Zero - Charles Seife [76]
No instrument currently imaginable will give scientists the power to observe strings directly; nobody can think of an experiment that will give physicists evidence about whether black holes and particles are, indeed, strings. This is the chief objection to string theory. Because science is based upon observation and experiment, some critics argue that string theory is not science but philosophy. (A recent set of theories proposes that some of these rolled-up dimensions might be 10-19 centimeters or even larger, which would put them within the realm of experimentation. But at the moment, these theories are considered rogues—interesting ideas, but very long shots at best.)
Newton’s laws of motion and gravitation gave physicists an explanation for the way planets and objects move through the universe. Whenever a new comet was discovered, it gave additional support to Newton’s calculations. There were a few problems. Mercury’s orbit, for instance, wobbled in a way that disagreed with what Newton predicted, but on the whole, Newton’s theories were tested again and again, and they usually passed.
Einstein’s theories corrected Newton’s errors; they explained Mercury’s wobble, for instance. These theories also made testable predictions about the way gravity works. Eddington observed the bending of starlight during a solar eclipse, confirming one of those predictions.
String theory, on the other hand, ties together a number of existing theories in a very pretty way, and makes a number of predictions about the way black holes and particles behave, but none of those predictions are testable or observable. While string theory might be mathematically consistent, and even beautiful, it is not yet science.*
For the foreseeable future, banishing zero from the universe with string theory is a philosophical idea rather than a scientific one. String theory might well be correct, but we may never have the means to find out. Zero has not yet been banished; indeed, zero seems to be what created the cosmos.
The Zeroth Hour: The Big Bang
Hubble’s observations suggested that there was a time, called the big bang, when the universe was infinitesimally small and infinitely dense. Under such conditions all the laws of science, and therefore all ability to predict the future, would break down.
—STEPHEN HAWKING, A BRIEF HISTORY OF TIME
The universe was born in zero.
Out of the void, out of nothing at all, came a cataclysmic explosion that created all the matter and energy that the entire universe is made of. This event—the big bang—was a horrible idea to many scientists and philosophers. It took a long time before astrophysicists came to agree that our universe was finite—that it did, in fact, have a beginning.
The prejudice against a finite universe is ancient. Aristotle rejected the creation of the universe out of the void because he believed that the void could never exist. But this caused a paradox. If the universe could not spring forth from the void, then something had to be floating about before the birth of the universe; there had to be a universe before the universe was born. To Aristotle, the only possible way out of this quandary was to assume that the universe was eternal. It had always existed in the past, and would always exist.
Western civilization eventually had to make a choice between Aristotle and the Bible, which says that the finite universe sprang forth from the void and prophesies its ultimate destruction. Though the Semitic biblical cosmos toppled the Aristotelian one, the idea of an eternal, unchanging universe was not expunged completely, enduring even to the twentieth century. It led Einstein to what he called the greatest mistake of his career.
To Einstein, the general theory of relativity had a crucial flaw. It foretold the end of the universe. According to the equations of general relativity, the universe was unstable. There