Into the Impossible With Brian Keating - Michael Turner Explains the Origins and Mysteries of Dark Energy (#367)

Episode Date: November 14, 2023

Welcome to a very important, meaningful, and delightful episode of Into the Impossible, with an impossibly brilliant guest who has inspired me since my young days as a graduate – Michael Turner!  Michael Turner is a renowned theoretical cosmologist and professor of physics at the University of Chicago. He is a pioneer in exploring what he calls the dark side of the Universe. He coined the term dark energy, and his ideas led to the cold dark matter theory of structure formation.  Michael’s contributions to modern physics are truly invaluable, and I am beyond thrilled to have him as a guest on my show.  Join us as we explore the origins and evolution of the Universe!  Key Takeaways:  Intro (00:00) Judging a book by its cover: The Early Universe (01:44) Was there a Big Bang or not? (06:23) The most important discoveries in physics (12:44) The origin of dark energy (29:32) The Hubble constant and its precision (41:44) Magnetic fields, dark energy, and resolving the Hubble tension (48:20) Dark photons and dark stars (55:24) Outro (1:01:47) — Additional resources:  🥗 Thanks, HelloFresh! Go to HelloFresh.com/50impossible and use code 50impossible for 50% off plus 15% off the next 2 months. 📝 With a MasterClass annual membership, you can take one-on-one classes from the world’s best for $10 a month with your annual membership, get unlimited access to every class — and even better, right now, as an Into The Impossible listener, you can get 15% off when you go to MASTERCLASS.com/impossible. 🧑‍💻 Visit LinkedIn.com/IMPOSSIBLE to post your job for free! 📚 The Early Universe by Michael Turner and Edward Kolb: https://a.co/d/2HkzzzK  ➡️ Follow me on your fav platforms: ✖️ Twitter: https://twitter.com/DrBrianKeating  🔔 YouTube: https://www.youtube.com/DrBrianKeating?sub_confirmation=1  📝 Join my mailing list: https://briankeating.com/mailing_list  ✍️ Check out my blog: https://briankeating.com/blog.php  🎙️ Follow my podcast: https://briankeating.com/podcast  — Into the Impossible with Brian Keating is a podcast dedicated to all those who want to explore the universe within and beyond the known. Make sure to follow so you never miss an episode! Learn more about your ad choices. Visit megaphone.fm/adchoices

Michael Turner is a theoretical cosmologist, emeritus professor at the University of Chicago, and former director of the Gavily Institute for Cosmological Physics. He's a pioneer in exploring what he called the dark side of the universe. He actually coined the term dark energy, and his revolutionary ideas led to the cold, dark matter theory of structure formation. Mike's contributions to modern physics are truly invaluable, and I'm beyond thrilled to have him as a guest on my show. join us in a deep dive into the dark side of our twisted universe. Any sufficiently advanced technology is indistinguishable from magic. Open the pod bay doors, out.

Welcome everybody to a very important, meaningful and delightful episode of the Into the Impossible Podcast with an impossibly brilliant guest who I've been really, you know, in love with his mind, I was a wee lad, a graduate student. He's a legend in the field, and it's Professor Michael Turner, University of Chicago, theoretical cosmologists who among many things is rumored to have coined the term dark energy. Michael, is that correct? Did you coin the term dark energy? Guilty as charged.

Who can the, I guess, Wiki coined the term dark matter in German, correct? That's right. I can't pronounce the German, dunkel mater, or something like that. Yeah, I think you're closer than I'll ever get to it. Michael, where are you joining us from today? I'm joining from my office in Venice, California. I really appreciate your time and whatever you'll spare in person or online. But Michael, we have a lot to talk about. We'll run out of time before I run out of questions. Beg your forbearance as we go into the very first question that I ask all my guests who honor me with their presence on my humble podcast. and that is to judge a book by its cover.

And in your case, your book with Rocky Kolb, your colleague at the University of Chicago, has really influenced generations of cosmologists, of theoretical particle physicist, astrophysicist, experimentalists like myself. And I want to do the following, if you will. To judge the book by its cover, I would like you to describe the cover art, the cover title, and the subtitle. How did you and Rocky Colb come up with that? The original hardback version had a very boring cover. It was just white and the words early universe.

And if my memory serves me correct, there was no subtitle. And the paperback version, which you may be referring to, has a wonderful story with it. The cover is a beautiful image of a galaxy. Actually, for its time. I mean, today we get much better images from JWST. and the Hubble. So the title, that was exceedingly easy. Rocky and I were pioneers of studying the first microsecond. And I like to tell the joke by the time we got to cosmology, you know, everybody specializes. All that was left was the first microsecond. And that is the early universe, but we got there

at a very good time because the early universe had just opened up. Shortly before we got there, you couldn't talk about the early universe because it was just a mess. It was nuclei and protons and neutrons and neutrons sitting on top of one another. And we were there when the doors opened when people realized that it was quark soup. And early universe, you know, a good title's got to be simple. It's got to have cosmology. And early was where it was at. Do you want to hear the paperback version?

Yeah, because we're going to springboard from the paperback to a discussion. of these peculiar properties of galaxies, which in my mind, Michael, I'm not going to teach, I'm not going to let the student teach the master, but a galaxy is not exactly, at least when I was a kid, an early universe phenomenon of the first microsecond. So yes, how did that come to be? The whirlpool galaxy. So that's perfect. Our book did really, really well, and it was going into paperback. And I was in Aspen, Colorado, and they sent the artwork to me for the new cover. And it was this beautiful picture of a galaxy.

And I called up Rocky. And he said, well, you got the cover artwork. What do you think? And I said, it's beautiful, but it has nothing to do with our book. And he said, we'll take it. So our book is about the first microsecond. But that's where the blueprint for the universe got laid out. And that's where galaxies can trace

their origins to. So it's not quite fair to say that it was a bait and switch, that it's not really about the pretty galaxies you see in the sky. But the cover was chosen because, oh my God, well, I wish I could easily get copies here. It's so funny, Rocky and I pioneered a lot of ground there. I think we were book number 69. And David, we asked David to make some changes because he had a standard preface that talked about, you know, these are not to be designed to be polished. And they're typically from mimeograph notes. Yeah. And we said to David, David, what is a mimeograph machine?

And so we changed some of his forward. But they had a standard, you know, that's important when you have a brand. Frontiers and Physics was a brand. And it was very simple. It was white and blue. But then when some other publishing company took it over, and did the paperback, they made it really fancy. It's still in the top 200 of books in astrophysics, even, you know, it's coming up on its 30th,

30th anniversary, incredible, of the second edition, I think. Yeah, and I just got a royalty check yesterday. Wow, well, that's what all us authors make our living. Yeah, and I'm going to go to Starbucks and have a coffee on it. All right, well, let's get into some of the topics in there. particularly I wanted to be a little persnickety and kind of poke fun. Yeah, the galaxy is sitting there. And we've heard a lot lately about conflicts, not only with the structure formation within Lambda Cdeme, Lambda Cold Dark Matter model, the prevailing paradigm, I would say.

Not only that, but whether or not the Big Bang even happened. I don't know if you paid attention to this. There's some fringe. I won't call them crackpots. I won't call them cranks. I'll let somebody else do that. But there are people out there that are claiming and getting tremendous amount of attention, even from all the way up to Elon Musk, who was a physics major at UPenn for some time, as I understand it.

But he tweeted out, and Joe Rogan, who's become a friend of mine, tweeted out things about this. But anyway, Michael, what do you make of this controversy? Is it a tempest in a celestial teapot, as Dawkins might say? Yes. So, but let me, you know, the rich science is more complicated than. then was there a big bang or not? It's never yes or no. And I like to organize my thinking in science about things we know for sure that are never going away.

So one thing we know for sure that's never going away is the universe is expanding. I would add to that we also know that the expansion is speeding up, but we can get to dark energy later. So the universe is expanding. We have so much evidence for that. That's never going away. Well, if it's getting bigger than in the past it was smaller, and so if you extrapolate its size all the way back, the extrapolations would say,

you know the number better than I do, 13.8 billion years ago, it had zero size. And that's called the Big Bang. And the Big Bang theory is, you know, one of those funny things in science, it's not a theory about the Big Bang. It's a theory about the events after the Big Bang. So the stuff that we know for sure, the number one thing we know for sure, is that the universe was much, much smaller in the past.

And I would say that the number one thing we know for sure, how far, you know, when you say how small, do you really mean zero? Very, very, very, very strong evidence takes it back to a size that is 10 trillion times smaller than it is today. That's a lot smaller. Does it take it back to zero? No. And one of the big questions in cosmology that's going to take a while to answer is, was there a big bang? Was there ever a time when the universe had zero size? And that's a really rich question.

Another thing we know for sure that you know for sure, you've spent your career studying it, is it was a hot big bang. So it wasn't just any old big bang. In the past, it was really hot. And I don't know if you're allowed to use. words like this on your show, but I use it in the technical sense. It was hotter than hell. And so that comes to us from the cosmic microwave background. There's a microwave echo of the Big Bang. And that we can even get a picture of the universe. It's 13.8 billion years old today.

We can get a picture of the universe when it was only 380,000 years old, the infant universe. not 380,000 years ago, but when it was 380,000 years old, before galaxies and stars and all that. So the idea that, I mean, if you want to have an Oxford debate about, you know, whether or not there was a big bang, then if I were arguing, no, there wasn't, I would say, well, the big bang is, you know, when the universe was zero size, and we can't really say that. But the idea that the universe was much, much smaller, much hotter, and grew to a small. today. That's really the Big Bang theory, which is the events after the Big Bang. And I know there are people, some of them are engineers, some of them have degrees. I think there's someone even wrote a book called The Big Bang Never Happened, Eric Lerner. That's right. He's a provocateur. I even bought his book. I shouldn't have done it, but I did it because I was giving a public lecture in Aspen when the book

came out. And his, in fact, you will enjoy this, I hope. His number one piece of evidence, It was a very long book with a lot of words, but he had one piece of evidence was we hadn't found the small variations in the intensity of the microwave background that need to be there to explain galaxies. And what was funny about this book is literally written six months

before those variations were discovered and made your career possible because your whole career has been spent doing this extraordinarily hard work of studying these tiny, tiny, tiny variations that give us a picture of the infant universe. And you know this, and most scientists, this is, science is a continuing process where I would say we're very firm on understanding the universe back to a microsecond. And earlier than that, I would, that, that goes into my second bin

of really well-formulated ideas that are knocking at the door to become fact. And, and, you Inflation is one of those ideas knocking at the door to become fact. Another idea that's knocking at the door to become fact is that the dark matter that we just touched upon very briefly earlier is made of elementary particles left over from the Big Bang. That is not fact. You know, I would never, you know, say that that's fact. We have a lot of evidence for it, but it's really banging at the door, but we don't have the case for it. Likewise for inflation. There's a lot of, and so it's really easy to, you know, throw mud and get a headline.

The Big Bang never happened. You know, if I said, oh, the Big Bang happened, we found another piece of evidence for it. And I go to the editor of your, you know, the San Diego Union paper. Can I get that on the front page? Nah, I don't think so. I have someone who will say, the Big Bang never happened. Can I get that on the front page? Oh, yeah.

You said this place was steps from the water. We just haven't found the steps yet. How much did we save? Enough. Enough to get lost. Or you could book a stay with Hilton. Welcome to your ocean front room. Just steps from the water.

The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay. Hilton, for the stay. Yeah, that's right. the Big Bang's bleeding, so it's leading.

Exactly. Yeah, I make a lot of that. I made a video refuting Mr. Learner of the Plasma Physics Institute of the Western Pennsylvania. And that's fine. There's another gentleman, Rajenja Gupta, at the University of Ottawa, who's an actual professor and has worked in this field. And he reduced the age of the universe, you know, from infinity and static to a mere 27 billion years. and, you know, I'm happy to talk to these people. I generally think along the lines of Lord Martin Rees that, you know, debate is pointless.

It's not like people change their mind. You know, they love to hear debates. They love to watch debates. But it's like a baseball game. You go and see your bears and you don't want them to lose. It's not like you really want to, you know, see a great man. No, you want them to blow the other team out. At least I do with the Padres.

We know the Bears are going to lose, unfortunately. Yeah, I know. Well, the same with the Padres. But at least you've had a team that, you know, at least the Cubs have won a World Series. The Padres never have. But let's turn to inflation, because, as I said before we press record, your papers were really influential on experimentalists. And I don't know if you realize that.

But a lot of us who, you know, began our careers in the 90s with Colbin Turner later turned our attention to the search for some circumstantial, but nevertheless very probative information about inflation were to occur. And one of the most influential papers on a generation, my generation, was, you know, your papers on the scorecard for inflation. And I don't know if you can, you know, take us back to what it meant when you prepare these papers. Do you think about the audience as being, you know, particular people like young Brian Keatings, experimentalists, phenomenologists, how do you develop the brand of, and the taste that you have to develop things that would be of great utility to, theorist observers and experimentalists? What went into that thought process of that particular series of papers?

In science, there are people who just want to be clever and write clever papers. Some of the theorists are that way. And that's really important to have clever ideas and tools out there. And then there are people who would like to have clever ideas that are testable. and let's see if they're right or wrong, and if they're wrong, oh, whatever, but if they're right, that's very, very cool. And early universe cosmology underwent a transition. In the early days, we were just having a lot of fun. I mean, we would invent a new kind of universe every week, and discovery of those small variations in the intensity of the microwave background

in 1992, April 23rd, that was a really big deal because that meant you could really start testing these ideas. I've gone on record many places saying this. I've said it in a lot of papers. Alan Goose's theory of inflation is the second most important idea in cosmology ever, after the Big Bang, after George Gamoss Big Bang, whether or not it's right. And it has directed the field since his 1980 paper. It might have been 1981 when it was published. And so starting in the early 90s, there was the idea you might be able to test this theory. And it's a theory about events that happened a jiffy after the Big Bang. You know what a jiffy is, right? Yeah, it's a scosh. It's a little more than a scosh. Yeah, that's right. It's a microscosh. And, oh, no, maybe it's a,

it's 10 scoches. I always get that screwed up. So very early, you know, maybe 10 to the minus 35 seconds. And so you want to guide people. You also, and I want to test this on you, sometimes people think science is a cabal, right? Brian and Michael work together. And so. Big cosmology. Yeah.

Conspiratorial cosmology. Brian wants to confirm Michael's ideas and then, you know, blah, blah, blah. And typically the best compliment and an experimentalist can pay to a. a theorist is to try to disprove the theorist's idea. And inflation was like that. Its boldest prediction, and this was slightly before your time, but one of your mentors was involved in this. Its absolute boldest prediction was that the universe is flat, that it has the critical density. And the astronomers used to roll their eyes because they said, oh my God, we already know that the density is not the critical density, it's only 10%.

And so, you know, we love that inflation and the false vacuum energy and all that stuff, but changed the flat universe. And maybe later I'll tell you a story about where it almost got changed, but it didn't. And we stuck with the flat universe, and then dark energy came along. And the person who showed that was the first major test of inflation, because all the evidence at the time, which was not perfect, it was just, based upon counting up matter and you could only count up matter close to galaxies, said, no, you missed by a factor of 10. That's a pretty big error. One of your, I assume he was one of your

mentors, Andrew Lang at Caltech. He was your postdoctoral mentor, I think. That's right. Yeah, he and I make bicycle. And I don't know if you were involved in his boomerang experiment. It was a balloon. I wasn't. No, he hired me after I got fired by Sarah Church at Stanford and then, but she kindly arranged for a meeting with Andrew Lang, who had been her postdoc advisor, and then the rest, as they say, is history. And we went on with Jamie Bach to build Bicep. And then Bicep, I hope we get to that, because I am just in love with Bicep. As a father, I take great satisfaction. But anyway, Andrew's balloon experiment was fantastic, and that's how I met Andrew. We were together on the NASA Press conference, and we flew back from Washington, D.C. to Chicago. I had booked him for a colloquium,

and that was the first big piece of evidence. And then what you have spent most of your career studying these small variations in the intensity of the microwave background across the sky, about a part in 10 of the 5, really, really small, very, very hard to measure. That's a big area where you could test it. How do they vary from angle to angle and getting more technical? What are their statistics and so on and so forth? and so you've got to spell that out.

First of all, if you ever want people to say, oh, you made a prediction and it was confirmed, you got to make the prediction before it was confirmed. After it's confirmed, you say, oh, yeah, no, no, no, that's what I predicted. Retro-Odiction, yeah. Yeah, my neighbors do that. You know, everybody does that. Eric Lerner does that.

But you've got to get the predictions. And you also have to say, here's what's really important. One of the ones I take the most pride in in that paper, these variations, we have this term called scale invariant. So they don't change from scale to scale, but a very important thing is they're not scale invariant, they're almost scale invariant. And I believe my collaborators and I were the first ones to put that word in front of there saying an important test is that they're not quite scale invariant. So they're close, but they're 10% off. And if you find them to be exactly scale invariant, that would not be a feather in inflation's hat.

You want them to be slightly off, and they indeed are 10% off. And the experimentalists really paid attention to that. That was a big goal. Can we show that there's a statistically significant deviation from scale invariance? And then the one that, the big one, and I think most of my papers, I'm glad I was detecting the gravity wave signature, which at the time when I started writing, I'd be interesting to go back and look at the paper, that was going to be, that was so difficult to do. There was no, that one looked undoable. But if you're a theorist, you can't say, oh, by the way, here's a really cool prediction, but you're never going to do it. You've got to say, this is a really cool prediction. It may be impossible today, but cutting edge science is making the impossible just really. hard. And that's what you guys have done at Bicep. I mean, Bicep, to me, I am the biggest fan of Bicep. And when I know you had, I don't know if I want to call it a misstep, but a false alarm or

whatever it's called, I am your biggest defender because you guys set your sight on a goal. And you are more sensitive in looking for this signature. It's an important test of inflation, if you find this gravitational wave signature, you find out when inflation took place. Just like that. But it's really, really hard. It's more than a decade that you've been doing this. And you just keep, I watch you guys, if I would give you $100, you would go buy some more detectors for the focal plane because every penny that comes into this project, you make

the experiment more sensitive. and it's sitting down there at the South Pole. I hope it's running right now. Yeah, yeah. Well, it's been upgraded. It's on the fourth generation now. It's called Bicep Array. I went from Bicep 1, Bicep 2, Bicep 3, and now we gave up the creative naming scheme. But yeah, speaking of money, you know, you mentioned the royalties you're getting from the early universe. Hey there, fellow Voyagers into the impossible Tizai, your fearful host. Professor Brian Keating here with a tiny little homework assignment before we get back to the episode. and that's to make sure that you're subscribed to the podcast, either following it or subscribing to it,

depending on your podcast, catcher of choice. I did some research of my own and found out that about half of you are actually following or subscribing to the podcast. So please do that. And for some extra credit, if you're looking to boost your position on the grading curve, please leave a rating or review. It really helps us out tremendously. Do it. Do it now. Before you forget, let's go back to the episode.

Now you understand the reason that I'm calling you today, Michael. So let's talk about inflation just a little bit. I do want to say one thing. You brought up the very important fact that is missed by 99% of lay people and almost 100% of scientists, which is that the job of an experimentalist is not to prove theories. Our job, I call myself a theory exterminator because that's really what we should do. And I tell my students, Michael, and I wonder what you would tell a student, you know, starting off nowadays. But I say my experimentalist, I want you, experimentalist, to understand theory as well as a beginning theory graduate student. I just don't require that you come up with new theories or new tests or new models, but you should understand what you're doing, at least as well as a theorist.

Otherwise, you're, and I'm not, you know, condemning plumbers and electricians, but that's what I spend most of my time doing. I'm an electrician, a plumber, a technician, vacuum tube, plumber, you know, looking for leaks in helium lines. I mean, this is not something I needed to get a Ph.D. and cosmology to do necessarily. But what is the theoretical minimum? I told you the experimental minimum. I want my grad students to know theory, at least as well as a grad student in theory. I don't require him or her to make new theories. What's the theoretical minimum to use Lenny's term? I agree with everything you say, and I'm glad you're telling your students that. But what's interesting about science, and we'll come back to baseball, but I won't mention those pathetic Padres. science is a team sport. You're in a, and I don't mean collaborations, you're in a collaboration,

but more generally it's a team sport. So let me just talk about the theory side. So we need theorists who write papers where every damn one of them you can trust. You can take the numbers to the bank. And so that's somebody who gets on base, hits singles. In theory, there is a role for people who, swing for the fences, the Babe Ruth's, and most of their at-bats are strikeouts. We need those two, and you might say, well, which one do you want?

I want both, because if no one's on base when you hit the home runs, and so, and it's same in an experiment. I know, actually in your field, in the microwave background, there are some people in your field who are extremely distinguished. I don't want to mention names, because this could be taken. the wrong way, but who know how to get the science. Then there are people who know how to invent the instrumentation, but don't have a clue about the science. And so if you get those two together, Andrew could do both. And actually, Andrew also could conduct the orchestra. So he could put together.

He could manage the baseball team. And so I think science requires a whole bunch of different skill sets. on the theory side. But I guess all of them involve, you know, being able to work abstractly and having command of the mathematics of the day. I like to tell classes that in the history of science, you may push back on this, mathematics has always been the pacing item. And I can make a pretty good case about that, that, you know, we had the Greeks, And, oh, my God, nothing happened.

And then Euclid invented geometry. And algebra helped. The Arabs invented algebra. And then Newton came along and invented calculus. And you can see where our understanding of the universe jumped. Non-Euclidean geometry. Einstein came along. It was so abstract that people have a hard time believing this.

Einstein was not a very good mathematician. and he had his hired hand, Marcel Grossman, that's right. And so mathematics, a theorist has to know math, and do they have to know absolutely, you know, the cutting-edge math? They can't know old-fashioned math. Like if all you're good at is geometry, I think you might not be a great theorist, but you don't necessarily have to know string theory. So it takes different skill sets.

And you know the Weinberg Salams theory. Oh, my goodness, Nobel Prize winners. Shelley, who's a good friend, always swings for the fences. He is the big idea guy. Pass guest on the podcast. Shelly is amazing. He hates string theory. That's a whole other – I can't explain that.

We'll do that at a different time, yeah. And Steve sweat the details, and the combination of them getting the Nobel Prize is crazy because the two of them competed in high school, Bronx High School of Science, and there they are, you know, you're judging how good you are by how many other people are at my level. There's another guy who's as smart as I am. They both end up as assistant professors at Harvard sharing the same secretary. And then Steve gets famous for his paper on what's now called the Weinberg-Salem-Glaashell model. Shelly forgot he had invented the model because it was one of his

strikeouts because he didn't have a way that there was something missing from the model. And so then Shelley, oh my God, I hope you're, oh boy, I'm being, but Shelley has said all of this in print. He said Weinberg installed the toilet in his beautiful model, and that, which is the Higgs mechanism. But so I say this, they're both brilliant. We would not have the Weinberg-Salem-Glam Glash-out theory without the two of them and Abdu-Salem.

And I'm sure you see it in experiment. There's some people in your collaboration who are developing detectors for 20 years ahead, and you're trying to say, yeah, but we're trying to get these working at the South Pole. That's right. And, well, they're not going to help you with that. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals because we're built for what you're building. Fit for your ambition for Citizens Bank.

We love to plan. We love to forecast ahead. You sort of get a little bit of the thrill of the, you know, it's like when I say I want to drop, you know, five pounds. I'm glad to say I did it, Michael. I dropped five pounds, but it was from my chin to my waist. It wasn't that far. But, and later on, I want to ask you, I have a tradition. I'm going to ask you to ask my next guest a question.

My next guest is none other than Gerard et hoofed. I can't. The first thing is, how do you pronounce his name? But he's agreed to answer some questions on the podcast. So I'd love to get a question from you. to Gerard or Gerard, if you're willing to play that at the very end of that game in a couple of minutes. But before we do, I would be remiss. I had on this guy, David Chalmers. I don't know if you know who he is. He's a philosopher at New York University. He came up with this concept called

the hard problem of consciousness. I had on a guy named Nick Bostrom, and he invented the term the singularity, not the singularity. That's Ray Kurzweil. The simulation hypothesis. So all these guys come on and one's from Australia and David Chalmers is from Australia and I said, David, look, it would be, it would be as if I had on, you know, ACDC and I didn't ask them to sing back in black. You are the creator, the father, the paternal figure of dark energy. I would be as equally remiss as I would have been with Bostrum if I didn't ask, you know, him, I gave the example of Abba. If I didn't ask him to sing Dancing Queen, because he's from Sweden. Anyway, tell me, please, Michael, how did this come to you? What was the motivating, inciting

incident from literature we encountered these? What was the origin story of your child, dark energy? In the 90s, when you were a youngster, we had this idea called inflation. It predicted a flat universe, a critical density universe. We had this idea of cold, dark matter. These were the driving ideas. They were getting young people like you into the field. They were so beautiful. And they had a problem. Let's focus on the critical density problem. So the critical density problem was you have to find enough matter to get to the critical density. And early on, we looked at the measurements that had been made by the astronomers, and we realized they were missing the dark matter. and the dark matter is more diffuse than the visible matter,

and it's harder to measure things that are far away from you. And so we pinned our hopes on the dark matter was going to get the density all the way up to one, up to the critical density. In I think it was about 1994, there was a paper. I won't describe the details that really hit me in the face. It involved, we know at that time we knew how many, atoms there were. We just didn't know how much dark matter there was. And this paper used a very clever technique looking at the ratio of dark matter to ordinary matter in clusters and then scaling it up

saying that the total amount of ordinary matter is only about 30%. You're not going to get... That paper really eliminated the possibility that dark matter was going to take you all the way to one. So when you eliminate the impossible, whatever's left, no matter how ridiculous, I know I'm screwing up the quote, is likely to be the answer. And so you look at what could fill the gap, and what could fill the gap is something like Einstein's cosmological constant. And I've been writing papers, you know, theorists are always, you know, this is my main prediction, but I got in my back pocket an answer, just in case your experiment comes out a different way. Oh, here, look at this paper. Lawrence Krause and I wrote a paper saying the cosmological constant is back. And

And that was in 1995, and in 1998 it was discovered, blah, blah, blah. And then I realized in 1998 that the astronomers were going to say, okay, we're done. It's just the cosmological constant. And we do not know that. We absolutely do not know that. And so if you allowed this stuff to be called the cosmological constant, oh, my God, you guys have already measured it to better than 1%. We're done. But we realized, and it wasn't just for full employment, it was, we don't know what it is.

And so unless we change the name and explain to people why it's mysterious, unknown, I've called it the most profound mystery, not the most important mystery, but the most profound mystery. So it needed a new name. So what is the new name? Well, we got dark matter. That's really good, but it's not matter. And in the technical sense, and, you know, you. It's more like energy than it is like matter. And I'll just say that and not explain it because it's not worth explaining.

So, oh my God, dark energy and dark matter, dark side of the universe. Better get that copyrighted right away. So there it was. And then you have to lay out the story. So we don't know what dark energy is. We do know that the simplest example of it is Einstein's cosmological constant. but I won't go into all the reasons. It's a big puzzle.

It is a really big puzzle. And so about the same time, Martin White and I came up with, here's how you determine whether or not it is Lambda. I'll just use the letter, you know it, W. It's the W parameter. And so I made a really big deal of this is really important, and it's got a different name from the cosmological constant because it may not be the cosmological constant.

And you know this as well as I do. Today, all the measurements are consistent with dark energy just being a cosmological constant. However, if that's the answer, we don't know why. We don't know why such a cosmological constant would be so small. And so I remember the meeting. It was a wonderful meeting in Australia where I rolled out the new name. Actually, I don't know if you've ever seen this.

The first name I tried was Funny Energy. And I have a view graph that appeared in the New York Times. You're famously renowned for your sketching your artistic abilities. The focus groups told me, okay, oh, that's fantastic. You know, that's non-threatening. People will really love it. And then I said, well, it's going to take a billion dollars to figure out what funny energy is. Oh, you need a more serious name than that.

And so in August of 1998, at the Mount Stromlo meeting in Australia, I said, we're going to call this stuff dark energy. and the name has stuck. Some people don't like it. They want to call it dark negative pressure. I don't think the focus groups are going to like that. Dark energy is pretty good. But the purpose, get rid of all the silliness, two purposes. Number one, in order to make it a scientific target, you can't just say, oh, that funny

stuff that's causing the universe to speed up. It needs a short name. And then you need to quantify it a little bit, and you need to differentiate it. So dark matter has worked really, really well, but you have to differentiate it from dark matter. So it's got to be slightly different. It can't be a long, complicated name. And you have to be able to explain to people, oh, my God, you're just trying to be more famous than Einstein. Oh, no one could ever do that.

So why don't you just call it Einstein's cosmological constant? And the simple thing is we don't know that it is. It is the biggest puzzle. It's the most profound puzzle in all of science. and if we want people to really spend time trying to figure it out, we got to give it the right name. Yeah, I think it's good. Speaking of somebody who's got a name for, not a name, no pun intended, for neologisms,

I came up with a name bicep. NASA recently asked me to come up with a new name. Apparently the name Uranus is very embarrassing for some astronomers to announce. And we come up with ways around it workarounds like uranus, like urine is better than uranus. So I've been tasked by the NASA Task Force to come up with the new name. And I'm proud, I'm going to announce it right now. I've come up with the new name. It shall be known as your rectum. And I think it's going to stick, but it's up to folks like you. The focus groups will come into play. Michael, I want to read, I want to read something to you. And it's a, it's

kind of a hallmark for my listeners to eventually send you more and more of those precious royalty scratch checks. This is from an article you wrote, I believe, about 10, 15 years ago. No, it's 20 years ago. Oh, my God. This is incredible, Michael. And physics today, and it's about dark energy. And this is a section called Destiny. One thing you wrote is clear. Dark Energy leads to a vision and our view of cosmic destiny. With matter alone, destiny and geometry are one. Closed universes recalapse and open or flat universes expand forever. If dark energy is vacuum energy, our flat universe will continue accelerating to a bleak future in a hundred billion years. All but a few hundred galaxies nearby will have their light shifted too far into the red to be seen. If dark energy dissipates, the universe will

begin to decelerate, possibly even collapse. Then you go on to say dark energy is one of the deepest and most exciting puzzles in all of science. It is likely that a crazy new idea is needed to explain the cosmic speedup and resolve the cosmological constant problem. That does not mean that every crazy idea is a solution. The payoff will be well worth the effort. We will gain new insights into the nature of matter, space, and time, and shed light and our cosmic destiny.

And that, you said, was predicated on adding in your nine-year-old son's theoretical work and progress was assured. But, Michael, I want to take a quote from a very well-known scientist by the name of Al V. Cohen. who was in Annie Hall. Woody Allen comes up and his mother says, you know, he's not doing his homework to the psychologist. And the psychologist, why aren't you doing your homework, Alvi? And Alvi says, well, I just found out the universe is expanding.

And eventually everything will be so diffused and nothing will be. And his mother goes, shut up, you idiot. Brooklyn's not expanding. How do you deal with the existential dread of your creation, Michael? I've had on Adam Reese, I've had on Brian Schmidt on the podcast to lovely men who you know very well. They don't seem particularly overwhelmed by the existential, you know, kind of Weltschmerts, I think is the German term, for, you know, kind of world weariness. Does this affect you? I mean, you write so beautifully, so poetically.

I can't imagine you haven't thought of the philosophical, just as a man, as a father, as a, you know, as, you know, as. as a scholar. How does this knowledge of something you played a huge role in unleashing upon the universe, how does it affect you, if at all? Maybe it doesn't. Maybe it doesn't. And I may have gotten that out of my system. I started out being trained in physics. And at Stanford, my advisor wanted me to get more into astrophysics. And so I read an astronomy book. It might have been the one by George A. Bell, but they're all the same. It's the one for college courses. And And I came away so depressed. That was before dark energy, that the universe is so big and we're so small.

And so I kind of got that out of my system. There are people, as you know, Doug Adams and Lawrence Krauss. Freeman Dyson wrote the kind of first article about the long-term history of the universe. And there's so much to do today and so much to understand today. and I'm sorry I'm giving you the boring at least I'm a big company with two Nobel Prize winners. Own it all. Pay off your home, travel for life, drive a Ferrari.

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at Yamava celebrating its 40th anniversary. UN. Details at Yamava.com must be 21-20. Please gamble responsibly. Monopoly is a trademark of Hasbro. Hasbro is not a sponsor of this promotion. Do you know about... And the first guest on the end to the Impossible podcast was none other than Freeman Dyson. He was a Jason and he used to come to La Jolla every summer.

For some reason, he didn't like being in, you know, Prince of New Jersey in the middle of January. So he was a brilliant guy. He came down and we got to know each other. And one of my favorite memories, he met my, you know, then four-year-old. old and he was 94 or whatever at the time and I have pictures of them together. He's the lovely man. He was my first guest on this very podcast. So you're in great company, Michael, and you deserve it. I want to ask now about another, I mean, you've been at the center of so many of these really interesting conundrums. And I see you, there aren't the technicians. There are the kind of

people, the work-a-day people cash the paycheck and, you know, don't really think about the philosophical implications. I know that you're saying that you've resolved those philosophical implications. But what do you make of these recent kind of contraversies, as Freeman might say or Britt might say, about the Hubble concept, the Hubble Tension? I want to get into your work on magnetic fields, which is my preferred solution and rectification of the Hubble Tension. First, explain, is it really a problem that scientists are measuring this number, two different ways to subpercent precision? And as you pointed out, I think you coined this term, too, that precision causes.

cosmology is good, but accurate cosmology is better. I use that without giving you the royalties, but that will now change. Tell me, Michael, what do you make of the so-called Hubble Tension? What is it? And what does it mean for? The Hubble Tension talks to the maturity of cosmology. It used to be a science with very few facts. And now there are lots of facts. There's enough facts that we can measure things in multiple ways and do cross-checks. And so we can measure how fast the universe is expanding just by looking at the galaxies nearby. It's not easy. It's very hard work because you have to figure out their distances. You can measure it that way. And then you can use a way that's probably more familiar to you using the microwave background. And what you really do is measure how fast

the universe was expanding a really long time ago and then say, I know Einstein's equation tell me how the expansion rate should evolve with time, and I can run it up to today, and it should agree with what those who measure it doing now get. And so the good news is it does agree to better than 10%. And, oh, my God, when I was your age, getting a 10% measurement of the Hubble constant almost looked impossible, and it involved Wendy Friedman,

my Chicago colleague leading the Hubble Key project in doing it. So we have two different methods that agree to a precision that 20 years ago would have been enviable. But then when you look more carefully and take those numbers very seriously, they disagree, as you say, at a few percent level. And it's statistically significant. It's not just, oh, you know, because errors of measurement. And so this is an important cross-check. Cosmology is not used to having cross-checks. We now have a bunch of them.

This is an important one. And so the question is, and there are three outcomes, three possibilities. One, the microwave background could be wrong. I know you would find that measuring it from the microwave background could be wrong. Actually, there are four possibilities. the direct measurements could be wrong. Both the direct and the microwave background could be wrong. They both could be right.

But the extrapolation is wrong because there's something else in the universe besides atoms, dark matter, and dark energy. And that's what gets everyone excited is that there's something missing from this model. I think you use the term Lambda CDM. I know Adam gets very, very excited about that, and that's a possibility.

And Adam would be the first to say, were not there yet. And then what, and coming back to dark energy, we had a crisis then. We had a bunch of things that didn't work. I mentioned the flatness, but there were other puzzles that didn't work. You add one crazy thing, Lambda, and everything works. And so that looked pretty good to me and Lawrence Krauss, and we wrote a paper. Today, all of the fixes, they're so complicated and they just solve one problem. So you, you know, you put it, Feynman was one of my mentors at Caltech and he said, you know an idea is good. It's like putting a quarter in the Coke machine and 30 coaks come out. The golden gumball. Yeah. Yeah. And that's not happened with the,

the fixes like, they have all kinds of names that I could say early dark energy. I'll say early dark energy is the most popular one. And they don't even quite fix the problem. And then you say, okay, well, okay, let me pretend you fix the discrepancy. What else are you predicting? What else new is out there? Well, this was just a toy model. It was not meant to, so it doesn't, that doesn't mean it's not right, but it doesn't have the sound of being correct. And I'm usually pretty good at looking around the corners, and this is a real puzzle. I don't see where this is going to end. In fact, it would be wonderful to have a debate where it ended. And in the debate, you flip a coin to decide who takes what side.

Because there are powerful arguments on both sides. Oh, it's got to be new physics. There's an equally powerful argument. Oh, my God, that distance scale measuring galaxy distances is so hard. If you look at all the great astronomers, Hubble was off only by a factor of 10 in measuring distances. I mean, it's very hard to measure distances in the universe. So I don't know how that one's going to end. But it's either going to end, well, I guess it could end as the whole cosmology collapses.

I don't think that will be the case. Or it could end in, oh, there's a mistake, either in a microwave background or the local measurements. And now the two agree to 1%. So we have this end-to-end test. Or it could be, you know what, we just discovered, just like the discrepancy we had with the flatness of the universe, we just discovered something new about the universe. So it's exciting. That's the other misconception among lay people

and less so among professional scientists, unlike the job of what an experimentalist is supposed to do being not prove a theorist, but prove them wrong. But actually it's most exciting. I always think it's a little disingenuous, though, Michael, when people used to say, you know, the most exciting thing about the Large Hadron Collider would be if we don't find the Higgs boson.

I'd be like, yeah, I'd be really excited about losing using 10 billion euros, you know, just, you know, that would be so exciting to me. But, you know, other than that, in this situation, so many flowers can bloom. And one of the ones that I said appeals most to me, venally, because I've written papers about it with my friends in various locations like Levin Pococcian and others, about magnetic fields. So your paper, and this is the sign of just a Titanic intellect. So as we were talking, before we start recording, we were talking about your paper with Lawrence Widrow back from 1988. And I said in that paper, you know, it's being cited now as a, as, you know, one of the first

citations to axions and so forth. And you were kind of arguing with me, Michael, but I looked up the paper as we're, as we're talking. I have it downloaded. And, and, and nope, it's right there. Equation 3.1. Sorry. You talk about a, the axion, through which, through the anomaly couples to E.B, which for those out there, my audience is the most brilliant in the known universe and the multiverse, but that would be a forbidden interaction in classical electromagnetism. But Michael is so incredibly, you know, brilliant that you've forgotten more than most of us will ever know. And one of those things was how an axon, which has become a very popular candidate for the explanation of dark energies, you know, sinister older brother, dark matter.

I wonder, though, I don't want to talk too much about Axions unless you want to talk about it. I'm fascinated by them, and it's kind of buttering my bread lately because we're doing a lot of searches, as is your buddy John Carlstrom and the South Pole Telescope. And I like to think I play a little role in that, as I did with search for inflation with Bicep, and that I started to think about these parity-violating things back in 2007 as looking for these forbidden correlation functions in E.D.B of C-SibLE.D.B. and people, even John kind of laughed at me back then, but now he's come around, and I hope to have him on the podcast, too. But unless you want to talk about axioms, let's talk about electromagnetic fields, because these are the only things that we know for sure exists. We don't know if axions exist. We don't know what dark energy is, or, you know, maybe if it is a cosmological constant or not.

We don't know what dark matter, but we certainly know good as anything that magnetic fields exist in you and me and our planet. it in this meteorite, which, you know, blew my chances at a Nobel Prize in some ways. But I do give these away. If you have a .edu email address, I give them away on my website, Brian Keene.com. So you have a . . . . I'll bring you one when I come and see you up there in Venice. But Michael, how do magnetic fields originate in what was the concept for these early magnetic fields? And what would you rate?

If you were doing a Hubble Tension scorecard, as I would love for you to do, as you did with your magical inflation scorecard, please tell you. me, Michael, what would the idea of a primordial magnetic field rank? And what score would you give it for resolving potentially the Hubble Tension? Well, I would give any solution a pretty low score. Let's go back to dark energy. When Lawrence and I wrote the paper about Lambda, I would have given it a chance of maybe 10 or 20 percent being correct. And I really thought it was a good idea. So the... That calibrates things. Yeah, I want to calibrate it. So I think, I think, think any of the solutions I've heard, you know, less than 10%, a chance of being correct.

But that's really high because there's a lot of ideas out there. And you should not trust my opinion. The nature gets the last word, and the experimenters get the last word, and nature, or ugly experiments, kill beautiful theories. And so you can have the most beautiful theory. I don't know if you ever had John Ellis on your show, but he's a very distinguished article physics. Oh, no, not John Ellis. I had George.

And John Ellis said the first time, and he's a very creative guy, the first time he heard about the Weinberg's law model, he said, this is too ugly for nature to have chosen that. And it did. And so just because all this, I find all the solutions uncompelling, my opinion really doesn't count. We've got a problem to solve. And so we need ideas. And, you know, I'll give you, this is advice from an old person. So I did a tutorial with Feynman when I was an undergraduate Caltech. And so he looks at me, just like I'm looking at you right now.

And he says, I really envy your ignorance. And so I'm going, oh, that's great. Thank you. Thank you very much, Professor. Ultimate backhanded compliment. Well, what he meant was on the theory side is that the older you get, the less creative you get. And you know too much. and you get a germ of an idea and you can just completely discard it.

And most ideas, the first rendering of most ideas is just wrong. And so, but if you kill that little germ of an idea. So, for example, you know, magnetic fields explaining the tension, what I'm 100% sure of is that the solutions that have been written are not right. Whether or not they have a germ of a good idea, I don't know. And so, and I'm the wrong person to ask because you get old and you get, you know so much more. And worse than that, you know that most ideas are wrong. So, you know, if someone comes in and says, okay, it's your life, the stakes of this question are your life, is this new idea right or wrong?

I'm going with wrong because I'm going, I'm going with the smart money because, and so, and it just doesn't matter. there's so many examples. Neutrino oscillations. All the theorists said, oh, my God, neutrino mixing angles are really small and it's matter-induced. That's so pretty. The creator could not have chosen to do that.

It's large mixing angles all the way. The creator did not take the beautiful route. So what young people can do is put ideas out there. And a lot of them are just crap or most of them are wrong. Some of them are even crap. But it's generating those ideas. the hard thing. The easy thing is being the critic and testing them is not always easy either.

But so I just don't want to discourage people from having ideas. So my current betting odds on the Hubble problem, I gave you four solutions. 25, 25, 25, 25. It's a real puzzle. That's a uniform prior for those of you playing at home. I think maybe if I could be, you know, so temeratist is to suggest what Feynman might have also been. implying, and he would have had a field day with me because he would have been very envious of my ignorance because there was a surfeit of it. But there's a feeling that you get. I finished reading Moby Dick 20 years ago. I started it 800 times, never finished it. But when I was done, I was like, oh, I really wish I could read this again for the first time. And, you know, you kind of

feel that way sometimes when you're building a new experiment, you know, in those heady early days are, I assume, a theory coming up with a theoretical idea. But it's just so, it is important to realize that, yes, ideas, on the one hand, ideas are cheap and everybody's got an idea, and the hard thing is follow through, which takes a lot more time and attention and so forth. But I think being guided by these big principles, trying to do, as, you know, another great orator said, you know, that the mankind's reach should exceed his grasp. That's the challenge.

That's what makes it so fun to be a physicist when there are. are so many different possibilities that you could be right, you could be wrong, and you should have a little bit, I always say you should have a humble, you know, kind of form of swagger. You should know that you're probably wrong, but if you don't have a little cockiness, you're never going to take on Mother Nature. You know, she's just too powerful. So let's conclude in the next, you know, few minutes. If you have a few more minutes, Michael, I'd love to talk about your thoughts on, you know,

upcoming guests. I have two upcoming guests that you know very well. One is Katie Freeze, who you wrote many papers with, but also with David Schram, who I never really got to know David. He passed away, unfortunately, you know, before I came of age. But talk about, you know, Katie, who's coming, he's actually coming to UCSD in a week to give our prize colloquium here. But talk about their ideas. She's come to attention lately for this notion of dark stars. and that possibly being an explanation. I wonder if you could channel your friend, your colleague, David, and say,

what would he make of these new ideas? And what do you make of these very creative ideas like dark photons, dark stars? You're the king of the dark, Michael. So please, opine for us on the state of this. And then we'll conclude in a bit. David Trem was my mentor. And I will never forget the day

that he died. I just, I don't even want to think about it. And Katie was a student at Chicago, and David was her advisor, and I also worked with Katie when she was a student. And so Dark Stars is really great. I can't possibly believe it's true. I can't find out anything wrong with it, but most importantly, it's very testable. And I also like what you said about the swagger. Katie's had the right amount of swagger that you got to let go of an idea if somebody can show you that it doesn't work.

But if it's testable, that's very important. And Steve Weinberg once said that you can find countless examples where the theorists did not stick to their ideas enough. The microwave background being one. Gamoff, they could have predicted it. They could even, anyway, it's an interesting. Dickie, Dickie did predict it and tried to measure it and then he forgot about it. And so I think the dark stars, I just can't possibly believe it's correct. And then Katie says, well, tell me what's wrong with my arguments

and tells me what's wrong with these simulations. And that would be amazing. The dark photons, so this is another one that would be interesting to get Katie's opinion on this. Here we have a dilemma. My generation said, guess what? We've got it down. There's one dark matter particle. It completes the grand unified theory or the theory of everything.

There's just one particle missing. And guess what? That one particle missing also is the dark matter. We've got this really simple story. We called the 2010s, the decade of the wimp of the weekly interacting massive particle. And you're either looking for the light of supersymmetric particle or the axion. and Rocky and I and others said by 2020 we'll be done. We'll know the answer.

And, well, of course, we don't quite know the answer. We haven't ruled either one out. But it's not looking good. And so the young theorists said the new paradigm is the tip of the iceberg is the dark matter particle. And the rest of the iceberg underwater that we can't see is a whole new dark world. All kinds of other particles, dark photons, dark. dark this, dark, that. It seems awfully extravagant to me. For one problem, you invent a whole new world, but they've convinced me that I'm being fairly simple-minded saying, you know, we just

had one thing left to do. And now a question for a tuft. Well, he's so smart. And he thinks about things in a very deep way. I was at a meeting with him five years ago, and I was trying to think, but I would really like to know his opinion on inflation. Roger Penrose, who I don't know if you've had on your show or not, but he does not think very highly of inflation. And he thinks that it's just a blind alley. And you've probably had Andre Linday who thinks, you know, Andre Linday once said the only way you can disprove inflation is with a better theory.

You can't do it with an experimental data. and he thinks very highly of it. Gerard thinks about things in a way that I can't often understand and he's extraordinarily mathematically powerful. When I hear him talk about black holes, I know I can't understand that. I get confused by that.

But I would love to have just open-ended, what do you think about inflation? Are we on the right track? Is it a distraction? Where is that train going? Okay, Michael, the last question, I usually ask a bunch of questions based on Arthur C. Clark, who is the namesake of this podcast because he said, the only way to know the

limits of the possible is to go beyond them, into the impossible. You brought up Arthur Conan Doyle's similar statement. But I want to, and sometimes I lay on my department chair, Clark's other maxim, which is that for every expert, there's an equal and opposite expert. I love that one. But I'm going to do a different one. Also having to do with impossibility. And it's the following quote, when an elderly or distinguished scientist says something is possible, he is very likely to be correct. But when he says something is impossible, he is very likely to be wrong. I want to ask you, Michael, what have you been wrong about? What have you changed your mind about and sort of an advice to an earlier form of Michael? I think we just covered the one that I'm struggling with. And I think the struggle, struggles are really

big, you know, this dark matter thing, have I, for the most of my career, been looking at it the wrong way, that it's either the Axion or the Neutralino, and you've heard of the Wimp Miracle, I hate that term, it's not, you will not find it in the early universe, because it seems clear to me, I mean, you've heard me kind of dismissive, I didn't mean to be dismissive, but saying this whole idea that you're inventing a dark world to explain one experimental fact, that seems so extravagant, but maybe I'm just looking at it the wrong way, that this is the piece, the only piece of the dark world that we can see. And I'm just so fixed in my old ideas that there's just one last thing to find, like Michelson was, saying, oh, you know,

in the 1900s physics is done, we're just putting extra decimal places on. So I would say that for me, you're watching a struggle. And I give talks, I have to give talks at Dark Matter meetings and I'm slowly evolving. I'm at least willing to admit they may be right. And usually I can see around corners and see the end. This puzzle I cannot see around the corner. Michael, I appreciate you so much. I hope you'll come down to San Diego and maybe give a colloquium of your own. We'd love to host you here. And it's been a delight, as I knew it would be. And I hope someday we can do a part two. It's been fascinating journey through the history and your philosophy and also the culture and taste that it takes to build a brand as strong as the Turner brand.

Thank you so much. And best of luck to everyone that you mentioned, except for those hated Dodgers. Thanks a lot, Brian. It's been fun. And I do hope I will get down to San Diego one of these days.