| | The Search for Unity Continues | To find unity in the dazzling multiplicity of things, to forge a common framework of understanding, is an ancient quest not just confined to science. It seems to run in our blood. But in physics, more than any other field, that quest has been a driving force behind new discoveries and an overarching goal for the future. Thales of Miletus was early on the unification scene when, in the sixth century B.C., he argued that water lies at the basis of everything… Anaximenes of Lampsacus, also in the sixth century, took up the theme of unification. For him, though, the primordial essence wasn't water but air. After all, air is what we breathe, what sustains us throughout life. His contemporary, Heraclitus of Ephesus, plumped for the element fire because "all things are exchanged against fire, and fire against all things." But Anaximander, a pupil of Thales, disagreed with these views. He didn't think that any known substance could be the basal stuff of the cosmos. There was no way, he argued, that fire could form from water, or vice versa, because every observation showed the two to be incompatible. So, for him, the cosmic commonality must be something else—an infinite, eternal substance that embraced the world in its entirety. This ethereal substrate Anaximender called apeiron, which means, simply, "boundless." Pythagoras and his slightly crazy band of followers were also early on the TOE [Theory of Everything] trail, insisting that mathematics—numbers, especially—underpins the kaleidoscope of physical phenomena. And Aristotle, too, played his part in the business of unification by formulating principles (albeit flawed) for all motion on Earth. But the first great cosmic synthesis in the modern sense would have to wait another twenty centuries for Isaac Newton, who built on the work of Kepler and Galileo (not to mention Hooke, Boyle, and others). In Newton's hands the whole Aristotelian concept of movement was shattered. As the historian Richard Westfall has pointed out, "To Aristotle, to move was to be moved. The motion of any body required a moving agent." Newton brought to center stage the notion of inertia, which allowed motion without cause. Galileo had already laid siege to Aristotle's distinction between "natural" and "violent" motion; Newton completed the demolition. And just as he unified all types of terrestrial movement, so he showed that there aren't different rules for Earth and what lies beyond it; the law of gravitation is truly democratic. In the second half of the nineteenth century the marriage of electricity and magnetism, officiated by Maxwell, took place. Subsequently, the Scotsman brought together electromagnetism and optics by showing that light is just a form of electromagnetic radiation. Never before had so many phenomena owed so much to so few laws, summarized in just four relatively simple equations. And if electricity and magnetism—two seemingly disparate forces—could be amalgamated, then why not also gravity? ... For the last thirty years of his life... Einstein struggled to combine electromagnetism and general relativity into what he called a unified field theory. His only reward for this lengthy, quixotic venture was disappointment; his effort ended in failure and his sad isolation from the mainstream physics. "I have become a lonely old chap," he wrote to a friend in the early 1940s, "who is mainly known because he doesn't wear socks and who is exhibited as a curiosity on special occasions." Others were, understandably far more excited by the possibilities of quantum theory, the central premises of which Einstein utterly rejected, though, ironically, he had been a quantum pioneer and had won his Nobel Prize for this work, not for relativity. As more became known about the goings-on inside the nuclei of atoms and of the way subatomic particles interacted and changed from one form into another, it became clear that there were two other fundamental forces at work in nature besides gravity and electromagnetism. They are known as the strong and weak forces—everyday names for effects that are remarkably well hidden from everyday view. Both are important only over tiny distances, such as those found within atomic nuclei. That there must be another force, more powerful than electromagnetism, was recognized in 1921 by the Englishman James Chadwick (discoverer of the neutron in 1932) and the Swiss physicist Etienne Bieler. This strong force had to be able to bind together the contents of the nucleus in spite of the determined attempts of the positively charged protons to hurl themselves apart. The Italian-American physicist Enrico Fermi first recognized the weak force in the 1930s; among other things Fermi realized, it is responsible for radioactive decay. While Einstein had spurned anything to do with quantum tomfoolery in his efforts to unify gravity and electromagnetism, physicists at large strove to bring the weak and strong forces under the same umbrella as electromagnetism by making full use of the science of the ultrasmall. Quantum physics—quantum mechanics as it's generally known (to contrast it with the Newtonian variety)—is all about dealing with energy transactions in the form of minuscule bits called quanta. Scratch beneath the surface and it's a very weird subject indeed, full of counterintuitive ideas that Einstein found completely unbelievable. Yet most scientists managed to turn a blind eye to its more bizarre implications and simply continued to use the equations that governed the play of matter at the quantum level. | — David Darling, Gravity's Arc: The Story of Gravity from Aristotle to Einstein and Beyond, Chapter 12 – All Together Now | Indexes/21 |
0 comments:
Post a Comment