Interview with Steven Weinberg (Introduction)

by David Turell , Sunday, March 29, 2015, 15:47 (3526 days ago)

81 years old atheist and still at work. Seems to be not a fan of the multiverse, but still a supporter of string theory.-https://www.quantamagazine.org/20150317-sciences-path-from-myth-to-multiverse/-"I am not a proponent of the idea that our Big Bang universe is just part of a larger multiverse. It has to be taken seriously as a possibility, though. And it does lead to interesting consequences. For example, it would explain why some constants of nature, particularly the dark energy, have values that seem to be very favorable to the appearance of life. Suppose you have a multiverse in which constants like dark energy vary from one big bang to another. Then, if you ask why it takes the value it does in our Big Bang, you have to take into account that there's a selection effect: It's only in big bangs where the dark energy takes a value favorable to the appearance of life that there's anybody around to ask the question.-"“You don't have to verify every prediction to know that a theory is correct.”-"This is very closely analogous to a question that astronomers have discussed for thousands of years, concerning the Earth and the sun. Why is the sun the distance that it is from us? If it were closer, the Earth would be too hot to harbor life; if it were further away, the Earth would be too cold. Why is it at just the right distance? Most people, like Galen, the Roman physician, thought that it was due to the benevolence of the gods, that it was all arranged for our benefit. A much better answer — the answer we would give today — is that there are billions of planets in our galaxy, and billions of galaxies in the universe. And it's not surprising that a few of them, out of all those billions, are positioned in a way that's favorable for life.-"It's not part of the requirement of a successful physical theory that everything it describes be observable, or that all possible predictions of the theory be verifiable. For example, we have a very successful theory of the strong nuclear forces, called quantum chromodynamics [QCD], which is based on the idea that quarks are bound together by forces that increase with distance, so that we will never, even in principle, be able to observe a quark in isolation. All we can observe are other successful predictions of QCD. We can't actually detect quarks, but it doesn't matter; we know QCD is correct, because it makes predictions that we can verify.-"Similarly, string theory, which predicts a multiverse, can't be verified by detecting the other parts of the multiverse. But it might make other predictions that can be verified. For example, it may say that in all of the big bangs within the multiverse, certain things will always be true, and those things may be verifiable. It may say that certain symmetries will always be observed, or that they'll always be broken according to a certain pattern that we can observe. If it made enough predictions like that, then we would say that string theory is correct. And if the theory predicted a multiverse, then we'd say that that's correct too. You don't have to verify every prediction to know that a theory is correct.-"There's something I've been working on for more than a year — maybe it's just an old man's obsession, but I'm trying to find an approach to quantum mechanics that makes more sense than existing approaches. I've just finished editing the second edition of my book, Lectures on Quantum Mechanics, in which I think I strengthen the argument that none of the existing interpretations of quantum mechanics are entirely satisfactory."