The famous Feynman Lectures on Physics hosted free for all by Caltech (and taking a peek at entropy . . . )
|December 7, 2013||Posted by kairosfocus under Education, Physics, science education, ID Foundations, thermodynamics and information|
Christmas is early this year.
Here are the famous Feynman Lectures on Physics (Vol II is forthcoming) hosted for free by Caltech.
A useful point of reference for one and all.
Just for fun, note here on on entropy, irreversibility and the rise of disorder:
Where does irreversibility come from? It does not come from Newton’s laws . . . . We already know . . . that the entropy is always increasing. If we have a hot thing and a cold thing, the heat goes from hot to cold. So the law of entropy is one such law . . . .
Suppose we have a box with a barrier in the middle. On one side is neon (“black” molecules), and on the other, argon (“white” molecules). Now we take out the barrier, and let them mix. How much has the entropy changed? It is possible to imagine that instead of the barrier we have a piston, with holes in it that let the whites through but not the blacks, and another kind of piston which is the other way around. If we move one piston to each end, we see that, for each gas, the problem is like the one we just solved. So we get an entropy change of Nkln2, which means that the entropy has increased by kln2 per molecule. The 2 has to do with the extra room that the molecule has, which is rather peculiar. It is not a property of the molecule itself, but of how much room the molecule has to run around in. This is a strange situation, where entropy increases but where everything has the same temperature and the same energy! The only thing that is changed is that the molecules are distributed differently. We well know that if we just pull the barrier out, everything will get mixed up after a long time, due to the collisions, the jiggling, the banging, and so on . . . .
Everyone knows that if we started with white and with black, separated, we would get a mixture within a few minutes. If we sat and looked at it for several more minutes, it would not separate again but would stay mixed. So we have an irreversibility which is based on reversible situations. But we also see the reason now. We started with an arrangement which is, in some sense, ordered. Due to the chaos of the collisions, it becomes disordered. It is the change from an ordered arrangement to a disordered arrangement which is the source of the irreversibility.
It is true that if we took a motion picture of this, and showed it backwards, we would see it gradually become ordered. Someone would say, “That is against the laws of physics!” So we would run the film over again, and we would look at every collision. Every one would be perfect, and every one would be obeying the laws of physics. The reason, of course, is that every molecule’s velocities are just right, so if the paths are all followed back, they get back to their original condition. But that is a very unlikely circumstance to have. If we start with the gas in no special arrangement, just whites and blacks, it will never get back.
Sounds familiar? It should . . .
Here is Sewell again:
. . . The second law is all about probability, it uses probability at the microscopic level to predict macroscopic change: the reason carbon distributes itself more and more uniformly in an insulated solid is, that is what the laws of probability predict when diffusion alone is operative. The reason natural forces may turn a spaceship, or a TV set, or a computer into a pile of rubble but not vice-versa is also probability: of all the possible arrangements atoms could take, only a very small percentage could fly to the moon and back, or receive pictures and sound from the other side of the Earth, or add, subtract, multiply and divide real numbers with high accuracy. The second law of thermodynamics is the reason that computers will degenerate into scrap metal over time, and, in the absence of intelligence, the reverse process will not occur; and it is also the reason that animals, when they die, decay into simple organic and inorganic compounds, and, in the absence of intelligence, the reverse process will not occur.
The discovery that life on Earth developed through evolutionary “steps,” coupled with the observation that mutations and natural selection — like other natural forces — can cause (minor) change, is widely accepted in the scientific world as proof that natural selection — alone among all natural forces — can create order out of disorder, and even design human brains, with human consciousness. Only the layman seems to see the problem with this logic. In a recent Mathematical Intelligencer article [“A Mathematician’s View of Evolution,” The Mathematical Intelligencer 22, number 4, 5-7, 2000] I asserted that the idea that the four fundamental forces of physics alone could rearrange the fundamental particles of Nature into spaceships, nuclear power plants, and computers, connected to laser printers, CRTs, keyboards and the Internet, appears to violate the second law of thermodynamics in a spectacular way.1 . . . .
What happens in a[n isolated] system depends on the initial conditions; what happens in an open system depends on the boundary conditions as well. As I wrote in “Can ANYTHING Happen in an Open System?”, “order can increase in an open system, not because the laws of probability are suspended when the door is open, but simply because order may walk in through the door…. If we found evidence that DNA, auto parts, computer chips, and books entered through the Earth’s atmosphere at some time in the past, then perhaps the appearance of humans, cars, computers, and encyclopedias on a previously barren planet could be explained without postulating a violation of the second law here . . . But if all we see entering is radiation and meteorite fragments, it seems clear that what is entering through the boundary cannot explain the increase in order observed here.” Evolution is a movie running backward, that is what makes it special.
THE EVOLUTIONIST, therefore, cannot avoid the question of probability by saying that anything can happen in an open system, he is finally forced to argue that it only seems extremely improbable, but really isn’t, that atoms would rearrange themselves into spaceships and computers and TV sets . . . [NB: Emphases added. I have also substituted in isolated system terminology as GS uses a different terminology. Cf as well his other remarks here and here.]
Muy interesante. END
PS: Taking walks . . .