I guess I should tell you what inspired this question. I was watching this piece on a British museum on TV. And they were saying, the public really doesn’t like seeing depictions in museums about more relatively recent human tragedies, like the Nazi holocaust. Because it just seems too near, it would seem. But things like the Spanish Inquisition or the witch hunts of the distant past don’t bother people, because it seems so long ago. Anyways, that has nothing to do, directly at least, with my question.
But it did make me think, as I said. I should point out, this is a purely physics question, not really a philosophical one. Does the past still exist? I mean, is there a place in time, where the poor victims of the holocaust, for example, are still suffering terribly? Just a physics question, as I said. (Don’t worry though, if that bothers you. The flipside of that, if true, would mean the happy events in your life will forever exist.)
So does the past still exist? Or is it forever gone? And do the things there (as per my example) still go on there, or are they effectively gone (to use a past tense verb)?
Thank you in advance for your kindly and civil replies .
You have/are/will experience events for a set period of time, not forever. Forever is all of time, the events of your past did not take all of time. I don’t know if you can actually return to the past, none of my time machines has worked as of yet, but if you can it will be the present when you get there.
Yeah, whether we exist in a block universe or not, we already know that our subjective experience of time is that it passes and the present is fleeting. So nobody is experiencing horrible events till the end of the universe, they experience it for a moment. The question is whether this passage of time that we feel is just an illusion.
“Still” is an inherently presentists word, so no, the past does not “still” exist. Does the past always have existence to those cruel ancient ones watching us and manipulating us for their amusement from beyond the four dimensions of time and space? Yes. Certainly.
Well…doesn’t relativity tells us that different observers can view the same event as happening at different times? They are not simultaneous.
It is possible to construct a hypothetical situation where someone is only now witnessing the events of the holocaust and think those events are happening in their “now.”
I believe relativity would say both observers are correct. That suggests that your past can be someone else’s now. So…does the past no longer exist?
It does, and I’m ok with the idea of the block universe, but each observer only experiences an event as a momentary thing. It’s just that no two observers would agree exactly on when something happened.
A subtle question like this always needs to be phrased precisely in order for an answer to be meaningful, but a precise phrasing of this question is very difficult within the context of human language. What tense do you even use when asking it?
For those of us who prefer a written presentation, there’s also a transcript here.
To be honest, I don’t think it’s one of her better offerings—lots of talk about how Einstein was the first to realize the correct structure of time, but Einstein also realized that physics is missing something essential about time, namely, that the moment of ‘now’ never features in it:
In general, physical description only becomes applicable to the real world once you supply what’s sometimes called ‘indexical data’: the when, where, and what, so to speak. Like a map only becomes useful once you find the little ‘you are here’-arrow, physics only starts yielding concrete data once you select some special point in time and space—say, your particular reference frame. Physics yields the generic, the universalizable, but we’re interested in the particular—how fast or slow a clock ticks for you, say.
Arguments for the existence of a block universe, or a multiverse, or some such, forget that; because there is no special ‘now’ in physics, every point in time must exist; because the wave function of quantum mechanics is a superposition of distinct possibilities, they must all exist, in ‘parallel universes’ if need be. But this is just to make the artifacts of theory-making into properties of reality—like concluding that because the orrery runs on gears and wheels, so, too, must the planets.
I believe that the basic problem is that the physical description of the world is essentially structural (consisting of relations), and structure underdetermines content, so we need to supply non-structural data to complete the picture (i. e. a concrete experience here and now). Failing to do so then essentially removes the particular in favor of the generic. This is one of science’s greatest strengths, of course—to find that which transcends all individual viewpoints, and thus, can be validly called objective. But one shouldn’t then conclude that since this is all that can figure in scientific theories, it’s all that can exist. Just because the rules of chess fail to specify any particular game, doesn’t mean we have to accept that all chess-games ‘exist’ in any sort of way ‘out there’. There’s just the game being played; its description by means of the rules simply fails to specify it fully.
Or to give another example, there’s the famous “Barn Door Paradox”, which reconciles whether relativistic foreshortening can allow a pole to (very!) briefly fit between two barn doors shorter than the pole. The answer is that from the framework of the pole, the barn doors aren’t shut at the same time! This definitely makes “now” a problematic concept in Special Relativity, in which case we have difficulty saying what really is past and what isn’t.
My very primitive understanding of relativity is that, yes, there theoretically exists some frame from which an observer would perceive the Holocaust or whatever as happening “now”. But that’s not the frame the actual victims exist in, so they could not be said to be “still suffering”, or more precisely, to have experienced any particular trauma more than once.
If a boxer gets punched in front of 60,000 people, they will all experience that event from very slightly different points of view, but the experience for the boxer is the same as if there had been no witnesses at all. This is the same idea, except swap out “very slightly” for “almost unimaginably”.
Except that we have information about the past but not the future. Time is different. Efforts to construct a physics in which time is an “illusion” have all been unsuccessful.
Well, if there is enough mass in the universe, it will one day start to contract back into a singularity and effect will precede cause, resulting in everyone walking and talking backwards.
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