Could Our Universe Be a Simulation? ‘Glitches’ at the Limits of Reality Could Offer Clues, Physicists Suggest

Here’s what you’ll learn when you read this story:

• Some physicists compare the Planck length—the smallest meaningful scale we know—to tiny “pixels” that could form the fabric of space.
• Another constant of the universe is light speed. It might be thought of as the rate at which reality “updates,” similar to a computer simulation.
• Some scientists are considering the idea that the universe is a simulation. It’s still hard to say how we’d ever prove it, but we might be able to stress test reality and find certain glitches as clues.

Reality appears to be continuous in every direction. Spacetime looks smooth and measurable—and for the most part, it is. But when you get down to the fundamental universal constants underpinning everything, such as Planck length and the speed of light, science can’t yet explain their origin. Some scientists have broached the controversial idea that our universe has certain properties because it was designed to.

It starts with examining these constants, the unchanging physical properties that can’t be parsed any further. Planck lengths, which represent the smallest scale we know in which matter can exist, could represent “pixels” that form the framework of space. Each “pixel” is only 1.6×10−35 meters, which is infinitesimally small, even compared to a proton, a building block of atoms. A proton is still 100 billion billion times the Planck length.

This “pixel” length is important—physicists derived it as the spatial scale at which quantum mechanics and gravity intersect. And it represents the smallest discrete distance that light travels. In a sense, the speed of light—a constant 186,000 miles per second in a vacuum—may be the “frame rate” at which reality updates each pixel. At this tiniest of scales, quantum physics principles begin to take over. We see it in the phenomenon between atoms or electrons, sometimes called “spooky action at a distance”—that’s when an action performed upon one tiny particle produces an effect in a very far-removed one.

The quantum world seems to defy the everyday world around us. What makes its mechanics difficult to understand is that quantum particles only seem to have definite properties when we measure them; it’s as if they are rendering on demand, like in a game. Entangled particles maintain correlations across vast distances, behaving less like separate objects and more like data.

So let’s add all of these elements up: the pixels, the speed of light, and the quantum phenomena. Why is our reality apparently built around these fundamentals? Paul Davies, PhD, a theoretical physicist at Arizona State University, has proposed that these properties of the universe combined seem to indicate that reality acts like a simulation. The idea of “simulation theory” has been around for at least 20 years, popularized by philosopher Nick Bostrom, but appearing in science fiction long before that. However, Davies notes that this idea is a thought experiment only. He also cautions that the hypothesis may never be testable, and so may never hope to gain the status of a true scientific theory.

“In a sense, one can make up anything,” Davies says. “The best comment I know about it is an article by John Barrow many years ago, in New Scientist, entitled “Glitch”—in which he says that ‘the flaws of physics may tell us more about reality than the laws of physics.’ Basically, if the universe is a simulation, it need not be perfect, so one might look for ‘glitches’ in the natural order of things.”

How do you falsify the simulation hypothesis? Davies says that while it’s an intriguing idea, the end point might be closer to mythology than science. “So the argument is fun to think about—and I keep a little corner of my mind open to it—but it doesn’t provide a sensible career path for a practicing scientist. It’s more of interest to philosophers, and theologians.”

It’s also of interest to physicist Melvin Vopson, PhD, at the University of Portsmouth. He has examined whether the universe could be “tuned” to existence as a simulation and has published a book about it, called Reality Reloaded: The Scientific Case for a Simulated Universe. Testing the nature of our reality has limitations, he says, but there may be forms of evidence that we can pursue—those glitches Davies mentioned.

“Assuming the universe is indeed some kind of computational construct, essentially to prove it one would need to have access to similar capabilities and tools utilized to run the computation that renders our reality. Since these capabilities would be beyond our constructed realm, what we are left with is a range of limited scientific and metaphysical clues that we could identify and stress test empirically,” he says. “Strangely, those very limitations I mentioned could also be a valuable pathway to extracting these clues, by intentionally pushing physical systems to the limits of our constructed reality and observing their behavior.”

Vopson named a couple of ways we could do that. One kind of experiment would be conducted close to the speed of light, and so show how space and time are intertwined at the universe’s essential speed limit. Another would be through quantum mechanics tests, which would show the limits of space, matter, and energy at a very small scale. By looking at these scales, he says, we are already able to shatter illusions, such as the world as a continuum, “when in fact the universe is discrete, much like a pixelation or discrete digits in a computer system.” The entanglement of quantum particles is a good example of this discreteness, because it shows that matter itself “has in fact a dual wave-particle nature, and matter is only rendered on demand and on observation,” he says.

Vopson does add that “nobody will ever accept the sim theory as a fact, without empirical evidence, and that includes me, too.” However, he suggests that empirical evidence could arise someday from a novel experiment, though he can’t foresee how it will come about. Or perhaps new evidence will emerge through advancements in artificial intelligence (AI), he says—that, again, is difficult to forecast.

While we can’t quite prove that the universe is a simulation, what we can show is that we have a lot of tools for considering the cosmos. Perhaps with advancements in AI or experiments, we can learn more, but for now we will need to be content with leaving many of these questions about our reality to philosophy, rather than science.

It’s an approach that Davies agrees with. He says his biggest objection to a scientific investigation is that calling the universe a simulation is a “cop-out.” That’s because scientists, by their nature and profession, are looking for scientific explanations of the universe around us. On the other hand, he says, it’s easy to imagine “a world in which pretty much anything can happen, like the dream world, and explain it by saying that this reality is simply what the simulator has chosen.”