Simulation theory

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A number of different writers, technologists, and futurologists have predicted that the available computer power in the future will be enormous. Future civilizations may have the capability to create simulations with a high level of detail. These would simulate the universe and its laws, allowing for the emergence of self-conscious entities that could communicate with one another. They could be simulations of that civilization's forebears, and since they would run on very powerful computers, they could run a great many of them [1] [2]. The idea that our universe is a software process running on some deeper computational substrate is known as the Simulation Argument (or Simulation Hypothesis). Nick Bostrom has provided an argument for this thesis, and while other philosophers are taking this idea seriously, physicist suggest that there might be practical ways to find evidence that confirms it [3] [4] [5].

Simulation argument

The philosopher Nick Bostrom (University of Oxford) explored, with rigor, the issue of the simulation argument, for the first time, in a 2003 article. The type of simulations he explored are not akin to the ones in the movie Matrix, for example. In the film, the world was simulated but the conscious minds were not. On the contrary, the simulations explored by Bostrom do not have a biological component, being run on a deeper level hardware or in virtual machines inside other simulations. The argument takes into account the assumption of substrate-independence and the technological limits of computation, and a bland indifference principle [1] [4].

Assumption of substrate-independence

Substrate-independence is a common assumption in the philosophy of mind studies. It asserts that human consciousness is not dependent on a biological substrate. It could, theoretically, be replicated in silicon-based processors, provided the system has the right sort of computational structures and processes, with fine-grained detail like on the level of the individual synapses. The replication would not, necessarily, have to be perfect; just good enough that a human-like subjective experience could be generated. This assumption, although not universally, is widely accepted [1] [4] [6].

Currently, there is not enough computer power to run the computational processes required to replicate the human brain for the emergence of consciousness. Even if they were available, there is still a lack of knowledge in how to program such a thing. Besides this, there would also need to be sophisticated ways of making a very detailed scan of a human brain. These are only technical difficulties, and not physical law or material constrains. A sufficiently advanced civilization with enough computing power to create conscious minds in computer hardware would be classified as posthuman [4] [6].

Technological limits of computation

Although we are still a bit far off in the creation of conscious minds in computers, due to the limits in technological development, some have argued that if technological progress continues unhindered, those problems will be surpassed. For the simulation argument, it does not matter the timescale in which humankind will reach a posthuman stage where such a capability will be available [1].

It is not possible, presently, to set an upper bound limit to the computing power that will be available to future posthuman civilizations. Indeed, such a civilization could even have the capability to convert planets and other astronomical resources into computers with power beyond imagination. A lower bound for computation in a posthuman future is easier to establish, assuming only mechanisms that are already understood. Some authors have suggested a computer system roughly the size of a sugar cube that would perform 10^21 instructions per second, and another with the mass of a planet that could perform 10^42 operations per second [1] [6].

There are also some estimates regarding the amount of computer power needed to emulate a human mind. One gives a figure of ~10^14 operation per second for the entire brain, and another that is based on the number of synapses and their firing frequency gives a number between ~10^16 to 10^17 operations per second. Beyond these figures, the addition of an environment in a simulation will increase the computing power required. The value of the increase will depend on the scope and granularity of the simulation. To obtain a realistic simulation of human experience it is not required to simulate the universe down to the quantum level (something that could be infeasible unless a radically new physics is discovered). What is necessary is that the simulated humans interact in normal human ways with their simulated environment and do not notice any irregularities. Indeed, according to Bostrom (2003), “a posthuman simulator would have enough computing power to keep track of the detailed belief‐states in all human brains at all times. Therefore, when it saw that a human was about to make an observation of the microscopic world, it could fill in sufficient detail in the simulation in the appropriate domain on an as needed basis. Should any error occur, the director could easily edit the states of any brains that have become aware of an anomaly before it spoils the simulation. Alternatively, the director could skip back a few seconds and rerun the simulation in a way that avoids the problem.” [1]

In conclusion, the main computational cost to create completely realistic simulations seems to be in simulating organic brains down to the neuronal or sub-neuronal level. Since a posthuman civilization may build a great number of very powerful computers capable of running simulations indistinguishable from reality, the computing power available to them is enough to run a huge number of ancestor simulations [1].

The core argument

The core of the simulation argument does not try do demonstrate that reality is, in fact, a simulation. It merely shows that one of three propositions should be accepted as true [1] [3]. The general idea can be understood without mathematics, although a formal version of the argument uses probability theory [7]. Although each of the propositions may seem implausible, if the simulation argument is correct, at least one is true [6]. According to Bostrom (2003, 2006), the three proposition presented are:

1. Almost all civilizations at our level of development become extinct before becoming technologically mature.

2. The fraction of technologically mature civilizations that are interested in creating ancestor simulations is almost zero.

3. You are almost certainly living in a computer simulation. [1] [6] [7]

If the first proposition is false then a major portion of all species at our level of development will achieve the posthuman stage (technological maturity). On the contrary, if true, it does not mean that humanity will face extinction soon but that it is unlikely to reach a posthuman stage. It is also possible that a civilization could remain arrested for a long time at the current level of technological development before going extinct [1] [6]. If the second proposition is also false then it follows that a portion of these species that are technologically mature will use some of their computer resources to run ancestor simulations, recreating minds like ours and doing so in vast numbers. In order for it to be true, there needs to be a convergence among the development of advanced civilizations, in which almost none of them are interested in running computer simulation, or have wealthy individuals interested in doing that. Another possibility is that they have enforced laws that prevent individuals from acting on their desires to run simulations. Advanced posthuman civilizations could also perceive the ethical problem of running ancestor-simulations, due to the suffering that is inflicted on the inhabitants of the simulation. This could lead to the prohibition of such simulations being created. Finally, if the third proposition is true, then reality is almost certainly a computer simulation created by an advanced civilization [1] [6] [7] [8].

If the proposition that we are living in a computer simulation is true, then the universe that we are observing is a small piece of the totality of physical existence, and the physics of the universe in which the computer is running may not resemble the physics of our observable universe. Therefore, our world would not be located at the fundamental level of reality. The veracity of that proposition could also mean that it could be possible for simulated civilization to achieve the posthuman stage and run their own ancestor-simulations, on computers built in the simulated universe. These would be like “virtual machines”, which is a common concept in computer science. Also, virtual machines can be stacked, being possible to achieve several levels of simulations inside simulations. If our civilization develops ancestor-simulations, this would support the third proposition, leading to the conclusion that we would most likely be living in a simulations [1].

References

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Bostrom, N. (2003). Are you living in a computer simulation? Philosophical Quarterly, 53(211): 243-255
  2. Barrow, J. D. (2007). Living in a simulated universe. In Universe or Multiverse? Cambridge University Press, pp. 481-486
  3. 3.0 3.1 Steinhart, E. (2010). Theological Implications of the Simulation Argument. Ars Disputandi, 10(1): 23-37
  4. 4.0 4.1 4.2 4.3 Jones, A. Z. (2015). Are we living in a computer simulation? Retrieved from http://www.pbs.org/wgbh/nova/blogs/physics/2015/07/are-we-living-in-a-computer-simulation/
  5. Beane, S. R., Davoudi, Z. and Savage, M. J. (2012). Constraints on the universe as a numerical simulation. arXiv:1210.1847v2 [hep-ph]
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Bostrom, N. (2003). The simulation argument: why the probability that you are living in a matrix is quite high. Retrieved from http://simulation-argument.com/matrix.html
  7. 7.0 7.1 7.2 Bostrom, N. (2006). Do we live in a computer simulation? New Scientist, 192(2579): 38-39
  8. Bostrom, N. (2005). Why make a matrix? And why you might be in one. Retrieved from http://simulation-argument.com/matrix2.html