Big discoveries from little things

That's physicist Albert Michelson, at the University of Chicago in 1894, saying that fundamental physics was essentially finished. In the fifty years after Michelson's talk, physics discovered the following: special and general relativity, quantum theory, nuclear fission and the expansion of the universe. And it was just getting warmed up. The famously acerbic Wolfgang Pauli would have probably called Michelson's prediction as "not even wrong".

Michelson clearly was woefully wrong in saying that the main task of physics would henceforth simply be more accurate measurements. And yet it would be wrong to take him to task for a clearly mistaken view, for at least two reasons. Firstly, physics in 1894 explained an enormous range of phenomena. From Newtonian mechanics that explained everything from apples falling down to the motion of planets to thermodynamics which explained everything from the increase in disorder in physical systems to the practical workings of steam engines, physics clearly had proved itself to be a spectacularly successful science, so there was good reason to think that most of the fundamentals had been worked out. 

Secondly, the kinds of things physics was being unable to explain then could be seen as little more than annoying anomalies and exceptions; the behavior of glowing blackbodies, the slight anomaly in the motion of mercury around the Sun, the absence of the luminiferous ether. In fact, Michelson himself would perform an experiment just three years later, in 1887, that would lead to a very important negative result: the lack of detection of the ether that had been predicted as a medium for the propagation of light and other electromagnetic radiation which Maxwell had worked out.

Neither Michelson nor anyone else could have seen the profound new worlds hidden in these seemingly mundane anomalies. Problems with blackbody radiation led to the birth of Planck's quantum theory, and problems with the ether and with the anomalous orbit of Mercury led to Einstein's special and general theories of relativity. And at least in one sense Michelson's highlighting of more and more accurate measurements was spot on: the difference between the perihelion of Mercury predicted by Newton's theory of gravity and what was actually measured was tiny - Newton's prediction was off only by a millionth of one percent (which meant that Mercury would arrive at its perihelion only half a second later than what Newton predicted), but that little deviation hid a stunningly different and new view of nature that took Einstein's genius to uncover.

Rather than mocking Michelson's 1894 statement as a foolish failure of prediction or the product of tunnel vision, it's more important therefore to recognize what it implies. Firstly, it's clear that nobody and not just Michelson could have known how different the future of physics would be, giving currency to Niels Bohr's statement that prediction is difficult, especially about the future. But more importantly, it's enlightening to realize how seemingly mundane experimental anomalies can lead to completely new ways of looking at the world. 

In my view, the fifty years that followed Michelson's statement, although now rightly regarded as a triumph of theoretical physics, should be viewed as an even greater triumph of experimental physics. Both the old quantum theory invented by Planck and the new quantum theory invented by Heisenberg and others arose from small, anomalous observations in seemingly obscure and minor areas of physics. So did relativity. Without the exceedingly accurate measurement of the error in the predicted vs measured anomaly of Mercury's orbit, who knows how long it would have taken general relativity to come along.

The development of physics following Michelson's statement gives one hope that the biggest discoveries in science will continue to be hidden in some of the smallest discrepancies in experiment. This is especially true of biology where we are now in a position to detect very small differences in protein and gene expression. Experimentalists should keep on looking for minor anomalies in their observations; flies in the ointment; nagging little differences in numbers that should be explained by the existing theoretical framework but are not. Sometimes it will be nothing, often it will simply be a result of statistical error or random noise, but occasionally, just occasionally, it could be a glimpse of the crack of light from a door that opens on to a whole new world.