Sunday, May 25, 2008

Blog 1: Lunch with C.N. Yang

I once had lunch with C. N. Yang, the Nobel physicist at Stony Brook University. He told me that the major difference between physics and biology was reflected by what each department taught. In the physics department, he told me, any physics professor can teach any course in physics, but in a biology department a geneticist can’t teach ecology, a botanist can’t teach zoology, an endocrinologist can’t teach entomology. I often thought about his remark. It implies that the world of physics is much more connected than the world of biology. In physics almost all laws can be determined from the behavior of atoms, molecules, larger objects on earth, and astronomical objects. This is why a “theory of everything” is at least a plausible theory to pursue for a physicist. But biology is filled with diversity because of the evolution of life and its millions of species and specialized niches for life to live and the interplay of living things in communities and the interplay of molecules in cellular systems. The closest thing to holding all of biology together is evolution by natural selection, but unlike physical laws there are no biological laws that distinguish an animal from a plant or a bacterium unless one gets down to the molecular level where genes and metabolism seem to have universal attributes that cut across all forms of life. For those who seek the mystical, living stuff is irreducible. For reductionists or materialists (in the sense of scientists who refuse to invoke supernatural processes) it is a matter of complexity.

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