Genius_ The Life and Science of Richard Feynman - James Gleick [42]
The Newest Physics
The theory of the fast and the theory of the small were narrowing the focus of the few dozen men with the suasion to say what physics was. Most of human experience passed in the vast reality that was neither fast nor small, where relativity and quantum mechanics seemed unnecessary and unnatural, where rivers ran, clouds flowed, baseballs soared and spun by classical means—but to young scientists seeking the most fundamental knowledge about the fabric of their universe, classical physics had no more to say. They could not ignore the deliberately disorienting rhetoric of the quantum mechanicians, nor the unifying poetry of Einstein’s teacher Hermann Minkowski: “Space of itself and time of itself will sink into mere shadows, and only a kind of union between them shall survive.”
Later, quantum mechanics suffused into the lay culture as a mystical fog. It was uncertainty, it was acausality, it was the Tao updated, it was the century’s richest fount of paradoxes, it was the permeable membrane between the observer and the observed, it was the funny business sending shudders up science’s all-too-deterministic scaffolding. For now, however, it was merely a necessary and useful contrivance for accurately describing the behavior of nature at the tiny scales now accessible to experimenters.
Nature had seemed so continuous. Technology, however, made discreteness and discontinuity a part of everyday experience: gears and ratchets creating movement in tiny jumps; telegraphs that digitized information in dashes and dots. What about the light emitted by matter? At everyday temperatures the light is infrared, its wavelengths too long to be visible to the eye. At higher temperatures, matter radiates at shorter wavelengths: thus an iron bar heated in a forge glows red, yellow, and white. By the turn of the century, scientists were struggling to explain this relationship between temperature and wavelength. If heat was to be understood as the motion of molecules, perhaps this precisely tuned radiant energy suggested an internal oscillation, a vibration with the resonant tonality of a violin string. The German physicist Max Planck pursued this idea to its logical conclusion and announced in 1900 that it required an awkward adjustment to the conventional way of thinking about energy. His equations produced the desired results only if one supposed that radiation was emitted in lumps, discrete packets called quanta. He calculated a new constant of nature, the indivisible unit underlying these lumps. It was a unit, not of energy, but of the product of energy and time—the quantity called action.
Five years later Einstein used Planck’s constant to explain another puzzle, the photoelectric effect, in which light absorbed by a metal knocks electrons free and creates an electric current. He, too, followed the relationship between wavelength and current to an inevitable mathematical conclusion: that light itself behaves not as a continuous wave but as a broken succession of lumps when it interacts with electrons.
These were dubious claims. Most physicists found Einstein’s theory of special relativity, published the same year, more palatable. But in 1913 Niels Bohr, a young Dane working in Ernest Rutherford’s laboratory in Manchester, England, proposed a new model of the atom built on these quantum underpinnings. Rutherford had recently imagined the atom as a solar system in miniature, with electrons orbiting the nucleus. Without a quantum theory, physicists would have to accept the notion of electrons gradually spiraling inward as they radiated some of their energy away. The result would be continuous radiation and the eventual collapse of the atom in on itself. Bohr instead described an atom whose electrons could inhabit only certain orbits, prescribed by Planck