Whats the difference between an object moving and everything else moving? For an observer on the sun every one of us has huge momentum which would be preserved when entering a portal.
Momentum is always relative to some frame of reference. Momentum ‘toward’ the portal would be conserved and mirrored through the other portal.
The difference in this case is that the object has 0 momentum and the portal doesn’t impart its momentum to the cube because you can’t collide with the portal. There is no force acting on the object to make it move.
That is not how either relativity or momentum work. The cube is still inert and the portal’s movement would have no effect on it unless it has some acting force that pushes it when passing through. Even if the exit portal was moving, the cube would remain stationary unless it had nothing to rest upon and gravity pulled it down.
Whats the difference between an object moving and everything else moving? For an observer on the sun every one of us has huge momentum which would be preserved when entering a portal. Momentum is always relative to some frame of reference. Momentum ‘toward’ the portal would be conserved and mirrored through the other portal.
The difference in this case is that the object has 0 momentum and the portal doesn’t impart its momentum to the cube because you can’t collide with the portal. There is no force acting on the object to make it move.
Of course it has momentum relative to the portal.
That is not how either relativity or momentum work. The cube is still inert and the portal’s movement would have no effect on it unless it has some acting force that pushes it when passing through. Even if the exit portal was moving, the cube would remain stationary unless it had nothing to rest upon and gravity pulled it down.