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Author Topic: Can a goldfish swim in outer space?  (Read 11749 times)

Offline thedoc

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Can a goldfish swim in outer space?
« on: 14/09/2010 18:01:16 »
If I took my fish in its bowl  into orbit abroad the International Space Station? Now, assuming that the fish does actually survive the journey up there and it doesn’t get upset and all that kind of thing with the water coming out.. what would be the implications, in terms of physics, for a fish suspended in microgravity in its bowl in water? What do we think?
Asked by Warren


                                       

Go to the show page.

                                       

 or Listen to the Answer Part 1 Part 2
...or download as MP3 [1] [2]

« Last Edit: 14/09/2010 18:01:16 by _system »


 

Offline thedoc

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Can a goldfish swim in outer space?
« Reply #1 on: 14/09/2010 18:01:16 »
 Chris -   Warren said what would happen if I took my fish in its bowl  into orbit abroad the International Space Station? Now, assuming that the fish does actually survive the journey up there and it doesn’t get upset and all that kind of thing with the water coming out.. what would be the implications, in terms of physics, for a fish suspended in microgravity in its bowl in water? What do we think?
Dominic -   I think you would have some problems keeping the water in the bowl, obviously it would  start to slosh about. But once your fish started trying to swim along - and of course fish swim by pushing water backwards which propels them forwards by the conservation of momentum - that means that the water will be pushed out of the bowl and the fish will be swimming along in the air.  Now, I’m not sure whether a fish could swim in the air in the space station?
Chris -   I don’t think it would move enough air, would it?
Dave -   Someone has built a model fish made of a giant helium balloon which looks like a giant fish and it will swim through the air.  So a fish, I think, would swim through the air very slowly.   It would of course be running out of oxygen very quickly if it did that
Chris -   I think the water would fragment wouldn’t it, as Dominic says? Well let’s assume that the water is in the bowl to start with - there is no gravity pulling down because the water and the bowl and the fish are all in free fall in orbit around the earth, so there is no net force actually applying the water against the bowl so that the bowl pushes back on the water and holds it in. So if the fish sort of disturbs the water enough all those resonances are going to build up and the water is going to splash out of the bowl, probably in lots of little particles that are then going to blob around in the air in the space craft.  And that means the fish could end up quite literally out of water, so to speak.
Dave -   Although surface tension is quite strong – and if it is a small fish – surface tension will hold the water in the bowl for quite a long time, I would have thought, unless you really slosh it about, and if it was a small fish, probably, actually,  surface tension would  hold it in the water.

« Last Edit: 14/09/2010 18:01:16 by _system »
 

Offline Slugsie

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Can a goldfish swim in outer space?
« Reply #2 on: 16/09/2010 09:38:58 »
How about if the fish was in a sealed system such that the water couldn't leak or splash out?

I reckon the fish would have no real problems swimming forwards/left/right, but it might initially have a problem going up and down. On Earth fish do that by using their swim bladder to alter their overall density and thus sink or float. In zero/micro gravity that wouldn't work, so they wouldn't go up or down (relative to the fishes orientation). You'd probably end up with a confused fish.
 

Offline kenhikage

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Can a goldfish swim in outer space?
« Reply #3 on: 16/09/2010 13:38:47 »
I'm wondering about octopuses, in a sealed tank that is. They have some sort of sense that keeps them oriented to the horizon. Being the clever guys they are, I'd like to know how they would adapt to the space station. :-\
 

Offline RD

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Can a goldfish swim in outer space?
« Reply #4 on: 17/09/2010 05:15:02 »
Quote
Q. Can a goldfish swim in outer space?

A. Chris -   I think the water would fragment wouldn’t it,


Not necessarily ...



http://www.youtube.com/watch?v=zaHLwla2WiI&feature=related


So in space you don't need the stereotypical spherical fishbowl. :)
« Last Edit: 18/09/2010 00:14:59 by RD »
 

Offline imatfaal

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Can a goldfish swim in outer space?
« Reply #5 on: 17/09/2010 14:40:16 »
Seriously great video - I think it shows Dave was right on the podcast about how strong the surface tension is.  I love the second experiment with the water droplets inside the air bubble; mass transfers exchanging momentum.
 

Offline thedoc

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Can a goldfish swim in outer space?
« Reply #6 on: 10/12/2010 15:32:58 »
We discussed this question on our  show
 Chris -  Warren said what would happen if I took my fish in its bowl into orbit abroad the International Space Station? Now, assuming that the fish does actually survive the journey up there and it doesn’t get upset and all that kind of thing with the water coming out.. what would be the implications, in terms of physics, for a fish suspended in microgravity in its bowl in water? What do we think?
Dominic -  I think you would have some problems keeping the water in the bowl, obviously it would start to slosh about. But once your fish started trying to swim along - and of course fish swim by pushing water backwards which propels them forwards by the conservation of momentum - that means that the water will be pushed out of the bowl and the fish will be swimming along in the air. Now, I’m not sure whether a fish could swim in the air in the space station?
Chris -  I don’t think it would move enough air, would it?
Dave -  Someone has built a model fish made of a giant helium balloon which looks like a giant fish and it will swim through the air. So a fish, I think, would swim through the air very slowly. It would of course be running out of oxygen very quickly if it did that
Chris -  I think the water would fragment wouldn’t it, as Dominic says? Well let’s assume that the water is in the bowl to start with - there is no gravity pulling down because the water and the bowl and the fish are all in free fall in orbit around the earth, so there is no net force actually applying the water against the bowl so that the bowl pushes back on the water and holds it in. So if the fish sort of disturbs the water enough all those resonances are going to build up and the water is going to splash out of the bowl, probably in lots of little particles that are then going to blob around in the air in the space craft. And that means the fish could end up quite literally out of water, so to speak.
Dave -  Although surface tension is quite strong – and if it is a small fish – surface tension will hold the water in the bowl for quite a long time, I would have thought, unless you really slosh it about, and if it was a small fish, probably, actually, surface tension would hold it in the water.


Click to visit the show page for the podcast in which this question is answered. Alternatively, listen to the answer now Part 1 Part 2 ...or download as MP3 [1] [2]
« Last Edit: 01/01/1970 01:00:00 by _system »
 

Offline Chemistatwork

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Can a goldfish swim in outer space?
« Reply #7 on: 10/12/2010 16:23:39 »
How about if the fish was in a sealed system such that the water couldn't leak or splash out?

I reckon the fish would have no real problems swimming forwards/left/right, but it might initially have a problem going up and down. On Earth fish do that by using their swim bladder to alter their overall density and thus sink or float. In zero/micro gravity that wouldn't work, so they wouldn't go up or down (relative to the fishes orientation). You'd probably end up with a confused fish.

Yea the fish would probably be confused but there wouldn't be any side effects other than that. Regarding the water sloshing out of the bowl, if the fish was a small one in relation to the bowl and presumably not horribly confined, the force of the water moving back would probably dissipate since water has quite a large amount of inertia.
 

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Can a goldfish swim in outer space?
« Reply #7 on: 10/12/2010 16:23:39 »

 

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