From: Twink (neptune@mars.superlink.net)
Date: Sun Nov 30 1997 - 16:02:49 MST
At 01:45 PM 11/30/97 +0100, Anders Sandberg <asa@nada.kth.se> wrote:
>> No. This is not what I meant, though this too is possible. The dissipative
>> structure analogy still means that total order plus total entropy is a fixed
>> sum. Eventually, too, the system would run down.
>
>Hmm, as far as I know there is no conservation of order plus entropy;
>order is simply the negative of entropy, and the sum must according to
>the laws of thermodynamics always go in the entropy direction.
Only in a closed system. Your prigoginic universe -- one side as a dump, the
other to live in -- is merely a closed system on a higher level. The
possibility
Layzer discusses -- the expanding phase space idealization -- is not closed
on any level.
>But
>regions can achieve as much order as they want if they have energy and
>can pump away the entropy. So the main questions are if there is
>enough energy in an open universe, and if there are enough entropy
>sinks.
No. The point is Is the expansion rate fast enough to insure the universe
will never reach equilibrium. Layzer thinks it is. (For the record, his model
of cosmology is called the Cold Big Bang. See his _Cosmogenesis_ for
a lay account. He also presents his view in his _Constructing the
Universe_.)
>> To picture what I am talking about imagine a bunch of molecules in a
>> box. Let's say that at first they are all in one part of the box. After a
>> certain amount of time, ceterus paribus, they will be spread out -- in
>> the sense one would be likely to find them anywhere within the box.
>> This would be an equilibrium state -- or more, accurately, collection of
>> states. Now imagine that the box can expand faster than the
>> molecules move. The molecules will never be able to fill the whole
>> box, in the sense of the first example. One will always be able to
>> give a rough estimate of where they are.
>>
>> Now if the universe as a whole behaved like that...
>
>Yes, that would be nice. Unfortunately this is the
>ball-of-galaxies-expanding-from-a-center-somewhere-in-a-big-void-model,
>and not compatible with what we know or believe. The universe seems to
>be expanding more like a big balloon with galaxies on its surface,
>being slowly blown up. That means we do not get any low-entropy
>regions for free, even when the spacetime expands. A pity.
The box example is merely an analogy as is the "big balloon with galaxies
on its surface." BTW, the latter assumes the universe is positively
curved, which is what we were questioning!
Nonetheless, if the "ballon" can expand forever at a rate faster than
equilibrating interactions, then the same result occurs. I.e., there is no
heat death, expansion and order growth are eternal.
Daniel Ust
This archive was generated by hypermail 2.1.5 : Fri Nov 01 2002 - 14:45:10 MST