What are the physical mechanisms behind time dilation and its alternatives?

[Mentz114]

If time dilation cannot be explained in terms of fundamental physical processes, then there is no understanding.

I hope you are not confusing time dilation, the coordinate effect, with differential ageing, which is coordinate independent. The examples you give are based on proper times, and so confirm differential aging, not time dilation.

The problem with ascribing a physical change to a coordinate dependent quantity is that it immediately leads to a contradiction or paradox.

 

[ghwellsjr]

The issue here is not time dilation but the response implying there is no physical cause.
In the Hafele-Keating experiment, the clocks differed in accumulated time, and it wasn't because someone was looking at them. In the muon experiment, the larger fraction of survivors for the high speed particles was not because someone was looking at them. Viewing from the fast muon frame does not alter the percentage of survivors in the lab particles, i.e. you can't change the qty of particles in a sample by looking at it from a different reference point. The differences are real between objects compared together, therefore there are explanations in terms of physical processes. If time dilation cannot be explained in terms of fundamental physical processes, then there is no understanding. It's like pressing buttons on a TV, without knowing how the picture gets there! The coordinate transformations don't explain anything, they just provide a means of calculation from one frame to another.

As Mentz alluded to, Time Dilation does not have a physical cause but Differential Aging does and it is the Lorentz Transformation that provides that mechanism, not as applied to the coordinates of events in different frames but rather as it is applied to the laws of physics. Prior to Einstein, Lorentz and other scientists assumed that there was an absolute rest state in which light propagated at c and in which clocks and rulers were correct. They assumed that our clocks and rulers were incorrect and were physically distorted by moving through the ether and so they looked for an explanation. Einstein, on the other hand, determined that the same Transformation that Lorentz had figured out as applied to the laws of optics needed to be applied to every law of physics and so all the laws were modified to make them invariant under a Lorentz Transformation and that provides all the mechanism or physical explanation for differential aging and all the other observables that are the result of the Principle of Relativity.