Life, the universe, and everything with Nobel laureate physicist Saul Perlmutter (Transcript)

[00:00:00] Adam Grant:
Hey everyone, it's Adam Grant. Welcome back to ReThinking, my podcast on the science of what makes us tick. I'm an organizational psychologist, and I'm taking you inside the minds of fascinating people to explore new thoughts and new ways of thinking. Today, my guest is Saul Perlmutter. He's the Nobel Prize-winning astrophysicist best known for his discovery that the universe is expanding at an accelerating rate. Saul serves at the White House on the President's Council of Advisors on science and technology. He teaches classes at Berkeley on physics and music—'cause he plays the violin—and on sense, sensibility, and science. I can't imagine a better role model for all of us to sharpen our creative and critical thinking skills.

Well, I am thrilled to have you here, especially as, a once upon a time wannabe physicist. What was it that hooked you in physics of all the things you could have studied?

[00:01:04] Saul Perlmutter:
I think I'm just one of the kids who, uh, just always wanted to know how the world worked. In fact, if anything, I think I'm more curious about why everybody didn't, didn't get hooked. I think as a child I thought, "Well, here we are on this earth and it's our toy and, and nobody gave us the owner's manual, and doesn't everybody need to know the owner's manual?"

And I guess as you get older, you start to realize that well, somehow people all manage that we all work day to day without the owner's manual. But in my mind, I think still there's that sense everybody should want to know this stuff.

[00:01:33] Adam Grant:
That's so fascinating. I think that as far as I can remember, like, I've been obeying the laws of gravity. Nobody gave me the manual. I didn't need to know them, and yet I've been following them very dutifully. So—

[00:01:43] Saul Perlmutter:
I think you're doing a great job. I mean, just watching you, you're staying in your seat... [Laughter]

[00:01:48] Adam Grant:
[Laughter] Lifetime of practice. What can I tell you?

[00:01:50] Saul Perlmutter:
I love that.

[00:01:51] Adam Grant:
So thank you, Saul. So of all the things that you could have explored, how did you decide what about the world you wanted to understand?

[00:01:59] Saul Perlmutter:
I think I always was interested in the sort of the basics that you needed to know to understand the world. So you know, all the different languages of the different specialties interested me ‘cause I thought that they must be the ways in which you can understand things. I was always curious about how the mind works.

One of the things that I could still imagine going into is cognitive science-type questions as, as we would call 'em now. But then, all the basics of what are the fundamentals of the physical world that we live in struck me as they must be underneath everything else. And so, you know, now I come to think of it as, you know, what are the forces and what are the smallest particles? But I think at the time I was more interested in just what would be the most fundamental question you could ask from which you could learn everything else.

[00:02:43] Adam Grant:
Love it. When did you start to wonder about the scale of the universe?

[00:02:48] Saul Perlmutter:
Well, when I was in graduate school, I remember a period in which I was looking around for what would be a good meaty project to work on for my Ph.D. and you could do research of all sorts. In fact, I’d chosen Berkeley because it had such a wide variety of experimental topics that people were working on. But I found myself troubled because I really wanted an experimental topic that would feel really deep and almost foundational and, and philosophical. And you could do it perhaps by doing elementary particle physics, which seemed like it would be getting at some of these questions.

But as a graduate student, I was looking for something where you would feel a little bit more directly personally involved. And, uh, particle physics had become already a pretty big team activity, and I figured that as a grad student, I wouldn't necessarily get to shape the experiments as much. And then I remember realizing that you could, uh, possibly use, um, astrophysics as a way in, because you could see some really deep fundamental things there.

And even so, I was still hunting around for a good project. And finally, I came across this opportunity to measure the history of expansion of the universe and find out, for example, how fast the universe was expanding-- that could tell you something about the age of the universe. And then. it was even better than that. It turned out that you could actually use the measurement of the history of the expansion of the universe to find out whether the universe would last forever. And uh, or whether it would somehow come to an end, and also whether it was infinite or whether it was only a finite amount of real estate out there. And those struck me as the kind of deep philosophical questions that I'd always wanted to do.

[00:04:22] Adam Grant:
So I think we have a vested interest, as human beings, and the answers to all those questions. You are probably best known for your discovery that the universe is expanding at an increasing rate. You're probably gonna correct my description of that, but I first came across it when I was, uh, it was I guess the first, first semester of my freshman year of college. I signed up for two courses that I was thinking about shaping my major through. One was psychology, the other was astrophysics. And I remember—

[00:04:48] Saul Perlmutter:
—just like me.

[00:04:50] Adam Grant:
Well, clearly you made a better choice and had much more to contribute to physics than I did. But I remember just being horrified and almost existentially paralyzed by the idea that the universe was not only expanding, but the rate of expansion seemed to be accelerating. So I think that was your fault. Can you, can you first explain this discovery to me and then make me feel better about it?

[00:05:12] Saul Perlmutter:
Well, well, I should apologize, both to you and to my younger sister, because for her, even just when I start talking about the infinite universe at all, before we even start talking about whether it's expanding and whether the expansion is accelerating, she says it just gives her the willies. And I find myself thinking: “It's funny. Why does it not do that for me?”

For me, I think I've always felt like we were somehow in this very interesting place as humans ‘cause we, we are in a size where we get to look out at things that are much, much bigger than us and also look down at things that are much, much tinier than us, going down to the elementary particles. And so we're, we're certainly nicely contained in the middle. And then similarly, we are right in the middle of a period in which, you know, the universe was expanding, first very dramatically, and then it starts slowing down, and then it starts speeding up again.

But, we're kind of in a middle point where things aren't too far apart and things aren't too close together. And so we can actually look at things and it almost feels like we're in a nice cozy center in our universe where, you know, we, we get to look at everything. And if we had been around much earlier, it would've been hard to do anything ‘cause everything would've been too dense. And if we're around much later, it would be hard to do anything because you couldn't see any other galaxies. We would, we'd just be alone by ourselves. We'd never be able to figure this out. We were in a really nice spot.

[00:06:24] Adam Grant:
Wow. So optimal distance for a physicist to do research.

[00:06:27] Saul Perlmutter:
Exactly. The right size, we're the right time in history, it's almost perfect. Now, of course, may, maybe will, they'll turn out that the world is very different than we thought, and we'll realize that, oh, we were getting a very funny view from where we are right now. But at the moment that it in our, in our picture, it seems like we're very, very nicely oriented.

[00:06:45] Adam Grant:
Well, that's part of what I wanna talk about. Before we go there though, I would love to hear the story of, of how you made this monumental discovery. What were you doing? What did you see? How did you document something that, as far as I understand, that people in your field have been trying to study for decades, if not centuries?

[00:07:01] Saul Perlmutter:
Well, it was, there's a really lucky moment, and this is in the, the mid to late eighties, in fact, where people had for a long, long time, ever since Hubble and other colleagues saw that the universe was expanding, there had always been the thought that, well, that expansion can't go on for everything because all the stuff in the universe, um, everything gravitationally attracts everything else. So you would imagine that the expansion would be slowing down, and depending on the density of the universe, it would slow down, you know, more or less. And you could imagine that, um, if there's enough stuff in the universe, might even slow to a halt and someday, um, turn around in the collapse to a big crunch. And so that would be an end of, of the universe.

And people had thought that perhaps when you might be able to make that measurement by finding some distant object where you knew how bright it really was and using it as a distance marker across the universe because you would see how bright it appeared to you. And it didn't work out that well when people tried doing this with galaxies because it turns out galaxies, um, have evolved over time and they changed their brightness, and then people started to think that you could use these exploding stars—supernova.

[00:08:04] Saul Perlmutter:
And it was only in the, uh, late eighties when I was looking into this step, we started to realize that there was a certain subclass of supernova, called Type 1a supernova, which really were pretty good standard candles. They were almost always the same brightness, and you could use them to mark out across the distances of the universe. And we had just done a robotic supernova search project where we had figured out how to use all these modern detectors. At that point, the camera detectors that you have in, in everybody's cell phone today was a really new thing, and we just started to use them to, uh, be able to image things directly into your computer and have the computers hunt for the supernova in these fields full of galaxies. All the pieces were in place at just the right moment. And so that was when we started this project to look for very, very distant, exploding stars-- supernovae --and use them to map out the history of the expansion of the universe with all these digital, you know, computer programs to find these distant supernovae.

We thought that if we were really lucky, oh, we’d need about 30 of these supernovae, um, to get enough precision to measure whether or not it was slowing enough to come to a halt. Or whether, um, it was not slowing quite that much and it would then always slow, but keep expanding forever. And that seemed like it was a really great project ‘cause you could find out if the world was coming to the end in some billions of years, of course. If you could make that measurement, you could also tell whether the universe was infinite or not in space because if there's enough stuff in the universe, it has this weird property in Einstein's theory, general relativity of bending space, and so you could actually bend space in on itself if there was enough to slow the universe to a halt and have it collapse, that would also be enough to make it bend in on itself so there is only a finite amount of real estate out there. If you traveled in any direction as far as you wanted, you'd end up back somewhere where you were before. And I thought those were great questions. I couldn't imagine a better project. So that's how we got into the whole thing.

[00:09:54] Adam Grant:
Wow. And what did you see that led you to conclude that the universe was accelerating in its, in its expansion?

[00:10:03] Saul Perlmutter:
We thought it was gonna take us three years to find 30. At the end of three years, we had not yet found one. At the end of five years, we found our first of the very, very distant supernovae. You know, people had seen nearby supernovae before, but never the ones that we needed to make the, these very distant measurements. It wasn't until nine years in that we actually had a sample supernova big enough to actually measure this huge question, which by the way turned out to be 42 supernovae. And so those people who like the Hitchhiker's Guide to the Galaxy always enjoyed the fact that we were answering this deep question with 42 supernovae.

[00:10:31] Adam Grant:
Life, the universe, and everything.

[00:10:32] Saul Perlmutter:
Exactly.

[00:10:33] Adam Grant:
Right there.

[00:10:34] Saul Perlmutter:
So with 42 supernovae, we, we started actually pointing the points on the plot and you could plot the history of the expansion to see how it was slowing down. Weirdly, the points all missed the lines that we were expecting to differentiate between all the ones that slowed, where the universe slowed down. And we thought, "Well, all right, I'm sure there's some computer bug somewhere in the software or else, um, it'll turn out that we need an extra control in our analysis of the dust that could be absorbing the light from the supernova."

Or any, anything could be wrong. Almost all you do as a scientist is try and figure out what's wrong with your measurements. Your goal is, uh, to hunt through everything that could be wrong before anybody else figures out what's wrong with your measurement. That's basically what 95% of the life of a scientist is as far as I, I can tell.

[00:11:14] Saul Perlmutter:
But in this case, it didn't go away. We kept having these points appearing in the part of the graph where they, we didn't think they would be, and that happened to be the part of the graph where if the universe was slowing down earlier, but for the last half of its life, it's been speeding up, that's where these points would be. After about 7, 8, 9 months of hunting for all the things that could be wrong with the experiment, and all the things that could be wrong with the computer program, and doing all the sanity checks that we could possibly do, we started concluding, you know, I think this is actually the answer.

And so we started just beginning to give some talks about this and, and realized, you know, and obviously, we had to be very, you know, careful showing everything we had checked because otherwise, why would anybody believe this stuff?

[00:11:57] Adam Grant:
Wow. I, I have so many questions about this. I think the first one is people tend to think about science as this very cold, rational, calculative process, and yet I hear all this emotion in your voice when you talk about it. What was the emotional arc of that experience from the first inkling of, of this hypothesis and saying, "Wait a minute, like everything we think is true might be wrong" to ultimately, like "we have just discovered that in fact, most of the field is wrong”?

[00:12:25] Saul Perlmutter:
Well, well, I, maybe I should even go further back because the, I, it feels to me the whole scientific process is a, a amazing interplay of emotions and this cold rationality that you also are using at the same time. So at the very beginning, you know, as I was saying, the project wouldn't start unless you were really excited about the project, and that's what, you know, got, got me into it. The fact that you could measure something that seemed amazing. In fact, it seemed so much fun. I couldn't imagine. Why isn't everybody doing this?

The idea that you could find out if the universe was gonna last forever and if it was infinite or not. Now all you had to do was go out, measure the brightness of some of these exploding stars? It seemed like the whole field, everybody would be doing that? And I was, I was, you know, surprised that, that we couldn't, you know, convince people to let us use the telescopes at first, you know, for, for the purpose.

[00:13:07] Saul Perlmutter:
So there's that emotional aspect. Then, there's all of the, um, frustrations that you have to work your way through. The fact that for the first five years we had not yet found a, a single one of the supernovas that we were going to use is a really good example of, of the kind of thing that emotionally you have to be completely, you know, sure that you're making progress, that you're can tell that you're actually getting closer and closer.

And I think that one of the real tricks of science is the ability to stick with something long enough to get an answer, because most things take way longer than anything that most humans are willing to do just in the day-to-day life. So you need all this, this extra, you know, ability to fool yourself into thinking that you're, you're getting somewhere.

[00:13:49] Saul Perlmutter:
One of the very first big public presentations I gave was a department colloquium in the physics department at the University of California Santa Cruz, and distinguished, um, theoretical cosmology faculty there Joel Primack stood up afterwards, and he turned to the audience and he said he just wants to, to make sure the physicists in the audience really understand what a bizarre result this is and how it really changes the picture of, of cosmology and could even, you know, change our picture of some of the underlying physics of the world.

And of course, that was the moment in which I finally had that sense of "Wow. That's right. Yeah." I, I knew that was the case, but, but so the fun of it came to me at that moment when somebody else reacted to the whole thing. It's a very social activity, and all the work that you're doing that I was describing is done in groups, a small team of people, and we're all, you know, trying to, you know, help each other and, and make the whole thing work. And then it's a team activity because you need other people to listen to it and to help you decide: is this right? And is it exciting?

[00:14:47] Adam Grant:
Well, the result that you ultimately produced, I think is partially responsible for me choosing to steer away from astrophysics, because I remember just being mystified by a puzzle that I think you can finally help me solve two decades later, which is, on the one hand, I thought the universe was everything. On the other hand, it's supposed to be expanding, so what’s—

[00:15:06] Saul Perlmutter:
—what’s going on?

[00:15:07] Adam Grant:
What's it expanding into? Where is it going?!

[00:15:09] Saul Perlmutter:
That's almost the starting point of any time I talk to anybody about cosmology, because if somebody says to you, "Oh, and it's expanding." That's ridiculous, right? Because it's already infinite. Well, I think that one of the first things that everybody gets wrong is they start trying to picture a wall and that that wall is moving out. And of course, that can't be right if it's an infinite universe.

[00:15:28] Adam Grant:
Guilty as charged.

[00:15:29] Saul Perlmutter:
I always have to say, okay, when we say the universe is, expanding, first just picture a universe that we could live in today. So picture something that goes-- that's infinite, as far as you want in every direction. And every now and then there's a galaxy in that infinite universe. And how often you hit these galaxies is just a matter of what the average distance is between these galaxies if you were traveling around. And that is--sets the scale of the universe. So when we say the universe is expanding, all we mean is that we've puffed extra space between all of those points, between all those galaxies, and now you have to travel further to reach galaxies. All the expansion is happening between every object.

[00:16:06] Adam Grant:
I wish somebody had told me that. I might have, I might have landed on a different career path, although I, I really love the one that I chose. I wouldn't wanna undo it, but—

[00:16:14] Saul Perlmutter:
So maybe just as well?

[00:16:16] Adam Grant:
I feel like it worked out okay for all of us.

[00:16:17] Saul Perlmutter:
Okay. Good.

[00:16:22] Adam Grant:
One of the things that I'm very excited to talk about is the question of teaching people to think more like scientists. And obviously, that’s an enterprise that you're passionate about. You have a, a course on sense and sensibility and science that you teach at Berkeley. I've been working on some similar issues in, in writing Think Again and trying to teach people to, to operate more according to the principles of science. And what, I guess the, the place I wanna start is when do you consider something settled science? If I were to ask you, for example, like, what's the probability that Pluto is in fact a planet or that the earth is not round?

[00:16:57] Saul Perlmutter:
Well, the choice about Pluto being a planet or not, of course, um, is one that's much less likely to be settled because that's almost the definitional one, and we can keep playing with the definitions forever. I would say that what's really interesting to me about the way scientists, uh, have approached the world is that they really, really have to become comfortable with the idea that almost everything we know, we know with some degree of probabilistic credibility of different levels. That it goes all the way from things that we just barely are sure about and that we think we see some indication of, all the way to something that you would bet your life on and you would bet everybody's lives on.

We bet our lives every time we get on an airplane, right? We're really pretty sure we know enough about this combination of gravity and aerodynamics and all these different aspects that we can bet our life, that we can get on a multi-ton plane and the whole thing will fly. Um, however, almost every topic we talk about, um, even gravity and electricity, magnetism, there are new things that we can learn, and that's I think, one of the real fun aspects of science. But it's also where a lot of the flexibility of thinking comes from. The ability to learn something new, even about something that you thought you really understood and the ability to change your mind about something.

[00:18:14] Adam Grant:
Well, there have been a couple of papers that have come out recently suggesting that the blanket “Trust science” or “Believe scientists” recommendation does not help people. It seems to engender more resistance in people who are already cynical and also lead to unquestioning acceptance of pseudoscience among people who are gullible, right? That that what we wanna do instead is we actually wanna teach them how science works. And I can't think of a better person to do that than you. So if you encountered a flat Earther, what would you say?

[00:18:44] Saul Perlmutter:
Well, first of all, I say there's some things that people want to believe just ‘cause it makes them more comfortable in the world. And that my job isn’t to take away people's comfort in the world. It's only when you want to figure something out where you really need it to work and whether you need to be able to, to make it work with other people as well.

We, we tend to, um, like to see results that confirm things we already think we believe, and it's really hard to start to train yourself to look for results that might have a chance of proving something's wrong that you believe. And so just the trick of the brain that being able to hunt for ways in which you're getting it wrong is already a huge step forward. And being open to the possibility that something you think you're pretty sure about is wrong, and then looking for evidence for that that you're wrong is already a big trick of the trade. And so I think that that would be obviously highly relevant for somebody in the flat earth camp.

[00:19:35] Adam Grant:
Well, this is the perfect opening for a flat Earther, right? To say, “Here you are looking for all this evidence that confirms your silly round earth theory. But like I, I've gathered all this contrary evidence and like, you're not open to disproving your own theory…”

[00:19:50] Saul Perlmutter:
And that's completely fair game, right? What you find, of course, for any specific area that gets to be complex. Probably the flat Earth one is a little bit too easy in a certain sense, but almost any other topic where there's something that's more sophisticated involved in it, you'll quickly run into…There’s just lots of what looked like disparate evidence and that it's hard to tell, um, what to trust and, and what not to trust. What I've often been doing in a course like ours is trying to show how you look for a, a group of people who appear together to be trying to figure out whether they're wrong, and together are hunting for, you know, evidence that makes a current rounded story that fits with everything else we know. Any single piece of evidence isn't left by itself. It weaves into this raft of sticks that we, we weave together and, and that's what science is. I think a flat earth right now is a pretty bad example of a stick that would have a very hard time fitting in with everything else we know.

[00:20:52] Adam Grant:
Yeah, this, this speaks to something that, that really drives me crazy when the media covers science. When they're conflicting results to say, "Well, some studies say X, but other studies say reverse X.”

[00:21:03] Saul Permutter:
Right.

[00:21:04] Adam Grant:
No, we don't-- we shouldn't just be talking about both sides equally, you weigh the more rigorous evidence more heavily. You take the sticks that don't fit in and you ask, "Well, what's incomplete about the theory?" Not “are all the theories wrong or is science completely untrustworthy altogether?"

[00:21:19] Saul Perlmutter:
Absolutely. And I must say that I, I feel a little bit disappointed that the scientists, uh, of the last 10, 15 years weren't a little bit more, um, comfortable explaining some of this while they were presenting some of these important, uh, points about the world that we live in right now. I think they were, were scared and they were convinced by all those television producers that always come to me when they're making a new documentary and they say, "This is television. Everything has to be as absolutely simple as possible."

And I say, but my experience of talking to people is that they actually enjoy a little bit more detail and a little more texture. And the same thing I think was told to people when they were trying to discuss climate change. They said, “You can't explain to them that there's parts of the story that we don't understand.”

I think in some ways I, the same mistake was made in the way that the, the various recommendations for the pandemic were handled, that they often were presented as if, you know: “here is the answer. Don't ask any questions.” As opposed to: “Here’s our current answer, we're playing a football game against the virus. And, you know, don't be disappointed if we come back to you with a different play any more than you'd be disappointed um, if, if your football coach, um, told you we're actually doing a different play this next down.” That's the way it works.

[00:22:29] Adam Grant:
This is a great example of what in Philly we like to describe as trusting the process. Which as a Philly native, I'm sure you've, you've watched the Sixers over the, the past decade or so, and I, I keep wanting to say, "Look, this is not about trusting scientists. It's about trusting the scientific method, which is the most rigorous system that we have for ruling out false theories and accumulating evidence and trying to find less inaccurate theories. And I trust that process, not the flawed humans behind it."

[00:22:58] Saul Perlmutter:
Exactly. Exactly. Anyway, always point out that any given scientist will be getting things wrong at any given moment. That's not the process. The process is how does that interact with other scientists and how do they together figure out what's going on? And you know, basically, science is an aspirational method that actually works with very flawed individuals doing very, you know, flawed bits and pieces of the story. But ideally, it generates something that allows us to fly airplanes and, and, and, you know, and cure, uh, diseases. And, and, and we obviously can do things with that process that no individual could do, and that you don't want to feel like you're in the position of having to trust the individuals too often.

You know, there's some great individuals, but any one of us, when we teach the course, we point out that everything we're teaching in every one of these ideas in the course are things that we, the professors get wrong, and that we still get them wrong even after we teach them. And that, that the reason we're teaching them is so that we get a group of people around us who can help keep us honest and help us notice when we're getting them wrong, and that that's the process, really. Not teaching any individual to be infallible.

[00:24:07] Adam Grant:
I think that there's an interesting tension here in that I have often heard physicists stereotyped as the most arrogant of all scientists because they believe they can understand the universe, and I never could wrap my mind around that because any physicist, even early in training, knows how vast the unexplained universe is. So, can you make sense of that paradox for me? What is it that causes some physicists to become arrogant, and how do we maintain humility in that world?

[00:24:33] Saul Perlmutter:
I, I mean, for me, I think it's a, it's a great example of one of the balances that is in this game of science. If enough humans are working together well enough with enough humbleness individually, but arrogance collectively, we can solve the problems. And individually, physicists then can, when they talk, sound arrogant, but ideally what you want them to be is really arrogant collectively that, you know, as a race of humans, we can actually do something together. But I think it's an important part of the story to have that can-do spirit.

[00:25:10] Adam Grant:
Well, I hate to think of that can-do spirit as arrogance. I, I would like to think of it as, as some degree of bold ambition and maybe confident humility where we believe we're capable of great things, but we also know how limited our current knowledge and tools are.

[00:25:23] Saul Perlmutter:
I, no, obviously that's what you really want. We really want to feel like at the end, and I, and I'm probably just putting in a bit of an apology for the, uh, for the physicists who come across as, as arrogant. Of course, because some of them actually are. But that's another whole problem you know.

[00:25:35] Adam Grant:
[Laughter] That is a whole ‘nother conversation. One of the things I love most about science is how it can inform your daily life and decisions, not just the formal work of a professional scientist. So—

[00:25:46] Saul Perlmutter:
—and you've written about this, right? Extensively.

[00:25:48] Adam Grant:
I've been working on it, in part because I've been so enamored with how helpful it is for, for leaders and entrepreneurs to realize, you know what? A lot of my strategies are just hypotheses. My decisions are experiments, except I didn't have a control group. I was also really amused to see Jerry Seinfeld talk not too long ago about how he sees comedy as a scientific process where he's got a hypothesis about what's gonna make people laugh, he runs the experiment, and the audience response is evidence. And then he uses the data to revise his joke accordingly. I would love to hear how you apply scientific thinking to your life outside of, you know, the walls of science.

[00:26:23] Saul Perlmutter:
I, I, I, I love the fact that, that children are taught very early, early the one person cuts the cake and the person chooses which, which half they get. Um, It could be as simple as that, as ways of avoiding knowing which of two alternatives are gonna be the ones that you're going for. You can play that same game with yourself when you're, you know, trying to decide which information to, to take in some decision that you're trying to make.

And you could ask yourself, "Well, suppose I was, you know, already wanting the opposite of what I think I want, and I was trying to find evidence for that. What would I be looking for?" You're choosing odds rationally, you're, you're weighing what the options are in a way that you would if you were trying to make a scientific decision.

[00:27:01] Adam Grant:
You are the third Nobel laureate we've had on the show. I brought Daniel Kahneman and Esther Duflo, and I was curious about how winning the prize had affected their careers. So I've gotta ask you the same question.

[00:27:13] Saul Perlmutter:
Well, what's interesting is that in your own field, it really does not have a very major effect, because they already know you pretty well. But what it does change much more is your ability to have conversations outside your immediate world, because there, people who don't know you.

[00:27:28] Adam Grant:
I wanna wrap us where we started, which is, I am desperate to know, is the universe gonna last forever?

[00:27:34] Saul Perlmutter:
Ah.

[00:27:35] Adam Grant:
What do you think?

[00:27:35] Saul Perlmutter:
Okay, so the, the deep admission I have to make is that even though the whole point of the experiment that I started was to find out whether the universe will last forever and whether it's infinite or not. It turns out that once we discovered this new mystery of the acceleration of the universe, and now we're trying to figure out what, what’s causing it, I had to put off knowing the answer because, and depending on what it is that's actually causing the universe to accelerate, um, it could, um, be something that will change with time.

We're calling it dark energy right now as a placeholder, just ‘cause we don't know what it is, and so it doesn't tell us anything. But in the very, very earliest part of the universe, we believe that there wasn't a rapid acceleration and it stopped. The field that we think caused it to accelerate decayed away, and then the universe started to slow down. So for all we know, right now whatever it is that's causing the acceleration, since we haven't figured it out yet, it could decay away, and we could be back in the universe that's slowing down and coming to a halt someday in the future. So, because right now my job is to go out and try to figure out why we're seeing the acceleration, I might have to stay completely open in my mind to the possibility that it's one kind of dark energy or another kind.

And, so I can't take any favorites right now on whether or not it's going to come to an end or whether it's going to expand forever. ‘Cause I have to, you know, allow for both possible or more possible alternatives.

[00:28:54] Adam Grant:
That, I think that is the most encouraging answer I could possibly imagine to this question. Because you're saying, despite all the horror stories that we've heard, it is possible the universe will always exist.

[00:29:04] Saul Perlmutter:
Yes. And I will give you one, one extra piece of encouragement, which is that even in a universe that might come to an end, there's the interesting possibility that we get to have infinite number of thoughts before the universe comes to an end, and that we are able to basically accelerate our thinking process and relative to the skills of the universe, so that there's no end to our chance to explore and think. And so, um, that for me would be the ultimate loophole: that a universe could come to the end, but we still get to think infinite, infinitely, and to experience infinitely.

[00:29:39] Adam Grant:
Wow. Well, my, my only reaction to that is 42.

[00:29:46] Saul Perlmutter:
[Laughter]

[00:29:46] Adam Grant:
Thank you, Saul. This has been such a treat and so enlightening and surprisingly uplifting. I didn't know I would leave so excited about the future of the universe.

[00:29:54] Saul Perlmutter:
Well, glad to. And it's real pleasure. What we really want is not just a universe that can do its thing, but a human society, a you know, a world of people who can, uh, think together and actually solve these problems together. And so my, my optimism is even there. I think that, you know, if we make it through these periods and we get just a little bit further understanding of how to think together I, I, I think we will then be in great shape.

[00:30:17] Adam Grant:
Well, let's make that your next project. Thank you.

I love Saul's notion that we should be humble about our individual abilities, but confident in our collective capability. Take it from a Nobel laureate. You don't have to be the smartest person in the room. You just need to make the room a little smarter. ReThinking is hosted by me, Adam Grant, and produced by TED with Cosmic Standard.

Our team includes Colin Helms, Eliza Smith, Jacob Winik, Michelle Quint, Sammy Case, and Anna Phelan. This episode was produced and mixed by Cosmic Standard. Our fact-checker is Paul Durbin. Original music by Hansdale Hsu and Allison Leyton-Brown.

[00:31:02] Saul Perlmutter:
If you go backwards in times, the fun thing is that now you suck space out between objects, and things get closer and closer and denser to each other. And denser and denser until eventually, everything's almost on top of each other and in like this thick, deep soup of, of, of particles. When we say Big Bang, we really just mean that very dense, hot, thick soup time. And it's just that probably it wouldn't have sold as well if people called it The Big Soup.

[00:31:26] Adam Grant:
[Laughter] Yeah. The bang has more oomph behind it-- sounds like a more legitimate theory.