||It has been suggested that this article be merged into Simulated reality. (Discuss) Proposed since November 2014.|
The simulation hypothesis contends that reality is in fact a simulation (most likely a computer simulation), of which we, the simulants are totally unaware. Some versions rely on the development of simulated reality, a fictional technology. This technology has been a central plot device of many science fiction stories and films.
- 1 Origins
- 2 Simulation argument
- 3 Types of reality simulation
- 4 Consequences of living in a simulation
- 5 Testing the hypothesis
- 6 In popular culture
- 7 See also
- 8 References
- 9 Further reading
- 10 External links
In its current form, the Simulation Argument began in 2003 with the publication of a paper by Nick Bostrom. Bostrom considers that the argument goes beyond skepticism, claiming that "...we have interesting empirical reasons to believe that a certain disjunctive claim about the world is true", one of the disjunctive propositions being that we are almost certainly living in a simulation. Bostrom and other writers postulate there are empirical reasons why the 'Simulation Hypothesis' might be valid. Bostrom's trilemma is formulated in temporal logic as follows:
- "A technologically mature "posthuman" civilization would have enormous computing power. Based on this empirical fact, the simulation argument shows that at least one of the following propositions is true:
- The fraction of human-level civilizations that reach a posthuman stage is very close to zero;
- The fraction of posthuman civilizations that are interested in running ancestor-simulations is very close to zero;
- The fraction of all people with our kind of experiences that are living in a simulation is very close to one.
- If (1) is true, then we will almost certainly go extinct before reaching posthumanity. If (2) is true, then there must be a strong convergence among the courses of advanced civilizations so that virtually none contains any relatively wealthy individuals who desire to run ancestor-simulations and are free to do so. If (3) is true, then we almost certainly live in a simulation. In the dark forest of our current ignorance, it seems sensible to apportion one’s credence roughly evenly between (1), (2), and (3).
- Unless we are now living in a simulation, our descendants will almost certainly never run an ancestor-simulation."
Chalmers, in The Matrix as Metaphysics agrees that this is not a skeptical hypothesis but rather a Metaphysical Hypothesis. Chalmers goes on to identify three separate hypotheses, which, when combined gives what he terms the Matrix Hypothesis; the notion that reality is but a computer simulation:
- The Creation Hypothesis, that "Physical space-time and its contents were created by beings outside physical space-time" It is related to the Omphalos hypothesis in theology.
- The Computational Hypothesis, that "Microphysical processes throughout space-time are constituted by underlying computational processes"
- The Mind–Body Hypothesis, that "mind is constituted by processes outside physical space-time, and receives its perceptual inputs from and sends its outputs to processes in physical space-time".
Computationalism claims that cognition is a form of computation, and underpins much of the work in Artificial Intelligence. It is related to Functionalism, a philosophy of mind put forth by Hilary Putnam in 1960, inspired by the analogies between the mind and the theoretical Turing Machines, which according to the Church–Turing Thesis are capable of processing any given algorithm which is computable. Computationalism rests on two theses: (i) Computational Sufficiency, that an appropriate computational structure suffices for the possession of mind, and (ii) Computational Explanation, that computation provides a framework for the explanation of cognitive processes.
Computationalism assumes the possibility of Strong AI, which would be required in order to establish even a theoretical possibility of a simulated reality. However, the relationship between cognition and phenomenal consciousness is disputed by Searle in an argument known as the Chinese room. Further critics have argued that it is possible that consciousness requires a substrate of "real" physics, and simulated people, while behaving appropriately, would be philosophical zombies.
Types of reality simulation
Simulation of reality is currently a fictional technology, and non-fictional examples are limited to reality TV or computer simulations of specific events and situations. Current technology in the form of virtual, augmented or mixed reality is very limited in comparison to what would be needed to achieve a convincing simulation of reality. The following typology of the different forms of reality simulation is drawn from examples from both science fiction and futurology. One may usefully distinguish between two types of simulation: in an extrinsic simulation, the consciousness is external to the simulation, whereas in an intrinsic simulation the consciousness is entirely contained within it and has no presence in the external reality.
In a brain-computer interface simulation, participants enter the simulation from outside, directly connecting their brain to the simulation computer, but normally keeping their physical form intact. The computer transfers sensory data to them and reads their desires and actions back; in this manner they interact with the simulated world and receive feedback from it. The participant may even receive adjustment in order to temporarily forget that they are inside a virtual realm, sometimes called "passing through the veil", a term borrowed from Christianity, which describes the supposed passage of a soul from an earthly body to an afterlife. While inside the simulation, the participant can be represented by an avatar, which could look very different from the participant's actual appearance. The Cyberpunk genre of fiction contains many examples of brain-computer interface simulated reality, most notably featured in The Matrix trilogy.
Simulated individual in simulated reality
Assuming that a simulated human being could be conscious, an alternative to interfacing consciousness with a computer simulation would be to simulate both the human being and the surrounding reality.
Consequences of living in a simulation
Based on the assumption that we are living in a simulation, philosophers have hypothesised about the nature of their creators. A conclusion reached by Peter S. Jenkins at York University argues that there would be multiple reasons to create a simulation; In order to avoid the simulation creating another simulation, the first would be deleted.[clarification needed] As it is predicted that we'd have the technology to create simulations in the year 2050, long-term planning after that "would be futile". This, in turn, raises questions as to why the creators of the simulation would delete the simulation. More importantly, if our universe were one of many being simulated, the simulation argument could therefore be statistically applied to the creators saying they are in a simulation too.
Testing the hypothesis
A method to test the hypothesis was proposed in 2012 in a joint paper by physicists Silas R. Beane from the University of Bonn (now at the University of Washington, Seattle), and Zohreh Davoudi and Martin J. Savage from the University of Washington, Seattle. Under the assumption of finite computational resources, the simulation of the universe would be performed by dividing the continuum space-time into a discrete set of points. In analogy with the mini-simulations that lattice-gauge theorists run today to build up nuclei from the underlying theory of strong interactions (known as Quantum Chromodynamics), several observational consequences of a grid-like space-time have been studied in their work. Among proposed signatures is an anisotropy in the distribution of ultra-high-energy cosmic rays, that, if observed, would be consistent with the simulation hypothesis according to these physicists (but, of course, would not prove that the universe is a simulation). A multitude of physical observables must be explored before any such scenario could be accepted or rejected as a theory of nature. In a public discussion with Neil deGrasse Tyson, String Theory Physicist, Dr. James Gates, stated that he found self-correcting computer error code embedded within the fundamental structure of String Theory, which made him "question if (he) was living in the Matrix." 
In popular culture
Science fiction themes
Science fiction has highlighted themes such as virtual reality, artificial intelligence and computer gaming for more than twenty years. One of the first references to simulations occurred in the 1959 novel Time out of Joint by Philip K. Dick. In this the central character is trapped in a "bubble" of 1950s small town America. Simulacron-3 (1964) by Daniel F. Galouye (alternative title: Counterfeit World) tells the story of a virtual city developed as a computer simulation for market research purposes, in which the simulated inhabitants possess consciousness; all but one of the inhabitants are unaware of the true nature of their world.
Permutation City (1994) by Greg Egan explores quantum ontology via the various philosophical aspects of artificial life and simulations of intelligence. Other Egan novels, such as Diaspora (1997) and Schild's Ladder (2002) also involve simulated consciousness. In Iain Banks's The Algebraist, a simulist religion called "The Truth" is the dominant belief system of a considerable proportion of interstellar humanity.
In the 20th century both drama and film have repeatedly explored alternative realities, such as the Theatre of the Absurd, and cropping up unexpectedly in films such as It's a Wonderful Life, and the 1960s television series The Prisoner. The Truman Show (1998) was a fictional example showing the logical extension of this trend, in which the central character is trapped within a physical simulation and whose life is controlled by a director. The idea that reality might be a computer simulation was the central thesis of The Matrix Trilogy (1999–2003). However, many earlier science fiction plot lines incorporated variants this theme and its associated elements such as artificial intelligence.
Other feature films whose plot lines have explicitly involved the simulism hypothesis:
The 2012 play 'World of Wires' was partially inspired by the Bostrom essay.
- Bostrom, N., 2003, Are You Living in a Simulation?, Philosophical Quarterly (2003), Vol. 53, No. 211, pp. 243-255.
- The Simulation Argument Website FAQ 3
- Davis J. Chalmers The Matrix as Metaphysics Dept of Philosophy, U. o Arizona; paper written for the philosophy section of the Matrix website.
- The Simulation Argument: Why the Probability that You Are Living in a Matrix is Quite High, Nick Bostrom, Professor of Philosophy at Oxford University, 2003
- Davis J. Chalmers The Matrix as Metaphysics Dept of Philosophy, U. o Arizona; paper written for the philosophy section of The Matrix website.
- A Computational Foundation for Study of Cognition, Chalmers, D.J. University of Arizona
- Minds, Brains, and Programs John R. Searle, 1980, from The Behavioral and Brain Sciences, vol. 3.
- Fetzer, J. (1996) ``Minds Are Not Computers: (Most) Thought Processes Are Not Computational", paper presented at the annual meeting of the Southern Society for Philosophy and Psychology, Nashville, April 5.
- Historical Simulations – Motivational, Ethical and Legal Issues
- Beane, Silas; Zohreh Davoudi and Martin J. Savage (4 October 2012). "Constraints on the Universe as a Numerical Simulation". INT-PUB-12-046 (Cornell University Library). Archived from the original on 9 November 2012. Retrieved 28 December 2012. Lay summary – The Physics arXiv Blog (October 10, 2012).
ABSTRACT Observable consequences of the hypothesis that the observed universe is a numerical simulation performed on a cubic space-time lattice or grid are explored. The simulation scenario is first motivated by extrapolating current trends in computational resource requirements for lattice QCD into the future. Using the historical development of lattice gauge theory technology as a guide, we assume that our universe is an early numerical simulation with unimproved Wilson fermion discretization and investigate potentially-observable consequences. Among the observables that are considered are the muon g-2 and the current differences between determinations of alpha, but the most stringent bound on the inverse lattice spacing of the universe, b−1 > ~ 10^11 GeV, is derived from the high-energy cut off of the cosmic ray spectrum. The numerical simulation scenario could reveal itself in the distributions of the highest energy cosmic rays exhibiting a degree of rotational symmetry breaking that reflects the structure of the underlying lattice.
- For a general audience presentation of this work see: http://www.phys.washington.edu/users/savage/Simulation/Universe/
- Brantley, Ben (January 16, 2012). "‘World of Wires' at the Kitchen — Review". The New York Times.
- "Are We Living in a Simulation?" BBC Focus magazine, March 2013, pages 43–45. Interview with physicist Silas Beane of the University of Bonn discussing a proposed test for simulated reality evidence. Three pages, 3 photos, including one of Beane and a computer-generated scene from the film The Matrix. Publisher: Immediate Media Company, Bristol, UK.
- "Do We Live in the Matrix?" by Zeeya Merali, Discover, December 2013, pages 24–25. Subtitle: "Physicists have proposed tests to reveal whether we are part of a giant computer simulation."
- Are You Living In a Computer Simulation? Nick Bostrom's Simulation Argument webpage.
- Physicists say there may be a way to prove that we live in a computer simulation: Constraints on the Universe as a Numerical Simulation.