University of Washington physicists have come up with one way to test whether our universe is a giant computer simulation being run by our descendants.

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It is entirely plausible, says University of Washington physics professor Martin Savage, that our universe and everything in it is one huge computer simulation being run by our descendants.

You, me, this newspaper, the room you’re sitting in — everything we think of as reality is actually being generated by vast, powerful supercomputers of the future.

If that sounds mind-blowing, Savage and his colleagues think they’ve come up with a way to test whether it’s true.

Their paper, “Constraints on the Universe as a Numerical Simulation,” has kindled a lively international discussion about the simulation argument, which was first put forth in 2003 by University of Oxford philosophy professor Nick Bostrom.

A UW News posting explaining Savage’s paper has gotten more than 100,000 page views in a week, and ignited theories about the nature of reality and consciousness, the limits on computer networks and musings about what our future selves might be like.

Savage has been interviewed by U.S. News & World Report, The Australian and journalists in Finland, and his colleague and co-author, University of New Hampshire professor Silas Beane, has been interviewed by the BBC. UW physics graduate student Zohreh Davoudi also contributed to the paper.

“It’s sort of caught fire,” Savage said.

Bostrom, the Oxford professor, first proposed the idea that we live in a computer simulation in 2003. In a 2006 article, he said there was probably no way to know for certain if it is true.

Savage — who describes his “day job” as doing numerical simulations of lattice quantum chromodynamics — said a chance discussion among colleagues sparked the idea that there was a way to test the truth of Bostrom’s theory.

And although it might deviate from the work he usually does, it was a worthy question because “there are lots of things about our universe we don’t fully understand,” Savage said. “This is certainly a different scenario for how our universe works — but nonetheless, it’s quite plausible.”

In the paper, the physicists propose looking for a “signature,” or pattern, in our universe that also occurs in current small-scale computer simulations. One such pattern might be a limitation in the energy of cosmic rays.

Because this theory is starting to test the limits of this reporter’s scientific knowledge, we are going to rely on the words of UW News science writer Vince Stricherz, who translated the 14-page paper into laymen’s terms:

“There are signatures of resource constraints in present-day simulations that are likely to exist as well in simulations in the distant future, including the imprint of an underlying lattice if one is used to model the space-time continuum,” Stricherz wrote.

If our world is a computer simulation, “the highest-energy cosmic rays would not travel along the edges of the lattice in the model but would travel diagonally, and they would not interact equally in all directions as they otherwise would be expected to do.”

Got that?

In other words, even supercomputers capable of creating a simulation of the universe would be hobbled by finite resources, and one way we might be able to detect those limits is to look for cosmic rays that don’t travel the way they would be expected to travel.

Savage and his team are theorists, not experimentalists. They’re not planning to perform such a test, although other physicists have said they’re interested in doing so.

And such a test wouldn’t absolutely prove we live in a computer simulation — just that it is possible.

“It would just be a beginning,” Savage said. “It would be curious. It would stimulate further work.”

As of late last week, the UW News article had sparked a wide-ranging online discussion, with more than 100 responses.

Among them:

“It seems unlikely that someone who could do this would be using the same programming techniques that we are currently thinking about. So doing this test might prove we are a sim (simulation) of dim-witted aliens but could not disprove that we are sims of ones slightly smarter than ourselves.”

But — “IF we are in a simulation, then the world outside this simulated world is quite possibly COMPLETELY different from the world in it. We may very well be triple-headed, 7-legged cockroach-like creatures that decided to run a homo-sapiens simulation for the fun of it.”

“You folks take yourselves way too seriously,” another wrote. “This is proof we never should have legalized marijuana.”

Savage believes that at some point in the future, if mankind doesn’t self-destruct along the way, “we’ll try to do simulations of our history. We’ll create something that looks like our own universe.”

The paper concludes on this note: “There always remains the possibility for the simulated to discover the simulators.”

If life is a simulation, though, it doesn’t bother Savage.

“I don’t stay up at night worrying about it,” he said, laughing.

Katherine Long: 206-464-2219 or