I fear that this episode may have disappointed over 10 million people—because there was no physics in it. It has biology: crickets chirping, entomology, and even a discussion of the neurobiology of alcohol’s effect on the brain. But apparently no physics.
Not so fast. Physicists work on biological problems all the time. So much so that at my own university, UCLA, there is a popular undergraduate major in biophysics. The fundamental equation of the episode, the rate of chirps of a cricket versus temperature, as Sheldon tells us, was given by A. E. Dolbear in 1890. Dr. Dolbear was a professor of physics at Tufts College, not biology. If you look carefully, you will see his equations describing temperature (in Fahrenheit) versus the number of cricket chirps per minute on the whiteboard in the boys’ apartment.
Of course it must be given separately for the common field cricket (FC) as well as the Snowy Tree Cricket (STC) and even Katydid (K). Each chirp is made when the cricket rubs its right forewing against its left forewing that is covered with ridges. In the process, the creation of this sound is much like running your fingernail over the teeth of a comb. For insects, the behavior is called stridulation. For a person strumming a comb, it is probably just called annoying.
The alert viewer no doubt noticed that one digit was different on the whiteboard in the episode than above. Also, Prof. Dolbear’s first name was Amos, not Emile. So much for the fact checking by the show’s consultant.
Modern biophysics looks different from Dolbear’s time. Physicists work on fundamental biological problems, such how a cell works using the special points of view and tools they they have been trained with. For example, proteins drive much of the activity of a cell and the subtle folding and unfolding of proteins that occur versus temperature are key to the cellular activity. Using statistical mechanics, non-linear dynamics, and laboratory techniques borrowed from the physical sciences, physicists are characterizing this key aspect of proteins and thereby understanding the inner workings of a cell. In another example, a friend of mine tries to understand how our inner ear manages to be such a good amplifier, allowing us to hear both extremely quiet and loud sounds entirely with a small hair that moves only one billionth of a meter and produces very little extraneous noise.
Several years earlier Dolbear had previously done very important work as a physicst. In 1885 he performed the first wireless telegraphy—several years before Guglielmo Marconi.
So Dolbear was the first to perform wireless telegraphy. Without wireless telegraphy we’d have no radio. Without radio we’d have neither the technology for television, nor the first sit-coms written for radio. And without either, we’d have no show The Big Bang Theory.