# I Don't Understand Time

Originally published: 2013-04-28
Canonical URL: /2013/Apr/i-dont-understand-time/

Our subjective experience would have it that time "moves forward": the past is no longer, and the future is indeterminate and "hasn't happened yet." But it can't _actually_ work that way: special relativity tells us that there's no absolute space of simultaneity; given two spacelike separated events, whether one happened "before" or "after" the other depends on where you are and how fast you're going. This leads us to a "block universe" view: our 3+1 dimensional universe, past, present, and future, simply _exists_, and the subjective arrow of time somehow arises from our perspective embedded within it.

Without knowing much in the way of physics or cognitive science myself, I can only wonder if there aren't still more confusions to dissolved, intuitions to be unlearned in the service of a more accurate understanding. We know things about the past from our memories and by observing documents; we might then say that memories and documents are forms of probabilistic evidence about another point in spacetime. But _predictions_ about the _future_ are _also_ a form of probabilistic evidence about another point in spacetime. There's a sort of symmetry there, isn't there? Could we perhaps imagine that minds constructed differently from our own wouldn't perceive the same kind of arrow of time that we do?