Re: Boltzmann Brains, consciousness and the arrow of time

From: Stathis Papaioannou <>
Date: Fri, 2 Jan 2009 00:26:24 +1100

2009/1/1 "Hal Finney" <>:

> I want to emphasize that this picture of how Boltzmann fluctuations would
> work is a consquence of the laws of thermodynamics, and time symmetry.
> Sometimes people imagine that the fluctuation into the Boltzmann
> low-entropy state is fundamentally different from the fluctuation out
> of it. They accept that the fluctuation out will be similar to our own
> existence, with complex events happening. But they imagine that the
> fluctuation into low entropy might be much simpler, molecules simply
> aggregating together into some convenient state from which the complex
> fluctuation out and back to chaos can begin. While this is not impossible
> and hence will happen occasionally among the infinity of fluctuations in
> the Boltzmann universe, it will be rare. It will be no more common for a
> "simple" fluctation-in process to occur than for a simple fluctuation-out
> process. In our universe, knowing it will evolve to a chaotic heat
> death, we might imagine that molecules would just fly apart into chaos,
> but we know that is highly unlikely. Instead, by far the most likely
> path is a complex one, full of turbulence and reactions and similar
> activity. By time symmetry, exactly the same arguments apply during
> the fluctation-in phase. The vast majority of Boltzmann fluctuations
> that achieve a particular degree of low entropy will do so via complex,
> turbulent paths which if viewed in reverse will appear to be perfectly
> plausible sequences of events for a universe which is decaying from
> order to disorder, like our own.

This is an interesting idea. I had imagined that the fluctuations in
the decreasing entropy or winding up direction would involve chaotic
aggregation of matter which would then wind down in a more organised
way, giving rise to stars and planets and so on, but as you point out
there is no reason to assume this. I am not sure why you suggest that
the winding up direction lacks causality (leading to your question
about whether it could give rise to consciousness): if all the air in
the room moved to one side because, with incredible luck, the
molecules all vibrated in the same direction for a few seconds should
this event be called acausal?

If we are conscious in winding up direction and winding up is no less
likely to occur though interesting pathways than winding down, this
would imply that at any point, we have about an equal chance of living
in the winding up as the winding down phase: we would have no way of
knowing. This would be the case whether we are ordinary brains or
Boltzmann Brains, since in either case there has to be a winding up
before the winding down can happen. A further implication is that
there will be far more observer moments in the later stages of the
universe than in the earlier stages. This is because unlikely as it is
that the universe will wind up all the way to January 1st 2009, it is
even less likely to continue winding up to 31st December 2008 (it is
far more likely of course to only wind back to a state near the heat
death end times, but there are less likely to be observers there). If
you support the ASSA, that would imply that you are near your last
moment of consciousness, since OM's later in your life have a much
higher measure than earlier ones. Under the RSSA or if you take into
account Boltzmann Brains that would not be a problem.

Stathis Papaioannou
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Received on Thu Jan 01 2009 - 08:26:34 PST

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