Is artificial gravity scientifically possible?

[alfaniner]

Has anyone yet mentioned that the Coriolos effect would might produce some strange sensations when walking in a rotating environment designed to produce “artificial gravity?

It depends on how big the ring is.

...
One of the things I find amusing in science fiction is that when spacecraft start getting his with enemy weapons, they might lose power. The warp engines go off line. The lights fail. At some point there is only enough power for life support, and that is about to go, and everyone will die unless someone can effect repairs before the last commercial.

But the gravity generators never go offline, even in ships that have been adrift in space for hundreds of years.

In all the Star Trek I've seen (almost 100% up to two years ago) I can recall gravity being a story point only once. I think it was the premiere of Enterprise, where Travis found a "sweet spot" (null gravity) on the ship where he'd go to relax, and said every ship had one.

 

[theprestige]

One of the things I find amusing in science fiction TV shows is the amusing stories they can tell, even if their production budget doesn't stretch as far as realistic zero gravity.

It always strikes me as weird and a little depressing, the way so many people seem to think TV producers are too ignorant, or just don't care enough, to produce convincing low gravity effects.

 

[Giordano]

You tell us. What were the results, when you searched the thread for the word "coriolis"?

Pardon? I had read the full thread and did not notice mention of the Coriolis effect. However I thought that perhaps I might have missed such a mention, particularly if the word had not been used but the effects had been described. So I tried to be polite and cautious in launching my post.

Perhaps I didn’t make it clear enough that I was noting that these effects would exist, not simply asking if they had been mentioned or not?

Now that I’ve clarified this we can move on. Unless I’m missing the actual point of your post?

 

[Puppycow]

Physicist and science fiction writer Robert Forward wrote a book called "Indistinguishable from Magic", that alternated scientific essays about hypothetical advanced technologies common in science fiction and short stories featuring those technologies. As I recall, the artificial gravity chapter involved somehow manufacturing hyperdense matter and placing it in a thin layer under a surface, with sufficient mass that it generated gravity pulling toward that surface. It couldn't be turned on and off though.

I was thinking along the same lines, what if you had a piece of hyper-dense matter located someplace around the central core of the craft that would in essence, attract everything loose towards that central point?

You do see the problem with that though, right? If you have enough hyper-dense matter to create significant gravity, your spaceship is going to weigh as much as a small planet, and it will be much harder to maneuver and accelerate or decelerate.

 

[novaphile]

The best sci-fi has this covered.

You accelerate at up to 1 G until you're half way to your destination.

Everyone straps down and the ship flips over end to end.

Then you decelerate at the same rate until you arrive at your destination.

This way your ship doesn't need moving parts that are destined to fail, and really horrible interfaces between moving parts and non moving parts. It also means you don't have to have the universe spinning around outside your windows. AND it means that your ship can have common 'floor' surfaces that are always in the right place.

 

[theprestige]

Pardon? I had read the full thread and did not notice mention of the Coriolis effect. However I thought that perhaps I might have missed such a mention, particularly if the word had not been used but the effects had been described. So I tried to be polite and cautious in launching my post.

Perhaps I didn’t make it clear enough that I was noting that these effects would exist, not simply asking if they had been mentioned or not?

Now that I’ve clarified this we can move on. Unless I’m missing the actual point of your post?

You want to talk about the coriolis effect. Instead you're talking about talking about the coriolis effect. Does that make any sense to you?

 

[theprestige]

The best sci-fi has this covered.

You accelerate at up to 1 G until you're half way to your destination.

Everyone straps down and the ship flips over end to end.

Then you decelerate at the same rate until you arrive at your destination.

This way your ship doesn't need moving parts that are destined to fail, and really horrible interfaces between moving parts and non moving parts. It also means you don't have to have the universe spinning around outside your windows. AND it means that your ship can have common 'floor' surfaces that are always in the right place.

I can't think of any top tier SF that does this.

Mainly because the fuel requirements for constant 1G acceleration over interstellar distances are not in the realm of good SF.

Also because you'd reach light speed long before you reached even Alpha Centauri.

Also because you'd disintegrate from relativistic effects and particle impacts somewhere around 25‰ of light speed.

Unless you're talking about Larry Niven. In that case, I'll give you a pass.

 

[Puppycow]

Warning, more pedantry.

Maybe you can use the electromagnetic force, like in The Expanse, but that force acts differently from the force of gravity. It's very strong up close, but weakens quickly with distance.

Actually EM and gravity obey the same inverse square law. The difference arises because you can create an EM in a very small space but creating a gravity well requires a huge object. The large radius of the Earth vs the potentially very small radius of magnets leads to the difference you are talking about.

The "hyperdense matter" solutions that some people have mentioned in this thread would have the same fall off problem you mention here (assuming same size). Similarly, you can avoid the fall off problem with an EM solution by making the magnet large.

Thanks. So, conceivably, if you had people wear clothes made out of magnetic materials and put magnets in the "floor" . . . ? But that probably still wouldn't work because of the polarity problem. Magnets have 2 poles and one attracts but the other repels. It's not like gravity that just attracts everything with mass.

 

[Roboramma]

The best sci-fi has this covered.

You accelerate at up to 1 G until you're half way to your destination.

Everyone straps down and the ship flips over end to end.

Then you decelerate at the same rate until you arrive at your destination.

This way your ship doesn't need moving parts that are destined to fail, and really horrible interfaces between moving parts and non moving parts. It also means you don't have to have the universe spinning around outside your windows. AND it means that your ship can have common 'floor' surfaces that are always in the right place.

Completely impractical. Take whatever propulsion technology you're planning on using and consider how much fuel you'll need to carry to maintain constant acceleration over the time span of your trip. Don't forget to use the rocket equation.

Even if you could somehow produce large quantities of anti-matter, and store them safely for years on your spacecraft, this still wouldn't make sense. I don't think it would work even with something like a light sail powered by lasers back home (consider that the faster you go, the more redshifted the light from those lasers becomes, so they need to be more powerful to produce the same acceleration), but I haven't actually looked at those numbers so... maybe.

There are also the concerns related to traveling at relativistic velocities through interstellar space that theprestige mentions. So, you solve the problem of having your view through your windows spinning by carrying insane amounts of fuel and turning every speck of dust along your path into a nuclear warhead. Doesn't seem worth it to me.

The only reason to try to go very fast is some sort of time constraints. And the difficulty in doing so is immense.

My personal solution to interstellar travel is to take very long journeys at a slow pace. Hundreds of km/s instead of tens of thousands.

 

[Myriad]

My personal solution to interstellar travel is to take very long journeys at a slow pace. Hundreds of km/s instead of tens of thousands.

Yeah, but then your trip takes millennia instead of decades. You'd have to bring a Robert Jordan novel or something.

 

[Meadmaker]

Completely impractical. Take whatever propulsion technology you're planning on using and consider how much fuel you'll need to carry to maintain constant acceleration over the time span of your trip. Don't forget to use the rocket equation.

I hate the rocket equation.


Ok, so, last year I took an online class on space mission planning, and learned what the rocket equation was, and realized just how incredibly hard interstellar travel was.

It's all the equation's fault. If we could just get rid of the equation we could make it work.

 

[rjh01]

Has anyone yet mentioned that the Coriolos effect would might produce some strange sensations when walking in a rotating environment designed to produce “artificial gravity?

That is a good point actually. For example if a person throws a ball vertically upwards it will not come down in the same spot, like it would on earth. It will start having a horizontal vector from the thrower's point of view. A ball thrown at an angle would have a strange path. It could also produce motion sickness if a person is going up or down.

Not to mention the fact that a person's feet would have greater gravity than the person's head.

The frustrating thing is that I tried to do a google search and though found a bit on the Coriolis effect, not much about the strange effects it would have on humans in a spacecraft.

 

[Roboramma]

Yeah, but then your trip takes millennia instead of decades.

Yep. And just to get to a single nearby star.

You'd have to bring a Robert Jordan novel or something.

Or maybe even several.

 

[Skeptic Ginger]

Rubbish. It is all explained by the diagram below.

[qimg]https://cdn.vox-cdn.com/thumbor/bKdLGlz7prGZDTJ3T3MY097xyQU=/0x2:528x354/920x613/filters:focal(0x2:528x354):no_upscale()/cdn.vox-cdn.com/uploads/chorus_image/image/47077626/timecubeflierimg.0.0.gif[/qimg]

 

[Skeptic Ginger]

I seem to manage it.

 

[Skeptic Ginger]

The nature of gravity is unknown and the question you've asked is open.

Aha! This gives me a well-into-the-future sci-fi idea. Perhaps humans will one day harness dark matter and use it to create artificial gravity.

 

[Skeptic Ginger]

Physicist and science fiction writer Robert Forward wrote a book called "Indistinguishable from Magic", that alternated scientific essays about hypothetical advanced technologies common in science fiction and short stories featuring those technologies. As I recall, the artificial gravity chapter involved somehow manufacturing hyperdense matter and placing it in a thin layer under a surface, with sufficient mass that it generated gravity pulling toward that surface. It couldn't be turned on and off though.

Interesting. Harnessing black hole material.

Maybe add some king of mag-lev device that counters it to shut it off.

 

[Skeptic Ginger]

And it'd play havoc with your DeltaV

Good point. So it would have to be created in space and stay up there.

You would though, have the problem that the gravity made from some hyper-dense material would pull both ways. You might have an issue collecting space rocks on the hull.

I'd have the same problem with my dark matter device.

 

[Skeptic Ginger]

The problem with that gravity (and The Martian and others) is that you're always walking uphill.

But it's spinning, so it's like a treadmill moving under you. If you stand still you aren't even walking.


Rendezvous With Rama has an interesting description of the gravity you'd have with a miles long cylinder that was also spinning to create the gravity. You have to read it, it's too complicated to describe. It was different though, in that it wasn't the usual wheel shape.

 

[Roboramma]

Aha! This gives me a well-into-the-future sci-fi idea. Perhaps humans will one day harness dark matter and use it to create artificial gravity.

Where are you and Steve001 getting the idea that we don't understand gravity?

General Relativity gives us a powerful theortetical framework that has been tested to enormous precision. We can measure the time dilation across a distance of a few meters in the earth's gravitational field, gravitational waves from colliding black holes, the motions of the planets and artificial satellites and spacecraft in our solar system, precision experiments like Gravity Probe B, stars orbiting Sagittarius B*, the patterns in the CMB, etc. etc. and we don't have a single measurement that is inconsistent with GR.

There are some issues with quantizing gravity, but there is absolutely no reason to expect that quantum gravity would open the door to artificial gravity, other than of the mundane sort produced by acceleration which we already know how to produce (for instance in a rotating cylinder).