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My wife shared this picture with me today:

picture of a cartoon corgi doing the doggie paddle in space and moving forward

Adorable, but it got me thinking about that trope - swimming in space.

I've seen it before, mostly in cartoons and not live-action shows, the latter of which tend to have either more realistic space stations that astronauts pull themselves along on rails to get around in, or fictional artificial gravity.

My question then is three-part:

  1. Can a person actually 'swim' to get around in a real spacecraft?
  2. Could they do this in the vacuum of space? (Assuming they have proper space protection)
  3. Could a Pembroke Welsh Corgi on the ISS do a doggie paddle to get around?
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You can sort of swim, but it would be very slow. The viscosity of air vs water is very low. Therefore the 'scoop' your hands or feet can get of the fluid, to propel it, and thus move you around would need to be much higher.

If you had fans (or 'wings') on your arms you would be more effective.

As for the corgi? Not likely, or at least very, very slowly.

You might be more effective inhaling with a wide open mouth slowly, then quickly exhaling through a small mouth in the direction opposite you wish to go.

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    $\begingroup$ Astronaut Dan Barry tried "swimming" in the ISS. It did not work. space.stackexchange.com/questions/18386/… $\endgroup$ – Organic Marble Mar 30 '18 at 18:34
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    $\begingroup$ @OrganicMarble: Nowhere in the text in the linked answer does Barry actually mention "swimming" - reading that text, it sounds more like he was trying to move by thrashing his limbs, which doesn't work even in water. Additionally, swimming through air would be quite slow, to the point where it would take quite a while to realise that you were, in fact, moving. $\endgroup$ – Vikki - formerly Sean Aug 16 '20 at 19:38
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    $\begingroup$ 1. 'Sneezing and spitting didn't do much good either.' That implies that he sneezed and spat. Sneezing is an involuntary act, so how did he try it as a way to get to a wall. Sneezing in a space station or the like is highly frowned on, because it is unhygienic in the extreme, and disrespectful to everyone else, because whatever particles you sneeze out will float on the air rather than falling to the ground, and can easily be inhaled, a major health hazard. Deliberately spitting would be even worse. No astronaut would admit to having done that deliberately. 2. How would an astronaut not... $\endgroup$ – Matthew Christopher Bartsh Apr 22 at 21:48
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    $\begingroup$ @MatthewChristopherBartsh I hate to tell that I know Barry personally (here's a picture of he and I in a tank together) and I know for a fact that this happened. Theorize all you like. science.ksc.nasa.gov/shuttle/missions/sts-105/images/high/… $\endgroup$ – Organic Marble Apr 22 at 21:56
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    $\begingroup$ @MatthewChristopherBartsh - actually doesn't "conservation of momentum" only apply to the system as a whole and might not apply to an object subject to a small or large impulse in a liquid/gas with viscosity? In other words, if, while floating in air, you breath in slowly, that might not change your momentum much in the space you're floating in, but then you exhale quickly it could? Check your assumptions. The facile answer isn't always right. $\endgroup$ – davidbak May 5 at 21:14
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A person could swim. But that would take many, many effort to generate even a little of velocity. The viscosity of air is much lower than the viscosity of water. When you swim in water you are practically pushing the water away, creating a force that makes you go the direction you're swimming to.

Imagine this with air. You could simulate this yourself too: Standing on the bottom of a swimming pool and make a swimming movement with your arms and feel the effect of you pushing forward. Then try it in normal air, almost nothing would happen. Then again with a propeller it's a different story.

In the vacuum of space you can't do this of course. Since there's no mass to push away, nothing to swim in, nothing can make you push forward.

The Corgi in the ISS could theoretically do that. But, that would be more of an disappointment if you compare that with the moving picture. It would take a long time a little, so I don't think the dog will use that to move itself around.

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    $\begingroup$ In fact, you can "swim" in a vacuum, taking advantage of relativity: science20.com/hammock_physicist/swimming_through_empty_space . However, this is a very subtle effect, and takes hours to move a foot or two. $\endgroup$ – Skyler Feb 20 '18 at 16:45
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    $\begingroup$ Astronaut Dan Barry tried "swimming" in the ISS. It did not work. space.stackexchange.com/questions/18386/… $\endgroup$ – Organic Marble Mar 30 '18 at 18:33
  • $\begingroup$ @OrganicMarble Perhaps this could be an answer to the question? $\endgroup$ – joppiesaus Aug 20 '20 at 9:34
  • $\begingroup$ @Skyler Are you being serious? $\endgroup$ – Matthew Christopher Bartsh Apr 23 at 20:19
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    $\begingroup$ @MatthewChristopherBartsh are you as tired of having this discussion as I am? Didn't you ask a question about it? And write a whole bunch of comments about it on the other answer? For the record: it happened. I'm not responding to any more comments, chats, or questions on this matter. $\endgroup$ – Organic Marble May 1 at 20:49

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