NOTE: Jen-Luc Piquant is delighted to feature a guest post today by fellow science writer Amanda Gefter, author of the wonderful new book, Trespassing on Einstein's Lawn: A Father, a Daughter, the Meaning of Nothing, and the Beginning of Everything

I’m sure every freshly published author struggles with the ungainly demands of self-promotion. It’s taxing and embarrassing— shouting your title from the rooftops of social media, groveling for favors, trying desperately to be heard. And then, if you’re me, there’s an additional level of awkwardness that taints the whole effort when it suddenly dawns on you that you’ve been out in the world trying to promote a book about solipsism.

The book, Trespassing on Einstein’s Lawn, is the story of my 17-year journey with my father to figure out the nature of ultimate reality and what we discovered, quite frankly, is not what any marketing team wants to hear. Quantum mechanics, relativity, black hole physics, cosmology and string theory all point to the same radical, paradigm-shifting conclusion: every observer’s reference frame defines its own universe, singular and complete, and even though any reference frame is as good as any other, we can only speak about one at a time.

Me? I’ve got my reference frame – namely, “author.” And that puts me in the rather uncomfortable position of having to deny the existence of another reference frame – namely, “reader.” So when it comes to promoting my book, I’m kind of at a loss. If the universe is solipsistic, I’m pretty sure the twitterverse is, too.

My belief in this cosmic solipsism is a sad lesson in irony, really, because this whole thing – my career, my universe, my book—began with a conversation. I was fifteen years old, having dinner in a Chinese restaurant, when my father leaned over and asked, “How would you define nothing?” He told me that he was trying to understand how you can get something from nothing, how a universe could be born.

Over plates of cashew chicken, we vowed to figure it out.

At first it was just sort of a hobby, teaching ourselves theoretical physics and cosmology, and we didn’t realize how far out of control it had spun until we found ourselves impersonating journalists and crashing a physics conference in Princeton, New Jersey. It was after the conference, as we were trespassing on Einstein’s front lawn, two bogus press passes still hanging round our necks, that I realized our hobby had become something more like a mission – a joint, covert quest to figure out the nature of reality. I conjured up a journalism career as a front and my father and I spent the next decade traipsing around the country, meeting with brilliant physicists and discussing the deep mysteries of existence.

Our first major breakthrough came when we realized that physics can pin down what’s real and what isn’t. It’s one of those things that’s somehow stupidly obvious and yet deeply profound: something is real if it’s invariant. That is, something is real if it remains unchanged from one reference frame to the next. Just look at a rainbow. You’ll see one in the sky if you’re in just the right reference frame with the Sun shining in from behind you, and droplets of water in the atmosphere refracting the light. It’s pretty, but good luck trying to grab it. A rainbow is not a physical object stapled to the sky. It’s a product of your reference frame. Which is to say, it’s not real.

Ok, so what is real? Space? Time? Particles? Forces? Well Einstein showed that space and time aren’t real– they change from one reference frame to another. However, something remains invariant in the process: a unified, four-dimensional spacetime. “Space by itself and time by itself are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality,” the mathematician Hermann Minkowski declared.

And the thing my father and I learned is that ever since Einstein, theoretical physics has been one long death march for invariants. With his infamous discovery that black holes radiate, Stephen Hawking declared particles observer-dependent (along with fields and the quantum vacuum to boot). String theory did away with the invariance of dimensions and M-theory did away with the invariance of strings. By studying what happens when stuff falls into a black hole, Leonard Susskind discovered that the unified spacetime Einstein had left unscathed is itself observer-dependent. As for nature’s four fundamental forces, Einstein did away with gravity (“We are able to ‘produce’ a gravitational field merely by changing the system of coordinates,” he wrote) while the development of gauge theory took care of the other three. Every last one of the so-called fundamental ingredients of nature has turned out to be a shadow. Unreal.

When I look back on that spring day on Einstein’s lawn, the day when our journey took a turn for the crazy, I see my father and I operating under the rosy-cheeked premise that there was a single reality we both shared, a Kumbaya universe, a mutual home, a world “out there,” independent of our viewpoints.

Sure, there are things like shadows and rainbows that only exist in a given reference frame, we thought, but there also other things, real things, like tables and chairs, stars and galaxies, things that exist out there, in the universe, the ontological furniture in the common room of existence. Only now we’ve discovered that the common room is empty. There’s nothing out there. The common room—the universe—doesn’t exist. You’re left with a splintered, illusory, solipsistic reality and when it comes time to do PR for your book, you find yourself in a bit of an existential dilemma.

Given this whole situation, you might ask why I bothered to write a book in the first place. It’s a fair question. I remember early in the process my editor asked me who was the intended audience for the book. “Me,” I replied. I knew it wasn’t exactly what someone interested in book sales wanted to hear – after all, there’s only one of me, and I get a free copy. But it was the truth. I tried to write the book that I wanted to read. More to the point, I couldn’t speak for anyone else’s ontology. At the scale of publishing, quantum gravity effects are probably pretty negligible. But still.

The death of the last remaining invariants is a new development in physics, but the specter of solipsism has been looming for decades, ever since the first generation of quantum physicists struggled to understand what the theory meant. “It is conceivable we must give up on any ‘one-world’ view of physics,” the legendary physicist John Archibald Wheeler scrawled in his journal as he wrestled with the mystery of the quantum. Quantum theory seems to go haywire when you assume that multiple observers occupy the same universe. I might open Schrodinger’s box to find a dead cat, but what if the cat, the box, and I are sitting inside an even bigger box, one that some other observer—my father, perhaps— hasn’t opened yet? To me, that cat is dead, but to my father it’s simultaneously dead and alive, and so am I. If there’s only one reality, which one is it? Quantum mechanics is just boxes within boxes – unless you stipulate that there’s only one box, in which case the whole issue of writing books becomes a little thorny.

Hugh Everett knew what I’m talking about. In his famous 1955 dissertation, the founder of the “many worlds” interpretation wrote, “The interpretation of quantum mechanics…is untenable if we are to consider a universe containing more than one observer.” A possible escape route, Everett suggested, is “to postulate the existence of only one observer in the universe. This is the solipsist position, in which each of us must hold that he alone is the only valid observer...This view is quite consistent, but one must feel uneasy when, for example, writing textbooks on quantum mechanics…for the consumption of other persons to whom it does not apply.”

Despite all this, here I am, holding a freshly printed copy of my new book. Maybe I wrote it so I could feel less lonely, so that my thoughts could take physical form, so that they could become this object that can worm its way into other reference frames I myself could never visit and yet there they are, carrying a little piece of me with them.

Look: there’s my mind, sitting on someone’s nightstand beside the red-framed glasses. And over there – my mind has a coffee ring stain and a leather bookmark with tattered fringes peeking out the top. There’s my mind tossed on a chair, half obscured by a sweater. There it is being used a doorstop; there it is snuggled up with a stranger in bed. That person is reading my mind and she’s laughing. She’s crying, she’s writing in my margins, she’s rolling her eyes.

My mind is splintered, duplicated, repeated, cast out into universe after universe where it will live all these invisible lives, lives I will never know, a silent echo, and I’ll just be sitting here, in my own solitary world, straining to hear.

Amanda Gefter is the author of Trespassing on Einstein's Lawn: A Father, a Daughter, the Meaning of Nothing, and the Beginning of Everything.