Note: I cannot take full credit for this short story. I read it about a year ago on some web page and forgot where it was. I’m attempting to reproduce the story here, from memory.

It’s the year 2118, and I walk to work like any other day. The computer simulation research facility at the university is an interesting place to work. Mostly, we try to show what would happen in experiments that are too expensive otherwise. The computer systems have learned to simulate reality to such a high degree of accuracy that the value of real-world experimentation has diminished greatly.

I had taken Friday off, so first on my agenda was to discover what had been done while I was absent.

“Hey Jim,” Barbara said.

“Hello,” I replied.

“You’re going to want to look at this.”

“What’s up?”  I ask.

“Well, we were thinking about the 20th century research of physicists such as Stephen Hawking about what happened in the first moments of the Big Bang. We did some digging, and there is actually enough data and math out there on the subject to start the simulation. We spent the majority of Friday collecting the data and setting up the sim.”

“Okay… what happened?”

“Take a look.”

The computer displayed what appeared to be clusters of galaxies, and zooming in, individual stars within the galaxies. “How long has the sim been running?”

“Oh, we’ve been here all weekend. As you know, time is a variable here, so we advanced the clock about 8 billion years, and you have this. 5 billion years later, check out what happens.” She started to advance the clock and individual stars began to form planetary satellites. “Out of curiosity, we cataloged the stars with 8 planets, and came up with a surprisingly short list… only 350 million or so. Of these, maybe 10 million or so had planets with masses similar to our own solar system. And after some more digging, we found this planet.”

A blue-green globe appeared that looked shockingly familiar. “Is that…?” I asked, taking a closer look.

“It gets better. I zoomed in further, and the continental shelfs appeared very similar to our own. We’d have to get some geologists in here to date it, but we figured we could just advance the clock until we began to recognize our own planet more and more. It turns out it wasn’t as hard as you think. Civilization really changes a planet.”

“You’re not saying you can see us, I mean, humans, can you?”

“Yes.” Giggling, she advanced the clock further. The clock was now using the Gregorian calendar, today’s date, only an hour or so ago.

I saw myself taking a shower. “What is this, some kind of joke?”

“Sorry, but no, It’s not a joke. In fact, we’ve discovered we can’t advance the clock past the current time. Let me show you.” She changed view and pushed the clock as far as it could go. There was an image of the two of us, huddling over the computer monitor.

I jumped around, looking for the camera.

“There’s no camera. We can change the angle, if you want proof.” She rotated the view again, and the angle of the view of ourselves changed back and forth, so we could see ourselves from all angles.

Looking around, I saw no movement in the room.  Nothing was recording us.  I was dumbfounded, because  there I was, looking at the computer.  “How is this possible?” I finally managed to blurt out.

“We’re not sure. But it gives rise to some really interesting questions,” she said mysteriously.

“I’ll say. Turn it off… this is starting to freak me out.”

“I’m not sure we want to do that, actually.”

“Why not?”

“Well, think about it. In this simulation is a simulation of us, looking at another simulation of us, and so on, ad infinitum.” She explained.

“Right, the chain of simulations continues on forever.”

“Exactly. Now ask yourself, what is the probability that we are at the top of this chain of infinite simulations, and we are the real people and everyone below us is the simulation.”

“Huh? But you built this simulation yourself.”

“Well, I might be a simulation of the real me, in another universe above us. There is no way to tell. The fact that we can’t advance the date beyond the current time seems to indicate something. If we turn this computer off, we destroy the simulations, the universes below us. And if we’re just a simulation, we do it because the universes above us will also turn their computer off, destroying us, and everything we know.  So we can’t ethically shut down the simulation.”

“Yeah… I agree.  Don’t turn it off.”