Trespassing on Einstein's Lawn (45 page)

The question reminded me of the unease I had felt after learning that all the information contained in some volume of spacetime was proportional to the area of its boundary—as if a whole dimension was redundant. Was that what Wheeler had been thinking when he drew the surface of a sphere tiled with 0s and 1s? That the ability to read out the black hole's information content from its boundary meant that the world, at bottom, was made of information and that information, at bottom, was made of nothing?

Wheeler never stopped drawing his self-excited universe (American Philosophical Society library)
A. Gefter

January 8, 1988: “What comes closer to a circuit and to ∂∂ ≡ 0 than
what we can build—with imagination enough—out of questions and answers?”

October 20, 1985: “More and more certain everything must be built from ‘nothing.' What reasonable alternative is there!”

February 22, 2005: “Nothing! Nothing! You start with nothing to get everything.”

I spent the last day in the library alone with Wheeler's journals. We had made it through nearly all of them, and my father couldn't take another day off work, so I had come to finish reading the final entries without him.

Wheeler was over ninety years old now, and the journal entries became fewer and further between, and increasingly illegible. He continued drawing the U-diagram, the swoop of the curve growing shakier each time. He frequently quoted a poem by Piet Hein, a friend of Bohr's: “I'd like to know / what this whole show / is all about / before it's out.”

Eventually he began dictating his entries to his secretary, Jackie Fuschini. They grew strangely repetitive, as if Wheeler's thoughts were stuck in a loop. “Where do space and time come from?” he would ask, again and again, often followed by the refrain “It's all an illusion.” There were an oddly large number of references to Charles Darwin. “We think of the laws of geometry as having been established at the beginning of time, but were they?” Wheeler asked. “This question reminds us of another How Come, the species of plants and animals that we see today ‘here always' that the question was not so easy to answer became apparent to the young investigator aboard the HMS Beagle.”

He also returned to that central question: one observer or many?

November 8, 2005: “It's hard to ask ‘how come anything' when we take it for granted that we live in a world of space and time.… And if we are the ones who ‘build' the spacetime, how come we don't get [as many] spacetime[s] as people? How come just one? Pursue further that one.”

Wheeler was living with Janette in the Meadow Lakes nursing home, in Hightstown, New Jersey, just outside Princeton. Fuschini would visit him there and take down his thoughts in the journal.

October 11, 2006: “72 degrees, warm and sunny. Sitting on sun porch at ML, looking out picture window at beautiful flowers and shrubbery on patio. It is Indian summer.… John has nothing to report on space and time or Charles Darwin today.”

The next entry was dated December 7, 2006, and consisted of one surreal sentence: “Hope produces space and time?”

A year passed before another entry was written. In that blank space, Janette had passed away. She was ninety-nine years old when she died. They had been married for seventy-two years.

January 2008: “Johnny has not entered anything in the journal in a long time. The next time I visit we will begin.”

I turned the page.

It was blank.

The final entries of John Wheeler's journal (American Philosophical Society library)
A. Gefter

It was kind of crazy, how far this thing had come. One deceptively simple question—
How would you define nothing?
—had led me from a low-security conference center in Princeton to a quantum-rodent-infested London flat, from Brockman's Connecticut farmhouse to the New Mexico town that never was, from a library where I sobbed at the sight of a blank page to a Hertz car rental kiosk at San Francisco International Airport, where I now stood listening to refueling policies with my parents at my side.

My father and I were here to track down the answers to so many questions that remained. Like, why would nothing, the H-state, have ever changed, if it ever changed at all? What role do observers play in the universe's existence? If, as Guth said, “something
is
nothing,” why does the nothing
look
like something? What is the meaning of objects behind the cosmic horizon? Will the sales guy ever stop talking so we can hit the road in search of ultimate reality?

We had learned that the criterion for ultimate reality was invariance—if some feature of the universe is merely an artifact of an observer's perspective, then it's not a true ingredient of the reality that lies beneath. “Real” means “observer-independent.” And amazingly, we had found hardly anything that fit the bill. Relativity had booted space,
time, and gravity off the list, and with them concepts such as mass, energy, momentum, and charge. Gauge theory had crossed off electromagnetism and the nuclear forces, leaving no fundamental forces behind. Hawking radiation spelled the end of particles, fields, and vacua, while AdS/CFT and the holographic principle had wiped out dimensionality, strings, and spacetime. The only items remaining on our now threadbare IHOP napkin were the universe, the multiverse, and the speed of light, and, thanks to horizon complementarity, the first two had fallen under deep suspicion. I was growing increasingly convinced that my father's speculation might be right: that nothing is real. Which, of course, was to say that Nothing is real.

Wheeler's journals had taught me one thing for certain: whatever the answer to ultimate reality may be, it was going to have to navigate that Möbius dichotomy of inside and out, subject and object, referencing a single observer, no more than one at a time, and avoiding at all costs any confusing coauthorship structure.

Coauthorship seemed to be the source of every problem: it was the culprit behind the black hole information-loss paradox, Brockman and Matson hated it, it made a liar out of Wigner's friend, it drove Wheeler to study worm consciousness, and it undermined the very meaning of the word
universe.
After all, what is the universe if not the sum total of every possible point of view? Yet as I had learned from Susskind, summing points of view violates the quantum no-cloning theorem and leads us to overcount information by mistaking different views of the same bit for different bits.
About no feature of “It from Bit” do I feel less comfortable than whose bit.

No matter how many times he circled the issue, Wheeler never figured out how to fit a second observer into the self-excited circuit. Did that mean there is no second observer?
“The theory of [quantum] measurement is logically consistent so long as I maintain my privileged position as ultimate observer,” Wigner had said. Everett had agreed—reality makes sense so long as we're willing “to postulate the existence of only one observer in the universe.”

The whole situation was bumming me out. How exactly do you toss aside the existence of a second observer when the second observer is your
father
?

Physics may have been pushing for sole authorship, but to me it still sounded a lot like betrayal. Besides, we had already coauthored something: our life, my career, a secret mission, the universe. Was it really all an illusion? I tried my hardest to shove Matson's words back down, but they kept resurfacing like Whac-A-Moles:
Just think about it.

I sighed impatiently, then decamped for an empty seat on a nearby bench, abandoning my parents at the rental counter. Something was gnawing at my stomach. Bad pizza? Guilt?

Cosmology's standard model was rooted in coauthorship. The whole point of inflation, of having the universe temporarily expand faster than the speed of light, was to extend the big bang theory's reach beyond a single light cone. It's a theory about the space that lies on the other side of our cosmic horizon. Meanwhile, horizon complementarity forbids us from considering what exists on one side of a horizon and what exists on the other side as constituting a single spacetime geometry, replete, as it would be, with redundant information. And if that weren't bad enough, you can't stop the thing from going eternal, from producing a global multiverse, a single object that encompasses infinitely many spacetime regions separated by horizons. Cosmologists were asking for
infinite
coauthors. I had been shot down for two. And yet everywhere I looked, people were still talking about cosmology's golden age, as if nothing had ever happened at all.

Cosmology was going to have to change in a big way, but how? Could physicists rein in eternal inflation and trap it inside a single light cone, or would they have to go back to the drawing board and come up with a whole new theory? My father and I had come here, to California, to find out, and my mother had happily tagged along. “I know you'll be busy with reality,” she said, “but we'll just have to make time to go to the beach.”

I looked over at the counter and saw my father signing the last of the contracts and scooping up the keys to the Toyota that might lead us to some answers. My mother caught my eye and smiled. She smiled as if all was well, as if we all existed in the same, happy universe. “I can't make something out of nothing, and you can't,” Wheeler had written, “but altogether we can.” It was kumbaya cosmology. It was a
child's dream. Maybe the problem of the second observer was nothing more than the problem of growing up.

The next morning, my father and I took the BART train from downtown San Francisco to the Berkeley campus to meet Raphael Bousso.

Outside the physics building, I stared in disbelief at a parking sign:
Reserved for Nobel laureate at all times.

“Finally, a reason to want a Nobel Prize!” my dad said.

I nodded. It wasn't David Gross's dolphin-front office, but it was a damn good parking space.

Inside, Bousso welcomed us into his office. In his early forties, he was young and handsome, with a calm demeanor and a sweet smile. He had grown up in Germany and studied under Hawking at Cambridge before ending up at Berkeley, his accent a melodic mix of the three nations.

Nobel parking at the physics building, UC Berkeley
A. Gefter

My father and I wanted to know how the multiverse could survive the holographic principle, and Bousso was the guy to ask. Along with Joe Polchinski, it was Bousso who had discovered the string landscape—that collection of some 10
⁵⁰⁰
universes, each with its own physical laws and its own cosmological constant—opening the door to anthropic physics in the multiverse. But he had also discovered the most general form of the holographic principle. Known as the co-variant entropy bound, it showed that given
any
spacetime region—even one that is expanding or collapsing—the amount of information that can fit in that region can't exceed one-quarter the area of its boundary, which meant that the implications of the holographic principle were inescapable in cosmology. There was no avoiding it: spacetime is observer-dependent, and physics only makes sense according to the viewpoint of a single observer. How could Bousso possibly reconcile a global multiverse cutting across 10
⁵⁰⁰
or even infinite causal horizons with the local viewpoint demanded by holography?