How do you calculate entropy change of diffusion? The system will become less organized but will also become cooler. hmm

many definitions to energy

what causes the potential difference to exist?

ie... electrical generation is still just em. The electricity is not the energy itself, but a conversion that is useable.

A hot peice of iron, versus a cold one; what's the difference?

Is Heat....a force (causally)?

So 2 different molecular structures?

To know the spectrum of each structure, then plotting each maximum capacity (to retain energy) is possible. Will they be different?

will each have a different resonance state?

different capacities?

are you basically offering the demon (maxwell) without the doors?

seems maxwell was thinking that each structure can retain different 'potentials' which means that the equilibriation may not be as many believe (meaning: perhaps the 'mental experiment' will share an anology that reveals a reality that is against the entropic intent, to equilibriate)

seems he, even way back when, knew that each structure will have different kinetic states at the same temperature and could them vibrating structures be isolated to show different potentials of each.

That is how i see it.

Now the idea that each structure can retain different resonances, converted to wavelength (photons), shares each can maintain different energy states, within the same environment.

In the idea of a perpetual motion example, it seems a flame is just that. "start it, feed it, (maintain the environment), and it will continue perpetually' (forever) (of course, hypothetically but as well logically)

Is that 'flame' a system, that is taking from the environment, and increasing the total state of 'heat' above the environments equilibriated state?

Of course it is.

ie.... there is no closed system in the universe, because there is no perfect vacuum anywhere in the universe and in many cases, once a 'reaction' has begun, it will continue in a manner of consuming from its environment "to continue"........

i look at the idea of a closed system being relative to the necessity of causality, not the parameters of the observers choice.

From what i gleaned, heat is generally considered to be translational motion of particles; ie the motion of the entire molecule. This in turn gives rise to rotational, vibrational, and electronic energy levels. These can be expressed in many different forms.

For example, in a low band-gap semiconductor there will be many free electron-hole pairs, storing a portion of the heat energy of the semiconductor.

I am trying to devise an experiment that would show how brownian motion can do work - and how thermal energy manifests itself in brownian motion.

Indeed, and this is why there is no such thing as truly perpetual motion. Heat will always escape and eventually there won't be enough heat to run any machine.

and yet each molecule is its own unit, correct?

i agree

what are they storing? ie.... in a bohr analogy, could it be the 'x' that causes a quantum jump (changing the state of the atom itself)?


sounds like fun

(hint) the process is universal


please, don't tell the sun that!

First, the second law is a statistical law only, and so it is possible to violate it over short periods. Second, I seriously doubt anyone could construct such a machine and have it function as advertised. The opening and closing of the partition is itself work and requires one to expend energy. It is not at all clear why the increase in pressure from adding one molecule to contraptoion would balance out the work requires to open and close the partition.

The supposed reduction in entropy seems to mean "the entropy of the gas", but the seocnd law applies to the gas and the machine as a collective system, and states that the overall entropy of the system should increase. It is definitely possible to segregate hot molecules from cooler ones, but doing so increases the overall entropy in the universe in most every case.

Third, I think the information required to be gathered is somewhat substantial for the system as a whole. You not only need to know the velocity the incoming particle, but you need to keep track of the velocity of every particle in the region of the partition to ensure that you open and close the trapdoor at the right time so that no molecues from the high pressure side escape.

It seems to me that even if you can get this very hypothetical machine to function in the end, it will breakdown, leaks will form in the high pressure side, eventually the second law will reassert itself. That is all in keeping with the way the second law works. It's definitely possible to reduce the entropy of a gas through work. If it were not, then we could never pressurize any gas and could never create a vacuum. The keys are (A) that the system as a whole gas and technology create more entropy that that system had before the sorting and (B) even with repsect to the container alone, the second law still seems to conspire against it, because the container's integrity will have a finite life without regular maintenance...and maintenance is itself just more work and only delays the inevitable failure.

Yes, however the motion of all these particles is averaged to find the temperature.

Its something to do with semiconductor physics - there are electron-hole pairs, when an electron falls into a hole it emits radiation.

Yes, as defined by fluctuation theorem.
http://en.wikipedia.org/wiki/Fluctuation_theorem

Well, the point of creating a perpetual motion machine is to decrease the entropy of the universe. Perhaps a perpetual motion machine of the second kind would reduce the entropy for a long amount of time - going against fluctuation theorem, but not really breaking laws of physics.

You only really need to have a greater probability of a molecule arriving from one side to pass through a 'gate'. Whether or not this requires information is another matter..

Yes! The point is that there is no true perpetual motion.

If you have a closed system with a machine like this, you will actually increase the entropy of the system by turning it on. Although at first entropy will be lowered, eventually the machine will break down and release all the heat it has transformed into motion/work. But, since the machine breaks down it releases an extra bit of heat, altogether increasing entropy.

but the Max-demon, is not observing the average... except to set the environment, then separate the 'units' based on their kinetic energy.

something?

please look up the Bohr Model to fill in the "holes" for ya

"what" is emitted?

then for EACH change of state, does the analogy share that a photon, measured and describe with E=hv, is what 'causes' the 'state' of the atom?

that be the point. (ie.... i don't see the electron 'storing' heat but rather the photon increasing the resonant "state" of the atom)

that means, to look at the Demon, then even in the SAME environment (temp), each different ATOM (or molecule) can retain a different 'state' enabling the observed variations of kinetic potential.

To create an electron-hole pair a certain amount of energy is required, known as the band-gap energy. This energy can be supplied by photons and heat, among other things. This frees an electron from which can then move around freely in the lattice and conduct electricity. This electron leaves behind a 'hole', or ion, which can recombine with an electron. Once this happens the potential energy that was temporarily 'stored' by the electron-hole pair is released in the form of heat or photons. This is at least the very simple version that I understand. After this you can have mid-states which involve impurities, intra-band transitions, multiplicity states, and then you have to assume all of this happens in solution and is affected by the environment.


Going back to the Demon, here is an example-
imagine that the earth is devoid of all erossive forces. There are no lakes, no forests, no winds, no glaciers or rivers to sculpt the land. There are however mountains, but for the purpose of the demonstration there are no tectonics and the mountains are static and do not grow. The earth is a rock that orbits the sun. Its temperature varies wildly at day and at night, much like the moon. The entropy of the earth has reached a peak- outside of the meteorites that strike the earth, there is no motion and no force to make disorder.

Now imagine that there is a perpetual motion machine on this rock. It can transform heat, without temperature differences, into work. The machine, a robot, will carve pieces of the mountains out and send them tumbling down the mountain sides, in order to create disorder. The robot, although it violates the second law by creating work (not energy) where there should be none, is also creating disorder. And although the robot is sturdily made it does eventually break down, and tumbles down the mountain itself. Once it lies at the foot of the mountain, twisted and mangled, it has restored all of the heat that it has before drawn in in order to do work. Entropy once again reigns, but now with the extra addition of all the rocks that have been carved out and sent down the mountain, crumbling and forming dust and debris; in other words the perpetual motion machine has created disorder.

However, it is equally possible for another robot to go in and collect and compact all the dust and debris and bring it back up the mountain. Since there are no other errosive forces on the planet, this decrease in entropy is permanent since there will be nothing to bring down gravitational potential of the mountains. Even though this robot eventually breaks down it has reduced entropy more than it will produce.

Of course, the robots could be solar-powered and do all of this as well, in which case this reduction in entropy is offset by the increase in entropy produced by the sun. The difference is that a maxwell's demon does not require any source of energy but ambient heat - meaning that the planet could be a closed system, not orbiting a sun, and still have work done on it and this work could be directed to reduce entropy. And with the absence of any other forces this change would be permanent.

The concept of doing work so it reduces entropy doesn't add up. If work is done entropy increases, the demon would have to be able to 'read' a molecule's energy and direction without expending energy.

That's a bit of a paradox, observation is by definition an exchange of energy, so the problem is: how does the demon (daemon) actually "do" anything, can it open and close a "molecule door" without using energy? When would it "know" to do this? The problem sort of defines itself away.

Dr Z,

i like an imagination but that was a weeee too much for me.

look into the golden ratio and natures shells (the pattern).

http://bookbuilder.cast.org/view_print.php?book=12332

the math for that

then use the above information shared and perhaps identify how energy combines to enable mass to build that pattern. Note the ratio and think of energy riding on mass, that is absorbed (reverse of 'S"), to continue that 'progression'

it is the same EXACT process that enables Nano tech molecules to 'grow'

(from the environment is where the energy comes from (and it aint pairs of electrons))