Friday, December 16, 2005

Is our universe natural?

If any system should be natural, it’s the universe. Nevertheless, according to the criteria just described, the universe we observe seems dramatically unnatural. The entropy of the universe isn’t nearly as large as it could be, although it is at least increasing; for some reason, the early universe was in a state of incredibly low entropy. And our fundamental theories of physics involve huge hierarchies between the energy scales characteristic of gravitation (the reduced Planck scale, 1027 electron volts), particle physics (the Fermi scale of the weak interactions, 1011 eV, and the scale of quantum chromodynamics, 108 eV), and the recently-discovered vacuum energy (10-3 eV). Of course, it may simply be that the universe is what it is, and these are brute facts we have to live with. More optimistically, however, these apparently delicately-tuned features of our universe may be clues that can help guide us to a deeper understanding of the laws of nature.

source: Cosmic Variance
Sean Carroll's article: "Is our universe natural?"

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