# Speculative experiment: A golf ball at the frontier of the universe

Consider a golf ball in the center of an empty sphere (maybe a GR vacuum, I'm not so sure). Consider this empty sphere as being the only space available to the golf ball, it is surrounded by nether. Now give the ball a push.

Is there a mathematical formalism that can describe the evolution of the ball in such conditions (motion-wise, particularly at the frontier of the available space) ?

I realize that this is a highly speculative question that may pose several issues, I'm not so much interested in weither the experiment is possible as I am in knowing the theoretical frames that could represent such conditions (mainly, how do we interpret/represent nether in physics; do we ?)

• How can I give the ball a push when I am not there? The sphere is empty, except for the ball... that's your own rules. – CuriousOne May 20 '15 at 23:05
• What do you mean by "nether"? If the ball is in a GR vacuum, the behaviour will obviously depend strongly on what vacuum you choose. What is keeping the ball inside this chunk of the vacuum? Is it a physical wall, or some sort of mathematical device? – Harry Wilson May 20 '15 at 23:07
• By nether I mean that outside of this chunk of vacuum, there's no space-time. Your second question is very interesting, it is my main motivation: "what is keeping the ball inside this chunk of the vacuum". Interesting that you even ask the question, why should the ball be kept by something in the vacuum ? Where would it go otherwise ? I know realize that this may reach metaphysical levelsas many notions are unclear, and that may not the purpose of the website. But thank you for your contributions. – Golz May 21 '15 at 14:28
• Then again, I'm highly interested in the properties of GR vacuum which are scientifically relevant, if anyone could give some details it may answer my question. – Golz May 21 '15 at 14:34
• There is no outside of spacetime, at least it is not necessary for space-time to be embedded in something else. The whole concept of outside of space-time is the wrong kind of thinking. – Sebastian Riese May 21 '15 at 20:45