High acceleration in space travel

If a spaceship accelerates forward in 100’s of g’s, every living creature in it would turn into a soup.

But if a helium baloon was inside the ship, it wouldn’t fall down[1] like everything else, it would fly up with great intensity and pop that way.
https://www.youtube.com/watch?v=y8mzDvpKzfY

This brings to one’s mind a possibility between the two. What if an object had the same density as its surroundings in this spaceship? Then that object wouldn’t feel any gravity, even if it is millions of g’s. So, creatures from an underwater civilisation (or land creatures with a modified/assisted body) could immerse themselves in a liquid with the same density as their bodies and survive high g journeys.

Warp drives work by moving the space around the spacecraft, so no acceleration is felt on the inside, and wormholes reduce distances rather than increase speeds, so speeding up would probably only be a problem for the early game designs of spaceships.


  1. lets say the ship is going “up” ↩︎

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i came up with the same idea a few days ago, i specifically was assuming a creature in a life support suit that was immersed in a water-filled tank that had alcohol/salt added until the densities were identical. Two issues though:

1: if we both came up with it independently its way too obvious to work so i’ll try to see if its a thing already or if theres a huge flaw

2: what drive the exists under known physics could do hundreds of gees anyways?

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The problem with that is that this depends on the density of the surroundings, the helium is moving to a less dense space because it is less dense than it’s current surroundings, and a heavy object would move to a more dense space because it is more dense than it’s surroundings, if something is of equal density to it’s surroundings, then it will be crushed by the surrounding material becoming more dense, you will gain a higher density because your particals are being pushed closer together, and because you resist that more than water, the water will become more dense than you, and you will shoot towards the front of the ship, or be crushed to death.

I wonder if it’d be useful in surviving lower accelerations of only a few dozen Gs, and like shocking the water with salt right before and again during the acceleration, and once it lowers adding alcohol until you stop floating. Or swap it around of compressive forces outdo acceleration forces.

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Spacex’s starship is designed to have a mass of 5000 tonnes and the fuel makes 68% (3400 tonnes) of it. Lets say these will also be the typical numbers for a spaceship used in interstellar travel. Lets also say that 300 tonnes of fuel is antimatter (which is mass produced). 1/3rd of the exhaust will be used during the journey, 1/3rd in the return journey and 1/3rd is backup. The ship annihilates 100 tonnes of antimatter, which makes 9*10^21 joules. With it, the exhaust goes 112,6 thousand km/s backwards and the ship 32,6 thousand km/s forwards (10,9% the speed of light). This is a rough estimate. Lets say they burn the fuel in 1 week (to move at the maximum speed during most of the journey). That makes an acceleration of 5,4 g’s.

Okay nevermind I made a calculation error.

Uh, thats a massive oversimplification. first, youd need a magnetic bottle, an actual reason to have that kind of fuel ratio, and also, antimatter-matter reactions dont make normal exhaust. They make gamma rays. Light. Yes, light can power your ship. Definitely, but its the speed of an ion drive or solar sail. I think the only drives that can achieve any real g-forces are orion drives, chemical rockets, and thermal whatever rockets or maybe a REALLY high tech interstellar laser highway to a lesser extent.

Actually, when anti-matter and matter collide they trasform their mass into 100% energy (anti-matter is the only thing that is capable of doing a 100% mass to energy conversion). In 2000 NASA scientists even announced early designs for an anti-matter engine capable of producing a big amount of thrust using a little amount of anti-matter.

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what is pure energy though? in the case of at least electron/positron collision its gamma rays, im not so sure about the others. The nasa engine was probably an antimatter-thermal engine which is covered under

I never said anything about pure energy, I just said that they can turn 100% of the two objects mass into energy.

oh alright. Yeh it does that. its very cool

kinda scary

All atoms have been created when universe has been created.

Rocket engines just makes chemical reaction which creates controlled explosion(or something) to propel vehicle, but exhausted fuel is is there, behind ship, and might fall some day to our planet.

Now imagine there is drive that turns these atoms into energy.
I don’t know if there is anything theoretical that turns energy back into atom.
and now imagine fleet, army of ships with antimatter drive turning millions of atoms into energy daily just to go from point A to point B…

If you recreated the conditions after the big bang, you could create atoms from energy. Nothing precious is being lost. You can’t hold onto your atoms and live forever. The entropy will increase either way.

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Isn’t this entirely false?

Atoms did not exist for a long time after the beginning of the universe.

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sorry i meant mass

also im not scientist :disappointed_relieved:

Well that’s lucky because antimatter doesn’t destroy mass, due to E = MC^2 the amount of energy released by the reaction is exactly the same as the amount of mass put in, and the inverse is true, the energy released could theoretically be turned back into an equivalent amount of mass (M = E/C^2); keyword being theoretically, good luck catching it.

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(in my previous post i didn’t write “destroy” literally so i corrected it a bit btw)

If you said mass-energy, then I think you’d be correct. Like @Oncpapa already said about the energy mass equivalence.

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