# Artificial gravity...

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In a spinning torus a reasonable imitation of gravity can be produced, even though from the outside is is obviously not flat but curved.

But... What if you spun a cube? Even though the sides are flat from an outside observer would an interior observer feel like he was walking up hill and down as he progressed around the inside of the spinning cube?

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Wouldn't stepping onto a wall be supported as much as the "floor" he started from? I'm not sure why there would be an uphill/downhill difference on the inside of the spinning cube.

But if the cube is big enough, I think it would feel just like the torus, except the corners require a different step than a flat floor/wall, perhaps.

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3 minutes ago, Phi for All said:

Wouldn't stepping onto a wall be supported as much as the "floor" he started from? I'm not sure why there would be an uphill/downhill difference on the inside of the spinning cube.

But if the cube is big enough, I think it would feel just like the torus, except the corners require a different step than a flat floor/wall, perhaps.

I was trying to look at it from the standpoint of water, in a torus the water would look like a long lake or stream. My intuition tells me that water would pool up in the corners of a spinning cube but I am not sure.

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The radial distance  to the corners of the cube is larger, so the angular speed is different as is the apparent force.
And pressurization is easier with smoothly curved surfaces as opposed to sharp corners.

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At the the centre of any face of the cube, the centrifugal force would be normal to the surface. As you move away from the centre, the  force vector would move away from the "vertical" and it would feel (I think) like you were asking downhill. So the plane surface would feel like a domed surface.

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3 minutes ago, MigL said:

The radial distance  to the corners of the cube is larger, so the angular speed is different as is the apparent force.

Would this tend to make the water pool in the corners as the cube rotated?

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The 'fictitious' centrifugal force is at play here, because of the rotating frame, and is equivalent to Mrw^2, where M=mass, r=radial distance and w=angular speed.
In the corners both r and w are larger, so they feel a greater apparent force.
So, yeah, walking to the center of a face would be walking 'up-hill' and water would pool in the corners.

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4 minutes ago, MigL said:

So, yeah, walking to the center of a face would be walking 'up-hill' and water would pool in the corners.

And walking from the center to a corner would feel like downhill where the water pools. I understand where the Moontanman is coming from now.

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Thanks guys, this makes for some interesting possibilities...

1 hour ago, MigL said:

The 'fictitious' centrifugal force is at play here, because of the rotating frame, and is equivalent to Mrw^2, where M=mass, r=radial distance and w=angular speed.
In the corners both r and w are larger, so they feel a greater apparent force.
So, yeah, walking to the center of a face would be walking 'up-hill' and water would pool in the corners.

Would the observer feel lighter at the center of a face than at the corners as well?

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11 minutes ago, Moontanman said:

Thanks guys, this makes for some interesting possibilities...

Would the observer feel lighter at the center of a face than at the corners as well?

Yes. But if the difference was large enough to be noticeable then I suspect the tidal forces would be very uncomfortable, if not dangerous.

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3 hours ago, MigL said:

The 'fictitious' centrifugal force is at play here, because of the rotating frame, and is equivalent to Mrw^2, where M=mass, r=radial distance and w=angular speed.
In the corners both r and w are larger, so they feel a greater apparent force.
So, yeah, walking to the center of a face would be walking 'up-hill' and water would pool in the corners.

angular speed is the same, linear speed is greater

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For a person walking around the square, it would be similar to walking from one vee shaped valley to another with a hill in between. Something like this.

Though the "hills" wouldn't curve but act more like a flat surface tilting as you walk.

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Sorry Steve; you're absolutely right.
The proper terminology is the first thing you forget when its not used regularly.
Thanks for the correction.

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Here's another visualization of what walking around the spinning square would be like, showing 1 full side and part of two others:

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17 minutes ago, Janus said:

Here's another visualization of what walking around the spinning square would be like, showing 1 full side and part of two others:

Looks like it might be more than a bit weird!

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That's awesome Janus.

There should be a slight effect from which way it is spinning. So walking one way would have some different effects from the other depending on your speed.

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I would add that if you find different levels of gravity desirable, a circular cross section could still provide that.

You could simply go up a flight of stairs, to a level closer to the centre of rotation, and feel lighter. So just like on Earth, we would probably go upstairs to bed.

In space stations on a gigantic scale, you could maybe go upstairs to lower gravity levels as you get older, or if you're not well.

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16 hours ago, Janus said:

Here's another visualization of what walking around the spinning square would be like, showing 1 full side and part of two others:

if it was quite large, several kilometers across it might not be too strange but a torus would be easier to support as an endless suspension bridge type deal..

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3 hours ago, mistermack said:

I would add that if you find different levels of gravity desirable, a circular cross section could still provide that.

You could simply go up a flight of stairs, to a level closer to the centre of rotation, and feel lighter. So just like on Earth, we would probably go upstairs to bed.

In space stations on a gigantic scale, you could maybe go upstairs to lower gravity levels as you get older, or if you're not well.

...off to the basement to get some exercise in the "weight room"

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Just for the fun of it, here's the square habitat done with stair steps to make it easier to walk around the interior since near the corners, the slope approaches 45 degrees.  The simulated gravity will be ~41% higher at the corners than it is in the middle of each side, so you would be dealing with more "weight" as well as a steeper incline there.

Maybe it's just me, but there's something very "Esher-esque " about this image.

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1 hour ago, Janus said:

Just for the fun of it, here's the square habitat done with stair steps to make it easier to walk around the interior since near the corners, the slope approaches 45 degrees.  The simulated gravity will be ~41% higher at the corners than it is in the middle of each side, so you would be dealing with more "weight" as well as a steeper incline there.

Maybe it's just me, but there's something very "Esher-esque " about this image.

Or perhaps ;-)

Or this:

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23 minutes ago, Strange said:

Or this:

Very impressive. What is it meant to be ? One step forward ,two steps back? Plus ca change?

Edited by geordief

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1 hour ago, geordief said:

Or perhaps ;-)

Love the song, but prefer the Noel Harrison version.

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On 12/1/2017 at 5:47 AM, mistermack said:

I would add that if you find different levels of gravity desirable, a circular cross section could still provide that.

You could simply go up a flight of stairs, to a level closer to the centre of rotation, and feel lighter. So just like on Earth, we would probably go upstairs to bed.

In space stations on a gigantic scale, you could maybe go upstairs to lower gravity levels as you get older, or if you're not well.

On a small scale station, your flight of stair going from one level to another could look like this.*

Now you could align the stair case with the axis of rotation, but then Coriolis effect would try to push you sideways as you climbed or descended.  Even with the set up above, you'd want to point the staircase in the correct direction with respect to the rotation.  Here you would want the rotation to be clockwise.  This way, the Coriolis effect would tend to push you towards backwards( up-stair) when descending the staircase.  It would also tend to push you backwards when climbing, but this would probably be easier to deal with while climbing than while descending. If worse came to worse, you could design "up" staircases and "down" staircases curving in opposite directions relative to the spin. (Just avoid trying to go down the up staircase)

* I'm learning a new 3-D rendering software, so this is giving me an opportunity to play around with it

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