Gravity vs Centrifugal?

Question

I understand gravity as a force pulling me down to earth.

If I were inside a large cylinder in space and it was spinning with me going round with it I would experience centrefugal force. I would feel the same as I did on earth (assuming suitable spin speed).

Are these fields identical ? If so how do we know ?

Surely one is gravity and the other is caused by acceleration towards the centre of the cylinder.

Answer 1

The force of gravity is a consequence of geometry; imagine space and time as a fabric and a mass such as the earth. The earth is massive enough to curve space-time, which is why we are "pulled" to earth (that's how I picture gravity as a field). I would think that due to the equivalence principle, the two fields (gravitational and centrifugal) should look the same. The earth is rotating, and if you were in a spinning cylinder, you'd also be rotating regardless of the fact that you are nowhere near any source of gravity. In both cases, we are in non-inertial frames of reference, we are being accelerated.

Answer 2

Dr. Who always carried a simple device for determining whether he was on a planet or in a rotating space station. It's called a yoyo.

In centrifugal artificial gravity, the coreolis effect is opposite that of regular gravity. If the radius of the rotation is small, the coreolis effect is quite noticeable. You can even notice it by jumping straight up; you stay up longer than expected and you don't land where you started. If you run fast enough in the direction opposite to the spin, you may actually become weightless relative to the space station.

However, if the radius of rotation is many miles, you will have a hard time telling the difference.

Answer 3

Einstein proved long ago that acceleration and gravitational fields were indistinguishable.

Your assertion that you would feel the same as on earth is wrong.  In space, the earth's gravitational field would be canceled by the orbital motion of the capsule, and you'd feel only the effect of rotation about the cylinder axis.  On the surface you would feel the vector sum of the earth's gravitational field added to the acceleration vector caused by rotating with the cylinder.

I have experienced the later in an amusement park ride called the Hoffman Rotor, a cylinder with a vertical axis and padded interior walls around which the riders stand.  As the rotation increases a = V²/R presses your back to the wall.  Then the floor drops away and friction alone resists the earth's downward acceleration.  The combined rotating and constant accelerations is VERY disorienting, if not nauseating!

Answer 4

In a rotating space station, where the sensation of weight is generated by the spinning cylinder, the Coriolis forces will be massive. To distinguish the two fields, throw a ball and if its trajectory massively violates that of a parabola, you're in a space station.