w|habitable zone}} of a star is the range at which water is liquid. Notably, planets in the habitable zone are seen as options for colonization by humanity, which would mean greater funding for research. As such, researchers will go to great lengths to determine as many habitable planets as they can.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--175px--&amp;gt;  There's a pulsar here but it's probably fine&lt;br /&gt;
: A {{w|pulsar}} is a {{w|neutron star}} which emits beams of radiation while spinning very fast. The intensity of this radiation makes it extremely difficult for any form of life to exist in the system. This is in addition to the {{w|gravitational instability}}, and excess heat that the pulsar would produce. This lends a substantial level of irony to the &amp;quot;probably fine&amp;quot; comment. Also, it means that this system is technically a {{w|binary star}}.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--250px--&amp;gt;  A waterworld paradise with beautiful oceans and warm&amp;amp;mdash; wait, no, we just got new measurements, it's a hellish steam oven&lt;br /&gt;
: In any scientific field, new information may turn previously established knowledge on its head. Exoplanet research is no different, and a planet that at first seems to be habitable might turn out to be an incredibly deadly {{w|steam world}}. An example of this can be found in our own solar system with {{w|Venus}}, which was known to have clouds as early as the 1700s and was speculated to be habitable &amp;amp;mdash; but later, in the 1960s, those clouds were found to be made of steaming hot {{w|sulfuric acid}}.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--280px--&amp;gt;  Planet that could be habitable, if there's a form of life that hates water but loves acid and being on fire &lt;br /&gt;
: Scientists remain open to the possibility that life might form from different conditions than those found on Earth. That said, the speculation that life on this planet must &amp;quot;love acid and being on fire&amp;quot; is more than a little sarcastic. Possibly to a reference to the ''[[what if? (blog)|what if?]]'' article ''{{what if|30|Interplanetary Cessna}}'', in which Randall points out that the atmosphere on Venus is pretty survivable at 55km, except for the sulfuric acid, and way too hot at the surface.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--300px--&amp;gt;  Mini Neptune&lt;br /&gt;
: &amp;quot;Jupiter&amp;quot; and &amp;quot;Neptune&amp;quot; are rough size/mass categories for gas giants with a mass similar to Jupiter versus {{w|Neptune}}/{{w|Uranus}}.  A {{w|mini-Neptune}} would be smaller than Neptune, possibly small enough not to be a gas giant at all.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--345px--&amp;gt;  Lukewarm Jupiter&lt;br /&gt;
: A humorous extrapolation of Hot Jupiters, assuming that there are other named types of Jupiters. The French Wikipedia has [https://fr.wikipedia.org/wiki/Jupiter_ti%C3%A8de an article on warm Jupiters]. &lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--375px--&amp;gt;  Planet whose atmosphere is confirmed to contain atoms&lt;br /&gt;
: With interstellar distances, it is inevitable that some planets will be hard to get a read on. Here, the astronomers can only confirm the planet has an atmosphere, not what it is made of or how thick it is. If it has an atmosphere at all, there are very few options ''except'' for that to be composed of atoms.&lt;br /&gt;
:Possibly in reference to headlines about exoplanets whose atmospheres contain molecules that may indicate biological life, but extrapolated to comedic levels of vagueness. A similar 'too cautious' approach to the data can be seen in [[2359: Evidence of Alien Life]].&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--400px--&amp;gt;  Earthlike data artifact&lt;br /&gt;
: An {{w|Artifact (error)|artifact}} in this context is any error where it looks like something exists when it actually doesn't. This is usually caused by faults in the equipment. In this case the astronomers thought they detected an Earth-like planet, only to discover it was a data artifact. Either that, or it has turned out that {{w|Simulation_hypothesis|Earth itself is a data artifact}}, which would raise {{w|Epistemology|epistemological}} questions about the whole endeavour of studying the universe.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--455px--&amp;gt;  Cold Jupiter&lt;br /&gt;
: Implicitly the opposite of a &amp;quot;Hot Jupiter&amp;quot; described above. Used here as another extension of the &amp;quot;Hot Jupiters&amp;quot; running gag, &amp;quot;Cold Jupiters&amp;quot; is occasionally used in real astronomy but is fairly informal. The French Wikipedia has [https://fr.wikipedia.org/wiki/Jupiter_froid an article on cold Jupiters].&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--460px--&amp;gt;  Potentially habitable void&lt;br /&gt;
: It seems that the ideal orbital distance for habitable planetary conditions does not actually contain any planets. This would make it much harder to actually inhabit (the notional inhabitants would have to build a world to live on, and would have nowhere to easily locate themselves while the building was in progress), to the implied frustration of the astronomers. Confusingly, the illustration of the void is as a patch that crosses several of the planetary orbits. Since it cannot remain a void if a planet passes through it, this suggests it is an object (or rather a lack of objects) that orbits in its own right. This is not normally how habitable zones work — they are usually a span of potential orbits, forming a {{w|Annulus (mathematics)|ring}} (or {{w|Spherical shell|shell}}) around the star. Additionally, this region is positioned right between Cold Jupiter and Hot Mars, implying that is in between hot and cold, and between gaseous and rocky, being closer to Earth conditions.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--485px--&amp;gt;  Hot Mars&lt;br /&gt;
: Continuing the joke on Hot Jupiter. This assumes that if there's hot Jupiters, there must be a &amp;quot;hot&amp;quot; variant of every planet, including {{w|Mars}}.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--510px--&amp;gt;  Faint dust cloud that will cause several papers to be retracted&lt;br /&gt;
: This is in reference to the {{w|astronomical transit}} method of discovering planets by measuring periodic dips in brightness of the central star, done by missions like the {{w|Kepler space telescope}}. It turns out that not all variations in brightness are caused by planets, much to the disappointment of overeager data analysts and science news reporters; see, for example, {{w|Fomalhaut b}}, a former proposed exoplanet that turned out to be a dust cloud, or {{w|Tabby's Star}}, a star with odd irregular dimming pattern likely due to a dust cloud which was briefly thought by some to be an alien megastructure.{{acn}}&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--515px--&amp;gt;  Either a gas giant or a fist-sized rock, depending upon which calibration method you use&lt;br /&gt;
: Scientific instruments, including telescopes, must be calibrated in various ways, and different calibration methods can lead to different corrections applied to raw data and hence different values for calibrated data. This is exaggerated in the comic to make a raw observation emerge from the calibration correction process as two objects of vastly different size - a range of uncertainty between tens of thousands of kilometers and a few centimeters, perhaps nine orders of magnitude. This is not particularly precise, even for a [[2205: Types of Approximation|cosmologist]]. Also, a &amp;quot;fist-sized rock&amp;quot; would be impossible to detect around a distant star using current technology; it would be difficult to spot {{w|Russell's teapot|something of this size}} around {{w|Sun|''our own'' star}}. &lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--560px--&amp;gt;  Mini Pluto&lt;br /&gt;
: {{w|Pluto}} is already significantly smaller than most planets, thus its designation as a &amp;quot;{{w|dwarf planet}}&amp;quot;. A &amp;quot;mini Pluto&amp;quot; suggests an exoplanet that shares most of Pluto's features, but is somehow ''even smaller''.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--620px--&amp;gt;  Wet Saturn&lt;br /&gt;
: May be a reference to the 'fact' that &amp;quot;Saturn would float in water&amp;quot; {{w|Saturn#Physical characteristics|due to its density}}. The difficulty of finding a practical way to test this notwithstanding, perhaps someone managed it with this planet.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--745px--&amp;gt;  Planet whose surface may host conditions suitable for rocks&lt;br /&gt;
: As with the above planet whose atmosphere &amp;quot;contains atoms,&amp;quot; this planet is too difficult to get a read on, and the measurements are still so vague that it's unknown whether this planet is a rocky planet or a gas/{{w|ice giant}}.  This is also a play on the holy grail of exo-planet research -- finding a planet whose surface hosts conditions suitable for ''life''.&lt;br /&gt;
&lt;br /&gt;
; &amp;lt;!--840px--&amp;gt;  Somehow this whole system is smaller than the orbit of Mercury?!&lt;br /&gt;
: No planet, or anything other than an orbital path, shown. But apparently an indicator that all the rest of the given orbits (for Jupiter-likes, Mars-likes, dust clouds, etc., and even semi-inconvenient pulsars) exist within a planetary system that is ''extremely'' compact, fitting into a volume of space the size of that between our Sun and the orbit of its nearest planet, {{w|Mercury}}.&lt;br /&gt;
&lt;br /&gt;
: This is likely a reference to the fact that many exoplanets located so far have been in even tighter orbits around their star than Mercury is with the Sun. It is worth noting, however, that this is likely to be observational bias, as large and tightly orbiting planets have a significantly larger (and hence easier to identify) effect on their parent star. There are likely many small and more distantly orbiting exoplanets that we are simply unable to observe effectively at this time.&lt;br /&gt;
&lt;br /&gt;
: This is also likely a reference to the fact that the majority of stars in our galaxy are red dwarf stars, which are much cooler and dimmer than our sun. This means that the habitable zone and a wide range of solar irradiance can be found within a smaller radius from the star.&lt;br /&gt;
&lt;br /&gt;
; Title text&lt;br /&gt;
: The title text mentions a planet within an {{w|accretion disk}}, which means that the planet is passing through material inspiraling into some significantly more massive object and is likely inspiraling itself from resistive effects of passing through said material. Nevertheless, the researcher speaking assures us that the planet is in the disk's habitable zone, implying it is a worthwhile option for colonization. This is despite the observed location being likely temporary as the planet's orbit inspirals closer and closer to the central object, to say nothing of the likely constant bombardment of debris and potential radiation depending on how massive the central object is and how dense the accretion disk is.&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
{{incomplete transcript|This transcript sucks because I used AI, but it's a start. Feel free to discard it.}}&lt;br /&gt;
&lt;br /&gt;
:[Central diagram showing a star with various planets and objects orbiting around it, with labels and descriptions connected by dotted lines:]&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to a large planet very close to the star:]&lt;br /&gt;
&lt;br /&gt;
:Giant planet orbiting so close that it's actually rolling on the star's surface&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to a small object near the star:]&lt;br /&gt;
&lt;br /&gt;
:Hot Jupiter&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to a small object:]&lt;br /&gt;
&lt;br /&gt;
:Mini Neptune&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to a planet in the middle distance:]&lt;br /&gt;
&lt;br /&gt;
:Planet that could be habitable, if there's a form of life that hates water but loves acid and being on fire&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to another object:]&lt;br /&gt;
&lt;br /&gt;
:Cold Jupiter&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to a circled area:]&lt;br /&gt;
&lt;br /&gt;
:Potentially habitable void&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to another planet:]&lt;br /&gt;
&lt;br /&gt;
:Hot Mars&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to a planet:]&lt;br /&gt;
&lt;br /&gt;
:Planet that may actually be in the habitable zone, according to a very optimistic modeling paper by some desperate postdocs&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to a small object:]&lt;br /&gt;
&lt;br /&gt;
:There's a pulsar here but it's probably fine&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to another object:]&lt;br /&gt;
&lt;br /&gt;
:A waterworld paradise with beautiful oceans and warm-- wait, no, we just got new measurements, it's a hellish steam oven&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to a small object:]&lt;br /&gt;
&lt;br /&gt;
:Mini Pluto&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to another object:]&lt;br /&gt;
&lt;br /&gt;
:Lukewarm Jupiter&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to a planet:]&lt;br /&gt;
&lt;br /&gt;
:Planet whose atmosphere is confirmed to contain atoms&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to another object:]&lt;br /&gt;
&lt;br /&gt;
:Earthlike data artifact&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to another object:]&lt;br /&gt;
&lt;br /&gt;
:Wet Saturn&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to another object:]&lt;br /&gt;
&lt;br /&gt;
:Either a gas giant or a fist-sized rock, depending which calibration method you use&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to another object:]&lt;br /&gt;
&lt;br /&gt;
:Faint dust cloud that will cause several papers to be retracted&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to another object:]&lt;br /&gt;
&lt;br /&gt;
:Somehow this whole system is smaller than the orbit of Mercury?!&lt;br /&gt;
&lt;br /&gt;
:[Label pointing to another object:]&lt;br /&gt;
&lt;br /&gt;
:Planet whose surface may host conditions suitable for rocks&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&amp;lt;noinclude&amp;gt;&lt;br /&gt;
[[Category:Astronomy]]&lt;br /&gt;
[[Category:Exoplanets]]&lt;/div&gt;</summary>
		<author><name>MindTheGap</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3006:_Demons&amp;diff=355442</id>
		<title>3006: Demons</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3006:_Demons&amp;diff=355442"/>
				<updated>2024-11-02T15:50:51Z</updated>
		
		<summary type="html">&lt;p&gt;MindTheGap: /* Explanation */&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 3006&lt;br /&gt;
| date      = November 1, 2024&lt;br /&gt;
| title     = Demons&lt;br /&gt;
| image     = demons_2x.png&lt;br /&gt;
| imagesize = 285x458px&lt;br /&gt;
| noexpand  = true&lt;br /&gt;
| titletext = Though they do appreciate how much he improved the heating system for the flame pit.&lt;br /&gt;
}}&lt;br /&gt;
&lt;br /&gt;
==Explanation==&lt;br /&gt;
{{incomplete|Created by a DEMI-DEMONIC DOORMAN - Please change this comment when editing this page. Do NOT delete this tag too soon.}}&lt;br /&gt;
&lt;br /&gt;
{{w|Maxwell's demon}} is a thought experiment devised by {{w|James Clerk Maxwell}} that appears to refute the {{w|second law of thermodynamics}}, which roughly says that heat always flows from hotter regions to colder. In the thought experiment, two chambers, both containing a gas at the same temperature, have a door between them. A being (later called a demon by {{w|Lord Kelvin}}) lets only fast-moving gas molecules move from the first chamber to the second, and only slow-moving ones move from the second chamber to the first. The second chamber's gas gradually warms as the average speed of its molecules increases, and the first chamber's gas likewise cools. It should be noted that the action of such a Demon, if an actual physical being, following other physical laws, can be demonstrated to use up at least the amount of energy, that could later have been extracted from having a gas split up in a hot and a cold part. So such a demon can not, like the other types, exist in real life, and thus Maxwell's demon does not break the second law of thermodynamics.&lt;br /&gt;
&lt;br /&gt;
This demon behaves very differently from mythological {{w|demons}}, which exist in the afterlife (usually some form of {{w|hell}}) and punish evil humans after death by causing them great suffering, as for example boiling them in oil or casting them into flame pits.&lt;br /&gt;
&lt;br /&gt;
In this comic, [[Randall]] jokes that, if such a demon were to encounter more stereotypical mythological ones, he would probably not fit in very well, and would inevitably propose treating humans like the particles of the thought experiment. While a few physics-savvy humans might feel offended by such treatment{{Citation needed}}, for most, the suffering would stem from the anxiety of knowing that, once they cross the door, they are not allowed to return for all eternity. So, unlike particles which move by simple virtue of having energy, they must ''choose'' when to cross it. This modern psychological approach to torture stands out from ancient techniques of physical torture such as being boiled in oil or cast into a flame pit.&lt;br /&gt;
&lt;br /&gt;
The title text continues the joke by suggesting that while Maxwell's demon's idea for torturing the souls of the damned might seem whimsical to the other demons, it could still be used to heat the flame pits better. The other demons' appreciation of this technical improvement mirrors real-life situations where kids that &amp;quot;have trouble fitting in with the others&amp;quot; due to their unusual ideas for games and atypical interests (e.g. in thermodynamics) occasionally earn some appreciation when their cleverness is deemed useful.&lt;br /&gt;
&lt;br /&gt;
This comic was published on 1 November, 2024, the day after Halloween, around the time when many contemporary comic strips have demonic, supernatural or other spooky themes.&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:[Three demons, Cueball like in general appearance but with horns and pointed tails are standing together surounded by flames. The leftmost demon is holding a pitchfork and the next one has his hands down. They are looking at the third to the right standing a bit apart from them. This last demon, Maxwell's demon as given in the caption hold his arms up while looking at the other two.]&lt;br /&gt;
:Demon with pitchfork: What's our plan for the souls today? Boil them in oil? &lt;br /&gt;
:Middle demon: We could cast them into the flame pit. &lt;br /&gt;
:Maxwell's demon: What if we set up two rooms with a door in between, but– get this– '''''we only let them go through it one way!'''''&lt;br /&gt;
&lt;br /&gt;
:[Caption below the panel:]&lt;br /&gt;
:Maxwell's Demon had trouble fitting in with the others.&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&lt;br /&gt;
&lt;br /&gt;
[[Category:Physics]]&lt;br /&gt;
[[Category:Religion]]&lt;/div&gt;</summary>
		<author><name>MindTheGap</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3006:_Demons&amp;diff=355441</id>
		<title>3006: Demons</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3006:_Demons&amp;diff=355441"/>
				<updated>2024-11-02T15:48:23Z</updated>
		
		<summary type="html">&lt;p&gt;MindTheGap: /* Explanation */&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 3006&lt;br /&gt;
| date      = November 1, 2024&lt;br /&gt;
| title     = Demons&lt;br /&gt;
| image     = demons_2x.png&lt;br /&gt;
| imagesize = 285x458px&lt;br /&gt;
| noexpand  = true&lt;br /&gt;
| titletext = Though they do appreciate how much he improved the heating system for the flame pit.&lt;br /&gt;
}}&lt;br /&gt;
&lt;br /&gt;
==Explanation==&lt;br /&gt;
{{incomplete|Created by a DEMI-DEMONIC DOORMAN - Please change this comment when editing this page. Do NOT delete this tag too soon.}}&lt;br /&gt;
&lt;br /&gt;
{{w|Maxwell's demon}} is a thought experiment devised by {{w|James Clerk Maxwell}} that appears to refute the {{w|second law of thermodynamics}}, which roughly says that heat always flows from hotter regions to colder. In the thought experiment, two chambers, both containing a gas at the same temperature, have a door between them. A being (later called a demon by {{w|Lord Kelvin}}) lets only fast-moving gas molecules move from the first chamber to the second, and only slow-moving ones move from the second chamber to the first. The second chamber's gas gradually warms as the average speed of its molecules increases, and the first chamber's gas likewise cools. It should be noted that the action of such a Demon, if an actual physical being, following other physical laws, can be demonstrated to use up at least the amount of energy, that could later have been extracted from having a gas split up in a hot and a cold part. So such a demon can not, like the other types, exist in real life, and thus Maxwell's demon does not break the second law of thermodynamics.&lt;br /&gt;
&lt;br /&gt;
This demon behaves very differently from mythological {{w|demons}}, which exist in the afterlife{{citation needed}} (usually some form of {{w|hell}}) and punish evil humans after death by causing them great suffering, as for example boiling them in oil or casting them into flame pits.&lt;br /&gt;
&lt;br /&gt;
In this comic, [[Randall]] jokes that, if such a demon were to encounter more stereotypical mythological ones, he would probably not fit in very well, and would inevitably propose treating humans like the particles of the thought experiment. While a few physics-savvy humans might feel offended by such treatment{{Citation needed}}, for most, the suffering would stem from the anxiety of knowing that, once they cross the door, they are not allowed to return for all eternity. So, unlike particles which move by simple virtue of having energy, they must ''choose'' when to cross it. This modern psychological approach to torture stands out from ancient techniques of physical torture such as being boiled in oil or cast into a flame pit.&lt;br /&gt;
&lt;br /&gt;
The title text continues the joke by suggesting that while Maxwell's demon's idea for torturing the souls of the damned might seem whimsical to the other demons, it could still be used to heat the flame pits better. The other demons' appreciation of this technical improvement mirrors real-life situations where kids that &amp;quot;have trouble fitting in with the others&amp;quot; due to their unusual ideas for games and atypical interests (e.g. in thermodynamics) occasionally earn some appreciation when their cleverness is deemed useful.&lt;br /&gt;
&lt;br /&gt;
This comic was published on 1 November, 2024, the day after Halloween, around the time when many contemporary comic strips have demonic, supernatural or other spooky themes.&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:[Three demons, Cueball like in general appearance but with horns and pointed tails are standing together surounded by flames. The leftmost demon is holding a pitchfork and the next one has his hands down. They are looking at the third to the right standing a bit apart from them. This last demon, Maxwell's demon as given in the caption hold his arms up while looking at the other two.]&lt;br /&gt;
:Demon with pitchfork: What's our plan for the souls today? Boil them in oil? &lt;br /&gt;
:Middle demon: We could cast them into the flame pit. &lt;br /&gt;
:Maxwell's demon: What if we set up two rooms with a door in between, but– get this– '''''we only let them go through it one way!'''''&lt;br /&gt;
&lt;br /&gt;
:[Caption below the panel:]&lt;br /&gt;
:Maxwell's Demon had trouble fitting in with the others.&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&lt;br /&gt;
&lt;br /&gt;
[[Category:Physics]]&lt;br /&gt;
[[Category:Religion]]&lt;/div&gt;</summary>
		<author><name>MindTheGap</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=2612:_Lightsabers&amp;diff=231333</id>
		<title>2612: Lightsabers</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=2612:_Lightsabers&amp;diff=231333"/>
				<updated>2022-04-28T08:09:36Z</updated>
		
		<summary type="html">&lt;p&gt;MindTheGap: &lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;&amp;lt;noinclude&amp;gt;'':For the comic named &amp;quot;Lightsaber&amp;quot;, see [[1433: Lightsaber]].''&amp;lt;/noinclude&amp;gt;&lt;br /&gt;
{{comic&lt;br /&gt;
| number    = 2612&lt;br /&gt;
| date      = April 27, 2022&lt;br /&gt;
| title     = Lightsabers&lt;br /&gt;
| image     = lightsabers.png&lt;br /&gt;
| titletext = A lot of Jedi romances start with this turning into a Lady and the Tramp spaghetti situation.&lt;br /&gt;
}}&lt;br /&gt;
&lt;br /&gt;
==Explanation==&lt;br /&gt;
{{incomplete|Created by a MAGNETICALLY CONFINED PLASMA-SABER REACTOR - Please change this comment when editing this page. Do NOT delete this tag too soon.}}&lt;br /&gt;
A {{w|lightsaber}} is a fictional beam-like sword weapon used by members of the {{w|Jedi}} order and the {{w|Sith}} in the ''{{w|Star Wars}}'' franchise. This comic shows a lightsaber fight starting between two [[Cueball]]-like Jedi, one already presenting their blade in challenge and the second activating theirs in response. When the first strike is made between the two lightsabers, they seemingly meld together, with a bloop sound, like the beams are made of a liquid. This then causes the two light beams to be stuck to each other.  In in-universe &amp;quot;technical documents&amp;quot;, lightsabers are said to be made from magnetically-confined plasma, so perhaps the magnetic fields which were projected from each hilt have merged instead of repelling (or presenting as mutually impervious) as is usually expected.&lt;br /&gt;
&lt;br /&gt;
This scene actually looks a lot like what happens between Harry Potter and Voldemort's wands in the end of the fourth book, the {{w|Harry Potter and the Goblet of Fire|''Goblet of Fire''}}. Here two spells hit each other and connect the two wands, the wand holders then unable to release or disconnect the wands. &lt;br /&gt;
&lt;br /&gt;
In this situation one Jedi tries to shake the beam, maybe to break the bond, but instead the wave travels down the combined beam to also shake the other Jedi's hand-held hilt. When the vibration dies down the other Jedi then tries to deactivate his lightsaber as an attempt to end the connection. But the retraction of the entire double-sized light beam into the handle (as seen in the movies) causes both of the Jedi to be drawn together where they collide together, forcefully enough to render them both unconscious. The connected lightsaber handles lie next to them on the ground.&lt;br /&gt;
&lt;br /&gt;
The title text implies that such events are how {{w|Jedi}} romances start, comparing it to the famous &amp;quot;spaghetti scene&amp;quot; from the 1955 Disney animated movie ''{{w|Lady and the Tramp}}'' where the two titular characters unintentionally kiss after sharing a strand of spaghetti.  In the Old Republic, Jedi were forbidden from entering into romantic relationships (and discouraged from forming attachments in general), but in the pre-Disney ''Star Wars Legends'' continuity of the {{w|Star Wars in other media|Expanded Universe}}, {{w|Luke Skywalker}} and {{w|Mara Jade}} first met while fighting in the aftermath of the fall of the Empire, and then developed a romantic relationship.&lt;br /&gt;
&lt;br /&gt;
Star Wars is a [[:Category:Star Wars|recurring theme]] on xkcd, and lightsabers have been prominently featured before in, for instance, [[1397: Luke]] and [[1433: Lightsaber]], where the problem with the physics of a light beam as a sword is shown. But in general light does not interact with light as {{w|photons}} are {{w|bosons}} and can thus pass through each other. Interference, yes, but two pure light beams cannot collide and bounce back as when two lightsabers collide. Also as the comic Lightsaber mentioned above shows, there is no compatible real-world way of confining a beam of light, making it stop after about a meter (or anywhere){{Dubious}}&amp;lt;sup&amp;gt; - see {{w|Optical cavity}}&amp;lt;/sup&amp;gt;. So this is another time where [[Randall]] makes a joke about the physics of lightsabers.&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:[Two Cueball like Jedi are engaging each other in a duel using lightsabers over 12 panels of equal size, with sound effects as the only sound. In the first panel the left Jedi has his lightsaber extended holding it in both hand pointing towards the other, who at this time is just turning his lightsaber on.]&lt;br /&gt;
:''Tssssss''&lt;br /&gt;
:Click&lt;br /&gt;
&lt;br /&gt;
:[Almost same position of the Jedi, but the right Jedi's lightsaber has now extended, making a sound. He is holding it up near his head in both hands] &lt;br /&gt;
:''Tsss''&lt;br /&gt;
&lt;br /&gt;
:[Then they run towards each other and swing their lightsabers towards each other, two small arcs indicating the swing of the lightsabers.]&lt;br /&gt;
&lt;br /&gt;
:[The two beams hit each other and connects at the middle in a big bloop of light, with drops of &amp;quot;light&amp;quot; jumping off both above and below the connected lightsabers. Both Jedi still holds on to their handles with both hands. A loud sound comes out of the connection:]&lt;br /&gt;
:''Bloop''&lt;br /&gt;
&lt;br /&gt;
:[The Jedi stands still holding their handles. The beam is now forming a bow between the two handles.]&lt;br /&gt;
&lt;br /&gt;
:[The left Jedi violently shakes his handle causing a wave to travel down the beam towards the right Jedi.]&lt;br /&gt;
:Shake shake&lt;br /&gt;
&lt;br /&gt;
:[As the left Jedi's end of the beam comes to rest the wave travels all the way the right Jedi's handle causing his hands to shake, although a bit less than the original shake.]&lt;br /&gt;
:Shake shake&lt;br /&gt;
&lt;br /&gt;
:[Back to the bow of light between them, but the beam is visibly still shaking, but no wave is traveling any longer.]&lt;br /&gt;
&lt;br /&gt;
:[Same setting but the shaking has stopped. The right Jedi turns his lightsaber off on his handle with a sound:]&lt;br /&gt;
:Click&lt;br /&gt;
&lt;br /&gt;
:[The beam of light is retracted quickly into the handle of the Jedi turning his lightsaber off. So quickly that the two Jedi, still holding on to their handles are pulled up in the air and towards each other as the sound of the beam turning off is heard. Lines indicate their movement and shadows on the ground beneath them indicate they are in the air.]&lt;br /&gt;
:''Zhhhiiiip''&lt;br /&gt;
&lt;br /&gt;
:[When the beam is completely retracted the two handles collide and so do the heads of the two Jedi with a loud sound. They still hold on to their handles with both hands. They still hang in the air with shadows on the ground beneath them.]&lt;br /&gt;
:''Bonk''&lt;br /&gt;
&lt;br /&gt;
:[In the final panel the two Jedi lie unconscious on the ground with their heads towards each other and with their arms stretched out towards each other. The connected handles lie between them.]&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&lt;br /&gt;
&lt;br /&gt;
[[Category:Comics featuring Cueball]]&lt;br /&gt;
[[Category:Multiple Cueballs]]&lt;br /&gt;
[[Category:Star Wars]]&lt;br /&gt;
[[Category:Fiction]] &amp;lt;!-- Lady and the tramp in title text--&amp;gt;&lt;/div&gt;</summary>
		<author><name>MindTheGap</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=2349:_Rabbit_Introduction&amp;diff=196293</id>
		<title>2349: Rabbit Introduction</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=2349:_Rabbit_Introduction&amp;diff=196293"/>
				<updated>2020-08-21T17:23:57Z</updated>
		
		<summary type="html">&lt;p&gt;MindTheGap: /* Explanation */&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 2349&lt;br /&gt;
| date      = August 21, 2020&lt;br /&gt;
| title     = Rabbit Introduction&lt;br /&gt;
| image     = rabbit_introduction.png&lt;br /&gt;
| titletext = Washington state is seeing great success with reintroducing the Columbia River Basin subpopulation. We cannot allow them to further widen the interstate bun gap.&lt;br /&gt;
}}&lt;br /&gt;
&lt;br /&gt;
==Explanation==&lt;br /&gt;
{{incomplete|Created by a RABBIT RESEARCH GRANT COMMITTEE. More needed on the title text. Do NOT delete this tag too soon.}}&lt;br /&gt;
&lt;br /&gt;
[[Cueball]] is giving a presentation on the {{w|pygmy rabbit}} to a group of panelists, requesting a grant to introduce the species to the Eastern United States. The head of the panel, [[Blondie]], asks about typical reasons for introducing a species. If they were native to an area, but had been locally depopulated, re-introduction can help to restore the local ecosystem, but Cueball admits this is not the case.  Another reason animal populations may be introduced is to control a local pest (though [https://en.wikipedia.org/wiki/Rabbits_in_Australia#Effects_on_Australia's_ecology the effects of this can be difficult to predict]). Cueball seems to have no idea what the impact on the local ecosystem would be. In fact, he makes quite clear that his reasoning is simply that the creatures are tiny and cute, and he wants to spread them. He also appears to be entirely perplexed that the panel doesn't feel the same way. &lt;br /&gt;
&lt;br /&gt;
Blondie, very reasonably, immediately moves to deny the request. Not only would such a grant expend funds for no legitimate scientific or ecological purpose, but it would risk serious and unstudied impacts on the local ecosystem. However, at this point, the other three panelists [[White Hat]], [[Megan]] and [[Hairy]] have been swayed by Cueball's unconventional argument. All three of them are visibly entranced by the cuteness of the rabbits, and appear willing to fund the request, purely based on affection for the animals.&lt;br /&gt;
&lt;br /&gt;
The title text mentions the effort to reintroduce the {{w|Columbia Basin pygmy rabbit}} back into their native area of {{w|Columbia River drainage basin}}. [https://www.atlasobscura.com/articles/columbia-basin-pygmy-rabbits-washington After Nearly Going Extinct, Washington’s Pygmy Rabbits Need Room to Grow]. It refers to an &amp;quot;Interstate Bun Gap&amp;quot;, suggesting a competition between states over which has the most and/or cutest rabbits. The title text may also refer to the movie &amp;quot;Dr. Strangelove, or how I learned to stop worrying and love the bomb&amp;quot;, in which the character General Turgidson suggests: &amp;quot;Mr. President, we cannot allow a mineshaft gap!&amp;quot;, after a full-blown thermonuclear war seems unavoidable, and presidential advisor Dr. Strangelove suggest to move the political and scientific elite underground in mineshafts.&lt;br /&gt;
&lt;br /&gt;
This comic continues an XCKD tradition of dealing with the subjective cuteness of rabbits as a scientific discipline ([[1682: Bun]]). Munroe seems fascinated with the cuteness of lagomorphs, it being  [https://www.explainxkcd.com/wiki/index.php/Category:Buns a recurring subject in the strip].&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:[Cueball is standing in front of a screen and pointing at it with a stick. On the screen is a rabbit shown next to a smartphone, some keys on a key-chain, and two coins The phone is lager than the rabbit.]&lt;br /&gt;
:Cueball: The US's smallest rabbit species is the Pygmy Rabbit from Great Basin area.&lt;br /&gt;
:Cueball: We're seeking a grant to introduce them into the east.&lt;br /&gt;
&lt;br /&gt;
:[Blondie, White Hat, Megan and Hairy sits behind a long table. Blondie leans both her arms on the table. Hairy has one arm on the table. The other two have their arms down. Cueball replies to Blondie's question from off-panel.]&lt;br /&gt;
:Blondie: Are they native here?&lt;br /&gt;
:Cueball (off-panel): No.&lt;br /&gt;
:Blondie: Will they control some invasive pest?&lt;br /&gt;
:Cueball (off-panel): Dunno!&lt;br /&gt;
:Blondie: Then...Why would you do this?&lt;br /&gt;
&lt;br /&gt;
:[In a frame-less panel Cueball is seen in front of the screen, which is seen from the side. He points to something on the screen with the pointer, while looking over his shoulder.]&lt;br /&gt;
:Cueball: I don't understand.&lt;br /&gt;
:Cueball: Did you '''''see''''' how small they are?&lt;br /&gt;
:Cueball: They're so round!&lt;br /&gt;
:Cueball: Those ''tiny'' ears.&lt;br /&gt;
&lt;br /&gt;
:[Back to the four people behind the desk. Blondie and White Hat in the same positions but Megan has both her hands up into her hair, and Hairy has one arm on the table, and the other is held up high with a finger pointing up.]&lt;br /&gt;
:Blondie: I see. I'm afraid we'll by denying your grant.&lt;br /&gt;
:White Hat: Hang on. He '''''is''''' right about their ears...&lt;br /&gt;
:Megan: The little feet!&lt;br /&gt;
:Hairy: I vote we fund them!&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&lt;br /&gt;
&lt;br /&gt;
[[Category:Comics featuring Cueball]]&lt;br /&gt;
[[Category:Comics featuring Blondie]]&lt;br /&gt;
[[Category:Comics featuring White Hat]]&lt;br /&gt;
[[Category:Comics featuring Megan]]&lt;br /&gt;
[[Category:Comics featuring Hairy]]&lt;br /&gt;
[[Category:Buns]]&lt;/div&gt;</summary>
		<author><name>MindTheGap</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=2349:_Rabbit_Introduction&amp;diff=196292</id>
		<title>2349: Rabbit Introduction</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=2349:_Rabbit_Introduction&amp;diff=196292"/>
				<updated>2020-08-21T17:22:17Z</updated>
		
		<summary type="html">&lt;p&gt;MindTheGap: /* Explanation */&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 2349&lt;br /&gt;
| date      = August 21, 2020&lt;br /&gt;
| title     = Rabbit Introduction&lt;br /&gt;
| image     = rabbit_introduction.png&lt;br /&gt;
| titletext = Washington state is seeing great success with reintroducing the Columbia River Basin subpopulation. We cannot allow them to further widen the interstate bun gap.&lt;br /&gt;
}}&lt;br /&gt;
&lt;br /&gt;
==Explanation==&lt;br /&gt;
{{incomplete|Created by a RABBIT RESEARCH GRANT COMMITTEE. More needed on the title text. Do NOT delete this tag too soon.}}&lt;br /&gt;
&lt;br /&gt;
[[Cueball]] is giving a presentation on the {{w|pygmy rabbit}} to a group of panelists, requesting a grant to introduce the species to the Eastern United States. The head of the panel, [[Blondie]], asks about typical reasons for introducing a species. If they were native to an area, but had been locally depopulated, re-introduction can help to restore the local ecosystem, but Cueball admits this is not the case.  Another reason animal populations may be introduced is to control a local pest (though [https://en.wikipedia.org/wiki/Rabbits_in_Australia#Effects_on_Australia's_ecology the effects of this can be difficult to predict]). Cueball seems to have no idea what the impact on the local ecosystem would be. In fact, he makes quite clear that his reasoning is simply that the creatures are tiny and cute, and he wants to spread them. He also appears to be entirely perplexed that the panel doesn't feel the same way. &lt;br /&gt;
&lt;br /&gt;
Blondie, very reasonably, immediately moves to deny the request. Not only would such a grant expend funds for no legitimate scientific or ecological purpose, but it would risk serious and unstudied impacts on the local ecosystem. However, at this point, the other three panelists [[White Hat]], [[Megan]] and [[Hairy]] have been swayed by Cueball's unconventional argument. All three of them are visibly entranced by the cuteness of the rabbits, and appear willing to fund the request, purely based on affection for the animals.&lt;br /&gt;
&lt;br /&gt;
The title text mentions the effort to reintroduce the {{w|Columbia Basin pygmy rabbit}} back into their native area of {{w|Columbia River drainage basin}}. [https://www.atlasobscura.com/articles/columbia-basin-pygmy-rabbits-washington After Nearly Going Extinct, Washington’s Pygmy Rabbits Need Room to Grow]. It refers to an &amp;quot;Interstate Bun Gap&amp;quot;, suggesting a competition between states over which has the most and/or cutest rabbits. The title text may also refer to the movie &amp;quot;Dr. Strangelove, or how I learned to love the bomb&amp;quot;, in which the character General Turgidson suggests: &amp;quot;Mr. President, we cannot allow a mineshaft gap!&amp;quot;, after a full-blown thermonuclear war seems unavoidable, and presidential advisor Dr. Strangelove suggest to move the political and scientific elite underground in mineshafts.&lt;br /&gt;
&lt;br /&gt;
This comic continues an XCKD tradition of dealing with the subjective cuteness of rabbits as a scientific discipline ([[1682: Bun]]). Munroe seems fascinated with the cuteness of lagomorphs, it being  [https://www.explainxkcd.com/wiki/index.php/Category:Buns a recurring subject in the strip].&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:[Cueball is standing in front of a screen and pointing at it with a stick. On the screen is a rabbit shown next to a smartphone, some keys on a key-chain, and two coins The phone is lager than the rabbit.]&lt;br /&gt;
:Cueball: The US's smallest rabbit species is the Pygmy Rabbit from Great Basin area.&lt;br /&gt;
:Cueball: We're seeking a grant to introduce them into the east.&lt;br /&gt;
&lt;br /&gt;
:[Blondie, White Hat, Megan and Hairy sits behind a long table. Blondie leans both her arms on the table. Hairy has one arm on the table. The other two have their arms down. Cueball replies to Blondie's question from off-panel.]&lt;br /&gt;
:Blondie: Are they native here?&lt;br /&gt;
:Cueball (off-panel): No.&lt;br /&gt;
:Blondie: Will they control some invasive pest?&lt;br /&gt;
:Cueball (off-panel): Dunno!&lt;br /&gt;
:Blondie: Then...Why would you do this?&lt;br /&gt;
&lt;br /&gt;
:[In a frame-less panel Cueball is seen in front of the screen, which is seen from the side. He points to something on the screen with the pointer, while looking over his shoulder.]&lt;br /&gt;
:Cueball: I don't understand.&lt;br /&gt;
:Cueball: Did you '''''see''''' how small they are?&lt;br /&gt;
:Cueball: They're so round!&lt;br /&gt;
:Cueball: Those ''tiny'' ears.&lt;br /&gt;
&lt;br /&gt;
:[Back to the four people behind the desk. Blondie and White Hat in the same positions but Megan has both her hands up into her hair, and Hairy has one arm on the table, and the other is held up high with a finger pointing up.]&lt;br /&gt;
:Blondie: I see. I'm afraid we'll by denying your grant.&lt;br /&gt;
:White Hat: Hang on. He '''''is''''' right about their ears...&lt;br /&gt;
:Megan: The little feet!&lt;br /&gt;
:Hairy: I vote we fund them!&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&lt;br /&gt;
&lt;br /&gt;
[[Category:Comics featuring Cueball]]&lt;br /&gt;
[[Category:Comics featuring Blondie]]&lt;br /&gt;
[[Category:Comics featuring White Hat]]&lt;br /&gt;
[[Category:Comics featuring Megan]]&lt;br /&gt;
[[Category:Comics featuring Hairy]]&lt;br /&gt;
[[Category:Buns]]&lt;/div&gt;</summary>
		<author><name>MindTheGap</name></author>	</entry>

	</feed>