Einstein's special theory of relativity, developed in 1905, had a consequence that Einstein himself found deeply unsettling: it abolished the universal present. In Newtonian physics, there is a single "now" shared by all observers — events are either simultaneous or they are not, and this is an objective fact independent of who is looking. Relativity destroyed this. Two events that are simultaneous for one observer are not simultaneous for another moving relative to the first. There is no universal "now" — only local nows, dependent on the observer's frame of reference.
The deeper implication was drawn out by the mathematician Hermann Minkowski in 1908: if different observers disagree about what is simultaneous, but all observers agree on the spacetime interval between events, then what is truly real is not space and time separately but spacetime as a single four-dimensional structure. In this "block universe" — also called the "eternalist" view of time — the past, present and future all exist equally as regions of the spacetime block. Time does not flow. The universe does not evolve from past to future. All of it simply is — a four-dimensional object in which what we call "now" is just our local position in the block.
Einstein wrote to the family of his lifelong friend Michele Besso, who died in 1955 shortly before Einstein himself: "Now he has departed from this strange world a little ahead of me. That means nothing. People like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion." This was not poetic comfort — it was Einstein's genuine belief about the nature of time, derived from his own physics.
Quantum mechanics complicates the picture further but does not restore the classical flow of time. The many-worlds interpretation of quantum mechanics describes all possible outcomes of quantum events as equally real in branching timelines — a structure that resonates with Seth's probable realities. The timeless formulation of quantum mechanics (the Wheeler-DeWitt equation) describes the universe without any time variable at all — the equation that should govern quantum gravity contains no t. At the deepest level of physical description, time may not exist.