What does the universal prior actually look like?

Suppose that we use the universal prior for sequence prediction, without regard for computational complexity. I think that the result is going to be really weird, and that most people don’t appreciate quite how weird it will be.

I’m not sure whether this matters at all. I do think it’s an interesting question, and that there is meaningful philosophical progress to be made by thinking about these topics. I’m not sure where that progress matters either, but it’s also interesting and there is some reasonable chance that it will turn out to be useful in a hard-to-anticipate way.

(Warning: this post is quite weird, and not very clearly written. It’s basically a more rigorous version of this post from 4 years ago.) Continue reading