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Transcript: Could we be living in a simulation? I think that is related first of all to the question of what we mean by a simulation. If the question is, “Could we be living inside of a computer program?” then my answer would be: of course, yes.
Because the only thing that we get with some certainty from the outside world is information. And the only thing that we find with certainty in this information is regularity. And for a system to produce regularity in information (that is, discernible differences that change in a way that is somewhat not random and somewhat predictable), for this it needs to compute. So it’s necessary and sufficient for the universe—whatever else it does—that it computes. And we cannot really know what else it does.
So in my view it’s necessary and sufficient that the universe is some kind of computer in a pretty literal sense by the way we define computers and computer science. It doesn’t mean that we know what kind of computational class this system is in, and there is I think a lot of contest and ideas in physics what kind of computational class the universe really is and what capabilities it has. What can compute and what cannot compute. But still it’s computational in some sense.
The question of whether we are living in a simulation is more related to something more narrow, that is: this computer program that you’re living in intentionally created, or is it just a natural occurrence? And of course we cannot really know this because no feature in the world points at this thing being a simulation in this sense.
I don’t see anything that would convince me that you are in a simulation. But if it is one, I don’t think it’s for our benefit. I don’t think that all these galaxies and stars and all the intricate elementary particle structures that we can observe in some sense—they are not necessary for our experience as primates on the planetary surface. It would be needed to be painted on the telescopes and microscopes by the simulator. So I don’t think that these are smokes and mirrors when we look into the sky and we see these bazillions of galaxies.
I do think that if this is a simulation then there would be an important feature of the simulation, which means the simulation is not there to create us. The simulation is probably there to explore some aspects of hypothetical physics, and we are just a random side effect or an artifact of the fact that evolution is possible in this universe, so we could emerge in it.
I think it’s very unlikely that we are in a simulation, because if I would build a simulation of the universe I would make the computer that it runs on “irreversible”. What that means is that the operations that happen in that universe can delete bits. It means that a state that you observe in the universe can have multiple possible states that it comes from. And if you look at what we know empirically in physics, that doesn’t seem to be the case.
Our universe seems to be reversible. And this means we cannot really delete bits. If you cannot delete bits it means that everything that we like is irreversible. You stabilize your body temperature, you forget yesterday’s body temperature in your body. It means that you have to delete bits in some sense. All those things that we are interested in life—planets, stars, computers, organisms, minds—are irreversible in some sense. They all need to delete bits to keep their structures stable against the onslaught of the substrate, which has its different logic and its different direction that it wants to go into. So in some sense you get waste bits. You need to throw these bits out of your system, and this is what observers perceive as increasing entropy, these waste bits.
And if you would be living in a simulation like Minecraft, in Minecraft you can build perpetual mobiles [perpetual motion machines]. That’s because you don’t have entropies in Minecraft. Minecraft can delete bits. It can forget its previous state. This universe apparently cannot. So the reason why we cannot have nice things in this universe, why we cannot have perpetual mobiles, the entropy is always accumulating and is always going to get us in the end.
Maybe we’ll always have to die as living beings. But that’s why life is always temporary. Every self-stabilizing system will only have finite lifespan in this universe. That would not be a feature I would put into a simulation.