Todd,

I think the best way to attract people to science is to expose the contradictions that exist in it - so science becomes curious, otherwise it is boring. Below you give the common understanding of the first and second law - let me take the opportunity to show where thermodynamics is mythological, in my view.

Todd Duncan wrote:
> Hi everyone,
>
> Just a little background context for those who aren't so familiar with
> thermodynamics:
>
> The second law of thermodynamics expresses our experience that energy tends
> to dissipate with time, spreading out into forms that are less and less
> accessible for use to drive any particular process of interest.

Yes this is the conventional view but I am afraid natural processes contradict
it. For instance, as a gas expands spontaneously (and isothermally), no energy
is dissipated - rather, the gas' energy remains the same. As an endothermic
chemical reaction proceeds, the opposite process takes place - heat is absorbed
from the surroundings and converted into energy of chemical bonds. Roughly
speaking, half of the processes in the Universe dissipate energy, the other half
do the opposite.

There is a line of argument parallel to the energy-dissipation one. As the gas
expands, people see this as a movement towards chaos - as if matter
desintegrates with no tendency to restore its "integrated" state again. But what
if the gas gets adsorbed on some surface, or the gas molecules react chemically
and form macroscopic structures? Again, there are too opposite and equal
tendencies - towards desintegration and integration. Note that the concepts may
prove purely anthropomorphic - most probably, Nature does not care much about
our perception of integration and desintegration.

> According to the law of conservation of energy (the first law of
> thermodynamics), the total amount of energy is always conserved, so when you
> lose energy in one form, you always gain the same amount somewhere else, in
> another form. For example, a ball at rest at the top of a hill has no
> kinetic energy (the energy associated with motion) but it has gravitational
> potential energy because it's up on a hill. If it rolls down the hill it
> loses some of its gravitational potential energy, but exactly the amount it
> loses is converted into other forms -- in this case kinetic energy and a
> little heat due to the friction between the ball and the surface of the
> hill. No matter what complicated interactions might occur between the ball
> and its environment (it might hit something and emit sound waves, create a
> spark and give off light, etc), the total amount of energy always stays the
> same if you are careful to keep track and add it all up.

This discovery of Julius Robert Mayer is incomparable. He suffered derision at
first and then they put him in a mental institution, just in case.

> So a rough way to think of the second law is that it adds an additional
> constraint on energy transfer -- even though we never lose any energy, we
> *do* lose the ability to use it for things like powering lights or running a
> car. More and more of the energy goes into the form of heat which cannot be
> entirely transferred back into a mechanical process like lifting a weight or
> propelling a car. So for example in the case of a steam engine we start
> with energy in a "concentrated" and "useful" form -- ie energy stored in the
> chemical bonds of the coal or some other fossil fuel -- and at the end of
> the process we have some of that energy transferred into the energy of
> motion of the locomotive, and also some of it transferred into heat (in the
> air, the metal of the engine, etc.). The energy that is in the motion of the
> train we can fairly easily transfer into other forms (such as gravitational
> potential energy when the train goes up a hill). But we can only get a
> limited amount of the heat energy to go back into driving the train. No
> energy has been *lost* (it's still around in some form), but some of it is
> now unavailable to perform the work we want to use it for.

The problem with this line of argument is that a structureless system (gas) is
dealt with, and the conclusions are regarded as universally valid. Structured
systems exhibit essentially different properties. Some substances undergo huge
phase transitions in response to a small chemical "signal" and can do a lot of
work in the process. For instance, there are macroscopic polymers which, as a
small amount of protons are added to the system, contract and lift a heavy
weight. Then we remove the protons and the polymer returns to its initial
stretched state. At the expense of what does the polymer do the work? In order
to save the second law, we must accept the the operator, as he adds and then
withdraws the protons, does this huge amount of work and the polymer only
"transfers" it towards the weight. But this assumption is not very reasonable
since the amount of protons is very small - one simply cannot do so much work by
dealing with such a little quantity. (Of course, there is a more rigorous
analysis of the effect).

> One of the very interesting topics in the foundations of physics for the
> last 150 years or so (and continuing today, as Pentcho is pointing out) has
> been the process of clarifying exactly what the second law says about nature
> and the conditions under which it applies. These ideas are important for our
> discussions of science integration because the second law plays a very
> dominant role in our everyday lives, and is closely tied to understanding
> the direction to time which is such an important part of our experience.

At the conference, among other things, I shall try to prove that that part of
the second law that deals with the direction of time has nothing to do with the
one forbidding the existence of perpetual motion machines of the second kind.

> Also, more information about the San Diego conference on the second law this
> summer is available at http://www.sandiego.edu/secondlaw2002/ in case anyone
> else is interested.

Pentcho