It’s hard to swallow the idea that different people can experience time differently because we like to think that there’s an absolute true history of the universe. We imagine that in principle someone could write down a single (very, very long and mostly superboring) story about everything that happened in the universe so far. If this existed, then everyone could check it against their experience, and barring honest mistakes and fuzzy vision, the story would agree with what people saw. But Einstein’s relativity makes it clear that everything is relative, and even the description of events in
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