On 08 Aug, Philip <joyphil@xxxxxxxxxxx> wrote: > That wouuldn't work if the alien or me were observant. I would detect > the twist very quickly. I remembered Arthur C Clarkes big wheel and the > artificial gravity. Wouldn't all the little things inside end up on the > inside of the outer hull? The centrifugal force would be certainly > detectable. Gyros and all that. So Alien would fly up and correcting for > rotation see a stationary stone along side the rotating one. No problem. > Oh yes there is. > As there is really a gravitational attraction or push from the aether?, > then in my imaginary created empty space my two stones, my two beautiful > stones will come together with a big bang. Yes, well, I was just about to write and say that your scenario wouldn't work, because if the stones were going round each other, they would go round their common centre of gravity, so they would both be moving! Also, I hate to tell you this, but centrifugal force does not exist! It is quite difficult getting this across to pupils who have always assumed it to exist, but in a GCSE or A level physics paper, if you mention centrifugal force you get no marks! What feels like centrifugal force when you go on the "cage" at a fair, is really the outside wall pushing you inwards, or centripetal force. It just feels as though there is an outward force on you. You always feel a force in the wrong direction when you are in a vehicle which is accelerating. It is similar to the force pushing you back in your seat as a plane accelerates down the runway. The only force is the seat pushing you forwards to accelerate you to 300 mph, but it feels like a backward force. Alan Griffin