I went for a haircut a week or so ago and my barber asked me about the books I had been reading recently. He always has a book on the shelf next to him and sometimes I find him reading when I arrive and the shop is quiet. So it is not unusual for us to talk about our current books. I told him about ‘Reality+: virtual worlds and the problems of philosophy’ by David Chalmers which led into a conversation about the possibility that we are in a simulation. My posts on this topic [see ‘Are we in a simulation’ on September 28th 2022 and ‘Virtual digitalism’ on December 7th, 2022] have provoked a number of negative reactions. People either think I have written nonsense or would rather not consider the prospect of us being part of a giant simulation. Fortunately, my barber was happy to accept the possibility that we were part of a simulation which led to a discussion about whether our creator was the equivalent of a teenager playing on a computer in their bedroom or a scientist interested in the evolution of society; and, in either case, why they would have decided to give us hair on our heads that grows steadily throughout our life – perhaps as a personal indication of the passage of time or, simply to provide a living for barbers. The development of human society and the use of probability to reason that a more advanced society might have created a virtual world in which we are living also led us to talk about the probability that a more advanced society finding us on Earth would annihilate us without pausing to learn about us in the same way that we are destroying all other forms of intelligent life on the planet. For example, populations of vertebrates living in freshwater ecosystems have declined by 83% on average since 1970 [see World Wide Fund for Nature Living Planet Report 2022]. Maybe it would be preferable for someone to switch off the simulation rather than to suffer the type of invasion mounted by the Martians in the War of the Worlds by HG Wells.
The concept of digital twins is gaining acceptance and our ability to generate them is advancing [see ‘Digital twins that thrive in the real-world’ on June 9th, 2021]. It is conceivable that we will be able to simulate many real-world systems in the not-too-distant future. Perhaps not in my life-time but possibly in this century we will be able to connect these simulations together to create a computer-generated world. This raises the possibility that other forms of life might have already reached this stage of technology development and that we are living in one of their simulations. We cannot know for certain that we are not in a simulation but equally we cannot know for certain that we are in a simulation. If some other life form had reached the stage of being able to simulate the universe then there is a possibility that they would do it for entertainment, so we might exist inside the equivalent of a teenager’s smart phone, or for scientific exploration in which case we might be inside one of thousands of simulations being performed simultaneously in a lab computer to gather statistical evidence on the development of universes. It seems probable that there would be many more simulations performed for scientific research than for entertainment, so if we are in a simulation then it is more likely that the creator of the simulation is a scientist who is uninterested in this particular one in which we exist. Of course, an alternative scenario is that humans become extinct before reaching the stage of being able to simulate the world or the universe. If extinction occurs as a result of our inability to manage the technological advances, which would allow us to simulate the world, then it seems less likely that other life forms would have avoided this fate and so the probability that we are in a simulation should be reduced. You could also question whether other life forms would have the same motivations or desires to create computer simulations of evolutionary history. There are lots of reasons for doubting that we are in a computer simulation but it does not seem possible to be certain about it.