einstein
einstein
einstein
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electromagnetic phenomena.<br />
Up until then, Einstein had published five little-noted papers. They had earned him neither a doctorate nor a teaching job, even at a high school.<br />
Had he given up theoretical physics at that point, the scientific community would not have noticed, and he might have moved up the ladder to<br />
become the head of the Swiss Patent Office, a job in which he would likely have been very good indeed.<br />
There was no sign that he was about to unleash an annus mirabilis the like of which science had not seen since 1666, when Isaac Newton, holed<br />
up at his mother’s home in rural Woolsthorpe to escape the plague that was devastating Cambridge, developed calculus, an analysis of the light<br />
spectrum, and the laws of gravity.<br />
But physics was poised to be upended again, and Einstein was poised to be the one to do it. He had the brashness needed to scrub away the<br />
layers of conventional wisdom that were obscuring the cracks in the foundation of physics, and his visual imagination allowed him to make<br />
conceptual leaps that eluded more traditional thinkers.<br />
The breakthroughs that he wrought during a four-month frenzy from March to June 1905 were heralded in what would become one of the most<br />
famous personal letters in the history of science. Conrad Habicht, his fellow philosophical frolicker in the Olympia Academy, had just moved away<br />
from Bern, which, happily for historians, gave a reason for Einstein to write to him in late May.<br />
Dear Habicht,<br />
Such a solemn air of silence has descended between us that I almost feel as if I am committing a sacrilege when I break it now with some<br />
inconsequential babble . . .<br />
So, what are you up to, you frozen whale, you smoked, dried, canned piece of soul ...? Why have you still not sent me your dissertation?<br />
Don’t you know that I am one of the 1½ fellows who would read it with interest and pleasure, you wretched man? I promise you four papers in<br />
return. The first deals with radiation and the energy properties of light and is very revolutionary, as you will see if you send me your work first.<br />
The second paper is a determination of the true sizes of atoms ... The third proves that bodies on the order of magnitude 1/1000 mm,<br />
suspended in liquids, must already perform an observable random motion that is produced by thermal motion. Such movement of suspended<br />
bodies has actually been observed by physiologists who call it Brownian molecular motion. The fourth paper is only a rough draft at this point,<br />
and is an electrodynamics of moving bodies which employs a modification of the theory of space and time. 7<br />
Light Quanta, March 1905<br />
As Einstein noted to Habicht, it was the first of these 1905 papers, not the famous final one expounding a theory of relativity, that deserved the<br />
designation “revolutionary.” Indeed, it may contain the most revolutionary development in the history of physics. Its suggestion that light comes not<br />
just in waves but in tiny packets—quanta of light that were later dubbed “photons”—spirits us into strange scientific mists that are far murkier,<br />
indeed more spooky, than even the weirdest aspects of the theory of relativity.<br />
Einstein recognized this in the slightly odd title he gave to the paper, which he submitted on March 17, 1905, to the Annalen der Physik: “On a<br />
Heuristic Point of View Concerning the Production and Transformation of Light.” 8 Heuristic? It means a hypothesis that serves as a guide and gives<br />
direction in solving a problem but is not considered proven. From this first sentence he ever published about quantum theory until his last such<br />
sentence, which came in a paper exactly fifty years later, just before he died, Einstein regarded the concept of the quanta and all of its unsettling<br />
implications as heuristic at best: provisional and incomplete and not fully compatible with his own intimations of underlying reality.<br />
At the heart of Einstein’s paper were questions that were bedeviling physics at the turn of the century, and in fact have done so from the time of<br />
the ancient Greeks until today: Is the universe made up of particles, such as atoms and electrons? Or is it an unbroken continuum, as a gravitational<br />
or electromagnetic field seems to be? And if both methods of describing things are valid at times, what happens when they intersect?<br />
Since the 1860s, scientists had been exploring just such a point of intersection by analyzing what was called “blackbody radiation.” As anyone<br />
who has played with a kiln or a gas burner knows, the glow from a material such as iron changes color as it heats up. First it appears to radiate<br />
mainly red light; as it gets hotter, it glows more orange, and then white and then blue. To study this radiation, Gustav Kirchhoff and others devised a<br />
closed metal container with a tiny hole to let a little light escape. Then they drew a graph of the intensity of each wavelength when the device<br />
reached equilibrium at a certain temperature. No matter what the material or shape of the container’s walls, the results were the same; the shape of<br />
the graphs depended only on the temperature.<br />
There was, alas, a problem. No one could fully account for the basis of the mathematical formula that would produce the hill-like shape of these<br />
graphs.<br />
When Kirchhoff died, his professorship at the University of Berlin was given to Max Planck. Born in 1858 into an ancient German family of great<br />
scholars, theologians, and lawyers, Planck was many things that Einstein was not: with his pince-nez glasses and meticulous dress, he was very<br />
proudly German, somewhat shy, steely in his resolve, conservative by instinct, and formal in his manner. “It is difficult to imagine two men of more<br />
different attitudes,” their mutual friend Max Born later said. “Einstein a citizen of the whole world, little attached to the people around him,<br />
independent of the emotional background of the society in which he lived—Planck deeply rooted in the traditions of his family and nation, an ardent<br />
patriot, proud of the greatness of German history and consciously Prussian in his attitude to the state.” 9<br />
His conservatism made Planck skeptical about the atom, and of particle (rather than wave and continuous field) theories in general. As he wrote<br />
in 1882, “Despite the great success that the atomic theory has so far enjoyed, ultimately it will have to be abandoned in favor of the assumption of<br />
continuous matter.” In one of our planet’s little ironies, Planck and Einstein would share the fate of laying the groundwork for quantum mechanics,<br />
and then both would flinch when it became clear that it undermined the concepts of strict causality and certainty they both worshipped. 10<br />
In 1900, Planck came up with an equation, partly using what he called “a fortuitous guess,” that described the curve of radiation wavelengths at<br />
each temperature. In doing so he accepted that Boltzmann’s statistical methods, which he had resisted, were correct after all. But the equation had<br />
an odd feature: it required the use of a constant, which was an unexplained tiny quantity (approximately 6.62607 x 10 –34 joule-seconds), that<br />
needed to be included for it to come out right. It was soon dubbed Planck’s constant, h, and is now known as one of the fundamental constants of<br />
nature.<br />
At first Planck had no idea what, if any, physical meaning this mathematical constant had. But then he came up with a theory that, he thought,<br />
applied not to the nature of light itself but to the action that occurred when the light was absorbed or emitted by a piece of matter. He posited that<br />
the surface of anything that was radiating heat and light—such as the walls in a blackbody device—contained “vibrating molecules” or “harmonic<br />
oscillators,” like little vibrating springs. 11 These harmonic oscillators could absorb or emit energy only in the form of discrete packets or bundles.