(ORDO NEWS) — In a 2003 article, Oxford University philosopher Nick Bostrom outlined the likelihood that our reality is a computer simulation invented by an advanced civilization. In the work, he argued that at least one of three sentences must be true: civilizations usually die out before they develop the ability to create simulations of reality; advanced civilizations are usually not interested in creating simulations of reality; we are almost certainly living inside a computer simulation. Columbia University astronomer David Kipping recently took a close look at these propositions, also known as Bostrom’s “trilemma,” and proved that the probability that we actually live in a simulation is 50-50, Scientific American reports.
Creatures inside the computer
So let’s imagine that we are virtual beings living in a computer simulation. If this is the case, then the simulation is likely to create a perception of reality on demand, rather than simulate all reality all the time – just like a video game optimized to display only parts of the scene that are visible to the player. Astrophysicist and popularizer of science Neil DeGrasse Tyson on the talk show “Star Talk” (Startalk) suggested that maybe this is why we cannot travel faster than the speed of light.
Of course, such conversations may seem frivolous. But ever since Nick Bostrom wrote his seminal paper on simulation, philosophers, physicists, technologists, and even lay people have tried to identify ways in which we can figure out whether we are living in simulation or not. I note that most researchers are skeptical about the idea of a virtual universe, but Kipping’s work shows that if humans ever developed the ability to mimic conscious life, it would most likely be creatures inside a computer.
In 2003, Nick Bostrom envisioned a technologically advanced civilization that has enormous computing power and needs some of that power to simulate new realities with conscious beings in them. Given this scenario, his modeling argument showed that at least one sentence in the following trilemma must be true:
- first, people almost always die before reaching the modeling stage;
- second, even if people get to this stage, they are unlikely to be interested in modeling their own past;
- and third, the probability that we are living in a simulation is close to one.
To better understand Bostrom’s simulation argument, Kipping used Bayesian reasoning. This type of analysis uses Bayes’ theorem, named after Thomas Bayes, a British mathematician who lived in the 18th century. Bayesian analysis allows you to calculate the probability that something will happen (the so-called “posterior” probability), having previously made assumptions about the analyzed event (assigning it a “prior” probability).
We’re not living inside a simulation?
Kipping began by turning the trilemma into a dilemma. He condensed the first two sentences into one, arguing that both would lead to the same result – we are not living inside a simulation.
We simply assign an a priori probability to each of these models and proceed from the principle of indifference, which is the default assumption when you have no data or bias, ”Kipping said in an interview with Scientific American.
Kipping also argues that the more layers of reality were built into the simulation (like a nesting doll), the less computer resources would be required. In other words, the further down the rabbit hole you go, the less computing power you need to create a compelling simulation. The astronomer’s conclusion after he recounted the numbers was that the probability that either hypothesis is correct is about 50 percent.
But if people ever came up with such a simulation, the picture would change radically. The next stage of analysis required the comprehension of “parodic” realities – those that can give rise to other realities – and “unrelated” realities – those that cannot. If the physical hypothesis were correct, then the probability that we live in a barren universe would be easy to calculate: it would be 100 percent.
Kipping then showed that even in the simulation hypothesis, most simulated realities would be sterile. This is because as simulations generate new simulations, the computational resources available to each successive generation shrink to such an extent that the vast majority of realities will be those that do not have the computational power needed to simulate future realities capable of accommodating conscious creatures.
Put it all together in a Bayesian formula and you have the answer: the posterior probability that we live in a basic reality is almost the same as the posterior probability that our world is a simulation.
However, if the simulation has infinite computing power, then under no circumstances will we see that we are living in virtual reality, because it can compute whatever we want with the degree of realism that we want. But if we find ourselves living in a simulation, it will mean that it most likely has limited computing resources.
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