The Mammoth Book of Nebula Awards SF

“What are you planning exactly?”

“Replicating results, nothing new. The Feynman double-slit.”

He was quiet for a moment. “It’s good to see you working on something, but isn’t that a little dated?”

“Good science is never dated.”

“But what are you expecting to prove?”

“Nothing,” I said. “Nothing at all.”

The day we ran the experiment, the weather was freezing. The wind gusted in from the ocean, and the East Coast huddled under a cold front. I got to work early and left a note on Satish’s desk.

Meet me in my lab at 9:00.

—Eric.

I did not explain it to Satish. I did not explain further.

Satish walked through the door of room 271 a little before 9:00, and I gestured toward the button. “Would you like to do the honors?”

We stood motionless in the near-darkness of the lab. Satish studied the apparatus spread out before him. “Never trust engineer who doesn’t walk his own bridge.”

I smiled. “Okay then.” I hit the button. The machine hummed.

I let it run for a few minutes before walking over to check the screen. I opened the top and looked inside. And then I saw it, what I’d been hoping to see. The experiment had produced a distinctive banded pattern, an interference pattern on the screen. Just like Young, just like the Copenhagen interpretation said it would.

Satish looked over my shoulder. The machine continued to hum, deepening the pattern as we watched.

“Would you like to see a magic trick?” I asked.

He nodded solemnly.

“Light is a wave,” I told him.

I reached for the detector and hit the “on” switch — and just like that, the interference pattern disappeared.

“Unless someone is watching.”

The Copenhagen interpretation posits this: Observation is a principle requisite of reality. Nothing exists until it is first observed. Until then there are only probability waves. Only possibility.

For purposes of the experiment, these waves describe the probability of a particle being found at any given location between the electron gun and the screen. Until a particle is detected by some consciousness at a specific point along the wave, its location remains theoretical. Therefore, until a particle is observed passing through one slit, it could be equally anticipated to pass through either — and thus will actually propagate through both in the form of probability waves. These wave systems interfere with each other at regular intervals and thereby assemble a visible interference pattern on the capture screen behind the slits. But if a particle is detected by an observer at one slit, then that excludes the possibility of it passing through the other; and if it can’t propagate through both, it can’t compile an interference pattern.

This would seem self-contradictory, except for one thing. Except that the interference pattern disappears if someone is watching.

We ran the experiment again and again. Satish checked the detector results, being careful to note which slit the electrons passed through. With the detectors turned on, roughly half the electrons were recorded passing through each slit, and no interference pattern accrued. We turned the detectors off again — and again, instantly, the interference pattern emerged on the screen.

“How does the system know?” Satish asked.

“How does it know what?”

“That the detectors are on. How does it know the electron’s position has been recorded?”

“Ah, the big question.”

“Are the detectors putting out some kind of electromagnetic interference?”

I shook my head. “You haven’t seen the really weird stuff yet.”

“What do you mean?”

“The electrons aren’t really responding to the detectors at all. They’re responding to the fact that you’ll eventually read the detectors’ results.”

Satish looked at me, blank-faced.

“Turn the detectors back on,” I said.

Satish hit the button. The detectors hummed softly. We let the experiment run.

“It is just like before,” I told him. “The detectors are on, so the electrons should be acting as particles, not waves; and without waves, there’s no interference pattern, right?”

Satish nodded.

“Okay, turn it off.”

The machine cycled down to silence.

“And now the magic test,” I said. “This is the one. This is the one I wanted to see.”

I hit the “clear” button on the detector, erasing the results.

“The experiment was the same as before.” I said. “With the same detectors turned on both times. The only difference was that I erased the results without looking at them. Now check the screen.”

Satish opened the box and pulled out the screen.

And then I saw it. On his face. The pain of believing something which can’t be true.

“An interference pattern,” he said. “How could that be?”

“It’s called retrocausality. By erasing the results after the experiment was run, I caused the particle pattern to never have occurred in the first place.”

Satish was silent for five full seconds. “Is such a thing possible?”

“Of course not, but there it is. Unless a conscious observer makes an ascertainment of the detector results, the detector itself will remain part of the larger indeterminate system. The detectors don’t induce wave function collapse; consciousness observation does. Consciousness is like this giant roving spotlight, collapsing reality wherever it shines — and what isn’t observed remains probability. And it’s not just photons or electrons. It is everything. All matter. It is a flaw in reality. A testable, repeatable, flaw in reality.”

Satish said, “So this is what you wanted to see?”

“Yeah.”

“Is it different for you now that you’ve actually seen it?”

I considered this for a moment, exploring my own mind. “Yes, it is different,” I said. “It is much worse.”

We ran the slit experiment again and again. The results never changed. They matched perfectly the results that Feynman had documented decades earlier. Over the next two days, Satish hooked the detectors up to a printer. We ran the tests, and I hit print. We listened as the printer buzzed and chirped, printing out the results.

Satish pored over the data sheets as if to make sense of them by sheer force of will. I stared over his shoulder, a voice in his ear. “It’s like an unexplored law of nature,” I said. “Quantum physics as a form of statistical approximation — a solution to the storage problem of reality. Matter behaves like a frequency domain. Why resolve the data fields nobody is looking at?”

Satish put the sheets down and rubbed his eyes.

“There are schools of mathematical thought which assert that a deeper order lies enfolded just below the surface of our lives. Bohm called it the implicate.”

“We have a name for this, too,” Satish said. He smiled. “We call it Brahman. We’ve known about it for five thousand years.”

“I want to try something,” I said.