Regarding complementary and alternative medicine:
The sciences give a mostly coherent understanding of the world. Mostly coherent. [They do] give an understanding of the possible, the probable, the improbable and the impossible. Most of the sciences, unlike parts of medical science, are not concerned with the impossible. There is not complementary and alternative physics, or chemistry, or biochemistry, or engineering. These disciplines compare their ideas against reality, and, if the ideas are found wanting, abandoned. Perpetual motion is not considered seriously by any academic physicist; if perpetual motion were an alternative medicine it would be offered at a Center by a Harvard Professor of Medicine.
—Dr. Mark Crislip, infectious disease specialist, at Science-Based Medicine, April 8, 2011