[This is a transcript of the video embedded below.]

I really like the idea that we are living in a computer simulation. It gives me hope that the next level will get better. Unfortunately the idea is unscientific. But why do some people believe in the simulation hypothesis? And that’s exactly the problem with that? That’s what we’ll talk about today.

According to the simulation hypothesis, everything we experience has been coded by an intelligent being, and we are part of this computer code. That we in and of itself live in a kind of calculation is not unscientific. For what we currently know, the laws of nature are mathematical. So you could say that the universe really just calculates these laws. You may find this terminology a bit strange, and I would agree, but it is not controversial. The controversial thing about the simulation hypothesis is that it assumes that there is another level of reality at which someone or something controls the laws of nature or even interferes with these laws.

The belief in an omniscient being who can disturb the laws of nature but remains hidden from us for some reason is a common element of monotheistic religions. But those who believe in the simulation hypothesis argue that reason came to their belief. The philosopher Nick Boström, for example, claims that it is likely that we are living in a computer simulation based on an argument that looks like this in a nutshell. If there are a) many civilizations and those civilizations b) build computers that run simulations of conscious beings, then c) there are many more simulated conscious beings than real ones so you are probably living in a simulation.

Elon Musk is one of those who chose to do it. He also said: “It is very likely that we are in a simulation.” And even Neil DeGrasse Tyson gave the simulation hypothesis “better than 50-50 chances” of being correct.

Maybe you’re rolling your eyes now because the nerds are having fun, right? And of course, part of that conversation is just intellectual entertainment. But I don’t think popularizing the simulation hypothesis is completely innocent fun. It’s about mixing science with religion, which is a bad idea in general, and I really think we have better things to worry about than someone can pull the plug on us. I dare you!

Before I explain why the simulation hypothesis is not a scientific argument, however, I would like to make a general comment on the difference between religion and science. Take an example from the Christian faith of how Jesus heals the blind and lame. It is a religious story, but not because it is impossible to heal blind and lame people. One day we could do it. It’s a religious story because it doesn’t explain how the healing supposedly happens. The whole point is that believers take it by faith. In science, on the other hand, we need explanations of how something works.

Let’s then look at Bostrom’s reasoning. Here it is again. If there are many civilizations that are doing many simulations of conscious beings, they are likely being simulated.

First, it could be that one or both of the premises are wrong. Maybe there aren’t any other civilizations or they don’t care about simulations. Of course, that wouldn’t make the argument wrong, it would just mean that the conclusion cannot be drawn. But I’m going to disregard the possibility that one of the premises is wrong because I really don’t think we have good evidence for one side or the other.

The point I have seen people most often criticize Bostrom’s argument is that he simply assumes that it is possible to simulate a human-like consciousness. We don’t actually know that this is possible. However, in this case, an explanation would be required to assume that this is not possible. This is because, for all we currently know, awareness is simply a property of certain systems that process large amounts of information. It doesn’t matter what physical basis this information processing is based on. Could be neurons, or could be transistors, or it could be transistors that believe they are neurons. So I don’t think simulating the mind is the problematic part.

The problematic part of Bostrom’s argument is that he assumes that it is possible to reproduce all of our observations using not the laws of nature that physicists have confirmed with extremely high precision, but using a different underlying algorithm that the programmer executes . I don’t think Bostrom was up to this, but he did. He implicitly claimed that it was easy to reproduce the fundamentals of physics with something else.

Currently, however, no one knows how to reproduce General Relativity and the Standard Model of Particle Physics from a computer algorithm running on a machine. You can approximate the laws we know with a computer simulation – we do this all the time – but when nature actually works like that, we can tell the difference. Indeed, physicists have been looking for signs that the laws of nature really work step by step, like computer code, but their search has been empty-handed. It is possible to tell the difference because attempts to algorithmically reproduce natural laws are usually inconsistent with the symmetries of Einstein’s theories of special and general relativity. I will leave you a reference in the information below the video. The bottom line is that it’s not easy to outperform Einstein.

Incidentally, it doesn’t help if you assume that the simulation is being carried out on a quantum computer. As I explained earlier, quantum computers are special machines. Right now nobody knows how to put general relativity on a quantum computer.

A second problem with Bostrom’s argument is that a civilization must be able to simulate many conscious beings for this to work, and those conscious beings will themselves try to simulate conscious beings, and so on. This means that you need to compress the information that we think the universe contains. Bostrom must therefore assume that in some parts of the world where no one is currently looking, it is somehow possible not to care about the details and only fill them in in case someone is looking.

Again, he does not explain how this is supposed to work. What kind of computer code can actually do that? What algorithm can identify conscious subsystems and their intentions and then quickly input the required information without ever creating an observable inconsistency. This is a much more difficult subject than Bostrom seems to appreciate. In general, you can’t just throw away physical processes over short distances and still get the long distances right.

Climate models are an excellent example. We currently do not have the computing capacity to resolve distances below about 10 kilometers. But you can’t just throw away all of the physics below that scale. This is a non-linear system, so the information spreads out from the short scales into large scales. If you cannot calculate the short range physics, then you need to replace it with something in an appropriate way. Getting this anywhere near right is a big problem. And the only reason climatologists are getting it about right is because they have observations that they can use to verify that their approximations are working. If you only have a simulation, like the programmer in the simulation hypothesis, you can’t do that.

And that’s my problem with the simulation hypothesis. Those who believe in it may unknowingly make really big assumptions about what laws of nature can be reproduced with computer simulations, and they fail to explain how this is supposed to work. However, it is very difficult to find alternative explanations that match all of our observations with great precision. The simulation hypothesis is therefore not a serious scientific argument. That doesn’t mean it’s wrong, but it does mean that you have to believe it because you have confidence, not because you have logic on your side.


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