Re: The 2nd Law of Thermodynamics - Irrelevant to Origins

Paul J Gans wrote:
David Ewan Kahana <dek@xxxxxxx> wrote:

gesres@xxxxxxxxxxxxxxx wrote:
<<saying that the 2nd law of thermodynamics doesn't apply to the earth.
And that would mean that the 2nd law of thermodynamics is useless.
Obviously, the 2lot does apply to open systems. >>

That's silly. The 2nd law doesn't apply to the earth as a whole, but
it does apply to closed systems within the earth.

There is no such thing as a closed system ... this is
a theoretical idealization. Nevertheless, there exists
a second law of thermodynamics, and it applies to the
earth as a whole, as it does to all systems in nature.

No restriction to closed systems is necessary, or
else thermodynamics would be of very little use.

There are statements of the law that are special
to closed systems, and this leads to a lot of
confusion on the question.

Creationists do sometimes try to construct arguments
against the possibility of evolution in an open system
like the earth, on the basis of statements of the second
law which are special to closed, thermally isolated systems.
In such a case it's appropriate to point out that the
formulation of the law they are using is not applicable,
because it does not take into account fluxes of energy
and entropy across the boundaries of the system.

Here are some fairly general statements of the
second law, which make it clear that it applies
to all systems, whether open or closed.

Heat cannot of itself pass from a colder to a hotter body.
- Clausius

It is impossible for any device that operates on a cycle to
receive heat from a single reservoir and produce a net amount
of work.
- Kelvin-Planck

Every physical or chemical process in nature takes place in
such a way as to increase the sum of the entropies of all the
bodies taking any part in the process. In the limit, i.e. for
reversible processes, the sum of the entropies remains
unchanged.
- Planck

A transformation whose only final result is to transform into
work heat extracted from a source which is at the same
temperature throughout is impossible.
- Fermi

A transformation whose only final result is to transfer heat
from a body at a given temperature to a body at a higher
temperature is impossible.
- Fermi

The total entropy of a system and its surroundings
always increases for a spontaneous process; and
for a spontaneous process at a given temperature,
the change in entropy of the system is greater than
the heat divided by the absolute temperature.
- Ebbing

The sum of the entropy changes of a system and its
exterior can never decrease.
- Prigogine


Here are some more special statements of the law including
some for (hypothetical) isolated systems:

In isolated systems exchanging neither energy nor
matter with the outside world, their exists an inequality,
dS/dt >= 0, which ascertains the existence of a function,
the entropy S, which increases monotonically until it
reaches its maximum at the state of thermodynamic
equilibrium.
- Prigogine

Nature seeks to maximize the entropy [condition: isolated system]
- Nordholm

Nature seeks to minimize the free energy [condition: system of
fixed volume exchanging energy with its surroundings acting as
a thermal reservoir]
- Nordholm

David

Yup, but many of those are essentially the same thing.
And of course all of them are deducible from any one
of them.


Of course, though carrying out the proofs
of the equivalence of all the statements will
require doing some real math. Especially
if I'ld included the one due to Caratheodory.

And of course, this is only a tiny subset of the
many possible ways of stating the second law
without referring to closedness or openness
of the systems in question at all.

Ain't thermo grand!


It certainly is.

I think that we should harp on a major point. Large flows
of energy create structure. Or put another way, large
flows of energy make things move *away* from equilibrium.

These flows occur so often and so obviously on earth that
we don't even think of them.

For example, we think of water as "seeking its own level"
but anybody who has watched the ocean knows very well that
water in the ocean spontaneously rises up above sea level
in what we call "waves". And of course there is an energy
source driving that.

As another example, consider lightning. It too is, of course,
driven by an energy source.

Examples could be endlessly multiplied. Indeed I'd think
it useful to have such a list in the talk.origins FAQ.

In other words, why fight the battles on the creationist's
turf? The Second Law is non-trivial in application and
almost always neither the creationist nor the evolutionist
know the details (or the math.)

So when questions of this sort come up I suggest responding
with examples of the spontaneous formation of structure.
Stone bridges are another example. Snowflakes are another.



It's a very good idea to make up such a list. There was a
beautiful example I saw recently, in which non-trivial
structure formation was shown experimentally in a system
as simple as a mixture of hard sphere gases involving
spheres of two different sizes. The excluded volume
effect is enough to allow for phase transitions in which
the large spheres sort themselves towards the outside
of a vesicle containing the mixture, while the small spheres
congregate in the center.

Since interactions could be shown to be pure
repulsive in the system in question, it was a clear
case in which an increase of entropy drives
formation of simple structure by minimizing the
Gibbs free energy of the system.

I forget the reference, now, but it should be easy
enough to find.

David

.

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