Re: Philosophy specifies: organisms process information


"Bill Morse" <wdNOSPAmorse@xxxxxxxxxxxxxxxx> wrote in message news:6IAYh.55$Hd1.9@xxxxxxxxxxx
carlip-nospam@xxxxxxxxxxxxxxxxxxx wrote:

Friar Broccoli <EliasRK@xxxxxxxxx> wrote:
On Apr 24, 4:09 pm, carlip-nos...@xxxxxxxxxxxxxxxxxxx wrote:

[...]
Two things to remember:

1. For time-reversibility, you have to reverse *everything*, not just a
single
piece of the system.
2. Although the exterior of a black hole is static, the interior is not;
it is
a dynamical system, changing with time.

So if you want to look at the time reversal of an apple falling into a
black
hole, you have to reverse not just the apple, but the interior dynamics.
This gives you a "white hole," a perfectly good solution of the
classical field equations of general relativity (although one that
probably doesn't exist in our Universe).

Would this not also reverse 2LOT? (which is the subject of this
sub-thread.)

I'm not sure what it means to "reverse the second law of thermodynamics."
The second law is a statistical statement -- it says that given typical
initial
data, it is overwhelmingly likely for entropy to increase. A white hole
is *not* typical initial data.

(In the same way, ordinary classical (or quantum) dynamics tells you that
you can, in principle, set up initial data that lead to the molecules of
air in your
room to suddenly flow into one corner. This doesn't violate the second
law, because such initial data are extremely unlikely.)

Brian Greene also argues in "The Fabric of the Cosmos" that the second law
does not itself dictate an arrow to time - given any set of initial
conditions, a system should become more probable in either direction of
time. What gives time an arrow is a universe that is initially highly
ordered - and this order still requires explanation. I suspect from reading
your posts that you know a lot more about this than I, but I thought it
worthwhile to toss in to the discussion.

This is why I dislike the usual identification of entropy with 'disorder'.
Because the universe immediately after the big bang wasn't 'highly ordered'
as we usually understand that phrase. It was as disordered as it could be
and still fit into the same space. The universe hasn't really become more
disordered since then. Mostly, it has just gotten bigger. And cooler.
And as it cooled, the opportunity has arisen for a variety of exothermic
entropy-producing condensations, including gravitational collapse of stars
and planets, solidification of metals, and crystalization of minerals.
Which look to Friar Brocolli as if they are creating new kinds of order.
And, in a sense, they are.

It isn't the initial 'order' of the universe which requires explanation.
It is the initial smallness of the universe which we need to explain.
The expansion of the universe is not (AFAICT) driven by the 2LOT. However,
it does have the side effect of 'sucking' entropy out of the fermionic
(matter) components of the universe and transfering them to the bosonic
(radiation) components. Which then get a low entropy density due to the
expansion.

.

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