Tuesday, November 11, 2003
Before the Big Bang
The previous post is the perfect segue to this one where Dennis Overbye asks what happened before the Big Bang.
Still, this has not stopped some theorists with infinity in their eyes from trying to imagine how the universe made its "quantum leap from eternity into time," as the physicist Dr. Sidney Coleman of Harvard once put it. Some physicists speculate that on the other side of the looking glass of Time Zero is another universe going backward in time. Others suggest that creation as we know it is punctuated by an eternal dance of clashing island universes. In their so-called quantum cosmology, Dr. Stephen Hawking, the Cambridge University physicist and author, and his collaborators envision the universe as a kind of self-contained entity, a crystalline melt of all possibilities existing in "imaginary time."
At the moment there are two pretenders to the throne of that ultimate theory. One is string theory, the putative "theory of everything," which posits that the ultimate constituents of nature are tiny vibrating strings rather than points. String theorists have scored some striking successes in the study of black holes, in which matter has been compressed to catastrophic densities similar to the Big Bang, but they have made little progress with the Big Bang itself.
String's lesser-known rival, called loop quantum gravity, is the result of applying quantum strictures directly to Einstein's equations. This theory makes no pretensions to explaining anything but gravity and space-time. But recently Dr. Martin Bojowald of the Max Planck Institute for Gravitational Physics in Golm, Germany, found that using the theory he could follow the evolution of the universe back past the alleged beginning point. Instead of having a "zero moment" of infinite density — a so-called singularity — the universe instead behaved as if it were contracting from an earlier phase, according to the theory, he said. As if the Big Bang were a big bounce.
In their dreams, theorists of both stripes hope that they will discover that they have been exploring the Janus faces of a single idea, yet unknown, but which might explain how time, space and everything else can be built out of nothing. A prescription for, as the physicist Dr. John Archibald Wheeler of Princeton puts it, "law without law." Dr. Wheeler himself, the pre-eminent poet-adventurer in physics, has put forth his own proposal. According to quantum theory's famous uncertainty principle, the properties of a subatomic particle like its momentum or position remain in abeyance, in a sort of fog of possibility until something measures it or hits it.
Likewise he has wondered out loud if the universe bootstraps itself into being by the accumulation of billions upon billions of quantum interactions — the universe stepping on its own feet, microscopically, and bumbling itself awake. It's a notion he once called "genesis by observership," but now calls "it from bit" to emphasize a proposed connection between quantum mechanics and information theory.
Still, this has not stopped some theorists with infinity in their eyes from trying to imagine how the universe made its "quantum leap from eternity into time," as the physicist Dr. Sidney Coleman of Harvard once put it. Some physicists speculate that on the other side of the looking glass of Time Zero is another universe going backward in time. Others suggest that creation as we know it is punctuated by an eternal dance of clashing island universes. In their so-called quantum cosmology, Dr. Stephen Hawking, the Cambridge University physicist and author, and his collaborators envision the universe as a kind of self-contained entity, a crystalline melt of all possibilities existing in "imaginary time."
At the moment there are two pretenders to the throne of that ultimate theory. One is string theory, the putative "theory of everything," which posits that the ultimate constituents of nature are tiny vibrating strings rather than points. String theorists have scored some striking successes in the study of black holes, in which matter has been compressed to catastrophic densities similar to the Big Bang, but they have made little progress with the Big Bang itself.
String's lesser-known rival, called loop quantum gravity, is the result of applying quantum strictures directly to Einstein's equations. This theory makes no pretensions to explaining anything but gravity and space-time. But recently Dr. Martin Bojowald of the Max Planck Institute for Gravitational Physics in Golm, Germany, found that using the theory he could follow the evolution of the universe back past the alleged beginning point. Instead of having a "zero moment" of infinite density — a so-called singularity — the universe instead behaved as if it were contracting from an earlier phase, according to the theory, he said. As if the Big Bang were a big bounce.
In their dreams, theorists of both stripes hope that they will discover that they have been exploring the Janus faces of a single idea, yet unknown, but which might explain how time, space and everything else can be built out of nothing. A prescription for, as the physicist Dr. John Archibald Wheeler of Princeton puts it, "law without law." Dr. Wheeler himself, the pre-eminent poet-adventurer in physics, has put forth his own proposal. According to quantum theory's famous uncertainty principle, the properties of a subatomic particle like its momentum or position remain in abeyance, in a sort of fog of possibility until something measures it or hits it.
Likewise he has wondered out loud if the universe bootstraps itself into being by the accumulation of billions upon billions of quantum interactions — the universe stepping on its own feet, microscopically, and bumbling itself awake. It's a notion he once called "genesis by observership," but now calls "it from bit" to emphasize a proposed connection between quantum mechanics and information theory.
