Podcast

Where do good explanations come from? There’s currently an obsession with induction, the idea that you can predict the future from the past. You can say, “I saw one, then two, then three, then four, then five, so therefore next must be six, seven, eight, nine.” There’s a belief that this is how new knowledge is created, that this is how scientific theories are formed and this is how we can make good explanations about the universe. More

Many scientists and philosophers have talked about the concept of a multiverse. But we’re talking about a very strict, very sober understanding of what a multiverse is.  All of these universes in this multiverse obey the same laws of physics. We’re not talking about universes where there are other laws of physics. More

At this point people might object, “How dare you invoke in science things that can’t be seen or observed? This is completely antagonistic towards the scientific method, surely.” And I would say that almost everything of interest that you know about science is about the unobserved. Let’s consider dinosaurs. Dinosaurs are unobserved. More

We have to come to a deeper understanding of what is going on in this double-slit experiment. If we fire either a photon or an electron at that double-slit apparatus and put a detector at either of those slits, then we will detect a particle. We can detect that we’ve fired a particle; we can detect that a particle is going through those slits; and we can detect a particle at the projection screen as well. More

There’s a YouTube video in which Deutsch explains the famous quantum double-slit experiment, which is about particle-wave duality. Is light a particle or a wave? You pass it through a slit and, depending on whether there’s an observer and interference or not, it ends up in a wave pattern or as individual photons. More

Does probability actually exist in the physical universe, or is it a function of our ignorance? If I’m rolling a die, I don’t know which way it’s going to land; so therefore I put in a probability. But does that mean there’s an actual probabilistic unknowable thing in the universe? Is the universe rolling a die somewhere, or is it always deterministic? All probability is actually subjective. More

The overwhelming majority of theorems in mathematics are theorems that we cannot possibly prove. This is Gödel’s theorem, and it also comes out of Turing’s proof of what is and is not computable. The things that are not computable vastly outnumber the things that are computable, and what is computable depends entirely upon what computers we can make in this physical universe. More

There goes my solution for Zeno’s paradox, which says before you can get all the way somewhere, you have to get halfway there. And before you can get halfway there, you have to get a quarter of the way there, and therefore, you’ll never get there. One way to get past that is to say even a series of infinite things can have a finite sum. More

You said that we went from atoms in the time of Democrates, down to nuclei, and from there to protons and neutrons, and then to quarks. It’s particles all the way down, to paraphrase Feynman. We can keep going forever. But it’s not quite forever, right? At some point you run into the Planck length. More

All knowledge is conjectural. It’s always being guessed. It’s our best understanding at any given time. You’re right to say that the axioms might be incorrect. How do we know that an axiom is incorrect? Traditionally the answer has been, “Because it’s clearly and obviously the case.” How can you prove that x plus zero must equal x?  You just have to accept that it’s true. More