The Physics of DNA: Erwin Schrodinger's Psychic Network

       Part of the infuriating success of physicists comes from their ability to perform Sherlock-Holmes-like feats of deduction to come up with astoundingly accurate answers to seemingly unanswerable questions.  Perhaps the most famous example is Enrico Fermi's estimate of the power in kilotons of the first nuclear test explosions, which he accurately deduced by letting bits of torn paper flutter in the wind as the blast shockwave passed by.  Other examples of these fun "Fermi problems" include estimating how long you could run a light bulb using oil donated by one deceased dinosaur, or how many piano tuners there are in Chicago -- the point is to take a stab at an answer without any research, just using simple guesses.  Schrodinger himself used this skill to ponder the nature of genetics in a highly-influential book called "What is Life", written after he'd established himself as a giant in the early days of quantum mechanics.  (Schrodinger, as you may recall, is the cat-in-a-box guy, and is one of the two or three guys who started all of Quantum Mechanics.)

       In his book, written in 1944, he took a stab at guessing what might be behind the inheritance of genetic information (how exactly our traits get passed down from our parents), and got it pretty much right, from thought alone -- no experiments, no microscopes, he just reasoned out what sort of mechanism might be responsible, and what he described is instantly recognizable as DNA.  Keep in mind, before he and his friends invented quantum mechanics, nobody could explain why molecules of any sort (much less DNA) were even physically stable.  Hell, only 40 years earlier, Einstein provided the first actual evidence that *atoms exist*.  When Schrodinger wrote this book, the idea that purely physical stuff inside your body could be responsible for genetic inheritance was not such a safe bet.  There was at that time some initial research on DNA, but people didn't know what it was for -- some thought it might just be scaffolding, to help hold the cell up, a mistake akin to thinking the wall studs in your house could be used to check your email.

       Schrodinger's book inspired countless other physicists-turned-biologists.   (Incidentally, towards the end of the book Schrodinger also turns his attention to consciousness, one of the Pillars of Overambitious Theories of Everything that I discuss in my article "I've got a theory".)  His prediction that genetic inheritance comes from an "aperiodic crystal" (poetic, ain't it?) launched a whole generation of physics students to ponder whether biology might be a bit more fun to pursue.  He in turn was inspired by Max Delbruck, the father of molecular biology, who was probably the very first physicist-turned-biologist.  All you mol-bio students out there struggling to clone fruit flies in a petri dish (or whatever the hell you do) might be surprised to know that the scientist who started your field got his PhD in astrophysics.  Delbruck was a promising young theorist, working with the physics giants of the day like Niels Bohr and Wolfgang Pauli, before converting to biology.  He went on to found the molecular genetics group at Caltech, which became the center of early work on DNA -- essentially his lab was the first group to examine how DNA works (mutations and the like), accomplishments for which Delbruck won the Nobel Prize in 1969.  Delbruck himself was inspired to think about biology even before World War II, by the great physicist Niels Bohr (of the Bohr-model-of-the-atom fame).  You B-minus physics students out there might snicker about the "Bohr model" being aptly named, but that is why you're getting a B minus and Delbruck won the Nobel Prize.  You can trace a direct line of inspiration from Bohr down to Delbruck then to Schrodinger, a line that would then lead to perhaps the greatest discovery in 20th century biology.