Michael Nielsen – How science actually progresses

**Dwarkesh Patel** (0:00)
Today, I'm speaking with Michael Nielsen. You have done many things. You were one of the pioneers of quantum computing, wrote the main textbook in the field of the open science movement. You wrote a book about deep learning that Crisola and Greg Brockman credit them with getting them into the field. More recently, you're a research fellow at the Astera Institute and writing a book about religion, science, and technology. I'm going to ask you about none of those things. The conversation I want to have today is, how do we recognize scientific progress? And it's especially relevant for AI, because people are trying to close the RL verification loop on scientific discovery. And what does it mean to close that loop? But in preparing for this interview, I've realized that it's a more mysterious and elusive force, even in the history of human science than I understood. And I think a good place to start will be Michaelson Morley and how special relativity is discovered. If it's different than the story that you kind of get off of YouTube videos, anyway, I will front you that way and then we'll go in there.

**Michael Nielsen** (1:01)
Okay. Yeah. So Michaelson Morley is one of the famous results often presented as this experiment that was done in the 1880s and that helped Einstein come up with the special theory of relativity a little bit later. So sort of changing the way we think about space and time and our fundamental conception of those things. And there's kind of a big gap, I think, between the way Michaelson and Morley and other people at the time thought about the experiment and certainly the way in which Einstein thought or did not think about the experiment. In actual fact, he stated later in his life, he wasn't even sure whether he was aware of the paper at the time. There's a lot of evidence that he probably was aware of the paper at the time, but it actually wasn't just positive for his thinking at all. Something else completely was going on.
So what Michaelson and Moley thought they were doing was, they thought they were testing different theories of what was called the ether. So as you go back to the 1600s, Robert Boyle introduced the idea of the ether. Basically, the idea of the ether is, we know that sound is vibrations in the air, and then Boyle and other people got interested in the question of, like, is light vibrations in something? And they couldn't figure out what it was. Boyle actually did an experiment where he tested whether or not you could propagate light through a vacuum. He found that you could. You couldn't do it with sound. So he introduced this idea of the ether. And then for the next 200 or so years, people had all these kind of conversations about what the ether was and what its nature was. And the Michaelson and Moley experiment was really an experiment to test different theories of the ether against one another. And in particular to find out whether or not there was a so-called ether wind. So the idea was that the earth is passing through maybe this ether wind. And if it is passing through the ether wind, sort of this background, and you shoot a light beam sort of parallel to the direction the ether wind is going in, it'll get accelerated a little bit. And if it's being passed back sort of in the opposite direction, it'll get slowed down a little bit. And you should be able to see this in the results of interference experiments. And what they found, much to their surprise, I think, was that, in fact, there was no ether wind. And that ruled out some theories of the ether, but not all. And Michaelson certainly continued to believe in the ether.

**Dwarkesh Patel** (3:29)
Okay. So this is what was a shocking part of reading this story from the biography of Einstein that you recommended by, what was his first name?

**Michael Nielsen** (3:36)
Abraham Pius.

**Dwarkesh Patel** (3:37)
Abraham Pius, subtle as the word. And then also from Emery Lakatos, the methodologies of scientific research programs. The way it's told is that Michaelson morally proved that the ether did not exist. Therefore, it created a crisis in physics that Einstein saw as special relativity. And what you're pointing out is actually was trying to distinguish between many different theories of ether. You know, if you're in space or if you're on earth, it's the same direction of ether, or maybe the ether wind is being carried around by the earth, and so you can't really experience it on earth, but if you go to a high enough altitude, you might be able to experience it. In fact, the Michaelson's experiments were, the famous one is 1887, but he conducted these experiments for basically two decades.