Acceleration vs Gravity and effect on time/clocks

[DarioC]

Just kicking some things around and this came up:
Albert says that it is not possible to discern acceleration from gravity under his imposed conditions.
Question, does that apply to clock type "devices," and time?

As practical example; let us put a radioactive sample in an ultra-centrifuge and spin it up, monitoring the average radio-active decay rate. Will it be slower?

 

[Dale]

Just kicking some things around and this came up:
Albert says that it is not possible to discern acceleration from gravity under his imposed conditions.
Question, does that apply to clock type "devices," and time?

Yes.

As practical example; let us put a radioactive sample in an ultra-centrifuge and spin it up, monitoring the average radio-active decay rate. Will it be slower?

Yes. If you click on the sticky thread on experimental basis of SR and search for muon you will find some experiments (Bailey?) about exactly that.

 

[Janus]

Just kicking some things around and this came up:
Albert says that it is not possible to discern acceleration from gravity under his imposed conditions.
Question, does that apply to clock type "devices," and time?

As practical example; let us put a radioactive sample in an ultra-centrifuge and spin it up, monitoring the average radio-active decay rate. Will it be slower?

While the decay will be slower in the centrifuge, you have to be really careful how you interpret this. The slowing is exactly that which you would expect from time dilation for a clock traveling at the speed of the end of the centrifuge. The acceleration itself does not add any extra time dilation.

This can be shown by using centrifuges with different arm lengths if the speed at the end of the arm is kept constant, the time dilation remains the same, even though the acceleration experienced will be different.

So how do we equate gravity and acceleration when it comes to time dilation? First you have to realize that gravitational time dilation is related to gravitational potential and not gravitational acceleration. If you had a uniform gravity field (one that did not differ in strength with height) and put two clocks in it at different heights, the higher one would run faster compared to the lower even though they feel the same pull of gravity.

With acceleration, this same effect can be shown by having two clocks sitting in the nose and tail of an accelerating spaceship. The clock in the nose willing run faster than the one in the tail, even though they are both accelerating at the same rate.

 

[DarioC]

OK, thanks for the references. The one on "clock" velocity vs acceleration was most interesting.
DC