[This Road to VR story describes how physicists and philosophers think we can, and whether we should, gather evidence for the simulation hypothesis. See also a Space.com interview with Rodney Ascher, the director of the new documentary A Glitch in the Matrix that “tackles the theory head-on”; that story includes the film’s trailer (also available via YouTube); here’s an interview excerpt:
“SPACE.COM: How did making this film either confirm your belief in simulation theory or make you question it?
RODNEY ASCHER: Well there are two ways of looking at simulation theory, either as a scientific possibility that changes everything we think we know about the world around us or, secondly, as a metaphor. For the first, I believe I understand the premise after being immersed in the project for two years, but the idea still hasn’t crossed the threshold of ‘extraordinary claims require extraordinary evidence’ as best I can tell.
As a metaphor though, I see it as a very powerful way to describe the world and our place in it.
SPACE.COM: How does popular entertainment like sci-fi films, anime, comics, and immersive video games help acclimate humanity into the notion of digital existence?
ASCHER: Well, they visualize it, right? That makes it seem much more plausible. The late ’90s gave us ‘The Matrix,’ ‘Dark City,’ ‘The Thirteenth Floor’ and ‘eXistenZ’ (among others) and you have to say that when things get difficult, the idea that it’s not ‘real’ can be a handy pressure release if used in moderation.
A few people in the movie talk at length about video games and they do provoke a pretty profound question. Is there a comparable level above us that has the same relationship to us that we do to the video games we create and the characters we can interact with inside of?
SPACE.COM: What were some of the more surprising or shocking elements of your research for this documentary?
ASCHER: Well, certainly many of the details of the Josh Cooke story were shocking on their face, but my biggest surprise was how quickly interviewees went to religious and ethical places as they discussed the implications of simulation theory.”
The film is widely available, including on streaming platforms. See The Verge for a (negative) review. –Matthew]
[Image: Source: “Do We Live in a Simulation? Chances Are about 50–50” in Scientific American. Credit: Getty Images]
Reality Might Be a Simulation, Scientists Think It’s Possible to Find out for Sure
By Ben Lang
August 27, 2021
If you’re interested in VR, you’ve probably thought at least once or twice about the simulation hypothesis—the idea that we might actually already be living in a virtual reality world. Many people are passingly familiar with the idea, especially thanks to films like The Matrix, and it’s been a topic among philosophers—in some form or another—for perhaps more than a millenium. But did you know that scientists actually think it may be possible to experimentally verify if we’re living in a simulation?
The simulation hypothesis was boiled down into a useful thought experiment by University of Oxford philosopher Nick Bostrom in a 2003 paper titled Are You Living in a Computer Simulation? which was published in the peer-reviewed Philosophical Quarterly journal.
In the paper, Bostrom explores the idea that—given existing trends in computing power—a far future “posthuman civilization” will likely wield immense computing power—enough to be easily capable of running simulations of billions of universes just like ours. He raises the question: if we think humanity will one day be capable of simulating billions of universes… isn’t it likely that we’re already living in one of those billions of simulations rather than being real ourselves?
It’s an intriguing formulation of the simulation hypothesis that’s frankly quite difficult to argue against. Bostrom’s paper has spurred serious discussion about the topic; it’s been cited by more than 1,000 other academic papers since its publication.
Beyond philosophers, scientists have taken the simulation hypothesis seriously too, especially in the mysterious realm of quantum physics. Several papers have hypothesized ways of actually testing if our reality is a simulation.
Pushing the Limit
In the 2012 paper Constraints on the Universe as a Numerical Simulation, published in the peer-reviewed European Physical Journal A, physicists Silas R. Beane, Zohreh Davoudi, and Martin J. Savage write that recent developments in simulating quantum interactions point toward a future where a full-fledged universe simulation is possible, which suggests that “experimental searches for evidence that our universe is, in fact, a simulation are both interesting and logical.”
According to the authors, quantum computing looks like a reasonable foundation for simulating an entire universe. But like any program, a simulated universe will have some fundamental limitations of precision. If our reality is based on a quantum computing simulation, the authors argue, we should be able to predict some of those fundamental limitations and then go searching for them in nature.
Specifically the authors say they’re looking at “the possibility that the simulations […] employ an underlying cubic lattice structure,” which is foundationally similar to small-scale quantum computing-based simulations that humanity is capable of running today. If we could observe limitations in our reality that are consistent with an underlying lattice structure for space-time, instead of a continuous space-time, the authors say it could be evidence that our universe is indeed a simulation.
The authors leave us with a tantalizing conclusion—that it may be impossible for a simulation to be fully hidden from its subjects.
“[…] assuming that the universe is finite and therefore the resources of potential simulators are finite, then a volume containing a simulation will be finite and a lattice spacing must be non-zero, and therefore in principle there always remains the possibility for the simulated to discover the simulators.”
Reality Observed Rendered
In the 2017 paper On Testing the Simulation Theory, published in the peer-reviewed International Journal of Quantum Foundations, authors Tom Campbell, Houman Owhadi, Joe Sauvageau, and David Watkinson start with a similar premise to the above conclusion—that a simulated universe likely operates with finite resources. If that’s the case, they argue, we should be looking for evidence that the behavior of our universe is consistent with a simulation optimized for computing performance.
The paper introduces a concept that will be familiar to game developers—as a matter of optimization to run a game with finite computing power, games only render what the player can see at any given moment. Anything more would be a waste that would drastically slow down the game.
The authors point out that physicists are already aware of a feature of the universe that seems suspiciously similar to rendering a game only where the player is looking. That would be the so-called Wave Function Collapse, in which fundamental particles appear to act as wave functions up until the point that they are observed, at which point their wave characteristics “collapse” and into predictable particle interactions.
The paper lays out a number of specific variations of the perplexing Double-slit Experiment, that are designed to isolate the precise role of the observer in determining the experimental outcome. The ultimate goal of the experiments is to look for a situation in which the universe would change its behavior in order to avoid creating a paradox. If this was observed, the authors argue, it would be “an indicator of a VR engine [simulated universe] reacting to the intent of the experiment.”
Further the authors suggest that finding a conflict between likely requirements of any such simulation (logical consistency and avoidance of detection) could reveal observations consistent with a simulated universe.
“Two strategies can be followed to test the simulation theory: (1) Test the moment of rendering; (2) Exploit conflicting requirement of logical consistency preservation and detection avoidance to force the VR rendering engine to create discontinuities in its rendering or produce a measurable signature event within our reality that indicates that our reality must be simulated,” the authors write.
Features, Not Bugs
The universe is full of fascinating physics that have been experimentally confirmed but are still far from fully explained.
In an unpublished paper, circa 2018, titled The P2P Simulation Hypothesis and Meta-Problem of Everything, University of Tampa philosopher Marcus Arvan argues that many of the most confounding aspects of physics could be reasonably explained by our universe being the result of a specific simulation structure.
“Our world has a wide variety of deeply perplexing physical and philosophical features. Consider physics. At present, our two best theories of fundamental physics are the General Theory of Relativity, which explains gravitation, and Quantum Mechanics, which explains all other known forces. Both theories have been systematically confirmed by experiment—yet both theories tell us our world’s physics is incredibly strange.
General Relativity tells us that:
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- Space and time are relative to observers: simultaneous events in one reference frame are non-simultaneous from another, time moves at different rates depending on the observer’s frame of reference, and the physical properties of objects in spacetime (e.g. their length) depends on the observer’s reference-frame.
- The physical world has a ‘speed-limit’: no information can travel faster than light.
Quantum mechanics, in turn, tells us that all of the following are true of our world:
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- Quantum superposition: every particle simultaneously exists in many different eigenstates (i.e. a superposition of different space-time locations and properties).
- Quantum indeterminacy: the eigenvalue a particle will be observed to have upon measurement is indeterminate, in that the value can in principle only be predicted probabilistically.
- Wave-particle duality: every individual particle simultaneously has properties of particle (existing at a particular point) and a wave (spread out over space and time).
- Wave-function collapse: observation of a particle (or measurement of quantum system it is a part of) leads the wave-like features of a particle (viz. the particle’s superposition) to ‘collapse’ to a single observed value (i.e. the observed properties of the particle).
- Quantum entanglement: particles arbitrary distances apart can become entangled, such that changing the physical properties of one particle will instantaneously change the other particle’s properties without any observable exchange of information.
- Minimum space-time distance: there is a minimum space-time distance below which space and time themselves have no physical meaning (the Planck Length).
- Quantum retrocausality: measurements of a quantum system can have observable effects on the system earlier in time, causing wave-function collapse before the measurement is taken.
These features of our world are incredibly bizarre—yet they are implied by the equations of quantum mechanics, and quantum mechanics been systematically confirmed by experiment.”
The simulation structure that Arvan advocates as an explanation for these phenomena is a peer-to-peer (P2P) arrangement.
“[…] a particular kind of simulation—peer-to-peer networked (P2P) simulations—actually replicate our world’s relativistic and quantum-mechanical physical features due to the computational structure of peer-to-peer networking itself. For consider what a P2P simulation is. In contrast to dedicated server simulations—where there is a central computer representing the spatio-temporal locations of all objects in the simulation—a P2P simulation has no central computer at all: instead, a P2P simulation is simply a network of independent simulations interacting with each other. In a P2P simulation, each ‘user’ only ever experiences their simulation, and ‘the physical world’ that all users experience in common is just a superposition of all of the simulations interacting on the network.”
Arvan ultimately uses the paper to argue that the P2P simulation hypothesis is the best explanation to holistically explain a wide variety of physics and metaphysics mysteries that otherwise don’t seem to have an obvious means of unificiation.
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While it may be possible to discover if we’re living in a simulated virtual world, it seems we’re still far from actually doing so. One thing seems certain, however: even though our understanding of virtual reality, quantum computing, and AI is rudimentary compared to what would likely be needed to simulate an entire universe, eventually doing so in the far future seems entirely likely based on what we currently understand about reality.
Leading us to have to seriously consider… will we be the first beings in the universe to reach the necessary technological capability to run countless numbers of such simulations? Or are we one of many simulations already ongoing by beings that got there first?
Finding out might not be a great idea, actually. Philosopher Preston Greene has argued that discovering that we’re in a simulated universe could lead to the end of the universe itself.
“Think of it this way. If a researcher wants to test the efficacy of a new drug, it is vitally important that the patients not know whether they’re receiving the drug or a placebo. If the patients manage to learn who is receiving what, the trial is pointless and has to be canceled.
In much the same way, as I argue in a forthcoming paper in the journal Erkenntnis, if our universe has been created by an advanced civilization for research purposes, then it is reasonable to assume that it is crucial to the researchers that we don’t find out that we’re in a simulation. If we were to prove that we live inside a simulation, this could cause our creators to terminate the simulation—to destroy our world.”
So, are you taking the blue pill, and continuing to believe that our world is the real world—or the red pill, and wondering how deep the rabbit hole goes?