Why scientists cannot rule out the possibility that we are living in a simulation

During an interview at the Code Conference in 2016, SpaceX founder and CEO Elon Musk stated that there is a “one in a billion chance that this is base reality.” In other words, Musk believes that we are almost certainly living in a computer simulation.

The simulation theory is a very modern construct, born from ancient roots. It proposes that everyone and everything around us in this universe is all part of an elaborate artificial facade from a computer simulation created by a superior entity living far into what we perceive as the future. Put into simpler terms, this theory posits that humans are basically an advanced version of The Sims, which is a video game franchise where players create virtual people called "Sims" and help navigate their lives and satisfy their desires. According to the hypothesis, we are trapped in a pseudo existence like the Matrix.

Musk is not alone in this argument; several renowned scientists and philosophers, namely Neil deGrasse Tyson and René Descartes have expressed their support for this seemingly ridiculous hypothesis as well. The most notable advocate of the simulation theory is Nick Bostrom - a Swedish Oxford professor and director of the Future of Humanity Institute. In his paper titled Are You Living In A Computer Simulation? Bostrom states that at least one of these propositions is true:

1. The human species is very likely to go extinct before having the technological capability of running such advanced simulations.
2. Humans are extremely unlikely to run a significant number of simulations of their evolutionary history for moral reasons.
3. We are almost certainly living in a computer simulation.

Bostrom argues that if humans manage to survive extinction for long enough to simulate a universe that is indistinguishable from our own and have no legal restrictions or moral compunctions against running these simulations, the probability of the so-called “post-humans” running ancestor simulations is close to 1.

Although this theory does seem pretty absurd, it is not one that can be easily written off. In a span of only 50 years since the digital revolution in the 1970s, innovators have successfully developed photorealistic 3D simulations as well as devices with the capacity to learn and mimic many basic characteristics of human intelligence. If technology continues to progress exponentially as it stands currently, the possibility of future humans creating a simulated reality cannot be ruled out entirely.

Moreover, Musk hopes that we are living in a simulation, as “if you assume any rate of improvement at all, then the games will be indistinguishable from reality,” or the equivalent, that  “civilization will end.” In other words, if we are indeed living in a computer simulation, this indicates that humanity will manage to survive.

However, a question asked by skeptics when considering this theory is how humans in a simulation are capable of having abstract thought. Despite the complexity of this question, this can be answered using the assumption of substrate independence. According to Nick Bostrom’s paper, the idea is that “mental states can supervene on any of a broad class of physical substrates” and that “provided a system implements the right sort of computational structures and processes, it can be associated with conscious experiences.” This means that human consciousness does not only happen in the brain. With the right computational structures and processes, assuming that the technology for this is available, conscious thought can happen anywhere, such as in the silicone-based processor inside an advanced computer created sometime in the future. In short, everything we are thinking, feeling, and perceiving at this exact moment could very well be processed and sent from a computer.

If someone created our entire existence in a computer simulation, would that make this entity God? As can be seen, the simulation theory is undoubtedly one of the most difficult hypotheses to contemplate as looking into any part of the theory could lead to a rabbit hole of questions. In addition, the theory is capable of completely altering one’s perception of the world. All in all, it may be possible that you, me, and everything in this universe is actually part of one giant computer game— the world may never know.