Finite Spaces, and time travel possibilities

I think if space was finite, it would mean that one side of the universe is 2-dimensional, because only one side of the world we could see and to see the other side you would have to travel into nothingness, which we know is just a concept, which proves again that the universe has to be infinite.

I think you could not go back, or forword in time before you were born (if you could travel back in time), it would prevent any memory of what you did, because you wouldn't have been alive to do it, and see it.

past---------present---------future = x---------y---------z

x= negative infinity

z= positive infinity

y= z-x=0