Inspired by Scientific American’s special issue on Einstein’s theory of relativity, I recently posted a revised version of an essay on Einstein that I wrote a decade ago for The New York Times. To balance out that essay, which celebrates Einstein, I’ve decided to post an edited, updated version of another Times essay, which is critical, relatively speaking. John Horgan
In 1915, Einstein published his theory of general relativity, a radical new theory of of gravity. A decade earlier, Einstein’s so-called annus mirabilis, he wrote six papers that laid the groundwork for relativity and quantum mechanics, which together constitute the foundation for modern physics. As Scientific American states in its September issue, “no other scientist’s legacy looms larger over the 21st century than Einstein’s.”
Although I’m an Einstein fan, I feel compelled to deplore one aspect of his legacy: the widespread belief that science and common sense are incompatible. In the pre-Einstein era, T..H. Huxley, a.k.a “Darwin’s bulldog,” could define science as “nothing but trained and organized common sense.”
Quantum mechanics and relativity shattered our common-sense notions about how the world works. The theories ask us to believe that an electron can exist in more than one place at the same time, and that space and time--the I-beams of reality--are not rigid but rubbery. Impossible! And yet these sense-defying propositions have withstood a century’s worth of painstaking experimental tests.
As a result, many scientists came to see common sense as an impediment to progress not only in physics but also in other fields. “What, after all, have we to show for.....common sense,” the behaviorist B..F. Skinner asked, “or the insights gained through personal experience?”
Elevating this outlook to the status of dogma, the British biologist Lewis Wolpert declared in his 1992 book The Unnatural Nature of Science, “I would almost contend that if something fits in with common sense it almost certainly isn’t science.” Wolpert’s view is widely shared. When I invoke common sense to defend or--more often--criticize a theory, scientists invariably roll their eyes.
Scientists’ contempt for common sense has two unfortunate implications. One is that preposterousness, far from being a problem for a theory, is a measure of its profundity. Hence the appeal, perhaps, of dubious propositions like multiple-personality disorders and multiple-universe theories.
The other, even more insidious implication is that only scientists are really qualified to judge the work of other scientists. Needless to say, I reject that position, and not only because I’m a science journalist (who majored in English). I have found common sense--ordinary, non-specialized knowledge and judgment--to be indispensable for judging scientists’ pronouncements, even, or especially, in the most esoteric fields.
For example, Einstein’s intellectual heirs have long been obsessed with finding a single “unified” theory that can embrace quantum mechanics, which accounts for electromagnetism and the nuclear forces, and general relativity, which describes gravity. The two theories employ very different mathematical languages and describe very different worlds, one lumpy and random and the other seamless and deterministic.
The leading candidate for a unified theory holds that reality stems from tiny strings, or loops, or membranes, or something wriggling in a hyperspace consisting of 10, or 16 or 1,000 dimensions (the number depends on the variant of the theory, or the day of the week, or the theorist’s ZIP code). A related set of “quantum gravity” theories postulates the existence of parallel universes — some perhaps mutant versions of our own, like “Bizarro world” in the old Superman comics--existing beyond the borders of our little cosmos.
These theories are preposterous, but that’s not my problem with them. My problem is that no conceivable experiment can confirm the theories, as most proponents reluctantly acknowledge. The strings (or membranes, or whatever) are too small to be discerned by any buildable instrument, and the parallel universes are too distant. Common sense thus persuades me that these avenues of speculation will turn out to be dead ends.
Common sense--and a little historical perspective--makes me equally skeptical of grand unified theories of the human mind. After a half-century of observing myself and my fellow humans--not to mention watching lots of TV and movies--I’ve concluded that as individuals we’re pretty complex, variable, unpredictable creatures, whose personalities can be affected by a vast range of factors. I’m thus leery of hypotheses that trace some important aspect of our behavior to a single cause.
Over the past century, moreover, mind-science has been as faddish as teenage tastes in music, as one theory has yielded to another. Everything we think and do, scientists have assured us, can be explained by the Oedipal complex, or conditioned reflexes, or evolutionary adaptations, or a gene in the X chromosome, or serotonin deficits in the amygdala. Given this rapid turnover in paradigms, it’s only sensible to doubt them all until the evidence for one becomes overwhelming.
Ironically, while many scientists disparage common sense, artificial-intelligence researchers have discovered just how subtle and powerful an attribute it is. Over the past few decades, researchers have programmed computers to perform certain well-defined tasks extremely well; computers can play championship chess, calculate a collision between two galaxies, juggle a million airline reservations. But computers fail miserably at simulating the ordinary, experience-based intelligence that helps ordinary humans get through ordinary days. In other words, computers lack common sense, and that’s why even the smartest ones are so dumb.
Yes, common sense alone can lead us astray, and some of science’s most profound insights into nature violate it; ultimately, scientific truth must be established on empirical grounds. Einstein himself once denigrated common sense as “the collection of prejudices acquired by age 18,” but he retained a few basic prejudices of his own about how reality works. His remark that “God does not play dice with the universe” reflected his stubborn insistence that specific causes yield specific effects; he could never fully accept the bizarre implication of quantum mechanics that at small scales reality dissolves into a cloud of probabilities.
So far, Einstein seems to be wrong about God’s aversion to games of chance, but he was right not to abandon his common-sense intuitions about reality. In those many instances when the evidence is tentative, we should not be embarrassed to call on common sense for guidance.
Physics Titan Still Thinks String Theory Is "On the Right Track." See also my Q&As with physicists George Ellis, Carlo Rovelli, Garrett Lisi, Paul Steinhardt, Lee Smolin and Steven Weinberg--and my profile of Weinberg, which discusses at length the quest for a final theory of physics.