Transcript for Lisa Randall on Dark Matter & Dark Energy

Jim Fleming: Lisa Randall is a superstar in the world of theoretical physics. A cosmologist at Harvard, she's been pegged as one of TIME Magazine's 100 Most Influential People. Her latest book, "Knocking on Heaven's Door," examines some of the biggest mysteries in physics, including dark matter and dark energy. Steve Paulson wanted to know, Jjust what are the questions that Randall's most eager to answer?

Lisa Randall: One question has to do with how fundamental particles acquire their math. What is the nature of space-time, are there even extra dimensions beyond the three that we're familiar with? Those are some big questions that we might have some experimental answers to. Another question that we might possibly get some experimental answers to is: what is the dark matter in the universe? We know about ordinary matter, the stuff we're made of, the stuff our universe is made of, but six times the energy of that stuff is in stuff called dark matter. Which is matter, it clumps, it's just like matter in that sense, but it doesn't interact with light the way ordinary matter does.

Steve Paulson: And this is just remarkable, that, I mean, apparently, according to the mathematical calculations, only 4% of what we see, what we would consider to be the observable universe, is not either dark matter or dark energy. I mean, basically, everything that's out there, practically everything that's out there, is dark matter, dark energy, and we can't see it.

Randall: That's right. And sometimes I don't find that remarkable. Why should all matter in the universe be stuff what we human beings can see? I mean, because we interact with light, why should all matter in the universe have the same interaction with light? In fact, if anything is remarkable to me, it's that all these are so comparable. I mean, why isn't dark matter 500 million times bigger than energy and matter? I mean, what is this dark matter? And what is this more mysterious entity known as dark energy, that isn't even matter, it doesn't even clump, it just spreads throughout the universe. It's just energy. It's not carried by particles, it's just there, interacting gravitationally.

Paulson: When we talk about dark matter, is this stuff made up of atoms, like all the other stuff that we actually can see, or is it made up of something else?

Randall: Well, that's the whole point. It's almost certainly made up of something else. Because if it was made up of atoms, when we say it doesn't interact with light, we mean it really doesn't interact with light. And it very likely isn't a new type of particle, that interacts gravitationally, but could experience different forces, not necessarily the ones our matter experiences, our atoms experience. But it might interact with our matter. But it probably does so weakly. And so it's's just a very different type of stuff, but why shouldn't it be there?

Paulson: Do you think we will understand these things, dark matter, dark energy, with the existing theories that we have, or do we need a new paradigm to account for these phenomena?

Randall: I think there's a lot of rather compelling ideas for what dark matter could be. I mean, it's something I'm still working on. We still have new ideas, especially those ideas that relate dark matter to ordinary matter in ways that people haven't thought about before. So, there could be new ideas, but it's not that unlikely it will fall within, sort of at least the conceptual frameworks we're used to, the framework of particle physics. One of the really actually remarkable things, is that a candidate for dark matter, a possibility for what it could be, is a particle that has the mass to be produced--and we haven't talked about this yet, but the Large Hadron Collider, this machine in Geneva, that's going to illuminate these questions about mass, might also shed light on dark matter, because dark matter could have just the mass that it could be produced there. Dark energy is a very different kind of entity. If we are to understand it at a fundamental level, it will be in terms of a new framework, very likely. It could involve, again, very exotic things, which people have thought about, but would necessarily involve the idea of multiple universes, being able to sample those. So, there are some pretty exotic concepts that would be involved, even in that scenario, and certainly if we're going to explain it at a fundamental level.

Paulson: Hmm. So you're saying that maybe the only way we can explain in the future, dark energy, is...well, is through accepting the idea of the multiverse, of these different universes.

Randall: Well, it's an interesting question of whether we consider that an explanation. But it might well be that that's the most satisfying scenario that we come up with.

Paulson: Are these the kinds of questions that motivate you as a physicist? I mean, is this why you got into this line of work, to try to figure this stuff out?

Randall: Um, you know, I think a lot of people do get into it because they're interested in these big fundamental questions. I mean, I more came at it from a math background, and um, I like puzzle solving. I think I came at it because I liked, um, the kinds of things we do. I have to say at the back of my mind I like the idea of doing something fundamental, having some sort of lasting value, not something that would disappear tomorrow. So there was that in the sense of the big questions. But it also was just something I liked to do.

Paulson: And did you know this early on, that you wanted to be a physicist, I mean going back, I don't know, to your--

Randall: No, I don't think it--

Paulson: No?

Randall: It didn't even occur to me that one could be a physicist when I was growing up. I didn't grow up in that kind of environment. You know, by the time I started going to high school, it, you know, I started thinking about physics as a major.

Paulson: So then there was some moment in high school that turned you on--

Randall: Well, I took physics for one thing. (laughs) Also, um, there weren't people I knew who were scientists. It just wasn't something that really registered.

Paulson: Hmm. Now I get the impression that you are very interested in the art world as well, and the connection between art and science. Um, do you see many parallels between what a scientist does and what an artist does?

Randall: Well, they're both creative endeavors, where you're trying to comprehend or understand things that you've had trouble understanding. I think they both involve beauty at some level, but neither one sees beauty as necessarily an end in and of itself. Both involve, when done well, involve a lot of skill, but involve sort of asking the right questions beyond that skill. So I think there are many common elements. I mean, there's a big difference, which is that you can have something that's great and fantastic that just turns out to be wrong in science. I don't think there's that same notion of being wrong in arts. And I'd even say--and this is one of the themes that we explored in this little opera that we did--sort of a dissatisfaction, sort of like, there's things that you're just not explaining, you're not understanding, and you're sort of trying to scratch at that and see how you can get beyond it.

Paulson: What is the opera that you did?

Randall: We called it, uh, "Hypermusic Prologue: A Projective Opera in Seven Planes." It's something that I did with a composer name Hèctor Parra and it premiered at the Pompidou Center, which was just a really wonderful experience.

[Excerpt from the opera: "How to open up your world? Describe, reveal, share your truth!" (singing)]

Randall: Basically, Hector, the composer, wanted to write something about physics, but I also wanted it to be--and I think we both did--about creativity and discovery, and what it is that drives you to it and what it means and how will you understand it if you go and explore this other world of if you don't. So we ended up using sort of the physics I worked on, having to do with an extra-dimensional space, or warped extra-dimensional space, that I use to explain the weakness of gravity and even possibly an infinite extra-dimension. But we used this as a metaphor, and we have one of the singers goes out and explores to tries to find answers, and finds out the universe really is fundamentally different than what you see when you're just at home. That there are these hidden things that you can explore. And part of it is, you know, what it means in terms of science and the nature of experiment. How does a person who stays home understand this world that they will never experience themselves directly? What could be the evidence?

[Excerpt from the opera: unintelligible]

Paulson: You've thought a fair amount about creativity.  I mean, that's the subject of the last chapter in your book. Do very creative people, whether they're in science or in art, share the same basic impulses? Is there sort of a core creative process that happens in such people?

Randall: I'm not sure that's a simple question to answer, but I think one thing's an awareness of what's come before, but in a willingness to go away from that. Not entirely away, you know, so you're using what's come before, but able to twist it in an interesting way. You know, when we came up with the idea of an infinite extra-dimension, there were people who've worked on general relativity for years that never came up with it and couldn't believe we did it. But we were coming at it from a particle physics angle. We were actually, first of all, asking questions about acquiring mass and what space could do. In the process of doing that, we realized the consequences of those equations. What also helped us was we weren't aware that there was a theorem that said that was impossible. You know, it turned out that the theory was smarter than all of us and found a way twist around that theorem. So, I think it's sort of an open-mindedness, a broadness of thinking, but also having the skills but also the knowledge of what's come before. And sometimes it's, you know, ideas coming from different directions, being able to synthesize many different ideas, and that challenge is something that I think creative people can take on.

Fleming: Harvard physicist Lisa Randall talking with Steve Paulson. Her book is called "Knocking on Heaven's Door."


Comments for this interview