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grouchymusicologist comments on Open Thread: March 2010, part 2 - Less Wrong
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I vote "pleased", for the rather weak reason that this makes my preferences time-symmetric*.
* Edit: This is poorly-worded - what I was referring to was time shift symmetry.
But nothing else about the universe is time-symmetric, manifestly including our own revealed preferences -- I would rather be happy in the future but not in the past than be happy in the past but not in the future, if you gave me the choice right now. So this is the only argument I can think of to vote "not pleased" (of course, not displeased either) about one's past, but unremembered, happiness.
(I actually do vote "pleased," though, for the reason I argued here.)
I'm not sure that I'd prefer unrecalled happiness in the past to in the future, but I was thinking of (and should have named) time-shift symmetry, which the fundamental laws of physics are.
I actually agree with your argument for voting "pleased", though, so we might be simply in agreement.
Well then, I'm sure that addresses my objection. But a couple of minutes' googling isn't giving me a good sense of what time-shift symmetry is -- and my physics background is lousy. Could you give me a quick definition?
The laws of physics are invariant in time.
Edit: Clarification - if you write the laws of physics, nowhere do you invoke the absolute time; only changes in time. The outcome of any experiment cannot change just because the time coordinate changes; it can only change because other parameters in the situation change.
Thanks for that.
I remember hearing that there have been some hints that physical constants have changed over time. If they have then the laws of physics wouldn't be time invariant.
Anyone else recall anything along those lines? Wikipedia isn't terrible helpful.
I have not heard of any such theory becoming a credible candidate for acceptance, although I see no logical contradiction in such - my impression is that discovering a time-varying term would be as surprising as discovering energy is not conserved. For fairly fundamental reasons, actually.
Note that in GR defining energy consistently is tough. Doing it so it is globally conserved is even harder. We only really have local conservation, and the changing background of GR in cosmology is in some sense effectively the same thing as changing physical law.
Yes, they tend to be invariant in factors that don't exist ;-P