explain xkcd - User contributions [en]

2004: Sun and Earth

2018-06-19T17:49:28Z

162.158.150.106: /* Explanation */ {{Citation needed}}

{{comic
| number = 2004
| date = June 8, 2018
| title = Sun and Earth
| image = sun_and_earth.png
| titletext = But we don't need to worry about the boiling masses sandwiching the thin layer in which we live, since we're so fragile and short-lived that it's unlikely to kill us before something else does! Wait, why doesn't that sound reassuring?
}}

==Explanation==
This is one of a number of comics which describe everyday events in unusual terms, making them sound really weird. In this case, both the Sun and the Earth are "massive convective systems [blasting] huge plumes of heat", which contrasts sharply with the daily idea of the Sun being a ball in the sky and the Earth the thing under our feet.

{{w|Free convection}} is based on an difference in density. What is colder is typically denser, so gravity forces it downwards, displacing what is hotter (and less dense) upward (This should not be confused with {{w|forced convection}}, which uses fans or other devices that are not practical to build on the scale of a planet{{Citation needed}}). In the sun, most of the energy to drive this process comes from nuclear fusion, specifically the fusion of hydrogen into helium. We cannot directly see inside of the earth, but its core is known to be much hotter than its surface.{{Citation needed}}

The magnitude of these systems gives you an idea of the size of the fluctuations you can expect. The sun is very massive, meaning the fluctuations in its convective or heat-dissipating behavior are very large. This is an instance of the {{w|Fluctuation-dissipation_theorem|Fluctuation-Dissipation theorem}}. These fluctuations take the form of a solar flare, as explained below. For a more thorough (but non-technical) explanation of the role of gravity and entropy in such systems, see [https://arxiv.org/abs/0907.0659 this].

The {{w|Sun}} produces great amounts of light and heat and blasts it towards us, which is why we can live on Earth. Since Ludwig Boltzmann pointed out the fact in 1875, people have been working on establishing exactly how such far from equilibrium systems as life might depend upon, or be formed by ([https://www.quantamagazine.org/first-support-for-a-physics-theory-of-life-20170726/ like this article]), such massive entropy gradients as between the sun and earth (or rather the sun and empty space). Main sequence stars like the sun transport energy by {{w|Radiation_zone|radiation}} and by {{w|Convection_zone|convective currents}} of {{w|Plasma (physics)|plasma}}, bringing the heat generated in the core of the sun to its surface. These quickly moving charged particles create a massive magnetic field, which occasionally gets concentrated into a {{w|solar prominence}} which can snap, causing a large amount of charged particles to get shot into space as a {{w|solar flare}}. If the Earth happens to be in the direction of the solar flare, we can notice all sorts of interesting and often damaging effects. Thankfully, there are lots of other directions for the sun to shoot solar flares, so they don't come by the Earth that often.

The {{w|Earth#Internal_structure|Earth's interior}} is also very hot. {{w|Mantle convection}} causes {{w|plate tectonics}} which is the main cause of {{w|Volcano|volcanic activity}} (next to {{w|Mantle_plume|mantle plumes}}), which essentially also consists of huge blasts of heat.

This could sound like a very bad scenario, but the title text reminds us that the real scenario we live in is far worse, as we are not likely to die from a Sun blast or volcano eruption. In doing this, he indirectly points out the hard truth about our lives: that they're limited and they're short, and it is far easier to die of because of other things. In this way Randall attempts to give the reader an existential crisis; he concludes that his statement did not help to reassure himself.

This comic was likely inspired by the recent eruptions of the {{w|Kīlauea}} and {{w|Volcán de Fuego}}. In contrast, solar activity is currently low, because the {{w|Sunspot#Solar_cycle|sunspot solar cycle}} is in the low end of the 11-year cycle.

==Transcript==
:[The entire comic is within a panel. At the bottom of the image a curved shape depicting a small part of the Earth's surface and labeled as "Earth" is shown. At the top a similar sized shape but opposite curve is labeled as "Sun". The surface of the Sun is seething while on Earth's surface a few plants, two birds, and Cueball together with Megan are visible.]

:[Two arrows pointing to the Sun and the Earth with a caption applying to both of them:]
:Massive convective systems which occasionally blast huge plumes of heat at us without warning through mechanisms we can't directly observe and don't really understand.

:Cueball: What a nice day!

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Science]]

1992: SafetySat

2018-05-11T21:46:24Z

162.158.150.106: /* Explanation */ added that lighters can burst due to pressurized butane gas

{{comic
| number = 1992
| date = May 11, 2018
| title = SafetySat
| image = safetysat.png
| titletext = During launch, in the event of an unexpected sensor reading, SafetySat will extend prongs in all directions to secure itself and any other cubesats safely in the launch vehicle until the source of the problem can be determined.
}}

''Italic text''==Explanation==
{{incomplete|Created by a CubeSat so dangerous, I corrupted the image file and crashed the server (the first image upload was corrupt)- Please change this comment when editing this page. Do NOT delete this tag too soon.}}

{{w|Cubesat}} is a standard format for small satellites that can fit in a 10×10×10 cm format with a mass of less than 1.3 kg. They have been widely use by academics for research satellites, and by both small and large companies.

Cubesats are normally launched as a secondary payload often beside a deployment to the international space station. There are multiple safety rules to ensure that the cubesat cannot damage the primary payload. This design seeks to break as many rules as possible.

(from bottom left)

;Americium corners: {{w|Americium}} is a very dense, highly radioactive substance. Depending on the amount of Americium involved, this alone could shoot the mass over the 1.3 kg mass limit.
;Gun cotton: A form of nitrocellulose; it is explosive.
;Crude Oil: {{w|Exxon Valdez oil spill}}, {{w|Deepwater Horizon explosion}}... need we say more? Of course the leakable volume would not be near those levels, but plenty dangerous nonetheless if it were to leak though a faulty seal...
;Volatile Epoxy Seal: When this goes, everything gets coated in flammable crude oil.
;Celebratory Firework: Explosive Fire Source that can hit other satellites in the vicinity.
;CFCs/Ozone-depleting CFC Spritzer: {{w|Chlorofluorocarbons}} ({{w|CFCs}}) are fully halogenated paraffin hydrocarbons that contain only carbon, chlorine, and fluorine, produced as volatile derivative of methane, ethane, and propane. {{w|Freon}} is a common example of a CFC, and the use of CFCs has been linked to a depletion of the Earth's {{w|ozone layer}} leading many countries to ban their use. So spritzing CFCs in an area closer to the Ozone layer sounds like a good idea?
;Laser Pointer (Hubble-Seeking): Aiming a red laser at a visible light telescope is really bad for the telescope in question and its optics.
;Laser Pointers (Fixed): Theses three laser points will effectively point in 3 different random directions, which is not safe for other around this Cubesat.
;SDR/Software-Defined Radio (Code Editable via Public Wiki): This counts as a huge security risk.
;BIC Mini-Lighter: Fire source, resting on the can of crude oil. The pressurized butane could also make the lighter burst, allowing the sparkplug to ignite the volatile butane gas.
;Rare Earth Magnets: Very powerful magnets that have a high likelihood of messing up the electronics on nearby electronics, like other Cubesats.
;Wet Sand Dispenser:
;Batteries (EBay): The quality of batteries bought on the auction site can vary widely, and certain batteries exposed to conditions outside their design specifications can {{w|Battery_(electricity)#Explosion|explode or leak corrosive acids}}. These batteries might also be connected to the adjacent spark plug.
;Solar Panel (Found): The quality of the solar panel and the power it produces would have to be investigated thoroughly before being cleared for space flight.
;Spark Plug: Fire Source, if it was plugged in to electricity. Excess mass if not.
;Prongs: Prongs that extend in the event of an unexpected sensor reading at launch could damage the rocket and/or nearby cubsats/payloads.

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

{{comic discussion}}

1992: SafetySat

2018-05-11T21:38:03Z

162.158.150.106: /* Explanation */ added explanation for prongs

{{comic
| number = 1992
| date = May 11, 2018
| title = SafetySat
| image = safetysat.png
| titletext = During launch, in the event of an unexpected sensor reading, SafetySat will extend prongs in all directions to secure itself and any other cubesats safely in the launch vehicle until the source of the problem can be determined.
}}

==Explanation==
{{incomplete|Created by a CubeSat so dangerous, I corrupted the image file and crashed the server (the first image upload was corrupt)- Please change this comment when editing this page. Do NOT delete this tag too soon.}}

{{w|Cubesat}} is a standard format for small satellites that can fit in a 10×10×10 cm format with a mass of less than 1.3 kg. They have been widely use by academics for research satellites, and by both small and large companies.

Cubesats are normally launched as a secondary payload often beside a deployment to the international space station. There are multiple safety rules to ensure that the cubesat cannot damage the primary payload. This design seeks to break as many rules as possible.

(from bottom left)

;Americium corners: {{w|Americium}} is a very dense, highly radioactive substance. Depending on the amount of Americium involved, this alone could shoot the mass over the 1.3 kg mass limit.
;Gun cotton: A form of nitrocellulose; it is explosive.
;Crude Oil: {{w|Exxon Valdez oil spill}}, {{w|Deepwater Horizon explosion}}... need we say more? Of course the leakable volume would not be near those levels, but plenty dangerous nonetheless if it were to leak though a faulty seal...
;Volatile Epoxy Seal: When this goes, everything gets coated in flammable crude oil.
;Celebratory Firework: Explosive Fire Source that can hit other satellites in the vicinity.
;CFCs/Ozone-depleting CFC Spritzer: {{w|Chlorofluorocarbons}} ({{w|CFCs}}) are fully halogenated paraffin hydrocarbons that contain only carbon, chlorine, and fluorine, produced as volatile derivative of methane, ethane, and propane. {{w|Freon}} is a common example of a CFC, and the use of CFCs has been linked to a depletion of the Earth's {{w|ozone layer}} leading many countries to ban their use. So spritzing CFCs in an area closer to the Ozone layer sounds like a good idea?
;Laser Pointer (Hubble-Seeking): Aiming a red laser at a visible light telescope is really bad for the telescope in question and its optics.
;Laser Pointers (Fixed): Theses three laser points will effectively point in 3 different random directions, which is not safe for other around this Cubesat.
;SDR/Software-Defined Radio (Code Editable via Public Wiki): This counts as a huge security risk.
;BIC Mini-Lighter: Fire source, resting on the can of crude oil.
;Rare Earth Magnets: Very powerful magnets that have a high likelihood of messing up the electronics on nearby electronics, like other Cubesats.
;Wet Sand Dispenser:
;Batteries (EBay): The quality of batteries bought on the auction site can vary widely, and certain batteries exposed to conditions outside their design specifications can {{w|Battery_(electricity)#Explosion|explode or leak corrosive acids}}. These batteries might also be connected to the adjacent spark plug.
;Solar Panel (Found): The quality of the solar panel and the power it produces would have to be investigated thoroughly before being cleared for space flight.
;Spark Plug: Fire Source, if it was plugged in to electricity. Excess mass if not.
;Prongs: Prongs that extend in the event of an unexpected sensor reading at launch could damage the rocket and/or nearby cubsats/payloads.

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

{{comic discussion}}

1992: SafetySat

2018-05-11T21:31:43Z

162.158.150.106: /* Explanation */ added fact that fireworks also hit other stuff too

{{comic
| number = 1992
| date = May 11, 2018
| title = SafetySat
| image = safetysat.png
| titletext = During launch, in the event of an unexpected sensor reading, SafetySat will extend prongs in all directions to secure itself and any other cubesats safely in the launch vehicle until the source of the problem can be determined.
}}

==Explanation==
{{incomplete|Created by a CubeSat so dangerous, I corrupted the image file and crashed the server (the first image upload was corrupt)- Please change this comment when editing this page. Do NOT delete this tag too soon.}}

{{w|Cubesat}} is a standard format for small satellites that can fit in a 10×10×10 cm format with a mass of less than 1.3 kg. They have been widely use by academics for research satellites, and by both small and large companies.

Cubesats are normally launched as a secondary payload often beside a deployment to the international space station. There are multiple safety rules to ensure that the cubesat cannot damage the primary payload. This design seeks to break as many rules as possible.

(from bottom left)

;Americium corners: {{w|Americium}} is a very dense, highly radioactive substance. Depending on the amount of Americium involved, this alone could shoot the mass over the 1.3 kg mass limit.
;Gun cotton: A form of nitrocellulose; it is explosive.
;Crude Oil: {{w|Exxon Valdez oil spill}}, {{w|Deepwater Horizon explosion}}... need we say more? Of course the leakable volume would not be near those levels, but plenty dangerous nonetheless if it were to leak though a faulty seal...
;Volatile Epoxy Seal: When this goes, everything gets coated in flammable crude oil.
;Celebratory Firework: Explosive Fire Source that can hit other satellites in the vicinity.
;CFCs/Ozone-depleting CFC Spritzer: {{w|Chlorofluorocarbons}} ({{w|CFCs}}) are fully halogenated paraffin hydrocarbons that contain only carbon, chlorine, and fluorine, produced as volatile derivative of methane, ethane, and propane. {{w|Freon}} is a common example of a CFC, and the use of CFCs has been linked to a depletion of the Earth's {{w|ozone layer}} leading many countries to ban their use. So spritzing CFCs in an area closer to the Ozone layer sounds like a good idea?
;Laser Pointer (Hubble-Seeking): Aiming a red laser at a visible light telescope is really bad for the telescope in question and its optics.
;Laser Pointers (Fixed): Theses three laser points will effectively point in 3 different random directions, which is not safe for other around this Cubesat.
;SDR/Software-Defined Radio (Code Editable via Public Wiki): This counts as a huge security risk.
;BIC Mini-Lighter: Fire source, resting on the can of crude oil.
;Rare Earth Magnets: Very powerful magnets that have a high likelihood of messing up the electronics on nearby electronics, like other Cubesats.
;Wet Sand Dispenser:
;Batteries (EBay): The quality of batteries bought on the auction site can vary widely.
;Solar Panel (Found): The quality of the solar panel and the power it produces would have to be investigated thoroughly before being cleared for space flight.
;Spark Plug: Fire Source, if it was plugged in to electricity. Excess mass if not.

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

{{comic discussion}}

Talk:1028: Communication

2017-02-12T19:26:05Z

162.158.150.106:

I can't decide if the irony that this comic didn't communicate its idea well was intentional or if I just didn't get it at first because I'm dumb... {{unsigned ip|71.240.171.146}}
:Don't worry. Not everybody can read "international," so it may be a bit hard to interpret. Really, he's just citing John R. Trimble: ''"Clear writers assume, with a pessimism born of experience, that whatever isn't plainly stated the reader will invariably misconstrue."'' In this case, after several examples of ''poor'' communication (and the consequences) the only ''clear'' communicator is [[Beret Guy]], who rather adeptly shows rather than tells [[Cueball]] of the peril. Visual [http://wordnik.com/words/prolix prolix]? Maybe. As you say, that may be the point. -- [[User:IronyChef|IronyChef]] ([[User talk:IronyChef|talk]]) 02:44, 19 August 2012 (UTC)
:Well, it wouldn't be that you're dumb, it would be that you're "bad at reading comics" :) [[User:Jerodast|- jerodast]] ([[User talk:Jerodast|talk]]) 16:43, 21 December 2012 (UTC)

I don't believe that the holes are only one person deep. It seems as though the heads are level with the ground just to show who is falling into each hole at that moment. [[Special:Contributions/108.20.154.235|108.20.154.235]] 11:20, 21 September 2012 (UTC)

After panel 5-6, does WHG think that he actually communicated the left hole successfully to the girl, given that he does not understand her "hole!" message as a warning of the right hole? I remember that's how I read it the first time. {{unsigned ip|87.104.184.2}}

Where does the name Harry come from? Is this established usage on the wiki? Dropping it in the explanation out of nowhere is confusing. [[User:Jerodast|- jerodast]] ([[User talk:Jerodast|talk]]) 16:44, 21 December 2012 (UTC)

:Using names to refer to the characters was a tradition that was officially started back on the blog when Berg [http://www.explainxkcd.com/wiki/index.php?title=770:_All_the_Girls guest authored] one of the explanations. This makes it easier for everyone to be sure they are referring to the same character, and they're also cute fan-made names. [[User:Lcarsos|lcarsos]]<span title="I'm an admin. I can help.">_a</span> ([[User talk:Lcarsos|talk]]) 17:04, 21 December 2012 (UTC)

::Sure sure, I get that, but [[Cueball]] and [[Danish]] have pages where confused users can go to understand where the name came from. "Harry" just drops out of nowhere here. Does he appear in other comics? Should we make a page for him? [[User:Jerodast|- jerodast]] ([[User talk:Jerodast|talk]]) 16:19, 22 December 2012 (UTC)

:::I don't think we call him Harry, but there are other comics where a character with a little bit of hair shows up. If he shows up in at least 3 comics you can go ahead and create the category and his character page. [[User:Lcarsos|lcarsos]]<span title="I'm an admin. I can help.">_a</span> ([[User talk:Lcarsos|talk]]) 17:04, 22 December 2012 (UTC)

::::He was of course referring to [[Hairy]] which has been clarified long time ago. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:11, 16 March 2015 (UTC)

I disagree that the moral is that the best way to teach is to show someone, I believe the moral is that teaching hasn't happened until the learner understands. If you succeed in communicating by talking, that's great, if you succeed by showing, that's great too. However, if you try to teach by talking and the other person doesn't understand, you've failed. If you try to teach by showing and the other person doesn't understand, you've also failed. I'm going to make a change to include that. If anyone objects, revert it. [[User:Djbrasier|Djbrasier]] ([[User talk:Djbrasier|talk]]) 20:35, 22 August 2013 (UTC)
:I agree with you (that is a first ;-) I think you forgot to implement the change you were advocating for, and said you would make. I have tried to make it clear that it is about communication not about how you do it. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 17:20, 16 March 2015 (UTC)

I took the moral to be that you need to not immediately jump to what you're you're saying, rather talk a little first. [[User:Banak|Banak]] ([[User talk:Banak|talk]]) 17:00, 16 November 2013 (UTC)

I don't get what part of "there's a hole over there" is so hard to understand that you need to show them it for people not to be confused. Really, this comic must've been based on some special kind of stupid people.--[[Special:Contributions/141.101.81.208|141.101.81.208]] 07:56, 4 June 2014 (UTC)

:Are you familiar with the concept of a metaphor? Did you miss the xkcd comic where Randall himself pointed out that models are imperfect representations of abstract ideas (iirc, the example in question was gravity as it relates to spacetime, "what's pulling the planet down into the grid then?") It isn't lost on me that this comment is a year old, I just... it felt like it necessitated a response. If you're getting caught up in the specifics of this being a literal situation, then it's you who has missed the point. [[User:Aepokk|Aepokk]] ([[User talk:Aepokk|talk]]) 08:55, 6 September 2015 (UTC)

«It is very typical for the character Beret Guy to succeed, especially with something difficult, where White Hat fails.» I would be grateful for examples that show how this is typical. :-) [[Special:Contributions/162.158.150.106|162.158.150.106]] 19:26, 12 February 2017 (UTC)