http://www.cis.org.uk/forum/categories/physics-cosmology--maths/feed.rss Thu, 17 May 12 02:03:27 +0100 Physics, Cosmology & Mathematics en-CA http://www.cis.org.uk/forum/discussion/35/did-the-american-journal-of-physics-errs Tue, 24 Jan 2012 12:26:12 +0000 davidmihjn 35@/forum/discussions
“When creationists say, as they frequently do, that the theory of evolution contradicts the Second Law of Thermodynamics, they are telling us no more than that they don’t understand the Second Law (we already knew that they don’t understand evolution). There is no contraction, because of the sun!” (Richard Dawkins, The Greatest Show on Earth: The Evidence for Evolution, p. 415)

The Deputy Director of the National Center for Science Education, Glenn Branch, said that I was wrong and cited an article by Emory F. Bunn titled, “Evolution and the second law of thermodynamics,” published in American Journal of Physics [(2009) 77(10):922-925]. This article does indeed present calculations involving the sun showing that evolution does not violate the second law.

I think the American Journal of Physics erred in publishing this article it for two reasons.The first reason is that the insight evolution violates this law comes from biologists, and only biologists are qualified to discuss it competently. The second reason is that the author has an understanding of the second law that is different from my understanding of it. One of us must be wrong.

If a gas in a container is connected with a valve to a vacuum and the valve is opened, the gas will flow into the empty container. There is more knowledge of the location of the gas molecules in the small volume than in the large volume. There is an increase in disorder or a decrease in complexity. Entropy is another word for order. Entropy always decreases in nature, according to the second law.

If a gas in a container has a piston that can compress the gas, an animal can increase the complexity of the gas by pushing the piston. This does not violate the second law because the gas is not an isolated system. The idea that the complexity of the gas increases because the complexity of the animal decreases by a greater amount strikes me as being flat out wrong. The idea of calculating the decrease of the entropy of the animal and showing it is greater than the increase of the entropy of the gas strikes me as absurd. I don’t see any difference between such a calculation and the calculation offered by Emory F. Bunn.

Statistical mechanics explains why a gas will fill up a container. If a gas consists of N molecules, there are N! = N x (N - 1) x (N - 2)…  possible ways the molecules can be distributed in the container. The chance of getting any particular distribution is 1 in N!. I don’t know how to complete the proof. But I know Maxwell’s distribution of velocities in a gas and the bell-shaped curve are derived using Stirling’s approximation: log N! = Nlog N.

The primary structure of a large protein can have 600 amino acids. There are 20 different kinds of amino acids. Biologists imagine that the 600 amino acids are non-interacting particles, just like in a gas. Just as in statistical mechanics, biologists ask how many different ways there are of arranging 600 amino acids? The answer is 600 to the 20th power instead of N!. Thus, it is impossible to get a protein by random chance since there is only 3 billion years available for the protein to evolve. This is why biologists say evolution violates the second law. It is the same kind of reasoning that explains why a gas will fill up the entire container.

]]> http://www.cis.org.uk/forum/discussion/12/global-warming-confirmed-by-independent-study Wed, 26 Oct 2011 14:45:01 +0100 AnthonySmith 12@/forum/discussions
http://www.bbc.co.uk/news/science-environment-15373071
http://www.bbc.co.uk/news/science-environment-15400748

The study was set up in the wake of the "Climategate" affair, with funding from organisations that do not agree with climate change. But it seemed to confirm the previous consensus, that global warming is a reality.]]>