# How could a spaceship mimic gravity?

• Ara macao
In summary, the conversation discussed the possibility of creating artificial gravity on a spaceship. Ideas such as using centrifugal force, mass and magnetic fields were proposed. However, it was noted that these methods may not be practical due to issues such as varying gravity levels and the Coriolis effect. The suggestion of using a rotating cylinder as a container was also mentioned, but it was noted that the cylinder would need to be quite large for the gravity to be consistent.

#### Ara macao

As we know from movies such as "Star Wars" and "Star Trek", the characters move as if they were on a planet. The question is - could there be a mimic to gravity on the spaceship? Obviously, we cannot put too much mass on a spaceship, which would make the spaceship much more inert to acceleration/deceleration. So the obvious other force is the electromagnetic force. One could envision a very strong negative field on the bottom of the field, and people wearing positively charged packs that did not mix in with the surrounding areas. We can confine charges within magnetic fields. The gravitational field and the electromagnetic field both decrease as the square of distance, so the geometries of the two fields aren't likely to be different. So the question is, is such a system possible?

"Centrifugal force" is the usual solution to this problem. Just have the spaceship spin at a good rate, and the passengers can walk on the inside surface.

Moo Of Doom said:
"Centrifugal force" is the usual solution to this problem. Just have the spaceship spin at a good rate, and the passengers can walk on the inside surface.

I don't think so. Because the gravity change from your hands to your feet is probably quite different. And if you'll probably jump way higher than you would on Earth. The spaceship would have to be ridiculously huge to mimic gravity on Earth using that method.

Inertial compensators, duh.

Keep accelerating...? Start decelerating at the same rate when you're halfway through.

have it orbit the moon?

light_bulb said:
have it orbit the moon?

That won't work. Orbit is freefall, generally.

the Earth is to close for it to work

i don't know what I'm talking about here but let me give it a shot:tongue2:

if you put a planet into it's own independent orbit and calculated what it's optimal mass should be in relation to it's distance from the sun couldn't something be worked out where you have almost the same climate as earth? how about putting it on an opposite axis to that of our solar system?

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light_bulb said:
the Earth is to close for it to work

i don't know what I'm talking about here but let me give it a shot:tongue2:

if you put a planet into it's own independent orbit and calculated what it's optimal mass should be in relation to it's distance from the sun couldn't something be worked out where you have almost the same climate as earth? how about putting it on an opposite axis to that of our solar system?

You're second sentence is correct. What you say after that is... what can I say...

well best not to say anything

I don't think so. Because the gravity change from your hands to your feet is probably quite different. And if you'll probably jump way higher than you would on Earth. The spaceship would have to be ridiculously huge to mimic gravity on Earth using that method.

And what is wrong with "ridiculously huge" in space we have all the room and materials we need.

Chi Meson said:
You're second sentence is correct. What you say after that is... what can I say...

well best not to say anything

i won't get offended

i don't see what's wrong with it unless someone says something (or until i learn more) :uhh: yes i know that people can't build planets yet.

sas3 said:
And what is wrong with "ridiculously huge" in space we have all the room and materials we need.
I think we could get by with a cable significantly shorter than 200m. We could have a mass at one end and the cabin at the other. It might also be okay if there is a force of 1.0g at ones head and 1.25g at ones feet. It couldn't be much more difficult than building a large suspension bridge.

Perhaps we could use a magnetic field it the astronauts were willing to where steel gloves, steel baseball hat, and steel steel shorts(chainmail of course).

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Andre said:
But keep dreaming, we first have to keep this world turning.

I guess we will never have the opportunity to really think about it.

light_bulb said:
i won't get offended

i don't see what's wrong with it unless someone says something (or until i learn more) :uhh: yes i know that people can't build planets yet.

I just don't know where to start.

light_bulb said:
i won't get offended

i don't see what's wrong with it unless someone says something (or until i learn more) :uhh: yes i know that people can't build planets yet.
What does it have to do with the topic at hand?

dimensionless said:
I think we could get by with a cable significantly shorter than 200m. We could have a mass at one end and the cabin at the other. It might also be okay if there is a force of 1.0g at ones head and 1.25g at ones feet. It couldn't be much more difficult than building a large suspension bridge.).
1] You'd be okay if you only had one deck. But as soon as you have more, well, your grav is different on each deck. That's how people get injured.

2] Even at 200m you'd still experience the Coriolis force. Your "gravity" would be "warped". More injuries.

dimensionless said:
Perhaps we could use a magnetic field it the astronauts were willing to where steel gloves, steel baseball hat, and steel steel shorts(chainmail of course).
Magnetism falls off as the cube of the distance, creating a huge gradient.

maybe they have some way of making evreything in the cabin uniformly accelerate downwards. if they have tractor beams, why not have small ones lining the floor of your ship

hmm i believe that a big cylinder as a container would do, all you need is to spin it around the central axis of the cylinder, and there, the men inside feel artificial gravity to the inner layer of the cylinder...
the gravity is the same along each radius, problem is that to minimize acceleration differences you'll need the cylinder to be big enough...

if my calculations are correct, if you're 1.8 meters high, and you want a gravitational acceleration difference of 2 (m/s^2) between the top of your head and you're feet, and let's say your feet accelerate in 11 , and to of the head in 9, you'll need a 9.9 meters radius, which is pretty big... though if i was to live in space, i'd love to have one of those...

another way is to put a small cabin in the edge of the craft, far from the axis of revolution, its very possible to make a ship long enough so that the acceleration difference between different positions along the small cabin are small. though this way the parts closer to the axis of revolution wouldn't have the right acceleration...(such place could be used for machines and storage)

i guess that the 2nd option is the practical one, since real space shuttles are pretty long...

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