Religious conflict rolls across the Middle East, Southeast Asia, and Central Asia. A tiny, loony sect threatens to burn the Quran, and the world's leaders respond. You might not think there could possibly be any room in the headlines for a debate about the divine stirred up by a mere physics book. Think again. Several weeks ago, the London Times devoted much of its front page to heralding just that: "Hawking: God did not create Universe: The Big Bang was inevitable consequence of laws of physics, says Britain's most eminent scientist." In a high-profile flurry of attention that any author would envy, the archbishop of Canterbury, Britain's chief rabbi, and the chair of interfaith relations of the Muslim Council of Britain have all locked arms against Stephen Hawking's anti-God fluctuation in his new book.
Hawking has a track record for delivering utterances that endow his work with the aura of Holy Writ. Back in 1988, in his A Brief History of Time, he looked ahead and offered this pronouncement: "If we discover a complete theory, it would be the ultimate triumph of human reason—for then we should know the mind of God." Now, in The Grand Design, a popular synthesis of contemporary physical and cosmological theory, he dares to outdo himself: The new account of cosmogenesis he favors just might, he has decided, make the divine mind unnecessary.
What new theoretical developments since 1988 does Hawking point to that might obviate God the way oxygen displaced phlogiston? He takes the reader in steps, from the foundations of modern physics through a hope, a battle, and a leap of anti-faith. Let's proceed one at a time.
Hawking begins as every popular book on recent physics and cosmology does: by introducing the basic ideas of relativity and quantum theory. Relativity insists that our physics description of the world around us should not depend on our frame of reference. If a magnet and coil approach one another and make electricity in the coil, then this should be so whether we follow along with the coil or track the magnet. Perspective should not change our explanation of what happens.
This simple demand, along with Einstein's insistence that we never catch up with a beam of light (no matter how fast we go, light always appears to us to be passing at 186,000 miles per second), led to startling changes. To the shock of physicists, artists, poets, and the public, it turned out that duration, length, and simultaneity of events depend on movement. With general relativity (general in the sense of including not only constantly moving frames of reference but also accelerating ones), things got even more interesting: Einstein could consider the geometry of the whole universe (cosmology), and others began in the late 1930s to explore the bizarre, newly recognized phenomenon of black holes.
If relativity shook the classical world, quantum mechanics shattered it. In the 1920s, Niels Bohr, Werner Heisenberg, and Erwin Schrödinger brought to the world an account of physics in which electrons sometimes acted like waves and sometimes like particles. The idea of rigid causality had to be abandoned. When Richard Feynman and others combined relativity and quantum mechanics just after World War II, the result, a relativistic and quantum account of electric field, became a model of physical theory: The electric field became no more than the exchange of photons. In Feynman's way of thinking, in order to account for any event, every possible alternate "history" of the event had to be reckoned—and all the histories summed up. How does an electron interact with another? Feynman said: A photon could travel from one electron to another—or a photon could turn en route into a pair of particles that could then return to being a photon and complete the voyage. Even more complex processes could happen en route and all, in a certain sense, did. As physicists like to say, anything not forbidden is required. Hawking and his co-author, Leonard Mladinow, rightly emphasize this "everything that can occur does" philosophy. I wish more popular physics did.
Gravity resisted all attempts to be joined to the quantum theory of force fields. But in the 1980s, string theory began to take hold. The basic idea of string theory is that the fundamental objects in the world are not miniature BBs, but instead one-dimensional, stringlike bits of matter under enormous tension. Such a strand could have different vibrational states—like a violin string. The different "notes" would correspond to different energies. The world's most famous equation, E = mc2, then tells us that these different string vibrations would have different masses. Hope was high in the '80s that this would allow one type of string to stand in for many apparently different particles. For a brief and shining moment, a whole and complete unification of physics seemed to be within grasp. The dream was that mathematical self-consistency would rule out all but the one right theory. In the absence of that theory, the still-empty throne where it will sit has been called M-Theory. Find and fully articulate M, the hopeful suggested, and the historical mission of physics would come to a close.