[Serious] Is the Past Real?

[Angrboda]

I would disagree with that. The brain takes time to process the information from the senses. In fact, it can take fairly substantial fractions of a second to do so. So, the actual experience is always delayed from even the sensory event, let alone the event being sensed.

In the case of, say, a nuclear event at the site of an individual, it would be likely that no experience would be had at all since the vaporization of the body would happen much faster than the nerve signals and the brain processing. A nuke a kilometer away  would be a different matter, depending on the size and speed of the fireball.

Yes, I do agree that parsing out what constitutes the present subjectively from within the universe has value.  I am curious about time at the cosmic level. Does the universe, as a whole have multiple states. If space-time is entirely within the universe, then it would seem it could not have multiple states.

This reminds me a lot of questions about whether the physical universe is finite, whether it had a beginning, and so on. What lies beyond the last star? And what lies beyond that? These questions seem to be provoked by intuitions which were built for a problem space that has linear, inductively predictable properties, i.e. the macroscopic world around us. But we realize from both quantum mechanics and general relativity that these intuitions break down when we attempt to generalize these intuitions to other scales or questions. I suspect that questions of time and the geometry of the universe are likewise, that the paradoxes and puzzles are an artifact of our minds being built for answering different questions than these. Kant argues that our thought presupposes three-dimensional space and linear time, that we can't think outside those assumptions because they structure our thoughts. Wittgenstein has said that whereof one cannot speak, thereof one must be silent, but I'm not sure he's entirely correct about such things. If quantum mechanics and relativity are any indication, some of these questions may require a new way of speaking, of thinking things that cannot be thought. Feinman has said that if you think you understand quantum mechanics, you don't understand quantum mechanics. Likewise, the reality and ontology of time may be something that we can't properly understand, but with the aid of mathematics and empirical tools, we can develop models of it which can be reasoned about and tested.