Martin Posted December 29, 2009 Share Posted December 29, 2009 (edited) The cosmicweb computer simulations are the work of Andrey Kravtsov. Truly wonderful. There are some longer ones which were shown by Smoot in his TED talk. Google "Smoot TED" for a great 18 minute lecture on structure formation by a Nobel cosmologist. As I recall Kravtsov's computer animations show the condensation of dark matter only. Since there is is so much more of it, it dominates the process of structure formation. Penrose gave a talk at Cambridge in 2005 where he explained that the entropy of the gravitational field is defined differently from the entropy of, for example, a gas. In the case of a gas, uniformity = high entropy. The gas spreads out to fill the box uniformly and entropy increases. In the case of the gravitational field, uniformity is very unstable. Because of universal attraction. Clumping breeds more clumping. It is the opposite of gas intuition. In the gravitational field, uniformity = low entropy. The combination of geometry and matter naturally kinks and curdles and condenses (into cobwebby structure in this case) and entropy increases. I don't agree with all of Penrose talk because some parts were exceedingly speculative but his diagrams explaining entropy and the second law as applied to cosmology were pretty effective. http://www.newton.ac.uk/webseminars/pg+ws/2005/gmr/gmrw04/1107/penrose/ There are some Youtube videos of him giving essentially the same talk somewhere in the US in 2007 This is Penrose' brief illustrated discussion of the entropy concept: Here is a 9-minute segment where he explains that the entropy of gravity is different It's a popular non-technical talk. All on a pictorial/intuitive level. Don't watch unless you enjoy or at least have patience with that type of presentation. Edited December 29, 2009 by Martin 1 Link to comment Share on other sites More sharing options...
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