Trespassing on Einstein's Lawn (17 page)

In case that wasn't creepy enough, Wheeler proposed an even more extreme version. Imagine light traveling toward Earth from a quasar a billion light-years away, he said. A massive galaxy sits smack between the quasar and Earth, diverting the light's path with its gravitational field like a lens. The light bends around the galaxy, skirting either left or right with equal probability. Imagine, too, Wheeler said, that the arrival rate of the light is low enough that we can measure a single photon at a time. So we have our usual choice: we can keep a photographic plate centered at the arrival spot, where an interference pattern will inevitably emerge, or we can point a telescope to the left or right of the galaxy to see which path the photon took. Our choice determines which of two mutually exclusive histories the photon lived. It determines whether the photon traveled both paths or just
one. We determine its route (or routes) from start to finish, right now—despite the fact that the photon began its journey
a billion years ago.
There's no sense in asking which path(s) the photon “really” took; there's simply no “really” until we choose which measurement to make. When we do, we create a past that stretches back billions of years.

“We used to think that the world exists ‘out there' independent of us,” he said, “we the observer safely hidden behind a one-foot thick slab of plate glass, not getting involved, only observing. However, we've concluded in the meantime that that isn't the way the world works. In fact we have to smash the glass, reach in.”

Delayed-choice experiments have been carried out in laboratories, and each time they've worked just as Wheeler suggested. It's an established scientific fact: measurements in the present can rewrite history. No, not rewrite. Just write. Prior to observation, there is no history, just a haze of possibility, a past waiting to be born.
“There is no more remarkable feature of this quantum world than the strange coupling it brings about between future and past,” Wheeler wrote. If observations we make today can create a billion-year-old past, so, too, can observations made in the future help build the universe we see today.

If the total number of bits that constitute the universe is finite, and if we can count the bit-building contributions of all observers who will ever live, including those in the future, then it's at least plausible to suspect that observers create reality. That was Wheeler's vision, anyway.
“Except via those time-leaping quantum phenomena that we rate as elementary acts of observer-participancy, no way has ever offered itself to construct what we call ‘reality,' ” he wrote.

All in all it was a pretty incredible story—way more interesting than the usual bottom-up one in which the universe starts out in some hot, dense state, inflates, evolves, and 13.7 billion years later accidentally gives rise to moderately clever chunks of gray matter in a boring, linear march from past to future, cause to effect. But Wheeler's story left dangling a host of unanswered questions. Like, what counts as an observer? What gives the observer its special reality-building status? What physical mechanism allows observers to create bits of information through measurements? What does the “boundary of a boundary” have to do with a self-excited universe? And if observership is required
to give meaning (substance, reality) to existence, who observes the observer?

Wheeler's privileging of the observer followed Bohr's view of quantum mechanics, with observers standing outside the systems they're observing. At the same time, his self-excited circuit was a closed loop, with internal observers looking back to observe the same past that bore them, an ouroboros swallowing its tail. So which one was it? Inside or out?

Finally, I was left wondering about the very aim of the thing. If, as Markopoulou had told me, we each have our own light cones, rendering ordinary binary Boolean logic unfit for cosmic use, how could the grand total of all observers that will ever live join together to create a single object called “the universe”?

Wheeler's book didn't have all the answers, but I had the sense that it was raising the right questions.
“Can we ever expect to understand existence?” he asked. “Clues we have, and work to do, to make headway on that issue. Surely someday, we can believe, we will grasp the central idea of it all as so simple, so beautiful, so compelling that we will all say to each other, ‘Oh, how could it have been otherwise! How could we all have been so blind so long!' ”

A soft knock on the door jolted me out of Wheeler's world.

“You're up?” my father asked, peering in.

“I couldn't sleep.”

“Come outside,” he said. “There's supposed to be a meteor shower.”

I grabbed a sweater and some sneakers and we tiptoed downstairs so as not to wake my mother. Outside, we walked up the driveway toward the street, stopping once we had cleared the canopy of the maple tree and had a perfect view of the cloudless, starry sky. It was 3:00
A.M.
The houses were dark and the street was drenched in a uniquely suburban quiet, the click of cicadas and the hum of air conditioners saturating the thick summer air.

We stood side by side, looking up, waiting for the stray dust of a comet's tail.

“I think it's great you're going back to school,” my father said, his eyes on the sky.

“
New Scientist
is based in London, too,” I said. “I'm hoping that by being there I'll get to write more articles so I'll have a steady stream of excuses to talk to physicists.”

I blurred my gaze, trying to expand my peripheral vision.

“There's one!” we shouted simultaneously as a flash of light streaked across the sky.

“Jinx,” I said with a laugh.

“Do you ever think you want to be another kind of writer?” my father asked.

The question caught me off guard. “What do you mean?”

“You went to New York with the intention of becoming a novelist or a poet,” he said. “And it's so great what you're doing with journalism. I'm just worried we're taking it too far, that I'm steering you too far off course. Are you sure this is what
you
want to be doing?”

I thought for a moment in silence. He wasn't wrong. I
did
want to be another kind of writer. It had never been my dream to report on physics, an ill-fitting journalist hat balanced precariously on my head. My dream had always been to
write
—to take amorphous thoughts and morph them, to ink them on the page, to give them form and heft and permanence, like turning nothing into something, however small. Writing, for me, was about muddling through ideas, turning them over, viewing them from every angle to see where they led, even if they only led back to themselves. My favorite stories and poems shined a spotlight on the writer's thought process, exposing all of its cracks and contradictions. But the writing I did as a journalist was just the opposite. Its light revealed only the end products of thought, the conclusions. Science journalism's express goal was to hang over the writer's mind a veil so opaque that the reader would mistake the writer's thoughts about the world for the world itself—the world as seen from an impossible God's-eye view, a paradigm of objectivity and at the same time a lie. For me, hiding the writer's thoughts strips writing of its greatest gift: its ability to grant us access to other minds. Writing has the potential to be magical because it lets us see the one thing we can never see; it opens our eyes to that feature of the world that is most profoundly invisible. Writing is the rock we can kick to refute our loneliness,
to cure the claustrophobia that comes from being trapped inside a one-sided mind.

But it was okay with me that my journalism wasn't exactly the kind of writing I had dreamed about. Journalism wasn't my goal, it was my disguise. It was my laminated invitation to the ultimate reality party, and I wanted to see how far it could take us.

“This thing is important to me,” I said as another streak of light caught my eye. “The writing will have to come later. When it does, I'll have something to say.”

He smiled.

“What about you?” I asked.

“What about me?”

“You read every new physics book the minute it's published, every science magazine, every journal. You added a new bookcase. Is this taking you away from
your
work?”

“I guess I feel it's equally important,” he said. “Maybe more. Fungal infection of the lung or nature of reality?” He paused. “Sometimes I wish I were an astrophysicist. If I were a little younger, I might consider switching.”

“You still could,” I said.

He didn't respond.

We stood in the street in silence. Comet dust blazed across the sky.

Thanks to yet another not-particularly-well-thought-out plan, I was moving to London. If Bostrom had gone to the London School of Economics to study the philosophy of science, decided that reality was probably a simulation, and befriended John Brockman, I thought, it had to lead to something. I had no intention of giving up the journalism gig, but I wanted to step back and see the big picture. I didn't want to lose sight of the goal of this thing.

“Never get too comfortable,” my father had once told me. “As soon as you feel settled, it's probably time to take things to the next level.”

Wheeler had said that philosophy was too important to be left to the philosophers. But I figured it couldn't hurt.

So I rented a flat on the first floor of a charming white townhouse in a posh little cul-de-sac in Notting Hill. My parents and brother came with me to check it out.

“It's a bit small,” the real estate agent warned us as she jiggled the key in the lock, “but very modern.”

She opened the door and I peered in. It was indeed a bit small.

I turned to my family. “Maybe we should go in two at a time?”

My mother and I walked into the studio apartment. It really was pretty modern. Everything was shiny and new, like a luxury apartment that someone had accidentally stuck in the dryer and shrunk.

“The wood floor is just lovely,” the agent pointed out. I nodded. It was, although for that square footage they could have encrusted it in diamonds without having to jack up the rent.

I looked around: there was a one-seater couch, which someone more pessimistic might have called a chair, and a round desk/coffee table/dining table just big enough for a laptop. Or a plate.

“Where's the bed?” I asked.

The realtor pointed up over my head. I followed her gaze to a small, steep ladder leading up to a loft bed above the couch. “Well, that works,” I said, noting the two-foot clearance between the bare mattress and the ceiling. “I'll just have to remember not to sit up.”

“And this is the kitchen?” my mother asked, as if perhaps there were a real kitchen hidden in a closet somewhere.

The agent nodded. “And everything is new!”

“Everything” consisted of a miniature sink, miniature stove, and miniature refrigerator.

“Maybe there's a miniature grocery store nearby that sells miniature food?” I offered up helpfully.

“There's no freezer?” my mother asked, knowing full well the answer.

I shrugged. “But how convenient that you can reach everything in the kitchen from the couch!”

“It's brilliant how they mounted the telly on the wall here,” the agent said. “It doesn't take up any space, and you can see it from every spot in the flat!”

“Yes.” I smiled. “A real feat of engineering.”

“I'll step outside so Dad can come in,” my mother said, sounding defeated.

My father came in and gazed around, unsure of what to say.

“Aren't the wood floors lovely?” I said, nudging him.

He nodded, then whispered, “Do you think this place is subject to quantum effects?”

“How much is the rent?” I asked the real estate agent, then winced at her reply. The place was more expensive than any apartment I had rented in New York, and a fraction of the size. But it was in a beautiful neighborhood and a minute's walk to the Tube station that would take me directly to campus. Besides, I wasn't planning on bringing much stuff. Looking around, I couldn't imagine what kind of place I'd get for less.

“Okay,” I said, “I'll take it.”

If I had come to London to ponder the nature of reality, I had clearly come to the right place. In my philosophy of science class, we discussed it endlessly. Is there a reality? Is it sitting “out there,” independent of us? If so, what is it made of? How can we distinguish it from mere appearances? Is there any hope we'll ever know it at all?

In class, we debated the merits of realism and antirealism. Realism is the commonsense belief that scientific theories describe true things about the world—a real world that exists whether or not we're looking—and that electrons, quarks, dark matter, and whatever other objects appear in our best theories, whether or not they can be observed directly, are
real
objects, the true ontological furniture of a singular, mind-independent world.

Antirealism is an umbrella category for all sorts of ideas that reject realism in one way or another. There's Kantean antirealism, which says that while there is a real world out there independent of us, there's no way for us to know it. There's Berkeley's
esse est percipi
, the more radical claim that behind appearances lurk more appearances, that objects are made not of atoms but of thoughts. There's social constructionism, which says that reality and truth are whatever we agree to call reality and truth, a theory that reminded me of something my New School
postmodernist friends would say and then argue that it had to be true because they believed it, even after I had pointed out that by not agreeing with them I had, by their own definition, proven them wrong. On the saner side there's instrumentalism, which simply states that science is a tool for predicting the outcomes of experiments; whether or not there is a reality, and whether or not we can access it, is entirely beside the point.