Trespassing on Einstein's Lawn (59 page)

My father's reasoning was impressively similar to the kind of reasoning I had encountered from physicists over the years. Wilczek, for instance, had written,
“The most symmetric phase of the universe generally turns out to be unstable. One can speculate that the universe began in the most symmetric state possible and that in such a state no matter existed.… Eventually a patch of the less symmetric phase will appear—arising, if for no other reason, as a quantum fluctuation.… This event might be identified with the big bang.… Our answer to Leibniz's great question ‘Why is there something rather than nothing?' then becomes ‘Nothing is unstable.' ”

Of course, we had since learned the problem with the whole “nothing is unstable and quantum fluctuations will change it to something” idea. It was a global story told by an omniscient narrator, a narrator with an impossible God's-eye view, a reference frame situated outside the H-state, relative to which the H-state, which by definition has no outside, would change. What's more, it presupposed quantum mechanics, leaving Wheeler's question dangling, unanswered:
Why the quantum?

But now, thanks to Rovelli, I had the beginnings of an answer. “Why the quantum?” was the same as “Why non-Boolean logic?” But non-Boolean logic, I now knew, was a fictitious logic, the logic that crops up when you cut across horizons, when you try to describe reality from multiple points of view simultaneously. Quantum logic is non-Boolean because reality is radically observer-dependent. Because there's no singular way things “really are.” There was my “really” and my father's “really,” but never both.

The H-state couldn't change because it has no outside. But from here on the inside, it could
appear
to change, as if something is just what nothing looks like from the inside. Here on the inside, with a finite speed of light, observers can't see the whole thing. Their perspective is bounded. But when you put a boundary on the H-state, it's no longer the H-state. It's no longer nothing. It's something.

Of course, the problem with
that
idea was that it required a finite speed of light to define the light cones that in turn define an observer's perspective. The stubborn speed of light was still hanging on, untouched on the IHOP napkin, leaving one last ingredient irreducible and inexplicable.
If observers create reality, where do the observers come from?

I flipped the pages of my father's notebooks, frustrated. With a star drawn next to it, my father quoted Lao Tzu: “To find the most precious of pearls doesn't compare to discovering the source of all things.”

A few days later, I awoke to find a paper lying on the floor outside my bedroom door. My parents had both left and gone to work. Groggy, I picked it up. There was a note attached:
A clue? L, D.

I sat back down on my bed to read. It was a typed transcript of a talk given by a French astrophysicist named Laurent Nottale. Strangely, the conference from which the talk came was not about physics but about Buddhism. I laughed. Physics and Buddhism? Throw in Bob Dylan and some oatmeal-raisin cookies and you've got my father's paradise.

Relativity, Nottale explained in the talk, is about emptiness, the emptiness of motion and of space and time. Einstein's happiest thought was that a man in free fall can't feel his own weight.
“Thanks to this,” Nottale said, “he has realized that gravitation that looks so solid and so universal has no intrinsic existence.” It's observer-dependent. It's not ultimately real.

“Form is emptiness, emptiness is form,” Nottale says, quoting the Heart Sutra. “This is what relativity tells us.”

When I got to page ten, I discovered that my father had highlighted a section of text.
“Form is emptiness because it is always possible
to find a reference system in which the thing disappears. At this stage, it can really help us to understand in which reference system the thing disappears. The answer is that it is in the proper reference system … the self reference system, in itself.… It is true for any property we may consider. This property can disappear in the proper reference system. Consider whatever you want, like a color, a form, an object, a mass, a particle, and put yourself into it, in the interior of the thing, then the thing disappears. In the color, there is no color.… What makes the color is the wavelength. If you are smaller than the wavelength, the concept of color does not even exist. It disappears completely. If you are
in
light, participating in its motion, light and time disappear (this is what Einstein understood at the age of fifteen and what led him to build ten years later his first theory of relativity). Therefore, in motion, there is no motion, in position, no position, in particle, no particle.”

If you are in light, light disappears.

I dropped the paper in my lap.
Holy shit.

That was it.

That was the answer.

The teenage Einstein had asked what light would look like if you were running at the same speed alongside it. But what happens when you invert the question and ask, what does the universe look like to light? What does a photon see?

Light, by definition, uses up its entire spacetime quotient on space, leaving none for time. In other words, it sees all of space in no time. From my point of view, the light leaving a star 5 million light-years away takes 5 million years to reach my eye. But from the light's point of view, its journey is instantaneous. From the light's point of view, the speed of light is not the speed of light. It has no speed. It is everywhere at once in a single instant. A photon doesn't see the universe. A photon sees a singularity.

It sees
the H-state.

It was all dawning on me now. So much depended on the speed of light: the existence of horizons, light cones, information bounds, reference frames, observers. As long as it was invariant, so were they.

Wheeler had worried about light's invariance, too. On August 27,
1985, he had written in his journal, “My picture (U-diagram) shows a reflexive system, but one with at least one primitive element, that dashed line.” That dashed line was the finite and invariant speed of light. Wheeler's self-excited circuit could explain away everything—except that.

But now I saw that the speed of light
isn't
invariant. It isn't real.
Here's the reality test. If you can find one frame of reference in which the thing disappears, then it's not invariant, it's observer-dependent.
Nottale had pointed out the one frame in which the speed of light disappears: the frame of the light.

Horizons—the last remaining ingredients of reality, the last remnants of a sandcastle fading back into the boundless sameness of the beach, that dashed line reaching back through cosmic history, the final bulwark that stood between something and nothing—were built of light, light frozen in place by acceleration and by gravity.

But horizons don't have horizons.

Boundaries don't have boundaries.

The boundary of a boundary is zero.

That evening, I invited my father to have dinner with me at our Chinese restaurant, the one where he had first asked me about nothing.

It was a little corny, I knew, forcing that kind of cinematic symmetry on my own life. But it felt right. It reminded me of how far we'd come, and at the same time of how so little had changed. Besides, I knew how much he loved the cashew chicken.

We arrived at the restaurant and sat down at what we swore was our original table, though I suspected that was some kind of mutual false memory. After we ordered our food, I pulled out my notebook. “Okay,” I said. “I've made a list of the key clues.” I read them off one at a time.

One: Nothing is defined as an infinite, unbounded, homogeneous state. Which means that “something” is defined as a finite, bounded state. To turn nothing into something, you need a boundary.

Two: There are no nonzero conserved quantities. Everything is in some sense nothing.

Three: All of physics seems to be defined on boundaries. On horizons.

Four: The laws of physics make sense only within the reference frame of a single observer, a single light cone.

Five: Given a single reference frame, an entire observer-dependent cosmic history will unfurl, thanks to top-down cosmology and Wheeler's delayed choice.

Six: Horizon complementarity and holographic spacetime suggest that nothing beyond my horizon is real. As if the region carved out by my light cone is the be-all and end-all of reality.

Seven: The positive value of our cosmological constant ensures that for any given reference frame there exists an inescapable and observer-dependent boundary. The universe is fundamentally fragmented. Wait forever and you'll never see the whole thing.

Eight: The low quadrupole in the cosmic microwave background seems to suggest that the entire universe is the size of the observable universe.

Nine: The relational nature of quantum mechanics and the inescapable limitations of Gödelian self-reference ensure that a subject can never be an object in its own frame, and that in turn the world is always broken into pieces.

Ten: M-theory, our best description of the physical world to date, appears to have no ontology.

Eleven: Reality is radically observer-dependent. Every possible ingredient of ultimate reality, every item on the IHOP napkin, has been crossed off. Nothing is invariant. Nothing is ultimately real.

“Those clues paint a pretty striking picture,” my father said.

That was an understatement. The whole thing was kind of uncanny, how it all fit together. But into what exactly? Into Nothing?

“What do you think it all means?” I asked.

“I'm thinking what you're thinking,” he said. “That everything is nothing, the H-state, and that it only looks like something when you have a limited, internal perspective. And you
have
to have a limited, internal perspective because no external perspective exists. There's no outside. But there's still some transformation you can make, by going
to the point of view of the light, of the horizon, to get you back to the nothing that's always there.”

That
was
what I was thinking. My father's definition of nothing as an infinite, unbounded homogeneous state carried two implications: nothing has no outside, and nothing will never change. At first that had seemed like a nonstarter—if it can't change, how could the universe ever be born? But Smolin's first principle of cosmology held the answer: the origin has to come from
inside the nothing.
Given some internal reference frame with a boundary, a universe is born, its history unfurling from present to past. A top-down universe that exists only relative to its reference frame. Beyond the bounds of the frame, there's nothing.

The failure of the God's-eye view signaled the nonexistence of any reality beyond a single observer's point of view. After all, why would all of physics be defined in terms of a single reference frame unless the single reference frame
defined
the universe?

“You know, if you started from the premise that internal reference frames create the universe by transforming a boundless nothing into a bounded something, then you'd actually
expect
physics to make sense only within a single frame at a time, with nonsensical redundancies cropping up any time you mistakenly talk across horizons,” I said. “And if a single reference frame marks the edge of reality, you'd think you might see evidence that there's nothing beyond the cosmic horizon.”

“Evidence like the low quadrupole in the CMB?” my father asked, grinning.

I grinned back. It was a tantalizing prospect.

One thing was clear: the key to existence was a boundary. From the beginning I had worried that light cones alone wouldn't be enough. Given infinite time, any given light cone would engulf the entire H-state, turning the something back to nothing again. It seemed you needed something more permanent—something like the kind of perpetual boundary dark energy provides. Then again, maybe it was enough to say that no observer can measure himself. Maybe Gödelian incompleteness and the impossibility of self-measurement keep the nothing at bay, the world always carved in half, observer and observed.

To turn nothing into something, you needed information bounds, a finite amount of information to get it from bit. “Something of an information-theoretic character is at the bottom of physics, spacetime, existence itself,” Wheeler had written on his way to the hospital. “This is a quick sentence if anyone asks me for a last word before I leave this Earth.”

I had wondered why, of all the profound thoughts rolling around in his head, Wheeler had chosen that one to be his final word on the nature of reality. Why not the self-excited circuit? Or the boundary of a boundary? Why information?

Now I was beginning to understand what information really was: asymmetry. To register a bit of information, you need two distinguishable states: black or white, spin up or spin down, 0 or 1. You need twoness. After all, entropy was a measure of missing information, and with entropy comes symmetry. A smoothly distributed gas, the epitome of high entropy, looks pretty much the same everywhere—it's highly symmetric. And what's symmetry? It's redundancy of description, a redundancy of information. If you need to describe a five-pointed snowflake, the only information you require is the information describing one of the points along with the fact that there are five of them. You don't need individual information for each of the points because it's just the same information repeated over and over again. A five-pointed snowflake is symmetric in that its information repeats five times. The more symmetry something has, the less information it contains.

My father's H-state was a state with no differentiation whatsoever. A state of perfect symmetry. That meant it had zero information, which made sense, considering it was nothing. So how do you get information from the H-state, turning nothing into something? You put a boundary on it. The boundary breaks the symmetry, creating information. But the boundary is observer-dependent, and so is the information it creates.