- #1

Luigi Fortunati

- 47

- 0

A----------B

There is no way of knowing if B is standing still while A is moving at speed v (to the right), or if A is standing still while B is moving at speed -v (to the left).

This shows that speed is relative.

But if the two spaceships A and B on approaching at increasing speed (that is, if there is an acceleration), they can both legitimately support the other to accelerate, even when only one of them has its own accelerometer measuring a non-zero acceleration?

It seems to me not.

Is this last case sufficient to show that acceleration * is not * relative to the reference?