Good news, everyone: According to new physics research, reality is probably not a quantum computer simulation designed by a hyper-advanced alien civilization.
Takes a load off, doesn’t it?
To back up: The Simulation Hypothesis, sometimes called the Simulation Argument, is a concept that’s been bouncing around in scientific circles for several years–and in science fiction stories for several decades before that. The gist, according to proponents, is that all of reality is actually an incredibly complex computer simulation created by an advanced civilization. This controlling civilization may be an existing alien culture, or it may be a future iteration of humanity, one of many spun out into the far-future multiverse of parallel realities.
Oh, it’s a trip, man. While the idea itself isn’t particularly new–we’re all familiar with The Matrix movies–what a lot of people don’t know is that Simulation Hypothesis is considered entirely valid, so far as it goes, by a wide range of philosophers, mathematicians, physicists, and metaphysicists. At the 2016 Isaac Asimov Memorial Debate in Washington, D.C., celebrity astrophysicist Neil deGrasse Tyson hosted a two-hour debate on the subject. Elon Musk has suggested that, considered from a certain point of view, it’s pretty much a lock that we’re living inside of some kind of cosmic hard drive.
The core of the argument—perhaps made most strenuously by the philosophers David Chalmers and Nick Bostrom—concerns the incredible rate of computer advancement we’ve seen in recent decades, specifically with games and simulations. We’ve gone from the Atari 2600 to high-resolution virtual reality in forty-some years. Projecting that rate of advancement forward, unthinkable amounts of computing power will be available to advanced species, either our own or others in the universe, who might like to create the ultimate cosmic [simulation]. These sims would essentially replicate physical reality down to the subatomic level. Approximated humans within the simulation–that’s us–would be conscious entities.
“If you assume any rate of improvement at all, then the [simulations] will become indistinguishable from reality,” Musk says.
Some proponents of the idea take it one step further: If future computers can generate limitless simulated universes, then the likelihood of our current reality being the original universe, or the Prime Reality, is actually quite small. In fact, it’s statistically probable that we’re already living inside some kind of cosmic computational construct.
In short: We’re in the Matrix.
Do The Math
Clearly, the Simulation Hypothesis depends upon several key assumptions: Will advanced and/or future civilizations survive long enough to develop this technology? Will they run these simulations on 21st-century Earth? Could advanced simulation avatars actually exist as conscious, self-aware entities? These are some of the reasons, technically speaking, that the simulation concept is properly designated as a hypothesis and not a full theory.
In October 2017, a team of mathematicians and physicists published a research paper that takes an admirably straightforward and two-fisted approach to the question. They decided to get to the bottom of things by using some very powerful computers to crunch some heavy-duty numbers.
The conclusion: Based on everything we now know about physics and computers, it is mathematically impossible for the known universe to be a computer simulation. Theoretical physicists Zohar Ringel and Dmitry L. Kovrizhin–from the University of Oxford and the Hebrew University in Israel–published their findings in the prestigious journal Science Advances. If you speak math, you can read all about it .
Since I don’t have a PhD or three, Kovrizhin kindly agreed to break it down for me. Emailing from his lab in Oxford, he writes that to really and truly simulate the universe, our hypothetical future computer would need to replicate phenomena down to the quantum level.
“In quantum mechanics, which is the basis for understanding of the nature, a system of particles is described by a Hamiltonian, an object that can be written as a matrix,” Kovrizhin says. “In order to simulate a quantum mechanical system, one would, in general, have to diagonalize this matrix on a computer, which is a computationally difficult task when the size of the matrix becomes large.”
According to the research team’s best approximations, it would require a terabyte of RAM to store just 20 spins of a single particle on the quantum level.
“If one tries to extrapolate this to few hundreds of spins, then building a computer with such a memory would require more atoms than there are in the universe,” Kovrizhin says.
It gets much more complicated than that, as you might imagine. Corresponding with Kovrizhin is a lot of fun if you enjoy discussing the Schrödinger equation and quantum Monte Carlo, which is likely the most efficient possible algorithm for simulating quantum particles, and the one his research focused on. One important detail is that Kovrizhin and his colleagues didn’t actually set out to prove or disprove the Simulation Hypothesis. Their conclusions were a kind of side effect generated by a separate study concerning quantum systems and computational algorithms. Ultimately, the new research just indicates that advanced civilizations could not simulate the known universe using our current understanding of computing technology.
It’s entirely possible, of course, that future civilizations will have developed technologies and computing systems we can’t even imagine at this point. That flips us back to the fundamental question: If we are in an advanced simulation, isn’t it possible that all of our calculations–all we think we know about the impossible complexity of the quantum realm–is just part of the simulation?
“This is an interesting philosophical question,” Kovrizhin says. “But it is outside physics, so I would rather not comment on it.”
La La Land
This is the point of departure at which conjecture on the Simulation Hypothesis gets genuinely bananas. The debate becomes so abstract that we move out of the realm of science and into more notional areas of religion and cosmology. The physics turn into metaphysics.
If there really is an alien civilization or entity powerful enough to simulate reality down to the quantum level, then how is that different from theological concepts of divine pantheons or the Prime Mover creating heaven and earth? Think about this stuff long enough, and the mind starts to form a recursive loop, a Möbius strip of existential speculation. It’s a great party topic–grab your favorite alkaloid and go for it.
Mathematician Marcus Noack has spent a lot of professional and discretionary time contemplating the Simulation Hypothesis. Currently a postdoc researcher at the Lawrence Berkeley National Lab (address: 1 Cyclotron Road), Noack specializes in computational physics–the one branch of science maybe best equipped to wrangle with the cosmic sim concept.
From a strictly rational, hardware-conscious point of view, Noack is skeptical. He agrees with the recent mathematical research that computers, as we understand them right now in the year 2018, will never be able to simulate an entire universe.
“The more computing power I want, the bigger the computer must be,” Noack says. “That’s because hard drives are actual physical things that I can touch. If I want to accurately model the universe–the movement of every subatomic particle in the cosmos, from the Big Bang onward–it’s not possible. I cannot overstate how far away that idea is from the reality of computation as we know it today.”
From a more existential point of view, however, Noack concedes that there is plenty of wiggle room in the idea.
“Let’s just say there is a future civilization that has perfected this, that has technologies we don’t know,” he says. “Well, what you’re doing in computational physics is, you’re modeling the world. If that model is complete, and we’re actually inside of it, then we wouldn’t know. In a sense, we can’t know. There’s no chance we could look over the horizon and see that we’re in a simulation.”
Tiffany Li, resident fellow with Yale Law School’s Information Society Project, agrees in principle with that assessment. As an attorney specializing in technology and information science, Li is entirely proficient with the tools of the trade: logic, argument, rhetoric. She comes at the problem as an issue of epistemology–how do we know what we think we know?
“Philosophically, of course, I think most scholars would agree that it’s very difficult to prove anything at all in this region,” Li says, speaking from her offices at Yale. “The question of what reality is, or whether what we perceive is real, these are questions that have plagued philosophers for millennia.”
Li suggests that the Simulation Hypothesis fits squarely into a long tradition of existential speculation that we can trace from ancient times—the Taoist parable of the Butterfly Dream, for instance—all the way through to The Matrix movies.
“Or how about Descartes?” she suggests. ” Cogito ergo sum (I think therefore I am). That’s very similar. That’s in the 1600s, and he’s looking at the same problem. How do we determine what is real?”
Start asking around, or clicking around, and you’ll find that plenty of people have cannonballed straight into the rabbit hole that is the Simulation Hypothesis. TV writer and media personality Rick Rosner—sometimes billed as the world’s second-smartest man—is among many who have speculated on potential rips in the Matrix. You may have heard some of these theories, concerning the Berenstain Bears and the La La Land/Moonlight mix-up at the 2017 Oscars. The idea is that, every now and again, something slips sideways in our simulated universe, giving us a peek behind the cosmic curtain.
Rosner takes a contrarian approach: He’s less interested with these supposed reality slips than with the conspicuous absence of such glitches, historically. If the Matrix does freeze up, we’re not likely to see it.
“Our universe appears to be 13.8 billion years old, and it appears to have been unfolding steadily without glitches or signs of external intervention,” Rosner says. “So, with a simulation this vast and self-consistent, the odds that it will begin unraveling when and where we’re able to see it are near zero.”
Reckless conjecture is all good and well, of course. It’s practically our species’ national pastime. Evidently, a governing principle of the human condition is that we are not allowed to know, existentially speaking, what the hell is going on. But at the end of the cosmic day, a single practical question remains: If you were to find out–tomorrow around noon, say–that the universe is indeed a computer simulation, would it change anything? Would it make a difference in how you live day-to-day life?
“Not for me, it wouldn’t,” says Noack, who has plenty to keep him busy at the Lawrence Berkeley lab. As a practical matter, Noack says, there is no point to actually making a decision on the issue. We can’t know for sure, and tomorrow is coming either way.
“We’re trying to make this distinction–are we living in a simulation, or are we not?” he says. “Maybe there is no difference.”
“Even if we were to someday find out we’re living in the Matrix, there is literally nothing to suggest that there’s a way out of that,” she says. “There’s nowhere to escape to. It doesn’t make sense.”
Instead, Li suggests that everyone should just remain calm and carry on.
“It’s a really great thought experiment, and it’s useful for getting people to think about philosophical concepts,” she says. “But it’s also important to invest our resources and our energy to solve the problems we see in the real world right now.
“Whatever this world is.”