Quote by yuiop
A clock low down in a gravitational field really does tick slower (than a clock higher up) and is not an artefact of light signal travel times.

I am not saying it is an artifact what I am saying is that the time dilation and the change in light travel time are the same thing. Time dilation is always a comparison of at least two clocks and in the case of gravitational time dilation this is dependent on the gravitational potential differential which is equivalent to the light travel time change between going from A to B and B to A (which of course might not even be constant).
Quote by yuiop
Not quite sure what you are getting at here. I was proposing only comparing the elapsed times of the clocks when they are stationary and alongside each other at the start and end of each experiment. This eliminates any light travel time difference.

My point is that the light travel time difference, e.i. time from A to B and B to A is directly proportional to the difference in time accumulation of the respective clocks.