# Artificial gravity on a ship without the whole ship rotating

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1. Mar 31, 2018

### caters

I know that rotation can cause there to be artificial gravity. But I was thinking of making a floor plan that is all horizontal with the generation ship having a rocket shape and with it being longer than it is wide and wider than it is tall.

So I was thinking of giant centrifuges on every floor.

The centrifuge underneath the floor would cause there to be a downward gravity and no worries about the Coriolis effect. At least I think it would. And I think that there is a way you can configure all the centrifuges so that the gravity everywhere is 1g.

So how fast would each centrifuge have to rotate in order to have 1g gravity downward throughout the ship?

The problem I see with rotation of the entire ship is not the Coriolis effect per se but rather dizziness and nausea, especially if a person already has dizziness or nausea. Basically, rotation of entire ship = gravity + motion sickness + dizziness(fluid in ears rotates in response to the ship rotating and thus the brain gets confused). Plus, potential collisions would be way worse due to the rotation.

With the centrifuges I do believe that the floor in the middle would need to have its centrifuge rotating the fastest and the ones on the top and bottom have their centrifuges rotating the slowest for 1g gravity.

Whatever the answer is, I know that there have to be different rotation rates for gravity to be even.

Note: I am using newtonian gravity here, in other words a true force. General relativity would just make things way more complicated than it has to be.

2. Mar 31, 2018

### kuruman

Do you really understand how a centrifuge works? If you do, please explain to me where the axis of rotation of the giant centrifuges might be in relation to the rocket. If you don't, please do some research on centrifuges. You can start here. https://en.wikipedia.org/wiki/Centrifuge

3. Mar 31, 2018

### caters

The axis of rotation of the giant centrifuges would be 90° in relation to the rocket, exactly the direction I want the gravity in. If the gravity is downwards than I do believe I would need to have the giant centrifuges have the axis of rotation be 90° in relation to the rocket.

4. Mar 31, 2018

### Staff: Mentor

The “artificial gravity” of a centrifuge only works if you are spinning with the centrifuge.

5. Mar 31, 2018

### caters

Wait, what? I thought you could have artificial gravity without the whole ship rotating by using centrifuges. And like I said in the OP, rotation means potential collisions are way worse which is why I am wanting to avoid having the whole ship rotating if at all possible while having artificial gravity. Now it seems impossible because either the ship would be way too massive to be a ship anymore(basically giving you an iron planet if that makes any sense) or it would need to rotate.

6. Mar 31, 2018

### kuruman

Think again.

7. Mar 31, 2018

### Staff: Mentor

You can test this out pretty easily. Get a centrifuge and three samples of some mixture. Put one of the samples in the centrifuge and place one near the centrifuge in the non spinning location where you think the artificial gravity field will act and the last across the room. Spin the centrifuge to full speed for a few minutes and then pull out the sample. Compare the sample that was in the centrifuge to the one that was nearby. It should be visibly obvious which one experienced more gravity. Then compare the one nearby to the one across the room, they should look very similar.

8. Mar 31, 2018

### Staff: Mentor

When you are in a centrifuge, the fluid in your ears is not rotating with respect to your ears, so there is no reason it could cause dizziness.

9. Apr 1, 2018

### jrmichler

No so. Google motion sickness centrifuge for details. I experienced this ten years ago when my then 12 year old daughter persuaded me to ride the Gravitron with her. She spent the next couple hours riding that thing, I spent the next hour laying on the ground. It spins 24 RPM and the riders experience 3 G's.

10. Apr 1, 2018

### Staff: Mentor

See:
https://en.wikipedia.org/wiki/Motion_sickness

While the article is a bit weak, it doesn't contradict what I said. The following aspects of what you and your daughter experienced do not apply to a spaceship:
1. Multiple accelerations and deceleration in a short time (disturbing your inner ear fluid).
2. Multiple orientation changes in a short time.
3. Eye/ear motion mismatch.

Googling a bit more, I see a few articles suggesting the Coriolis effect is a problem, so the larger the centrifuge the better. Also, that the transition between different gravity states is believed to be a significant cause.

https://www.nasa.gov/mission_pages/station/research/experiments/359.html

11. Apr 1, 2018

### Filip Larsen

12. Apr 3, 2018