Why Does the World Exist?: An Existential Detective Story (18 page)

Even with this image in mind—a not-altogether persuasive one—I remained perplexed. A champagne bubble forms in the course of time. But Vilenkin’s bubble that appears out of nothingness is a bubble of
spacetime
. Since time itself (along with space) is created in the transition from Nothing to Something, this transition can’t very well take place
in
time. It seems to unfold logically rather than temporally. If Vilenkin is right, nothingness never had a chance: the laws of physics eternally ordained that, with some appreciable probability, there would be a universe. But what gives ontological clout to these laws? If they are logically prior to the world, where exactly are they written down?

“If you like,” Vilenkin told me, “you can say they’re in the mind of God.”

Perhaps, I thought after talking with Vilenkin, this is the best that science could do. It could show that the laws explaining how things happen
within
the world also explain why there should
be a world at all
—and hence, why there is Something rather than Nothing. The laws of classical physics, including those of Einstein’s general relativity, were not up to this challenge. They could describe the evolution of the universe, but they could not account for its coming into being; indeed, they broke down at its point of origin. Quantum cosmology was an improvement. It could treat the origin of the world as just another quantum event, one mercifully free from the need for a First Cause. It could show that, ontologically speaking, the universe might indeed be a “free lunch.”

But quantum cosmology cannot, scientifically speaking, be the last word. The problem is that, as yet, no one has been able to explain how
gravity
fits into the quantum framework. Gravity is, after all, the force of nature that determines the overall architecture of the universe. On such a large scale, Einstein’s general relativity suffices to explain the workings of gravity. But when the entire mass of the universe is packed into a volume the size of an atom—as was the case just after the Big Bang—quantum uncertainty causes the smooth geometry of general relativity to break up, and there is no telling how gravity will behave. To understand the birth of the cosmos, we thus need
a quantum theory
of gravity, one that “unifies” general relativity and quantum mechanics. Stephen Hawking himself has conceded as much. “A quantum theory of gravity is essential if we are to describe the early universe,” Hawking declared in 1980, in his inaugural lecture as the Lucasian Professor of Mathematics at Cambridge University. “Such a theory is also required,” he said, “if we are to answer the question: Does time really have a beginning?”

Today, more than three decades later, physicists are still searching for a theory of the type that Hawking had in mind, one that would tie up all the forces of nature—including gravity—into a single neat mathematical package. It is not yet clear what form this final theory will take. At the moment, the physics community is pinning its hopes on “string theory,” which seeks to interpret all of physical reality as consisting of tiny strings of energy vibrating in higher-dimensional space. Dissenters from the string-theoretic consensus are trying other approaches. And a few physicists think the whole idea of unification is a pipe dream.

What might a final theory—or a “Theory of Everything,” as it’s sometimes called—tell us about the origin of the universe? Such a theory is likely to go deeper than the quantum cosmology of Hawking, Vilenkin, and company. (String theory, for example, offers glimpses of a pre–Big Bang reality where the very notions of space and time have no purchase.) But could it provide a convincing rationale for the world’s existence? And could it provide a convincing rationale for
itself
? If it is truly a Theory of Everything, it ought to be able to explain why it is itself true. Could the Theory of Everything turn out to be self-subsuming?

The thinker in the best position to answer such questions, I knew, was Steven Weinberg. No physicist has been more central to the quest for a final theory. In 1979, Weinberg was awarded the Nobel Prize in Physics for his role, a decade earlier, in unifying two of the four fundamental forces of nature: the electromagnetic force and the “weak” force (responsible for radioactive decay). Both these forces, his work helped to show, were merely low-energy aspects of a more basic “electroweak” force. For this and related achievements, Weinberg has a good claim to be the father of the “standard model” of particle physics, which represents the most complete understanding we have of the physical world at the micro-level.

Weinberg is also an exceptionally eloquent expositor of science. In 1977 he published
The First Three Minutes
, a cinematically gripping account of the primeval universe in the explosive moments after the Big Bang. (It was on the last page of this book that he made his to-be-notorious declaration, “The more the universe seems comprehensible, the more it also seems pointless.”) In 1993 he published
Dreams of a Final Theory
, which explained, with real philosophical profundity, what was at stake in the quest to unify the laws of nature. Weinberg described how physicists, guided by their sense of mathematical beauty, sought deeper and deeper principles that would merge the standard model and Einstein’s general relativity into an all-encompassing final theory. This would be a point where all the arrows of explanation converge—where every
why
is absorbed in an ultimate
because
. Weinberg explained why he thought that contemporary physics might be on the verge of discovering just such a theory. He even confessed to some sadness at the prospect, writing that “
with the discovery
of a final theory we may regret that nature has become more ordinary, less full of wonder and mystery.”

Just how much cosmic mystery did Weinberg think the final theory would leave as a residue? He was quite explicit in denying that it could explain literally
everything
. For example, Weinberg did not think that science could ever explain the existence of moral truths, owing to the logical gap between the scientific
is
and the ethical
ought
. But could science explain the existence of the world? Could it account for the triumph of Something over Nothing?

I was eager to put such questions to Weinberg. In fact, I was eager to meet him, period. There was no other living physicist I regarded with such awe. And there was no other physicist (with the exception of Freeman Dyson) who had such a gift for putting his ideas in lapidary form. Besides, Weinberg seemed to be an extraordinary-looking fellow, judging from descriptions of him I had seen in the press. “
With his crab-apple cheeks
, vaguely Asian eyes, and silver hair still tinged with red, Steven Weinberg resembles a large, dignified elf,” one journalist wrote of him after an encounter. “He would make an excellent Oberon, king of the fairies in
A Midsummer Night’s Dream
.”

So, feeling rather like Nick Bottom myself, I got in touch with Weinberg. He teaches at the University of Texas in Austin, having come there in 1982 after previously holding the Higgins Chair of Physics at Harvard. I proposed making a pilgrimage to Austin to talk to him about the mystery of existence. He responded graciously to this threatened imposition on his time. “If you are coming all the way down here from New York, I’ll even buy you lunch,” he wrote in an e-mail. The universe, I thought, was not the only free lunch.

The prospect of visiting Austin for the first time was an added allurement to me. From what I had heard of the place, I pictured it as a wondrous bastion of avant-garde culture and bohemian living in an otherwise medievally backward state. It even seemed to be theologically progressive. When I had asked Weinberg, who has inveighed against religion (“
With or without religion
, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion.”), how he could be happy in a Baptist hotbed like Texas, he assured me that, far from being uniformly fundamentalist, some of the Baptist congregations there were so liberal as to be indistinguishable from Unitarians. And I was impressed by Austin’s reputation as the live-music capital of the world, even if indie rock was not exactly my dish.

So I eagerly booked a flight to Austin and made a reservation at the Intercontinental Hotel for what promised to be an intellectually stimulating and altogether delightful weekend—not realizing that my plans were about to be destroyed by a little eruption of
le néant
into my life.

Interlude

Nausea

I
t was early afternoon on Saturday when my plane touched down at the Austin airport. For a late-spring day, the heat and humidity were surprising, and even in my linen suit, elegantly rumpled as always, I felt a little uncomfortable.

On the way downtown I noticed a lot of activity in the streets. It seemed that some sort of outdoor music festival was getting under way.

After checking into my hotel, I went for a stroll around the old downtown. By now the music festival was in full swing. Rockabilly garage bands blared away on every block; beery throngs pressed in and out of bars; meat sizzled on grills in the middle of the closed-off streets. The noise was intense. So were the smells.

Making my way through the cacophonous crush under the hot sun, I pretended that I was Roquentin, the existential hero of Sartre’s novel
Nausea
. I tried to summon up the disgust he would feel at the surfeit of Being that overflowed the streets of Austin—at its sticky thickness, its grossness, its absurd contingency. Whence did it all spring? How did the ignoble mess around me triumph over pristine Nothingness? Roquentin, overwhelmed by the gelatinous slither of existence that environed him in his lonely wanderings through Bouville, was moved to shout, “Filth! What rotten filth!” I might have done the same, but my epiphany was too feeble to justify such an anguished outburst. Besides, everyone around me seemed to be having an awfully good time.

By evening, the streets of Austin had quieted down a little. I asked the concierge at my hotel for advice on where to dine. He recommended a restaurant called the Shoreline Grill, which was located next to Lady Bird Lake, a river-like body of water, apparently named for the late wife of President Lyndon Johnson, that ran through the city.

When I got to the restaurant, I encountered a group of high-school students arrayed in formal wear. It was prom night in Austin, and they were having a fancy dinner there before going to the dance. As I was to discover a few weeks later, Steven Weinberg also happened to be dining at the Shoreline that night, in another room from the one where the maitre d’ seated me. That, as events fell out, was as close as our world-lines came to intersecting.

It was only dusk when I finished my meal in the midst of the prom-goers. On leaving the restaurant, I noticed a large and relatively silent crowd of people assembled by a bridge that spanned Lady Bird Lake. They seemed to be waiting for something. I asked one of them what was going on. He pointed under the bridge. “Bats,” he said in a hushed voice. “They’re all going to take off together in just a few minutes. Happens every night. It’s something to see.”

Looking more closely at the dark underside of the bridge, I saw that it was a continuous carpet of hanging bats—more than a million of them, I was told. They were “Mexican free-tailed bats.” On nice evenings, like this one, tourists and locals would line the lake shore to await the dramatic moment when the bats, ravenous for their nightly meal of insects, took wing in a single giant swarm, blackening the sky.

Having nothing better to do, I sat down on the grassy bank of the lake and waited along with them. The minutes passed. The bats did not stir. A boat chugged by. More minutes passed. Still the bats did not stir. It grew dark. Disappointed, the crowd began to drift away. I got up off the grass and walked back to my hotel, thinking that this unfulfillment was not a good omen for my meeting the next day with Weinberg.

When I entered my room, I noticed the light on the phone was blinking. Someone had left a message. It turned out to be the couple who were taking care of my dog, a little long-haired dachshund named Renzo, during my absence from New York. I called them immediately. Renzo, they gravely told me, had had some kind of seizure earlier that day. While frolicking in the chicken run of their weekend farm in rural Pennsylvania, he had suddenly collapsed with a howl. They had wrapped his semi-comatose body in a cold wet towel and driven him to the emergency room of a nearby animal hospital.

I imagined Renzo alone in a dark and unfamiliar kennel, possibly dying, and wondering, in his flickering consciousness, where I was. There was no choice. After an hour or so of haggling with various airlines, I had arranged to fly back to New York first thing in the morning. I sent a regret-filled e-mail to Weinberg, telling him that a “family emergency” had intervened to make our lunch the next day impossible. Then I dropped into bed and had a fitful night of sleep as the noisy air-conditioning in my room cycled on and off.

When I called the animal hospital the next morning, they told me that Renzo seemed better. He had eaten a little food and had even tried to bite one of the vets. Cheered by this news, I managed to endure the tedious sequence of connecting flights home. But when I was reunited with my dog at the end of that long day, my optimism vanished. Something was terribly wrong with him.

Subsequent X-rays confirmed my worst fears. Renzo’s lungs and liver, the vet told me, showed signs of cancer. The cancer had probably metastasized to his brain, causing the seizure. He seemed to have lost his sight and sense of smell, which suggested that the parts of his cortex responsible for visual and olfactory processing had been destroyed.

Renzo’s once-rich canine sensory world had disappeared into nothingness. All he could do was blindly stumble around in circles, whimpering in distress. Only when I held him in my arms did he seem to get some relief.

So I spent the next ten days holding him. Occasionally he would lick my hand or even wag his tail a little. But his condition was clearly getting worse. He stopped eating. He was unable to sleep, crying through the night in pain. When even the strongest painkillers would not abate his agony, I knew it was time for the inevitable.

I stayed in the room with my dog during his euthanasia. The process took about a half hour. First, Renzo was given a tranquilizing shot. This caused his writhing and whimpering to stop. Stretched out on the table, at peace for the first time in days, he suddenly looked much younger than his fourteen years. He was breathing slowly, and his eyes, though sightless, were open. Then a catheter was inserted into his paw for the lethal injection.

The vet in charge of all this looked like a young Goldie Hawn. She and her assistant took turns with me stroking Renzo during the preparations. I did not want to break down sobbing in front of them.

Fortunately, I have a good trick for maintaining my outward composure in such situations. It involves a beautiful little theorem about prime numbers, originally due to Fermat. Pick a prime number—13, for example. See if it leaves a remainder of 1 when divided by 4. If it passes this test—as 13 does—then, says the theorem, that prime number can always be expressed as the sum of two squares. And sure enough, 13 = 4 + 9, each of which is a square. My trick for controlling myself in moments of unbearable emotion is to run through the numbers in my head and apply this theorem to each one in turn. First, I check to see whether the number is a prime that leaves a remainder of 1 when divided by 4; if it is, I mentally break it down into two squares. For the smaller numbers, this is easy. It’s immediately apparent, for example, that 29 is a prime number that leaves a remainder of 1 when divided by 4, and it’s also easy to see that 29 is the sum of the two squares 4 and 25. When you get past 100, though, both tasks become more challenging if you don’t have pencil and paper. Take the number 193. You have to poke it a bit to make sure that it is indeed the right kind of prime for the theorem to apply. And once you have done this, it may take more than a few seconds to see that the squares it breaks up into are 49 plus 144.

I had made it past 193 and was still dry-eyed at the moment the vet gave Renzo the final injection, the one that would paralyze his nervous system and shut down his little heart. It did its work quickly. Just a moment after the plunger was fully depressed, he exhaled in a burst. “That was his last breath,” the vet said. Then he exhaled again, and was still. Good dog.

The vet and her assistant left me alone in the room so that I could sit for a while with Renzo’s lifeless body. I opened his mouth and looked at his teeth, something he would never let me do when he was alive. I tried to close his eyes. After a few more minutes, I left the room and paid the bill, which included a “communal cremation” with other dogs that had been put down. Then, carrying only Renzo’s blanket, I walked home.

The next day, I called Steven Weinberg at his home in Austin to talk about why the world exists.