15 December, 2005Issue 5.1Science

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Everyone Loves Einstein

Jacob Foster

John Stachel (ed.)
Einstein’s Miraculous Year: Five Papers That Changed the Face of Physics
Princeton University Press, 2005
248 pages
ISBN 0691122288

The rough contours of the story are, by now, a commonplace. In 1905, everything changed. The journal Annalen der Physik published five papers by an academically unaffiliated patent clerk named Albert Einstein—papers that argued persuasively for the existence of atoms, overturned commonsense Newtonian notions of time and simultaneity, and suggested that light was actually composed of the tiny units or quanta we now call photons. Jump forward one hundred years, and that patent clerk (or rather the amusing old man he was to become) is one of the most recognizable icons of our time, his unruly mop of white hair an essential badge of genius. Students—not just the terminally unhip physicists who emulate him in their lack of socks and disordered dress—decorate countless dorm rooms with his impish face. Time magazine even went so far as to proclaim him Person of the 20th Century. In the traditional hagiography, the young Einstein is the ultimate underdog, coming from nowhere to storm the gates of orthodoxy and re-imagine the physical universe; the old Einstein is more sage than scientist, left behind by his own revolution and wandering the streets of Princeton like Walter Matthau in I.Q.—charming, to be sure, but mostly harmless.

As we celebrate the centenary of his world-changing discoveries, it is the old Einstein that dominates the iconography. Indeed, it is Einstein-as- wise-old-man who gazes from the cover of the 2005 edition of Einstein’s Miraculous Year, Princeton University Press’s lovely annotated collection of the five seminal papers—a treat supplemented by explanatory essays, two fine introductions by John Stachel of Boston University (perhaps the greatest living Einstein expert), and a foreword by Oxford’s own Roger Penrose. With no disrespect to cover illustrator Shirley Breuel intended, old Einstein is a mistake here. Einstein’s Miraculous Year is a rare tribute to the one man no one invited to the centenary: the young Einstein.

Stachel’s achievement lies in disentangling young Einstein from the forest of mythology that has sprouted up around him. The icon of old Einstein—what Stachel calls ‘Einstein as aged sage and saint of legend’—has so obscured Einstein the man that Stachel’s introductory essays will come as a bracing surprise even to those familiar with the Einstein story. The first introduction, written specially for the centenary edition, vigorously debunks the myth of Einstein as a counterculture intellectual, chafing under the strict Teutonic academic establishment.

Stachel replaces the purely anti-authority Einstein (who did tend to say things like ‘Long live impudence’) with a more subtle, ‘polarized’ individual, torn between an intense individualism and an equally intense desire for the approval of leaders in his field. Stachel quotes a poignant letter Einstein wrote after the eminent Paul Drude rejected his overtures: ‘From now on I’ll no longer turn to such people, and will instead attack them mercilessly in the journals, as they deserve. No wonder little by little one becomes a misanthrope.’ What young academic hasn’t uttered such words in exasperation? The chief culprit in suppressing this vulnerability turns out to have been Einstein himself—the old Einstein—whose reminiscences emphasise his early independence at the expense of his perfectly human ‘longing for recognition and … vulnerability to slights.’

Stachel’s discussion of Einstein’s creative process is equally illuminating. Einstein’s creativity seems to have required periods of solitude interspersed with interaction—not collaboration—with peers. His way of thinking was highly non-verbal, and rested on strongly developed physical intuition. This physical intuition, as Stachel emphasizes, was ‘visual and muscular.’ Hence Einstein’s frequent use of gedanken or thought experiments, the most famous of which is no doubt his image of ‘chasing after a light ray at the speed of light.’ But such insights, no matter how profound, are useless unless translated into mathematics and the written word, and for this task Einstein depended on so-called ‘sounding boards’ with whom he would discuss his various ideas, digesting his visual and kinesthetic concepts into a form accessible to others.

This process no doubt explains Einstein’s particular lucidity in his more ‘revolutionary’ papers, especially ‘On the Electrodynamics of Moving Bodies,’ which unveils the theory of special relativity. Unlike the other papers of this collection, which require some familiarity with physics, ‘On the Electrodynamics of Moving Bodies’ can be enjoyed by any lay reader with a comfortable grasp of high school algebra. I should also note that—in profound contrast to most contemporary physicists, who publish at an extraordinarily rapid pace—Einstein was a ruminative thinker, and all five of his ‘great papers’ were the result of many years of steady intellectual effort.

On the subject of collaboration, Stachel disposes handily of the faddish theory that Einstein developed at least some of his groundbreaking ideas jointly with his first wife, Mileva Mariƒá. Although the story of ‘Albert and Mileva’ is of considerable interest, especially as it is the template of a pattern of sacrificing personal relationships for work that was to persist through Einstein’s life, the notion that Mariƒá was a powerful physicist later air-brushed out of history by some sinister physics patriarchy is simply untrue, and Stachel doesn’t shy from doing the documentary leg-work to prove this. Sensationalising the Einstein-Mariƒá story does a profound disservice to those women who have been denied the full recognition they deserve, like Rosalind Franklin, who should have won a Nobel for her work on DNA, or current Oxford visiting professor Jocelyn Bell Burnel, who should have shared the Prize for the discovery of pulsars.

Although Stachel focuses heavily on Einstein the man in his centenary introduction, Einstein’s work takes center stage for the rest of the book. The nature and context of this work, like the nature and character of young Einstein, have been subject to some misrepresentation—frequently through comparison to the work of Isaac Newton in 1666, the original annus mirabilis or ‘miraculous year’. Newton, though only twenty-four, is often portrayed as having forged ex nihilo the calculus, classical mechanics, and theories of universal gravitation and optics—in one intense year of creativity. This is at best a caricature, as Stachel elaborates at length in his second introduction: while his discovery of the calculus was indeed the work of a ‘mature genius in mathematics,’ Newton’s physics was in every way preliminary, and it took many years of intense effort before Newton would grow into the physical genius he is now universally recognised to have been. Newton—an intensely private and indeed paranoid and disturbed man (who allegedly claimed on his deathbed that his greatest achievement was dying a virgin)—also cared not a whit for public recognition. Indeed, Newton’s friends had to systematically drag his early work out of his notebooks and into the public eye. By annus mirabilis analogy, Einstein’s achievements (he most definitely did not die a virgin) are also usually presented in the ex nihilo fashion. Einstein, the romantic outsider, in one year shatters the foundations of classical theories of light, mechanics, and electromagnetism!

Well, not quite. Einstein was no outsider, and he was desperate for the recognition of his peers. While he had yet to receive a doctorate at the beginning of 1905, Einstein had published ‘five respectable if not extraordinary’ papers in Annalen. Nor was he an idle student, like the Newton of 1666. Einstein was a married man, a father, and a full-time clerk at the Swiss Patent Office. While mathematically nowhere near as prodigious as Newton, Einstein was by 1905 a powerful theoretical physicist, and indeed the style displayed in all five of the centenary papers is one of careful analysis and criticism of existing theory that becomes the spring-board for his so-called ‘revolutionary’ ideas. In fact, if the five papers are examined carefully, it becomes clear that Einstein in 1905 did not aim to destroy the foundations of classical physics, but rather to ‘extend and perfect’ them.

So what were these five papers? The first in the volume is in fact Einstein’s doctoral dissertation, ‘A New Determination of Molecular Dimensions.’ Surprised? While a clever piece of work, the dissertation is nothing extraordinary, and uses techniques from the classical theory of moving fluids and diffusion. This was, of course, before the days of atomic force microscopy, so the connection between macroscopic physics and a microscopic description in terms of atoms, molecules, and so on was a topic of viable and vigorous research. I must confess to finding the dissertation a bit bland, but it certainly demonstrates Einstein’s mastery of the theoretical methods of his day and his capacity to apply them in novel ways.

Einstein’s paper on Brownian motion—the random motion of very small particles in a liquid, first studied by Robert Brown in 1828—is, in contrast, one of the masterpieces of the kinetic theory of heat (the notion that heat can be explained as the random motions of the microscopic particles making up matter). Einstein argues—leaning on previous work in statistical physics—that Brownian motion is due to the fluctuations of the molecules making up the liquid, and predicted the displacement over time of the small particles suspended in the liquid. Although it took some time for experiment to confirm Einstein’s results, the paper became one of the most compelling arguments for the reality of atoms (which were, even in the early 1900s, of dubious ontological status).

Both the dissertation and the Brownian motion paper lie firmly in the classical tradition, and clearly support Stachel’s claims that Einstein’s concern was at this point the apotheosis of classical physics. Although less obvious, the same can be said of ‘On the Electrodynamics of Moving Bodies,’ the ‘special relativity’ paper. A ‘relativity principle’ (the equivalence of physics in any uniformly moving reference frame) had been a part of classical mechanics since the days of Galileo. This is why, for example, a ball tossed into the air on a train falls back into your hand instead of flying off or being left behind. Einstein perceived that the same sort of principle should extend to electromagnetic phenomena. Yet the best theory governing the behaviour of charged particles at the time, the Maxwell-Lorentz ‘electron theory,’ postulated an absolute reference frame, the ‘ether frame’, in which the electromagnetic field lived. After struggling with this problem for years—often through his thought experiments—Einstein realized that the problem lay not in the idea of a relativity principle or in classical electromagnetism per se, but rather with their fundamental conception of space and time.

Newton’s mechanics relied upon the notion of an absolute space (a sort of universal coordinate system) and an absolute time (one, single clock ticking off seconds at exactly the same rate everywhere in the cosmos). If absolute space and time are abandoned in favour of another absolute—an absolute speed of light in all reference frames—then Maxwell-Lorentz theory could accommodate a relativity principle. Einstein viewed this paper as a ‘theory of principle, rather than a constructive theory.’ What he meant is simply that, rather than trying to explain physical phenomena by building them up from a microscopic description, he is generalizing from experiment certain principles that lay down rules nature appears to obey. Einstein’s most famous result—that mass m and energy E are equivalent, and that E = mc2, where c is the speed of light—is derived as a consequence of the special theory in Einstein’s fourth paper, ‘Does the Inertia of a Body Depend on Its Energy Content.’ The practical importance of the special theory and the consequent equivalence of mass and energy could perhaps best be illustrated by noting that 2005 is also the 60th anniversary of Hiroshima and Nagasaki.

In the last paper of the collection, Einstein once again comes back to statistical physics. Proceeding as before through a careful critique of existing theory, Einstein argues persuasively for ‘the limited ability of both classical mechanics and Maxwell’s electromagnetic theory to explain the properties of electromagnetic radiation.’ Pushing the classical analysis to its logical limits, Einstein identifies the places where the current theories break down. He proposes as a solution the quantum hypothesis—that light is not made up of continuously varying waves but of tiny bundles of energy called quanta, which carry an energy proportional to their frequency. In a stunningly brief and insightful piece of physics (for which this paper is usually remembered) Einstein then uses the quantum idea to explain the emission of electrons by certain metals in response to light (the ‘photoelectric effect’), accounting for the observed dependence of the velocity of emitted electrons on the frequency but not the intensity of the incident light.

Although it was for his work on the photoelectric effect that Einstein won the Nobel Prize in 1921, the true revolution initiated by this work—quantum mechanics—never secured Einstein’s approval. He remained forever sceptical of the fundamental status that quantum mechanics assigns to probability. Typically, Einstein expressed this belief as a principle, ‘God does not play dice.’ His friend Niels Bohr, one of the founders of quantum theory, also had a principle: ‘Einstein, stop telling God what to do.’ Although triumphalists of the mainstream tradition usually bemoan Einstein’s ‘failure’ to accept quantum mechanics, there remain a small but significant number of (often eminent) quantum ‘sceptics’ who, with Einstein, believe that the foundations of quantum mechanics themselves require revision, and that God doesn’t play dice after all.

So as the centenary of his miraculous year comes to a close, I wonder—why does everybody love Einstein? Part of it has less to do with who Einstein was than with what we made of him a patron-saint for science. When science can unmake the very stuff of the universe and threatens all life through nuclear holocaust, Einstein’s strong principles, good humour, and benevolence make him a comforting presence in the technocratic priesthood. But I’d like to think that there is much to be learned from Einstein as he actually was. He balances independence with humanizing vulnerability—the ideal role model for those young people, of extraordinary temperament and vision but of ordinary human weakness, who are most likely to lead the revolutions of 21st century science and culture. He failed to balance his private and his professional lives—a cautionary tale for those at risk of sacrificing domestic happiness on the altar of their curiosity or ambition. And as anyone reading his beautiful papers can attest, he teaches us how to ask the deepest questions of our world—and how to answer them.

Revolution must begin with the methodical, careful, and critical analysis of what has come before, for past errors usually point the way to future discovery. It must progress through years of false starts, blind alleys, and whimsical thought experiments. Revolution is the ultimate victory of human ingenuity and intelligence over the mystery of the world—and it is Einstein’s lesson to us. Unlike the bomb-makers of Los Alamos, who teach us that imagination can destroy, Einstein reminds us of what imagination can create. He gave us a new space, a new time, a new world. And the Einstein of 1905 dares us to do the same.

At least, that’s why I love Einstein.

Jacob Foster is a DPhil student in Mathematical Physics at Balliol College, Oxford, though he prefers the job description ‘Theorist’. His scientific interests range from quantum gravity and cosmology to the statistical mechanics of networks.