In this comic, we see Beret Guy walking in from the left, as Cueball is sitting on a couch, typing on a laptop on his lap, with its power cord unplugged. Instead of connecting it to the wall socket, Beret Guy picks it up and blows air into the loose end of the cord, as if inflating a balloon — and the laptop inflates. It then floats away, making Cueball grab for it as Beret Guy casually walks away. (See an instance where Cueball inflates something in a similar unexpected way in 1798: Box Plot).
It is not possible to inflate a laptop like this, and (with rare exceptions) it is not possible to inflate anything by blowing down a power cord. Beret Guy has previously demonstrated several supernatural abilities, for instance with power cords, such as in 1293: Job Interview.
In general, human breath should not be buoyant enough to lift much in an atmosphere of ordinary air. The only chemical difference between dry air and dry exhaled breath is the conversion of oxygen (molecular weight = 32) to carbon dioxide (MW=44), not counting substances in such low concentrations that their effect on the average molecular weight of the air (MW=29) is negligible. A change of concentration of the CO2 from 0.04% to about 4% is typical. This increases the average molecular weight. However, exhaled breath is also usually much more humid than air, increasing the concentration of water (MW=18) from a typical value of 1% to approximately 5%, which decreases the average molecular weight. The two changes approximately cancel each other.
|| Dry air
| Air with
with 5% water
Because humans are warm-blooded, human breath is slightly warmer than the surrounding air, and therefore has slightly fewer molecules per unit volume. This is also true of hot air balloons, but they operate at much higher temperatures than human breath and are therefore able to obtain a greater amount of net buoyancy. There is a standard cartoon convention that inflating something with breath nonetheless makes it lighter than air. Also, given Beret Guy's many manifestations of inexplicable phenomena, it is not too far fetched to believe his body is, in fact, expelling some form of lighter-than-air gas, similar to the character Rigel on Farscape who could "fart helium".
The title text involves some jokes on Unix systems. On Unix, everything is a file; even most of the hardware can be referenced by a (virtual) file. These virtual files usually are in /dev or another virtual filesystem like /sys or /proc. While /dev/input really exists and points to the input system (mice, keyboards, gamepads, etc.), /dev/inside doesn't. gzip is a common tool to compress files. The first joke is to compress the air inside the laptop (with the command
gzip /dev/inside) in order to deflate the laptop back to normal size. It is a pun with the literal meaning of "deflate", which is also the DEFLATE algorithm used by gzip (compressing files is also called "deflating"). Another joke is "piping", the act of using the output of one operation as the input to another. As the output of the gzip command would be compressed air, a physical pipe could be used to direct the air somewhere useful. The output of a command can also be redirected to a file. Since the hardware is a file, the suggestion is to direct the air to /dev/input (which, in this case, means the keyboard, but would actually be a directory on real system, which can't normally be piped into) to clean it, similar to "compressed air" dusting cans. The complete command would be
gzip /dev/inside > /dev/input. As this might cause a spray of unpleasant detritus (compare 237: Keyboards are Disgusting), the reader is advised to avert their eyes.
- [Beret Guy enters to find Cueball on a chair typing on a laptop. Cueball's power cord is unplugged from the wall.]
- Cueball typing: Type type
- [Beret Guy picks up the power cord. Cueball continues typing.]
- Cueball typing: Type type
- [Beret Guy blows into the plug end of the cord. The laptop abruptly inflates and Cueball jerks back.]
- Beret Guy: PBBBBT
- Laptop: FOOMP
- [Beret Guy walks away, leaving Cueball climbing up his chair to retrieve his inflated laptop which is now floating away.]
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Is there any reason why you would have to avert your eyes... i would think that it may create a dust cloud from the keyboard... but it is a fictional situations, so there may be other reasons...126.96.36.199 06:02, 16 July 2014 (UTC)
Has anyone noticed Beret's uncanny ability with power cords? Thendenster (talk) 06:29, 16 July 2014 (UTC)
What a stupid unrealistic comic. Things that are blown up with air don't float! >:-C --188.8.131.52 07:26, 16 July 2014 (UTC)
- They do if you start off underwater, or start off in your living room, and then dunk the balloon in crazy glue (to give the balloon shell some rigidity), and then take the inflated balloon underwater, or into a caisson, or a hyperbaric chamber - both 'easily' found at underwater worksites.
- Or if you're blowing a balloon using a straw that has a one way valve, which goes from your mouth, through your space-suit, and to a balloon which is outside your spacesuit, when you're on the Venusian surface.
- They can do so, even on Earth, if the air coming out of your mouth is filtered such that the only bits let through are the components of air that are lighter than the natural mixture of air. (For example, a power line that's been highly charged, could ionise Oxygen atoms much more preferentially than ionising Nitrogen atoms as the flow past the sharp edges of the prongs. The ionised oxygen would react with surrounding bits, and be fixed into a solid state... leaving only the Nitrogen to continue flowing). Nitrogen is lighter than Air. Do this for long enough (a big enough balloon) and it will start floating. If you want to do it faster, and with a smaller balloon - pass the exhaled air over some chemical that absorbs and reacts with carbon-di-oxide (Alkali[ne] hydroxides), absorbs and reacts with water vapour (dessicant), absorbs and reacts with oxygen (bacteria), and absorbs and reacts with nitrogen (nitrogen fixing bacteria). 184.108.40.206 17:39, 20 July 2014 (UTC)
You obviously don't know how gross a keyboard can be...
Also, if you think this is unrealistic, you obviously haven't read enough XKCD. 220.127.116.11 07:41, 16 July 2014 (UTC)
- Yes and as can be seen someone has already added a link to the previous comic on gross keyboards so... Kynde (talk) 07:45, 16 July 2014 (UTC) And who says that it is not blown up with helium or the like. First of all we would never see if a stick character was inflated - so Beret guy could be big and filled with helium. Or it is just his crazy ability that makes his blow into the socket turn the "air" into helium in the PC - or something much lighter since the shown inflation would never be enough to carry a laptop. In the end the whole comic is just an excuse to make three crazy puns (like them or not, that is up to the reader) and refeer back to 237 Kynde (talk) 07:45, 16 July 2014 (UTC)
- I think 18.104.22.168 is being sarcastic. Pointing out the fact that things filled with air don't float instead of the obvious impossibility of blowing air through an electric wire. 22.214.171.124 14:46, 16 July 2014 (UTC)BK
- An object filled with air wont go up, but may still bounce out of hand and foat. In this case the sudden increase in volume have ejected the inflated laptop. Since an object almost-as-light-as-air is really sensitive to move of air, the laptop could (in the unlikely case of it happening) behave that way.126.96.36.199 09:11, 18 July 2014 (UTC)
Given that Beret Guy often does crazy correctitive things when he perceives something is amiss in his (surreal) visions of the world, I'm wondering if that's a specific protest against having the power chord plugged into the laptop but not the wall (during normal operation, I presume, rather than deliberately depleting the battery of testing the reduced-power settings, or temporarily while other powered devices require the power sockets with more urgency). I don't know whether I personally find this set-up more or less disturbing than a power-chord plugged into the wall but not plugged into the intended laptop. Although (apart from the risk of leaving residue across the pins), the comic's version is at least safer than the opening text of the explanation would suggest. 188.8.131.52 12:11, 16 July 2014 (UTC)
...inflation in an xkcd comic? Cue the inflatophobes... Greyson (talk) 13:34, 16 July 2014 (UTC)
Beret Guy is obviously exhaling a lighter-than-air gas, either by just taking a large breath of helium beforehand or by a very special cellular breathing process. Moreover, it should be noted that one averts one's eyes before something holy. 184.108.40.206 11:02, 16 July 2014 (UTC)
- You also avert your eyes when you know something is going to be propelled at your head from a compressed air keyboard... -Pennpenn 220.127.116.11 02:49, 11 June 2015 (UTC)
Transcript accuracy: is Cueball actually looking up in panel 2? He's still typing after all. (Also, [power chords?]) --18.104.22.168 00:48, 17 July 2014 (UTC)
why are all the ips from cloudfare servers? sockpuppets?22.214.171.124 09:08, 18 July 2014 (UTC)
- explainxkcd is hosted through Cloudflare's cdn and all of us connect through Cloudflare. --126.96.36.199 17:05, 9 July 2020 (UTC)
My mother once blown a lighter than air balloon, our best guess was that it was hot air from some fever or something. 188.8.131.52 19:56, 18 July 2014 (UTC)
- That would only work for as long as the air in the balloon is warmer than the air surrounding it. I doubt that the balloon is that good as an isulator to have this occur for long. --Lupo (talk) 11:13, 16 January 2020 (UTC)