Is the Past Still Here Now?

Time is one of the biggest mysteries, both in our lives and in the field of physics. We experience time as linear, with a distinct "now." However, physics offers a contrasting perspective. Albert Einstein's work revolutionized our understanding of time.
Space-time:
We tend to think of time as universal and constant. Einstein's theory of special relativity challenges this, building on Hermann Minkowski's idea of spacetime. Minkowski realized that treating time as a dimension, rather than a parameter, made Maxwell's equations in electrodynamics more sensible. Spacetime diagrams illustrate this, with straight lines representing motion. The speed of light is the maximum velocity and is typically depicted at a 45-degree angle. While time is still distinct from space in certain ways, it now functions as a coordinate label, devoid of a universal quality.
Special Relativity:
Einstein's theory hinges on four key principles: the finite and constant speed of light in a vacuum, the impossibility of exceeding the speed of light, and the equal validity of all observers' viewpoints. This theory has far-reaching implications.
Relativity of Simultaneity:
One consequence is the observer-dependent nature of "now." Einstein's thought experiment with mirrors and photons illustrates this. Different observers in relative motion will disagree on the simultaneity of events. While these discrepancies are negligible in everyday life, they become significant at speeds approaching the speed of light.
Block Universe:
Special relativity leads to the concept of the "block universe." If we accept that things exist "now" even if we can't perceive them, then, considering the equal validity of all observers, all events must exist "now." The block universe is static and unchanging.
Alternatives:
Other interpretations exist. One could argue that only things that are "now" and "here" exist, avoiding the block universe idea. Alternatively, one could define a notion of existence as a specific slice in spacetime, although this would likely conflict with observations.
Quantum Mechanics:
Quantum mechanics doesn't alter the block universe concept, as it remains compatible with special relativity. Although wave-function collapse occurs faster than light, it can't be observed, preventing any contradiction. Some argue that the indeterministic nature of quantum mechanics implies a special "now," separating the past from the future. While this might be true, the past still aligns with the block universe concept.
In Conclusion:
Our current understanding suggests that the past, present, and future all exist in the same way, forming the block universe.