Seeing the Natural World with a Physicist’s Lens

One theme of this blog—and indeed, one theme of the 4^th edition of Intermediate Physics for Medicine and Biology—is the role of physics in the biological sciences. So imagine my delight when Russ Hobbie sent me a similarly themed article from the November 1 issue of the New York Times (a publication that, alas, has more readers than does my blog). Natalie Angier, who studied for two years at that little college down the road in Ann Arbor, wrote an article titled “Seeing the Natural World With a Physicist’s Lens.” Its thesis is that many biological systems have evolved to perfection, in the sense that physical laws don’t let them get any better. Angier writes

Yet for all these apparent flaws, the basic building blocks of human eyesight turn out to be practically perfect. Scientists have learned that the fundamental units of vision, the photoreceptor cells that carpet the retinal tissue of the eye and respond to light, are not just good or great or phabulous at their job. They are not merely exceptionally impressive by the standards of biology, with whatever slop and wiggle room the animate category implies. Photoreceptors operate at the outermost boundary allowed by the laws of physics, which means they are as good as they can be, period. Each one is designed to detect and respond to single photons of light—the smallest possible packages in which light comes wrapped…

Photoreceptors exemplify the principle of optimization, an idea, gaining ever wider traction among researchers, that certain key features of the natural world have been honed by evolution to the highest possible peaks of performance, the legal limits of what Newton, Maxwell, Pauli, Planck et Albert will allow. Scientists have identified and mathematically anatomized an array of cases where optimization has left its fastidious mark… In each instance, biophysicists have calculated, the system couldn’t get faster, more sensitive or more efficient without first relocating to an alternate universe with alternate physical constants.

Angier has written a lot of articles for the NYT, and has published several books, that will be of interest to readers of Intermediate Physics for Medicine and Biology. Enjoy!