Viliam_Bur comments on Causal Reference - Less Wrong

30 Post author: Eliezer_Yudkowsky 20 October 2012 10:12PM

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Comment author: Viliam_Bur 25 October 2012 07:40:09AM *  1 point [-]

And at the beginning of the universe we have a set of states which just point time-backwards at each other, which is why we cannot go meaningfully more backwards in time.

Something like:
A1 goes with probability 1% to B1, 1% to C1, and 98% to A2.
B1 goes with probability 1% to A1, 1% to C1, and 98% to B2.
C1 goes with probability 1% to A1, 1% to B1, and 98% to C2.

So if you ask about the past of A2, you get A1, which is the part that makes intuitive sense for us. But trying to go deeper in the past just gives us that the past of A1 is B1 or C1, and the past of B1 is A1 or C1, etc. Except that the change does not clearly happen in one moment (A2 has a rather well-defined past, A1 does not), but more gradually.

Comment author: Eliezer_Yudkowsky 25 October 2012 08:00:07AM 1 point [-]

As I understand it, this is not how standard physics models the beginning of time.

Comment author: [deleted] 25 October 2012 06:26:35PM 2 points [-]

I don't think anyone takes seriously the way standard physics models the beginning of time (temperature and density of the universe approaching infinity as its age approaches zero), anyway, as it's most likely incorrect due to quantum gravity effects.

Comment author: wedrifid 25 October 2012 10:21:14PM 0 points [-]

I don't think anyone takes seriously the way standard physics models the beginning of time (temperature and density of the universe approaching infinity

This is a correct usage of terminology but the irony still made me smile.

Comment author: [deleted] 26 October 2012 12:35:45AM 1 point [-]

What?

Comment author: RobbBB 09 June 2013 11:10:18PM 1 point [-]

I think wedrifid is pointing to the irony in saying that the 'standard' model is (on some issue) standardly rejected.

Comment author: Viliam_Bur 25 October 2012 09:24:06AM 0 points [-]

Oh. I tried to find something, but the only thing that partially pattern-matches it was the Hartle–Hawking state. If we mix it with the "universe as a Markov chain over particle configurations" model, it could lead to something like this. Or could not.