Making Sense of the Multiverse

So, what does Stephen Hawking’s The Grand Design tell us about God?

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.

It hasn’t happened—no fully defined M theory has yet come to rule. But that isn’t all. Theorists realized that string theories had more solutions than anticipated. A lot more—maybe 10500 of them, maybe an infinite number. And each solution gives a different picture of the allowable particles and laws. What to do? Some string theorists despaired. Other string theorists tried to rethink the situation to achieve the desired unique solution to a unique theory. Anti-stringers sharpened their scissors. Give up, they said, and say the laws just happen to be what they are.

Others, now including Hawking, embraced what has come to be known as the multiverse: The idea is that there are actually many universes, each with its own set of laws and particles. Advocates see it as a natural continuation of Feynman’s vision. All possible histories have indeed been followed, but this time not merely to describe the many ways a photon can go from Electron A to Electron B—this time to account for the history of the universe itself and all its laws.

As Hawking puts in it The Grand Design: “the universe appeared spontaneously, starting off in every possible way. Most of these [alternative beginnings] correspond to other universes. … [S]ome … are similar to ours, most are very different.” So how to understand the fact that we find ourselves in a universe with atomic laws that operate in such a way as to make matter and life possible? If the charges on a proton and an electron were not very, very close to equal and opposite, we wouldn’t be here… a miracle tuning, or a divine intervention? It is no miracle, Hawking joins multiverse supporters in saying—any more than it is a miracle that we find ourselves on a planet in that narrow region of temperature where water is liquid.

Multiverse advocates contend that the origin (or, more precisely, origins) resides in quantum fluctuations—new universes pop into existence with no more fuss than a photon transforming into an electron-positron pair and then returning to its good old photonic self. The initial spark just happens because quantum mechanics tells us that, with some probability, new universes will come into existence. Physics can account not only for how the universe works but for why it is there at all. No divine help required. It is quantum physics all the way down—accompanied by just the right lot of elementary particle physics and string theory.

The archbishop of Canterbury, with the concurrence of eminent colleagues across the religious spectrum, begs to differ with Hawking. “Belief in God is not about plugging a gap in explaining how one thing relates to another within the universe,” he announced. But tell that to Pope Pius XII, who half a century ago proclaimed support for the “fiat lux” in the early glimmers of a big-bang cosmology. Or tell it to the group of Cambridge physicists around the same time who were pushing for a no-first-moment account: a steady-state cosmology that would wipe out the big bang, undermining an overly religious moment of creation. Once you start reading God’s presence—or his absence—into the ever-evolving equations of physics, it is hard to keep him from coming and going, creating a stir in the process. Hawking, who briefly left the door open for the mind of God two decades ago, surely knew he would stir an outcry by slamming it shut. In fact, it was no doubt part of his grand design.

Like Slate on  Facebook. Follow us on  Twitter.