For more than two centuries after Newton published his theories of space, time, and motion in 1687, most physicists were Newtonians. They believed, as Newton did, that space and time are absolute, that force causes acceleration, and that gravity is a force conveyed across a vacuum at a distance. Since Darwin there are few professional biologists who are not Darwinians, and if most psychologists no longer call themselves Freudians, few doubt that there is an unconscious or that sexuality plays a big role in it. So as we celebrate the 100th anniversary of Einstein’s great discoveries, the question arises: How many professional physicists are Einsteinians?
The superficial answer is that we all are. No professional physicist today doubts that quantum theory and relativity theory have stood up to experimental tests, but the term “Einsteinian” does not exist. I’ve never heard or read it. Nor have I ever encountered any evidence for a “school of Einstein.” There is a community of people scattered around the world who call themselves relativists, whose main scientific work centers on general relativity. But relativists make up only a tiny minority of theoretical physicists, and there is no country where they dominate the intellectual atmosphere of the field.
Strange as it may seem, Albert Einstein, the discoverer of both quantum and relativity theory, and hence clearly the preeminent physicist of the modern era, failed to leave behind an intellectual following with any appreciable influence. Why most physicists followed other leaders in directions Einstein opposed is a story that must be told if this centennial year is to be other than an empty celebration of a myth, unconnected to the reality of who Einstein was and what he believed in.
Physicists I’ve met who knew Einstein told me they found his thinking slow compared with the stars of the day. While he was competent enough with the basic mathematical tools of physics, many other physicists surrounding him in Berlin and Princeton were better at it. So what accounted for his genius? In retrospect, I believe what allowed Einstein to achieve so much was primarily a moral quality. He simply cared far more than most of his colleagues that the laws of physics should explain everything in nature coherently and consistently. As a result, he was acutely sensitive to flaws and contradictions in the logical structure of physical theories.
Einstein’s ability to see flaws and his fierce refusal to compromise had real repercussions. His professors did not support him in his search for an academic job, and he was unemployed until he found work as a patent inspector in Bern, Switzerland. The problem was not just that he skipped classes. He saw right through his elders’ complacent acceptance of Newtonian physics. The young Einstein was obsessed with logical flaws that were glaringly obvious, but only to him. While the great English physicist Lord Rayleigh said he saw “only a few clouds on the horizon” remaining to be understood, the 16-year-old Einstein wondered what would happen to his image in a mirror if he traveled at the speed of light.
From the outset, Einstein’s single goal in science was to discover what he called theories of principle. These postulate general rules that all phenomena must satisfy. If such theories are true, they must apply universally. In his study of physics he identified two existing theories of principle: the laws of motion set out by Galileo and Newton and the laws of thermodynamics. The basic principle of the first is the relativity of uniform motion, that the speed of your own unchanging motion is impossible to detect. Einstein’s discovery of special relativity came from 10 years of meditation on how to reconcile the relativity of motion with James Clerk Maxwell’s theory of electromagnetism, which describes the propagation of light.
While he mused about electromagnetism, Einstein made thermodynamics the focus of his early work. He began by following the Austrian physicist Ludwig Boltzmann, who argued that the laws of thermodynamics could be derived from applying statistics to the motion of atoms. This view was unpopular at the time because many influential professors did not believe matter was made of atoms. They instead regarded matter as continuous. Einstein’s work led to his demonstration, in 1905, that Brownian motion—the incessant, jerky movements of pollen grains or other tiny objects immersed in liquid—offered a proof of the existence of atoms.
At the same time, Einstein applied Boltzmann’s approach to thermodynamics to electrodynamics. This led to his discovery of the photon, a discrete packet of electromagnetic energy, and to the realization that such a packet must be both a wave and a particle. Although Einstein was thus the discoverer of quantum phenomena, he became in time the main opponent of quantum mechanics. By his own account, he spent far more time thinking about quantum theory than he did about relativity. But he never found a theory of quantum physics that satisfied him.
There are by now only a small minority of physicists who think Einstein was right to reject quantum theory as the foundation of our scientific description of nature. No theory has been more successful at explaining a vast array of experimental data. It is the basis for our understanding of virtually all of physics, with the possible exception of gravity and cosmology.
Einstein was willing to concede that quantum mechanics explains the recorded behavior of the subatomic world, but he was convinced it had two flaws. First, it fails to give precise predictions for the outcomes of individual processes. Instead, it gives only statistical predictions. To check them, one must do an experiment many times and compare the resulting distributions of outcomes with the predictions. Second, quantum theory fails to give an objective picture of the world that is unconnected to our role as observers. The formulas of quantum theory correspond to our actions in preparing experiments and measuring their outcomes. Einstein objected to this because he believed strongly that physics should provide a picture of nature “as it is in itself.”
After 1930, virtually all of Einstein’s colleagues were certain that the revolution was over and that physics was nearly complete. Nearly alone in his stance, Einstein saw the quantum as only a stepping stone to the real thing, which he continued to search for all the rest of his life.
