Before electronic computers had actually been built, Alan Turing mathematically proved a fundamental and profound property of them which has been exploited in innumerable ways as they developed and became central to many of our technologies and social interactions. A computer of sufficient complexity, which is, in fact, not very complex at all, can simulate any other computer or, in fact, any deterministic physical process whatsoever, as long as it is understood sufficiently to model in computer code and the system being modelled does not exceed the capacity of the computer—or the patience of the person running the simulation. Indeed, some of the first applications of computers were in modelling physical processes such as the flight of ballistic projectiles and the hydrodynamics of explosions. Today, computer modelling and simulation have become integral to the design process for everything from high-performance aircraft to toys, and many commonplace objects in the modern world could not have been designed without the aid of computer modelling. It certainly changed my life.
Almost as soon as there were computers, programmers realised that their ability to simulate, well…anything made them formidable engines for playing games. Computer gaming was originally mostly a furtive and disreputable activity, perpetrated by gnome-like programmers on the graveyard shift while the computer was idle, having finished the “serious” work paid for by unimaginative customers (who actually rose before the crack of noon!). But as the microelectronics revolution slashed the size and price of computers to something individuals could afford for their own use (or, according to the computer Puritans of the previous generations, abuse), computer gaming came into its own. Some modern computer games have production and promotion budgets larger than Hollywood movies, and their characters and story lines have entered the popular culture. As computer power has grown exponentially, games have progressed from tic-tac-toe, through text-based adventures, simple icon character video games, to realistic three dimensional simulated worlds in which the players explore a huge world, interact with other human players and non-player characters (endowed with their own rudimentary artificial intelligence) within the game, and in some games and simulated worlds, have the ability to extend the simulation by building their own objects with which others can interact. If your last experience with computer games was the Colossal Cave Adventure or Pac-Man, try a modern game or virtual world—you may be amazed.
Computer simulations on affordable hardware are already beginning to approach the limits of human visual resolution, perception of smooth motion, and audio bandwidth and localisation, and some procedurally-generated game worlds are larger than a human can explore in a million lifetimes. Computer power is forecast to continue to grow exponentially for the foreseeable future and, in the Roaring Twenties, permit solving a number of problems through “brute force”—simply throwing computing power and massive data storage capacity at them without any deeper fundamental understanding of the problem. Progress in the last decade in areas such as speech recognition, autonomous vehicles, and games such as Go are precursors to what will be possible in the next.
This raises the question of how far it can go—can computer simulations actually approach the complexity of the real world, with characters within the simulation experiencing lives as rich and complex as our own and, perhaps, not even suspect they're living in a simulation? And then, we must inevitably speculate whether we are living in a simulation, created by beings at an outer level (perhaps themselves many levels deep in a tree of simulations which may not even have a top level). There are many reasons to suspect that we are living in a simulation; for many years I have said it's “more likely than not”, and others, ranging from Stephen Hawking to Elon Musk and Scott Adams, have shared my suspicion. The argument is very simple.
First of all, will we eventually build computers sufficiently powerful to provide an authentic simulated world to conscious beings living within it? There is no reason to doubt that we will: no law of physics prevents us from increasing the power of our computers by at least a factor of a trillion from those of today, and the lesson of technological progress has been that technologies usually converge upon their physical limits and new markets emerge as they do, using their capabilities and funding further development. Continued growth in computing power at the rate of the last fifty years should begin to make such simulations possible some time between 2030 and the end of this century.
So, when we have the computing power, will we use it to build these simulations? Of course we will! We have been building simulations to observe their behaviour and interact with them, for ludic and other purposes, ever since the first primitive computers were built. The market for games has only grown as they have become more complex and realistic. Imagine what if will be like when anybody can create a whole society—a whole universe—then let it run to see what happens, or enter it and experience it first-hand. History will become an experimental science. What would have happened if the Roman empire had discovered the electromagnetic telegraph? Let's see!—and while we're at it, run a thousand simulations with slightly different initial conditions and compare them.
Finally, if we can create these simulations which are so realistic the characters within them perceive them as their real world, why should we dare such non-Copernican arrogance as to assume we're at the top level and not ourselves within a simulation? I believe we shouldn't, and to me the argument that clinches it is what I call the “branching factor”. Just as we will eventually, indeed, I'd say, inevitably, create simulations as rich as our own world, so will the beings within them create their own. Certainly, once we can, we'll create many, many simulations: as many or more as there are running copies of present-day video games, and the beings in those simulations will as well. But if each simulation creates its own simulations in a number (the branching factor) even a tiny bit larger than one, there will be exponentially more observers in these layers on layers of simulations than at the top level. And, consequently, as non-privileged observers according to the Copernican Principle, it is not just more likely than not, but overwhelmingly probable that we are living in a simulation.
The author of this book, founder of Play Labs @ MIT, a start-up accelerator which works in conjunction with the MIT Game Lab, and producer of a number of video games, has come to the same conclusion, and presents the case for the simulation hypothesis from three perspectives: computer science, physics, and the unexplained (mysticism, esoteric traditions, and those enduring phenomena and little details which don't make any sense when viewed from the conventional perspective but may seem perfectly reasonable once we accept we're characters in somebody else's simulation).
COMPUTER SCIENCE. The development of computer games is sketched from their origins to today's three-dimensional photorealistic multiplayer environments into the future, where virtual reality mediated by goggles, gloves, and crude haptic interfaces will give way to direct neural interfaces to the brain. This may seem icky and implausible, but so were pierced lips, eyebrows, and tongues when I was growing up, and now I see them everywhere, without the benefit of directly jacking in to a world larger, more flexible, and more interesting than the dingy one we inhabit. This is sketched in eleven steps, the last of which is the Simulation Point, where we achieve the ability to create simulations which “are virtually indistinguishable from a base physical reality.” He describes, “The Great Simulation is a video game that is so real because it is based upon incredibly sophisticated models and rendering techniques that are beamed directly into the mind of the players, and the actions of artificially generated consciousness are indistinguishable from real players.” He identifies nine technical hurdles which must be overcome in order to arrive at the Simulation Point. Some, such as simulating a sufficiently large world and number of players, are challenging but straightforward scaling up of things we're already doing, which will become possible as computer power increases. Others, such as rendering completely realistic objects and incorporating physical sensations, exist in crude form today but will require major improvements we don't yet know how to build, while technologies such as interacting directly with the human brain and mind and endowing non-player characters within the simulation with consciousness and human-level intelligence have yet to be invented.
PHYSICS. There are a number of aspects of the physical universe, most revealed as we have observed at very small and very large scales, and at speeds and time intervals far removed from those with which we and our ancestors evolved, that appear counterintuitive if not bizarre to our expectations from everyday life. We can express them precisely in our equations of quantum mechanics, special and general relativity, electrodynamics, and the standard models of particle physics and cosmology, and make predictions which accurately describe our observations, but when we try to understand what is really going on or why it works that way, it often seems puzzling and sometimes downright weird.
But as the author points out, when you view these aspects of the physical universe through the eyes of a computer game designer or builder of computer models of complex physical systems, they look oddly familiar. Here is how I expressed it thirteen years ago in my 2006 review of Leonard Susskind's
The Cosmic Landscape
:
“What would we expect to see if we inhabited a simulation? Well, there would probably be a discrete time step and granularity in position fixed by the time and position resolution of the simulation—check, and check: the Planck time and distance appear to behave this way in our universe. There would probably be an absolute speed limit to constrain the extent we could directly explore and impose a locality constraint on propagating updates throughout the simulation—check: speed of light. There would be a limit on the extent of the universe we could observe—check: the Hubble radius is an absolute horizon we cannot penetrate, and the last scattering surface of the cosmic background radiation limits electromagnetic observation to a still smaller radius. There would be a limit on the accuracy of physical measurements due to the finite precision of the computation in the simulation—check: Heisenberg uncertainty principle—and, as in games, randomness would be used as a fudge when precision limits were hit—check: quantum mechanics.”
Indeed, these curious physical phenomena begin to look precisely like the kinds of optimisations game and simulation designers employ to cope with the limited computer power at their disposal. The author notes, “Quantum Indeterminacy, a fundamental principle of the material world, sounds remarkably similar to optimizations made in the world of computer graphics and video games, which are rendered on individual machines (computers or mobile phones) but which have conscious players controlling and observing the action.”
One of the key tricks in complex video games is “conditional rendering”: you don't generate the images or worry about the physics of objects which the player can't see from their current location. This is remarkably like quantum mechanics, where the act of observation reduces the state vector to a discrete measurement and collapses its complex extent in space and time into a known value. In video games, you only need to evaluate when somebody's looking. Quantum mechanics is largely encapsulated in the tweet by Aatish Bhatia, “Don't look: waves. Look: particles.” It seems our universe works the same way. Curious, isn't it?
Similarly, games and simulations exploit discreteness and locality to reduce the amount of computation they must perform. The world is approximated by a grid, and actions in one place can only affect neighbours and propagate at a limited speed. This is precisely what we see in field theories and relativity, where actions are local and no influence can propagate faster than the speed of light.
THE UNEXPLAINED. Many esoteric and mystic traditions, especially those of the East such as Hinduism and Buddhism, describe the world as something like a dream, in which we act and our actions affect our permanent identity in subsequent lives. Western traditions, including the Abrahamic religions, see life in this world as a temporary thing, where our acts will be judged by a God who is outside the world. These beliefs come naturally to humans, and while there is little or no evidence for them in conventional science, it is safe to say that far more people believe and have believed these things and have structured their lives accordingly than those who have adopted the strictly rationalistic viewpoint one might deduce from deterministic, reductionist science.
And yet, once again, in video games we see the emergence of a model which is entirely compatible with these ancient traditions. Characters live multiple lives, and their actions in the game cause changes in a state (“karma”) which is recorded outside the game and affects what they can do. They complete quests, which affect their karma and capabilities, and upon completing a quest, they may graduate (be reincarnated) into a new life (level), in which they retain their karma from previous lives. Just as players who exist outside the game can affect events and characters within it, various traditions describe actors outside the natural universe (hence “supernatural”) such as gods, angels, demons, and spirits of the departed, interacting with people within the universe and occasionally causing physical manifestations (miracles, apparitions, hauntings, UFOs, etc.). And perhaps the simulation hypothesis can even explain absence of evidence: the sky in a video game may contain a multitude of stars and galaxies, but that doesn't mean each is populated by its own video game universe filled with characters playing the same game. No, it's just scenery, there to be admired but with which you can't interact. Maybe that's why we've never detected signals from an alien civilisation: the stars are just procedurally generated scenery to make our telescopic views more interesting.
The author concludes with a summary of the evidence we may be living in a simulation and the objection of sceptics (such that a computer as large and complicated as the universe would be required to simulate a universe). He suggests experiments which might detect the granularity of the simulation and provide concrete evidence the universe is not the continuum most of science has assumed it to be. A final chapter presents speculations as to who might be running the simulation, what their motives might be for doing so, and the nature of beings within the simulation. I'm cautious of delusions of grandeur in making such guesses. I'll bet we're a science fair project, and I'll further bet that within a century we'll be creating a multitude of simulated universes for our own science fair projects.
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Reviews with images
Best book on the subject
Simulation Hypothesis is probably the best book on the simulation argument, and definitely the most unique and readable. I appreciate that it goes beyond the standard arguments to integrate more cutting-edge science and consciousness-related phenomena.
Top reviews from other countries
sarah
I dont know as bought for someone else
Reviewed in the United Kingdom on December 19, 2023nick
Nice idea – spoiled by spelling errors and clumsy grammar
Reviewed in France on April 27, 2022
Ricardo
Analogies, and metaphors between reality and video games.
Reviewed in Mexico on August 14, 2019
