| Topic: |
Science > Physics |
| User: |
"Mike Christie" |
| Date: |
17 May 2005 09:00:05 PM |
| Object: |
Second law of thermodynamics and cosmic inflation |
I found the following critique of the argument that the second law of
thermodynamics is in conflict with the non-maximal entropy in the universe:
http://www.colorado.edu/philosophy/vstenger/Cosmo/face.txt
This makes sense to me. However, I have a question about this statement:
"Likewise, the organization of matter into galaxies and planets does not
require a violation of the second law of thermodynamics - now or in the
past. Though the universe starts as a black hole of maximum entropy, or
maximum disorder, it explodes into an expanding relativistic gas having
less than its maximum allowable entropy."
As I understand it, quantum fluctuations in the original universe were
inflated into the large scale structure we see around us. The original
universe was at maximum entropy; the current universe is not, because
the inflation preserved the structure of the fluctuations. I don't
understand why this is not a violation. As I understand it (from a
layman's point of view) the second law is essentially a statistical
statement, so asserting that this is a violation would make no
difference to the scope of the second law in the universe since that
time. And given that we have gone from a state of maximal entropy to
one of less than maximal entropy, on the face of it why would this not
be regarded as a conflict with the second law?
The reason I ask is that I understand that some anti-evolutionists have
made the argument that the non-maximal entropy in the universe requires
an external agent (i.e. an "intelligent designer") to introduce order to
the originally disordered cosmos, and the second law is the authority
they refer to. I can see how the quantum fluctuations resolve the
problem, but I'm curious if this could be regarded as (presumably the
only possible) exception to the second law, or if inflation does not in
fact contradict the second law.
Thanks for any information.
Mike
.
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| User: "Jim Black" |
|
| Title: Re: Second law of thermodynamics and cosmic inflation |
17 May 2005 11:09:09 PM |
|
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Mike Christie wrote:
I found the following critique of the argument that the second law of
thermodynamics is in conflict with the non-maximal entropy in the
universe:
http://www.colorado.edu/philosophy/vstenger/Cosmo/face.txt
This makes sense to me. However, I have a question about this
statement:
"Likewise, the organization of matter into galaxies and planets does
not
require a violation of the second law of thermodynamics - now or in
the
past. Though the universe starts as a black hole of maximum entropy,
or
maximum disorder, it explodes into an expanding relativistic gas
having
less than its maximum allowable entropy."
As I understand it, quantum fluctuations in the original universe
were
inflated into the large scale structure we see around us. The
original
universe was at maximum entropy; the current universe is not, because
the inflation preserved the structure of the fluctuations. I don't
understand why this is not a violation. As I understand it (from a
layman's point of view) the second law is essentially a statistical
statement, so asserting that this is a violation would make no
difference to the scope of the second law in the universe since that
time. And given that we have gone from a state of maximal entropy to
one of less than maximal entropy, on the face of it why would this
not
be regarded as a conflict with the second law?
Entropy is defined as being proportional to the logarithm of the number
of possible states an object could be in, and still look pretty much
the same to us. A shuffled deck of cards has a higher entropy than a
sorted deck of cards. Since there's no way to unshuffle the deck of
cards without looking at the cards, the entropy of the deck of cards
can only increase. Of course, you might be tempted to look at the
cards; that would allow you to sort them, but it would increase your
own entropy. But that's another story.
If you have two shuffled deck of cards and one sorted deck, the system
may appear to be more orderly than the old one, but its entropy is
greater, because there are more possible arrangements of the cards.
Likewise, as the universe expanded, there were more possible
arrangements of its constituents. Since the maximum possible entropy
of the universe has increased, it appears more orderly now, even though
its entropy is, in fact, greater.
As far as the writer's comments about the energy in the universe being
created by a quantum fluctuation at Planck time, you should be aware
that such ideas are pure speculation. They are neither backed up by
science, nor are they a part of the Big Bang model, or of inflation.
No one has any idea what happened in those very first moments of the
universe. Extrapolations back to that time based on what we do know
are not yet possible, because the laws of physics as we currently
understand them are known to become contradictory under the conditions
that would have been present then. The laws of physics we have now are
merely good approximations to the true workings of nature, and until
those approximations are improved, the very beginning of the universe
will remain a mystery.
-- Jim Black
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