An event in 4 dimensional spacetime is designated by coordinates x, y, z and t. Spacetime physically has the three spatial coordinates (x, y and z). Does spacetime also have a physical property that gives it a temporal coordinate? For example, the rate of time depends on the gravitational potential. Clocks run slower in the 4D space close to a large mass compared to the 4D space far from a large mass. Is this just an effect on physical objects such as clocks and atoms or does the space itself have a temporal property that is slowed by the effect of gravity?
This is a discussion question. Therefore, I will express my opinion. I believe in John Wheeler’s spacetime foam representation of spacetime. He said “Empty space is not empty. It is the seat of the most violent physics.” He then described spacetime on the scale of Planck length as having Planck length oscillations at Planck frequency. If spacetime has oscillations at a frequency that can be affected by gravity, then spacetime has an internal clock and a physical time component. Even the physical constants G, c, and ħ each have time components. It is not possible to define any of these three physical constants without introducing a local rate of time.
I think that spacetime must incorporate Planck frequency oscillations to achieve the temporal properties (the 4th dimension) of spacetime. Do you agree or disagree? If you believe spacetime does not have an internal clock (oscillations), then what determines the local rate of time?