Text 534, 111 rader
Skriven 2004-10-26 22:51:00 av Guy Hoelzer (1:278/230)
Ärende: Re: the why question
============================


Tim,

This has been a useful discussion for me, even though we haven't come to a
perfect agreement.  Thanks.

in article cllqu1$1u0c$1@darwin.ediacara.org, Tim Tyler at tim@tt1lock.org
wrote on 10/26/04 8:36 AM:

> Guy Hoelzer <hoelzer@unr.edu> wrote or quoted:
>> in article clc03g$24sv$1@darwin.ediacara.org, Tim Tyler at tim@tt1lock.org
>>> Guy Hoelzer <hoelzer@unr.edu> wrote or quoted:
>>>> in article cl65so$b0p$1@darwin.ediacara.org, Catherine Woodgold at
> 
>>>>> If you mean "maximizing, under the constraint of
>>>>> following all the other physical laws" -- is that really
>>>>> any different from just plain "following all the other
>>>>> physical laws"?  What exactly is your claim?
>>>> 
>>>> My claim is that this IS a physical law.  There is an ongoing debate about
>>>> whether this claim constitutes a fourth law of thermodynamics, or whether
>>>> it
>>>> can be accommodated by a minor modification of the way we articulate the
>>>> second law.  I am in favor of the latter.
>>> 
>>> Several points here:
>>> 
>>> I wouldn't even describe the second law of thermodynamics as a physical
>>> law.  It's not a "law" - since it permits exceptions
>> 
>> Our traditional understanding of a static 2nd law explicitly applies to to
>> closed systems, and there are no exceptions permitted or observed, AFAIK.
> 
> Violations of the second law are commonplace on small scales - e.g. see:
> 
> ``One of the most important principles of physics, that disorder, or
>   entropy, always increases, has been shown to be untrue.
> 
>   This result has profound consequences for any chemical or physical
>   process that occurs over short times and in small regions
>  
>   Scientists at the Australian National University (ANU) have carried out
>   an experiment involving lasers and microscopic beads that disobeys the
>   so-called Second Law of Thermodynamics [...]''

This is not inconsistent with my claim, because there cannot be such a thing
as a truly closed system inside of the universe.  Closure can only be
approximated at small scales.  In response to the interpretation of these
empirical results I can only predict that the apparent failure of the 2nd
law is due to either the cryptic openness of their system or a
misunderstanding of what went on inside.  If this prediction is false, then
so is my current paradigm.
 
>> So I do see it as a universal and physical law, albeit one that
>> appropriately leads to statistical sorts of models. [...]
> 
> It's no more a physical law than evolution is.  Evolution and
> the second law are *consquences* of the physical laws (and the
> initial conditions) - but they are not themselevs necessary to
> explain what happens in the world.  I.e. The physicist's "theory
> of everything" would make no mention of either concept.

I expect otherwise.  Do you know of any instances where someone has tried,
let alone succeeded, in deriving the second law from putatively more
fundamental physical laws?  Would you agree that your view of the 2nd law as
consequence is an unfounded (unproven? untested?) speculation at this point?
 
>>> Care to say what you have in mind for a modification of the second law?
>> 
>> I think that I've posted this before on sbe.  I would offer the following
>> conjecture as a universal physical law:  "Thermodynamics causes an
>> exploration of paths (e.g., mechanisms, processes) affecting the rate of
>> entropy gain within closes systems (I suspect that the whole universe is the
>> only truly closed system), and favors those that maximize this rate."
>> Favoring these paths is equivalent to the structure of the universe taking
>> the path of least resistance as it "falls" toward higher entropy levels.
> 
> In some respects, that seems weaker than the second law - in that it
> doesn't explicitly say that entropy can't decrease.

The static second law is completely subsumed by the one I stated in today's
universe due to the scale and particulate nature of the universe, and
because it implies that the absence of bias favoring decreasing universal
entropy.  I would, however, concede that this particular statement would
allow for instances of decreasing universal entropy during the earliest
moments following the big bang (if there was one).
 
> I agree with the spirit of this sort of idea - though as we've
> discussed, I have some issues about whether such maximisation
> will necessarily happen in the short term - since organisms
> can act to conserve resources in the short term under some
> circumstances - as a squirrel burying a nut demonstrates.

To reiterate my previous response, if you think that this is a counter
example to my argument, then you have not fully appreciated the argument.
Everything that the squirrel does increases universal entropy.  The law I
and many others are advocating as conjecture does not imply anything about
those activities that do not occur, such as eating every nut as soon as
possible.

Cheers,

Guy
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