believed that this chaotic behavior would help smooth out the universe, like the action of a blender, and explain why it currently appears pretty much uniform in all directions. He dubbed it “Mixmaster” after a vegetable processor advertised heavily at the time.

Subsequent research, however, showed that the Mixmaster wasn’t quite as effective as first thought. Like broken thermostats in a massive apartment complex, it didn’t level off the temperatures in different spaces enough. Some sectors would be hotter and others colder—unlike what astronomers observe today. Furthermore, an important paper by Stephen Hawking and C. B. (Barry) Collins, published in 1973, placed a damper on ideas that the universe ever was less isotropic than it is now. Entitled, appropriately enough, “Why Is the Universe Isotropic?,” the article made a strong case that the chances of any anisotropic universe (such as the Mixmaster model) evolving into what we currently observe were effectively zero.

The authors of the paper suggested one way of handling the matter, an argument known as the anthropic principle. Established by Brandon Carter, the anthropic principle asserts that the universe is the way it is because if it were any different it couldn’t possibility support advanced life. Conditions in an anisotropic cosmos would be too nasty and brutish to allow reasonable planetary systems to form. If there were any deviation from flatness and isotropy, there wouldn’t be cognizant beings, and no one would live to tell the tale. It’s the same reason why no one has written a book called “True Tales from the Earth’s Core.” No one lives in the core and no one could write such a book. Hence, by anthropic reasoning, we all live on the planetary surface.

Many physicists have dismissed the anthropic argument as too philosophical, even too religious, in nature—a far cry from the careful results of calculations. It smacks, they feel, of the line in Candide: “All’s for the best in this best of all possible worlds.” At least one physicist, Max Dresden of Stony Brook, jokingly attributed it to a modern-day version of anglocentrism. Just as the Victorians thought

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement