Re: Time as a Lattice of Partially-Ordered Causal Events or Moments

From: Bruno Marchal <marchal.domain.name.hidden>
Date: Thu, 5 Sep 2002 12:08:39 +0200

At 20:58 -0700 4/09/2002, Brent Meeker wrote:
> >> The second problem has to do with time and casuality. At
>>> a microscopic level QM is time symmetric. If we say there
>>> is no real collapse of the wave function - all evolution
>>> is unitary (and therefore reversible) - then it seems we
>>> should from each datum or measurement result, compute the
>>> past as well as the future. All that can be known of the
>>> past, what happened within our past light cone, is
>>> determined by the present. So does the universe split as
>>> we go back in time? If not, why not? Are we stepping
>>> outside physics and assuming that the experimenter, as an
>>> agent, sets up initial, but not final, conditions and so
>>> defines the arrow-of-time by his causal action as an
>>> agent outside of physics?
>
>> Hal Finney:That's a good question and one I don't really know the
>> answer to. It's possible that you're right, it has
>> something to do with initial conditions. Or it's possible
>> that universes are merging at the micro-scale even as they
>> are splitting at the macro-scale, which would also be
>> fundamentally due to initial conditions. For example,
>> dual-slit diffraction can be seen as worlds where
>> particles go through the slits separately merging to show
>> the interference.
>
>Brent: My concern goes deeper than that. I think that a TOE should
>explain time, not assume it. But MWI universe splitting or
>evolution of the wave equation of the universe seems to
>assume time.

This comes from the fact that MWI is explained most of the time
in the context of non relativistic QM (which assumes time and space).
But this problem disappear once you take into account the
space time structure of relativistic QM, where roughly speaking
moment of time are handled by "parallel" universes (see Deutsch FOR).
With quantum *general* relativity, where the universe differentiate
at the level of the space-time structure aswell, we get the
all topological approach transforming the search of natural law
into the search of knot invariant. I urge everyone interested
in TOES to read the pedagogical chef d'oeuvre "KNOTS and PHYSICS"
by Louis H Kaufmann. It is a shortcut to "standard TOES" (like
quantum gravity approach) and the link with the self-reference
logic approach is just a matter of ... time ;)

Of course we should not and cannot assume time, ... nor space.

Bruno
Received on Thu Sep 05 2002 - 03:11:58 PDT