Space swimming pool?

chrispenycate

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@ Ursa If the mock gravity is generated by centrifugal force (no, I'm aware of the fact centrifugal force is a rejected term in physics, being just a measurement of the inertia of the mass being constrained and accelerated in a circle, but is a force, it can be measured with a spring balance, ant it does operate out from the centre of rotation, so it's centrifugal, so there) we could have an enormous gyroscope at roughtly the centre of gravity of the spacecraft, or possibly two counter- rotating living rings, so the net sum of the rotational momentum is zero. When we're bringing the ship up to operational state all the water is in sealed tanks, and as we accelerate the flywheel (gyroscope) the ship starts spinning in the opposite direction (don't even ask about the bearings).Then, when you want to eliminate the gravity you jam a crowbar between the two rotating wheels, tha gyroscope (wheter or not it was a second living ring) and the main ship. Never mind they don't build crowbars that solid (considering the mass of the ship, they don't build girders that solid, and absorbing the petajoules of energy generated by using the wheel the rotor of a very large, shorted out electric motor would be no minor task.

Then, of course the water would go all Newtonian on us, not just slopping a bit as in the film. Perhaps the shockwave when the rotation stopped (accelerating from whatever rotation speed needed at that diameter to maintain 1g to zero in zero seconds would possibly not have reduced the swimmer to meat paste as it might have if she were not immersed in fluid, but the shock wave would have seriously scrambled her internal organs) would have transferred its energy to a water wave, tending to stick to the walls as it did the entire circuit of the poolroom because of the surface tension, but the released energy would boil quite a lot of it - and 'tending' in this chaos is a very approximate term, plenty of it would be explosion shattered into foam, or droplets, and swimming to any surface is not really a possibility.

So, for the images we saw inertial gravity simulation wouldn't work. We need a synthetic gravity generator which can be switched on and off, presumably using continuous power. I don't know how it might work - but no-one knows enough about gravity to be able to say with certainty that it can't be done. In which case, why does the water decide to climb out of the pool, where surface tension will stick it to the walls and distort its surface into a convex lens, rather than trying to form itself int a null-g sphere? Could it be that the walls of the pool are lower density than water, non wetting?

@VB If we do the conservation of energy/momentum equations on a body accelerating by ten metres per second squared, within a year, with a perfect drive (a reaction drive converting matter to energy and expelling the energy behind at light spee, ie. as electromagnetic radiation, within a year's cruising half the ship's mass has been converted. Admittedly, this gives us a lot less mass to slow down as we approach the destination, but for a star at four light years distance (and there aren't many closer than that) we're talking about the entire ship and its cargo massing less than a tenth of the mass of fuel. I'd really prefer a slightly more effecient means of travel, especially as that is assuming perfection - and engineers aren't good at perfection. I suppose vacuum energy - but still, conservation of momentum tends to hold.
 

hitmouse

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Raindrop by Hal Clement, takes this to its natural conclusion (suspended in space, enclosed by a membrane, big enough to require breathing apparatus), worked out from Clement’s usual hard sf angle. IF May 1965.

64FD801A-013F-402F-AF42-3C580831F039.jpeg
 

Ursa major

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I note the story The Altar at Asco is mentioned. Is ASCO the result of a future merger between Tesco and ASDA?

And are people having to pray to get deliveries made during, say, a pandemic...?

;):)
 

DannMcGrew

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@ Ursa If the mock gravity is generated by centrifugal force (no, I'm aware of the fact centrifugal force is a rejected term in physics, being just a measurement of the inertia of the mass being constrained and accelerated in a circle, but is a force, it can be measured with a spring balance, ant it does operate out from the centre of rotation, so it's centrifugal, so there) we could have an enormous gyroscope at roughtly the centre of gravity of the spacecraft, or possibly two counter- rotating living rings, so the net sum of the rotational momentum is zero. When we're bringing the ship up to operational state all the water is in sealed tanks, and as we accelerate the flywheel (gyroscope) the ship starts spinning in the opposite direction (don't even ask about the bearings).Then, when you want to eliminate the gravity you jam a crowbar between the two rotating wheels, tha gyroscope (wheter or not it was a second living ring) and the main ship. Never mind they don't build crowbars that solid (considering the mass of the ship, they don't build girders that solid, and absorbing the petajoules of energy generated by using the wheel the rotor of a very large, shorted out electric motor would be no minor task.

Then, of course the water would go all Newtonian on us, not just slopping a bit as in the film. Perhaps the shockwave when the rotation stopped (accelerating from whatever rotation speed needed at that diameter to maintain 1g to zero in zero seconds would possibly not have reduced the swimmer to meat paste as it might have if she were not immersed in fluid, but the shock wave would have seriously scrambled her internal organs) would have transferred its energy to a water wave, tending to stick to the walls as it did the entire circuit of the poolroom because of the surface tension, but the released energy would boil quite a lot of it - and 'tending' in this chaos is a very approximate term, plenty of it would be explosion shattered into foam, or droplets, and swimming to any surface is not really a possibility.

So, for the images we saw inertial gravity simulation wouldn't work. We need a synthetic gravity generator which can be switched on and off, presumably using continuous power. I don't know how it might work - but no-one knows enough about gravity to be able to say with certainty that it can't be done. In which case, why does the water decide to climb out of the pool, where surface tension will stick it to the walls and distort its surface into a convex lens, rather than trying to form itself int a null-g sphere? Could it be that the walls of the pool are lower density than water, non wetting?

@VB If we do the conservation of energy/momentum equations on a body accelerating by ten metres per second squared, within a year, with a perfect drive (a reaction drive converting matter to energy and expelling the energy behind at light spee, ie. as electromagnetic radiation, within a year's cruising half the ship's mass has been converted. Admittedly, this gives us a lot less mass to slow down as we approach the destination, but for a star at four light years distance (and there aren't many closer than that) we're talking about the entire ship and its cargo massing less than a tenth of the mass of fuel. I'd really prefer a slightly more effecient means of travel, especially as that is assuming perfection - and engineers aren't good at perfection. I suppose vacuum energy - but still, conservation of momentum tends to hold.
Oy! Couldn't I just use a pool cover?
 

hitmouse

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I note the story The Altar at Asco is mentioned. Is ASCO the result of a future merger between Tesco and ASDA?

And are people having to pray to get deliveries made during, say, a pandemic...?

;):)
Hehe. It is The Altar at Asconel. A bit of the cover is ripped off.
 
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