# Absolute movement

• B
• Ross Arden

#### Ross Arden

if you have 3 space ships on the x, y and z axis and they blast off...one of them must be moving in an absolute sense.

Is it the case that if there is absolute movement then there MUST be absolute time also?

if you have 3 space ships on the x, y and z axis and they blast off...one of them must be moving in an absolute sense.

No, once they stop accelerating then it would be equally true to say than anyone of the ships is stationary and the other two are moving.

Is it the case that if there is absolute movement then there MUST be absolute time also?

I'm not sure, but I believe that it would imply something like that.

but an observer standing at the origin of the coordinate system would have to say that at least one of them is moving in an absolute sense

If there is absolute movement then the thing that is moving absolutely is moving a set distance in a set time

but an observer standing at the origin of the coordinate system would have to say that at least one of them is moving in an absolute sense

The observer would say that all of them are moving relative to them. All of the spaceships would say that the observer is moving and they are stationary.

if you have 3 space ships on the x, y and z axis and they blast off...one of them must be moving in an absolute sense.
No, they are all stationary in their own rest frame, and the other ships are moving relative to them.
There is no absolute rest frame

but the observer would also have to say that one of the space ships is moving in an absolute sense. I am not saying he can tell which one, but one of them, including the observer must be moving
No, they are all stationary in their own rest frame, and the other ships are moving relative to them.
There is no absolute rest frame
But can anyone say they are all stationary?

one of them is definitely moving, it is not moving relative to something, it is absolutely moving

An observer at the launch site would see all of them moving.
The launch site is not in any special absolute frame though, it could be anywhere

is there a frame where the person in that frame can say they all stationary?

No, all of them are moving relative to any arbitrary spacetime coordinate you choose, other than where a ship is,

Dale
so at least one of them is moving in an absolute sense, ie an absolute distance in an absolute time?

Define what you mean by absolute.
It's trickier than it might at first seem.

Thread locked. @Ross Arden, you should accept the answers you were given. Thanks everyone.