Our best theory of gravity no longer belongs to Isaac Newton. It’s Einstein’s General Theory of Relativity. There’s just one problem: it is incompatible with quantum theory. The effort to tie the two together provides the greatest challenge to physics in the 21st century.

An icy wind cuts against my face as I step from the airport curb and get into a cab. The cab nudges into rush hour traffic and I stare at the wet snow splattering against the window. I am already regretting that I agreed to make this trip.

A long time ago—before things fell apart for him--Dr. Grant had been my mentor. I consented to his request that I visit him mostly because I felt sorry for him, for all the promise he had squandered, and for what little he had left.

But I was also a little curious. Time and circumstances had dragged Dr. Grant far down the back slope of his life. Even so, a mind as brilliant as his might still be capable of one last dazzling pirouette.

I was at MIT doing graduate work when I first met Dr. Grant. He was a towering figure in particle physics then, an innovative thinker with an unparalleled grasp of mathematics. He was often referred to as the next Stephen Hawking. So I was thrilled when he agreed to be my doctoral advisor.

Thursday afternoons we would meet in his small windowless office to discuss my thesis. The office was sterile and functional, a bookshelf along one wall, a blackboard along the other. The only personal touch was a sign that hung on the wall behind his desk. He told me that he had picked it up at a gag shop. The sign said: “I THINK, THEREFORE I AM. I THINK.”

After graduating, I secured a teaching position at Stanford. Dr. Grant and I stayed in touch at first. But as the years went on, he changed. His papers, once considered bold and innovative, began to drift more and more into questionable propositions. In his later years, he came to be viewed as a kook. He left MIT under duress and ended up at Indiana State. I lost contact with him after that

Then, last month, I ran into him at a conference in St Louis. I walked into an auditorium for a session on quantum physics. Dr. Grant was seated in the back row.

During the Q&A, Dr. Grant raised his hand.

“My finger is comprised of millions of molecules. Each of those molecules is comprised of atoms which, in turn, are comprised of subatomic particles. According to quantum physics, there is a non-zero probability that one of those particles is on Mars, is there not?”

“Until we collapse the waveform by observing it,” the speaker replied.

“And until that happens, there is a probability that more than one subatomic particle is on Mars. In fact, there is a probability that the entire finger is on Mars, right?”

“We observe it here. Therefore the waveform has collapsed.”

“But maybe I only think I’m observing it here,” Dr. Grant said.

I met Dr. Grant in the hallway after the lecture. In spite of his disheveled appearance, he assured me that things were going well.

“I feel like I’m doing the best work of my life right now,” he said, “I’m really excited about where this is headed.”

He put his hand on my shoulder. “You were always one of the few who really understood my work. I want to share this with you. You must visit me as soon as possible.”

Dr. Grant’s appears disoriented when we meet in his office. I worry that his mental faculties may be slipping. But once he goes to the whiteboard, I realize that his mind is as sharp as ever.

“We’ve been looking at the wrong end,” he says. “We should be looking at quantum physics from an holistic perspective. The anomalies exist because we haven’t been looking at all of the components. More specifically, we haven’t been looking at ourselves and the role we play as observers.”

“If the entire universe is Schrodinger’s cat,” he continues, “then we assume that, because we exist, the cat is alive. But what if some other observer outside our frame of reference observes the cat as dead? Our minds aren’t designed to grapple with that kind of ambiguity. We have to trust the math. That’s where you come into play.”

“You’re one of the few people able to fully understand my math. So now I need you to validate what are certainly the most important calculations of my lifetime. Perhaps everyone’s lifetime.”

“The key,” he continues, “is a set of state vectors that apply, not at the particle level but at the macroscopic level, encompassing the entire universe.”

Picking up a marker he begins scrawling on the white board, explaining at each step what he was doing, stopping from time to time elaborate on a point. I struggle to keep up at first, my mind unable to accept some of the concepts but unable to refute the math. Eventually, the light comes on.

“Astounding!” I exclaim, “This truly *is* revolutionary!”

“Well… let’s go one step further.”

He quickly erases the board and begins scrawling again.

“Let’s start with this state vector,” he says.

He is writing furiously now, not talking, only looking over occasionally to confirm that I am still following. Finally, he stops with a flourish and puts the marker down. I continue working through the calculations, not quite sure I understand the conclusion they seemed to lead to.

“This can’t be,” I stammer, a confused look on my face.

He hands me several sheets of paper with all of the calculations neatly printed by hand. “I need you to go back to Stanford and prove that I am wrong.”

“But…if this is true, we, our universe everything…” I stall.

“We don’t exist,” Dr. Grant finishes the sentence for me.

Outside Dr. Grant’s office building, I walk briskly to where the taxi is waiting. I’m running late, but I should have time to make my flight. I think everything will be okay. I think.