B Is Spacetime Really a Block Where All Moments Exist Simultaneously?

[Herman Trivilino]

Thank you for the responses. When I accelerate, though, doesn't that automatically mean I switched reference frames?

You are using "reference frame" to mean "reference frame in which I'm at rest". We usually just call this the rest frame.

When I switch reference frames in space time, clocks that were simultaneous go out of sync, so I am actually seeing things different physically (different readings on the clocks, different appearances of things due to more time having elapsed, etc.

When you utter a phrase such as "a clock located over there reads such-and-such right now" you have not made a statement about anything physical at all.

The time that elapses on any clock is a relativistic invariant, meaning it will be the same for all observers.