>>11753459>>11753459First off, there is no gravity other than the one the mass of the station itself "produces", which, due to it's low mass (relative to Earth) is negligeable.
I'll assume that was just a quirk of speech and not a lack of understanding. However, if that's not the case, I can explain that as well.
Now, the way you can tell it's spinning/rotating is super simple. And no, there is no need for a refrence point to determine that, but in the space station, there are many points of refrence. In the movie, there is a scene where a dude is running and you can see the whole station around him (pretty cool effect, might I add). Since there are other people on the station, the easiest method is to just ask them what they feel. You can see them above your head, yet they say they feel like they're on the ground. This means you both feel the same amount of force, but in opposite directions. You then walk around the station while they stay in place. After a bit, you're closer to them and at an angle, the entire time walking, you felt the same amount of force and they still report the same. Since you see that the station is a ring, and you are on the inside of it with your feet on the ring's surface, feeling the same amount of force at every pont, but in direction opposite of the centre it can mean only one thing, you're feeling centrifugal force. Centrifugal force is unique to rotating objects, and thus, the station is spinning at a constant speed!
One thing that the movie gets wrong is the size of the station. For the apparent centrifugal force to be to of same magnitute (strength) as gravitational force on the surface of the Earth, it would have to be absolutely huuuuge (theoretically, you could just have it spin super fast, but there are no materials that wouldn't shatter at high forces that such a speed produces). I get the decision to make it small tho, not very eye catching to see a guy run in what ammounts to a seemingy straight tunnel.
