Michael Nielsen: preference

Transcript context

…Here’s the bigger question I have. The muon example is a great example of these long verification loops and how progress seems to happen in the scientific community faster than these verification loops imply. Maybe the clearest example is Aristarchus in the second century BC comes up with the idea of heliocentrism. The ancient Athenians dismiss it on the grounds that we should see as the Earth is moving around the Sun, if really the Sun is the center of the solar system, the stars move relative to the Earth. The only reason that would not be the case is the stars are so far away that you would not observe this. And it’s only in 1838 that stellar parallax was actually measured. And so, we didn’t need to wait until 1838 to have heliocentrism. We didn’t need to wait for the experimental validation to understand that Copernicus is better in some way. In fact, when Copernicus first came up with his theories, it’s well known that the Ptolemaic model was more accurate because it had centuries of adding on these epicycles. What’s maybe less well appreciated is that it was also in some sense simpler. Because Copernicus actually had to add extra epicycles. It had more epicycles than the Ptolemaic model because he had this bias that the Earth should go in a perfect circle in equal time. Anyway, I think this is an interesting story because it’s not a more accurate theory. It’s not a simpler theory. So how could you have known ex ante that Copernicus was correct and Ptolemy was not? Good question. I don’t entirely know the answer. I can give you a partial answer that I, centuries in the future, start to find very compelling. I’m sure it’s part of the historic story at least. One of the big shocks for Newton, he did understand Kepler’s laws of motion eventually, so you’re able to explain the motions of the planets in the sky. But he also, out of the same theory, his theory of gravitation, was able to explain terrestrial motion. He’s able to explain why objects move in parabolas on the Earth, and he’s able to explain the tides in terms of the moon and the sun’s gravitational effect on water on the Earth. You have what seem like three very different disconnected phenomena all being explained by this one set of ideas. That starts to feel very compelling, at least to me. I think most people find that very satisfying once they eventually realize it. Have you read the Keynes biography of Newton?…

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