I was wondering about this hypothetical situation and wanted to clarify whether the following is true or not:
Consider a person playing with a slinky. The Slinky moves at relativistic speed.
The person is standing at location A and when he lets the slinky extend it reaches out to position B.
Would I be correct in saying that in the situation where the slinky is being extended to position B the time that is measured by the person playing with the slinky is not proper time, as the two events which are being measured do not happen at the same location but one at A and the other at B.
However if the person playing with the slinky were measuring the total time it took for the slinky to reach B and come back to A then he would measure proper time.
Also in the reference frame of the slinky the slinky is always measuring proper time as it feels as though it is stationary. (This statement is not truee as someone has already pointed out due to acceleration of slinky
Any help would be appreciated.