12:03 pm
Fri November 16, 2012

Searching For 'The Particle At The End Of The Universe'

Originally published on Fri November 16, 2012 2:02 pm



Why does stuff have mass, you know, that gives it weight? If you're a regular listener, you might recall that it has to do with how subatomic particles interact with something called the Higgs Field, right? Higgs boson, becoming more familiar? How do scientists know that? Well, it's theory. It's backed up by, in part, by the reported discovery of the Higgs Boson at the Large Hadron Collider at CERN, back in July.

But what does any of that mean, and what will the Large Hadron Collider be able to tell us about the world we live in, especially now after researchers say they've likely found the Higgs that has been predicted? What comes next? Joining me now is Sean Carroll. He's senior research associate in physics in the department - the Division of Physics, Mathematics and Astronomy at Caltech in Pasadena. He's author of the new book "The Particle at the End of the Universe," just out from Dutton. He joins us from the Caltech campus.

Welcome back to the program, Sean.

SEAN CARROLL: Thanks for having me, Ira.

FLATOW: Wow. You know, we heard about the Higgs Boson. Anything new you can add that we haven't already learned? There was so much coverage of this.

CARROLL: Well, the Higgs Boson is the force of 1,000 different stories that are gradually being told. I think that the most important single thing, I would say, is that it's a door. It's - we've been in one room, or one dwelling our whole lives as physicists, and the Higgs is the door to whatever comes next. And it might be exciting. It might be kind of barren and difficult to find things. But it's the beginning of a new era in theoretical and experimental physics.

FLATOW: There was some news just recently that said - that sort of confirmed that the kind of boson you found was the vanilla kind. Would that be accurate in calling it that?

CARROLL: Yeah, that's right. I mean, there was basically three kinds of possibilities we could have contemplated a couple years ago. One was the true nightmare scenario in which the Large Hadron Collider finds nothing, no new particles at all, and that would have been a disaster for particle physics.

Next best is you find the Higgs Boson and nothing else, because the Higgs is really what you expected to find. And then the best possibility is you find the Higgs, and then a panoply of other wonderful particles come after it. So we've ruled out number one. That's good news. We're still deciding between number two and number three.

FLATOW: So you - this whole thing about possibly finding supersymmetry, dark matter, dark energy, not yet?

CARROLL: Well, we could have found supersymmetry by now, and we haven't. That doesn't mean that we won't find it by looking harder. It means that, you know, we didn't find it under the lamppost in the easiest place it could have been. But the LHC, the Large Hadron Collider, is going to be turned off the beginning of 2013, and they're going to tune it up, fire it up at a higher energy in 2015. So we'll have another look at a place we've never looked before.

FLATOW: And they were all - scientists were already talking about building a bigger one, bigger collider.

CARROLL: Well, it takes 20 years to build it. You better start talking about it now if you want to get it within the lifetime of the people doing physics right now, yeah.

FLATOW: The word is that the Japanese are talking most about it.

CARROLL: At the moment, the Japanese are very interested. It would be a part of their recovery efforts after the tsunami hit a couple years ago. And it would certainly be an absolutely crucial international collaboration. So no one country's going to do it. So everyone's in favor of it until you decide where to put it, and then everyone else's enthusiasm dims a little bit.

FLATOW: And what would you want to find with it that you can't find with the one we have, with the Large Hadron Collider?

CARROLL: Well, there's two major things. One is that you know that the Higgs Boson is there, but you don't know why it has the particular mass that it does. In fact, your back-of-the-envelope calculations say that the mass should be something like a quadrillion times bigger. So that's a little bit of a mystery. And we have...

FLATOW: Wait, wait, that's a little bit of a mystery?

CARROLL: A little bit of a mystery, yeah. This is - you know, particle physics jargon, this is a little bit of a mystery. And we have theories that help explain this mystery, and all of them predict new particles at energies comparable to that where we found the Higgs Boson. So, one way or the other, one major target is going to be able to understand why the Higgs is where it is.

FLATOW: 1-800-989-8255, talking with Sean M. Carroll, author of "The Particle at the End of the Universe." He's senior research associate in physics at Caltech. If you'd like to talk about physics, particle physics, the Higgs boson - we'll go through the gamut because physics, you know, goes everywhere. Our number: 1-800-989-8255. You can also tweet us @scifri, @S-C-I-F-R-I.

Let's see if we go - oh, yes, calls are coming in. Let's go to Arne(ph) in Sacramento. Hi, Arne.

ARNE: Hi. Yes. I'm interested to know why did people start calling this particle the God particle. because then isn't that - doesn't that mean that once you find it, then it's the end-all, be-all and then you don't need anything else?

CARROLL: You know, after Ira's wonderful introduction, I thought this was going to be the one interview I did where we got through without talking about the God particle.

ARNE: Oh, I'm sorry.

CARROLL: That's OK. You know, you're...


FLATOW: You have Leon Lederman to thank for that, don't you?

CARROLL: I do, to thank for that, yes. Leon Lederman, a famous, fantastically talented Nobel Prize-winning physicist and a coiner of terminology, came up with the phrase the God particle to describe the Higgs boson. And that's - that was good because that's box office, that phrase.

You know, you can't stop using it. It's bad because, as Lederman himself later said, there are two sets of people who got upset with us - those who believe in God and those who don't believe in God - because the Higgs boson has nothing to do with God. It's important. That's what he was trying to get across. It's really like an extra special particle, but no religious implications follow from knowing the origin of electroweak symmetry breaking, I'm afraid.

FLATOW: Well, Leon always had a sense of the dramatic, right?

CARROLL: He did. And he was writing a book at the time when we in the United States were fighting for our version of the LHC, the Superconducting Super Collider, which we decided not to go forward with. And so he was - you know, it is not easy to get across how important the Higgs boson is. So he summed it up in a two-sentence phrase that was substantively way off the mark, but did a good job of impressing people with how central this is to how we think about the universe.

FLATOW: Well, better to have people at least talk about it than not to know how to talk about it, or at least raise the question, don't you think?

CARROLL: That's the philosophy, sure.



FLATOW: I see you're not happy with that. 1-800-989-8255 is our number. Let's go to Tulsa. Hi, Steve.

STEVE: Hello. How are you?

FLATOW: Hi there.

STEVE: Hey, thanks for taking my call. My question really comes down to kind of the colliders dealing with sound vibration, the vibration or frequencies against those particles.

FLATOW: Has there any - does it have any - yeah. Does the Large Hadron Collider have anything to do with research about sound and vibrations?

CARROLL: Sound it has nothing to do with, but vibrations are absolutely central. In fact, the hidden theme of my new book is that on the physics side of things, the theme is that we really need to take seriously quantum field theory, the idea that particles are not really the fundamental ideas of nature. It really is waves, and that's the only way you're going to understand why the Higgs boson is so important, because it's a field that fills space.

And when we say we've discovered this little particle, what we really mean is we've seen that field vibrating. So vibrations are at the center of all these ways of thinking about particle physics.

FLATOW: Mm-hmm. You know, I think people have a difficulty dealing with how a particle can create a field and how something you don't see can make a - give you mass and things like that; it's not something you see every day.

CARROLL: Well, they should. You know, it's something where we push our ability to make experiments and observations into a regime where our everyday life is completely unfamiliar with it. So it's no surprise that things seem very, very counterintuitive. The giving of mass is not that difficult to understand. It's like waving your hand in the air versus waving your hand through molasses, right? If there's some...

FLATOW: Right.

CARROLL: ...thick substance that you need to move through, then it's harder to get going, and that's what the Higgs boson does. It fills space and makes it harder for particles to move fast. They'd all be moving at the speed of light if the Higgs weren't there.

FLATOW: So it's sort of the ether for mass.

CARROLL: It is, except for two important things. Number one, the ether, this century-old idea, was all about electromagnetism.

FLATOW: Right.

CARROLL: It's all about photons, and the Higgs has nothing to do with photons.

FLATOW: Right.

CARROLL: And the other thing is that the ether has a rest frame. You can measure your velocity with respect to it. For the Higgs, you can't do that. It's the same no matter how fast you're moving, no matter where you are.

FLATOW: Talking about the Higgs with Sean Carroll on SCIENCE FRIDAY from NPR. I'm Ira Flatow.

What made you decide to write "The Particle at the End of the Universe"?

CARROLL: Well, perversely, I was interested in the fact that it's really hard to explain to people...


CARROLL: ...why this is so important. And so I said the physics hidden theme is field theory, but the personal hidden theme is why would so many smart, dedicated people devote their lives to looking for something that may or may not be there and has no possible application to anyone's everyday life? This is not going to cure cancer or make you a better smartphone. This is just about understanding how the universe works. So I wanted to convey some of that passion and excitement.

FLATOW: Let's see. We have lots of questions now. Time to answer some of them. Let's go to Sean(ph) in Pittsburgh, P-A. Hi, Sean.

SEAN: Hey. How are you?

FLATOW: Hi there.

SEAN: Good. Hey, quick question: If the Higgs is the force carrier for, you know, gravity, how do you explain that its life was so short-lived in the - you know, when they collided the beams and created this thing, you know, it disintegrated, you know, immediately. And, you know (unintelligible) force...


SEAN: That was my question.

FLATOW: That's a good question.

CARROLL: It is a good question. By definition, that means I know the answer to that one...


CARROLL: that the Higgs is not the force-carrying particle for gravity. The force-carrying particle for gravity is something called the graviton, which...

FLATOW: Have we discovered that yet?

CARROLL: We've not discovered individual gravitons. I discover the net effect of gravitons every time I get up in the morning and stumble to the floor. But individual gravitons just interact very, very weakly, so they're hard to detect. What the Higgs does is turn massless particles into massive ones.

And it's also true, if Isaac Newton had been in charge of gravity, that mass is what gives rise to gravity, right? But now that Einstein is in charge of gravity since 1915, we know that all forms of energy contribute to gravity whether or not there's mass involved. Photons certainly contribute to gravity in an important way. So mass and gravity are a little bit different and the Higgs is what gives mass to particles like electrons and quarks.

FLATOW: But didn't Einstein describe gravity in a geometric figure as something that you fall down into?

CARROLL: That's exactly right. So you can describe gravity either as the geometry of spacetime, or in a particle physics language as the exchange of these graviton particles. These turned out to be equivalent descriptions. So that's just part of the miracle of quantum mechanics.

FLATOW: And the great mystery is how to unite those two.

CARROLL: That is a little bit of a mystery, yeah. But you know, we don't want to overemphasize the mystery. We have a pretty good back-of-the-envelope theory of how gravity and quantum mechanics work together. It's just that when you push that theory too far, you 're get nonsensical answers. So as long as you only ask easy questions, we understand quantum gravity perfectly well.

FLATOW: You have defined physics for everyone.

CARROLL: Oh, yeah.


FLATOW: Don't ask the tough questions.

CARROLL: It's just that the barrier between the easy and the tough questions is different for different people, but they're always there.

FLATOW: All right. We're going to take a break and come back and talk lots more Sean Carroll, who's one of the great popularizers of science because he can speak English very nicely and explain things to us, and he does that very well. If you want a nice, easy explanation for the Higgs boson and all these kinds of concepts we're talking about, it's "The Particle at the End of the Universe," by Sean Carroll, who is senior research associate in physics at Caltech. Our number: 1-800-989-8255.

You can tweet us @SCIFRI, or go to our Facebook page, SCIFRI website,, and ask big questions there also. We'll be right back after this break. Stay with us.


FLATOW: You're listening to SCIENCE FRIDAY. I'm Ira Flatow. We're talking about "The Particle at the End of the Universe." That's a new book by Sean Carroll. And the particle he's talking about is the Higgs boson. But we're talking about all kinds of particles all through the universe. This has sort of become, Sean, I think, an ask-a-particle-physicist hour.


CARROLL: Here I am.

FLATOW: All kinds of questions and interesting ones that are coming up. So let's go right to them. Let's go to Sam in Berkeley. Hi, Sam.

SAM: Hi there.

FLATOW: Hi there.

SAM: I have a question about manipulation of spacetime. I'm not a physicist. I'm a biologist and a biochemist. But I read a lot of hard science fiction, a lot speculative science fiction, and I have this idea that as the understanding of particle physics deepens - I don't know about with the discovery of the Higgs boson but perhaps with discovery of underlying and associated particles, it might be possible to manipulate spacetime in such a way as to achieve instantaneous transportation from one location to another. And I'd like to ask you to speculate on that, please.

FLATOW: Faster than light.

CARROLL: Well, if I were a venture capitalist rather than a theoretical physicist, I would be very skeptical about this proposal. You never know, of course, and you should keep an open mind. But I want to emphasize again that the Higgs in particular is not something that relates to spacetime in any special way - that is, in any different way than other particles and fields do. Our best theory of spacetime was given by Einstein, who says that energy, mass, momentum, heat, pressure, all of those things warp spacetime in very specific ways. And that theory, general relativity, seems to be just as good now as it ever was.

People like me, you know, theoretical physicists, we invent alternatives and they get shot down one by one and Einstein is still standing. And if Einstein is right, I don't see any way to enable instantaneous transportation a la "Star Trek."

FLATOW: But there was something that Einstein called spooky action at a distance.

CARROLL: There was.

FLATOW: It's quantum entanglement, right?

CARROLL: Yes, there is. There very much is.

FLATOW: And that travels much - that's instantaneous. How come that works but what you're saying doesn't?

CARROLL: Well, something is instantaneous, but it's hard to put your finger on exactly what. The one thing we know is that you can't use quantum entanglement to send information faster than the speed of light. You can have things happen. And our description of what happens says that something happens over here and now you instantly know what will happen five light years away or whatever. But they - the people over there, five light years away, don't know that you've done your experiment.

So you haven't actually communicated anything to them. So it's not actually moving stuff, it's just changing our description of reality all at once all over the universe.

FLATOW: Do we know why that's true?

CARROLL: Well, we have theories. We have models in which that is a prediction, and those theories seem to be true. They fit all of the data. The theories are called quantum mechanics. It's not something that, you know, we did experiments and we were surprised to learn this weird effect. It's that we have this theory, quantum mechanics, that made these weird predictions. So people did very, very careful experiments to test it, and it's like, holy smokes, it seems to be right.

FLATOW: Mm-hmm. I'm still hearing Richard Feynman in my mind here talking.


CARROLL: Well, yes, it is true that quantum mechanics is the one thing we don't understand. Nobody understands quantum mechanics. And I actually, you know, this is a great subject for another SCIENCE FRIDAY show, I think, but I think I'm creeping up on understanding quantum mechanics better and better as I get - as I advance into my old age. I think that the surprising thing is not action at a distance. The surprising thing is locality. The surprising thing is that what I do here doesn't affect things a long way away. And that's our challenge to understand.


CARROLL: I'll leave you with that.

FLATOW: Yeah. That's good. Let's go to Ricardo in San Francisco. Hi, Ricardo.

RICARDO: Hello, gentlemen. And thank you for having this extraordinary program on our final boson. I have feeling that this will change fundamental physics by just being able to tell us on the program today if Higgs boson is the final element that brings dark energy and black matter into a good perspective for a new particle physics. And is it the final stage of understanding what black matter and dark energy is that holds our turkey together for Thanksgiving occurrence?

CARROLL: That's - it's a great point because we live in a turducken universe. There's all sorts of different ingredients that are involved in the list of what goes into the cosmos we observe. There's dark energy. There's dark matter. There's ordinary matter. The Higgs boson is the final piece of the ordinary matter puzzle. So as I like to say, you know, we've been thinking about the fundamental nature of reality for 2,500 years, and the easy part is now over. And it's time to move on to the hard part, the dark sector. And it's very, very plausible to imagine the Higgs boson studies will be helpful.

The Higgs boson is a lot more sociable than the other particles in the standard model. The other particles: the quarks, the electrons, the photons and so forth, they will - they're very cliquish. They will talk to particles within the standard model, but it's hard to get them to interact with particles outside. But the Higgs boson will talk to anybody. So it's very conceivable, at least - we can't say for short because the experiment hasn't been done yet. But someday, we will detect dark matter by a dark matter particle coming in, spitting off a Higgs boson, and that Higgs boson interacting with a piece of ordinary matter. That's something that we're trying to do right now, and it could be front page news any day.

FLATOW: Really?

CARROLL: Absolutely.

FLATOW: You just have to go through the data?

CARROLL: Well, we're collecting more data. We're building, you know, we build small experiments, and then we grow them. And right now, we're at the one-ton level. We're able to get like a ton of material that is searching for dark matter. And it's a matter of, yeah, integrating it overtime and building better more and sensitive detectors. But we're at the stage where our predictions are close to the experimental sensitivity. So that's a very plausible outcome.

FLATOW: I have to say, you have set a new record today. I think 22 years of SCIENCE FRIDAY, no one has ever used the word turducken on the radio program.


CARROLL: I just like to be topical here on SCIENCE FRIDAY.


FLATOW: Well, it is. It's a good time of the year to do that. What about the - let me go back to the other flavors of the boson that you say probably are not the one that we've discovered. Are they still possibly there, we just haven't seen them yet?

CARROLL: Well, absolutely. You know, one of - I think, as we mentioned, one of the promising ideas, frameworks for moving beyond the standard models will be called supersymmetry, and we haven't found it. Well, we haven't ruled it out so...

FLATOW: What is it?

CARROLL: It's a symmetry and especially super one. It's one that relates bosons and fermions. Bosons are the force-carrying particles, like gravitons, photons, gluons. Fermions are the matter particles. They take up space, the quarks, the electrons, the things that make up your atoms and so forth.

And in the standard models as we understand it, there's no relationship between them. Both kinds of particle exist, but they're just separate. Supersymmetry would say that for every boson, there's a matching fermion. And for ever every fermion, there's a matching boson. And it turns out that if you go through the math and you can make it worked, you can supersymmeterize(ph) the standard model of particle physics. And one prediction is you get not one Higgs boson but five Higgs bosons. So it might be that we haven't discovered the Higgs boson. We've discovered one-fifth of the Higgs boson that there are to be discovered, and the journey is just beginning.

FLATOW: And those mathematicians will keep going in giving you(ph) new things to do.

CARROLL: There is never any shortage. That's right.

FLATOW: Let's go to Brian in Lodi, California. Hi, Brian.

BRIAN: Hey, Ira. Thanks for taking my call.

FLATOW: Mm-hmm.

BRIAN: I was wondering if Dr. Carroll could speak a little bit towards the economic impact of colliders on the host country for the equipment and positive or negative or otherwise.

CARROLL: Well, it's a great question. The current way that we have of doing major experiments in particle physics is necessarily large, expensive and international. The LHC cost $9 billion, and that's spread over 15 years and over many, many countries contributing. It's a drop in the bucket compared to a typical national budget, but it's still a lot of money. We should just justify that.

And I think there's two justifications. One is that we want to know how the universe works. That's the real justification. That's a justification for the physicists who built the thing. It's not that there's going to be a Higgs boson ray gun or anything like. It's we want to know how it works. But it turns out that despite the fact that this is not why we do it, it is never less true that every time you put money into basic research, you get more out than you put it.

In the case of the Large Hadron Collider, we have better technologies for information processing and transfer data transmission, super conducting magnets better than any that have designed before, a million spin-offs that you didn't planned for. And, of course, the biggest spin-off of all is something called the World Wide Web, which was designed and built at CERN by particle physicists who wanted a better way of sharing data with each other.

FLATOW: 1-800-989-8255. We have a few tweets in from people who want to know: Does the Higgs boson have anything to do with string theory?

CARROLL: Well, it has something to do with string theory in the sense that string theory is supposed to be a theory of everything, and the Higgs boson is a part of everything. There is no closer connection than that in the sense that if string theory is right, then it's certainly plausible to get a Higgs boson, like we observed. But it's also very plausible to get when a string theory is wrong. So we know no more or less about string theory now than we did before we discovered the Higgs.

FLATOW: Are we going to have to give up on string theory any time soon?

CARROLL: I don't think so. It still is, far and away, the leading candidate for reconciling quantum mechanics and gravity. We might have to give up on our natural impatience that every time we have an idea, we want it confirmed or ruled out within the next 24 hours.

FLATOW: Well, this has been 30 years, has it not?

CARROLL: And it might be 1,000 more. I don't know.

FLATOW: Oh, OK. I just want to know what's the frame of reference.

CARROLL: It might be another 10, or it might be next year. But until someone comes up with a better way of reconciling these two things we know exist, quantum mechanics and gravity, string theory is still going to be something that people are going to be thinking about.

FLATOW: All right. Let's go to Austin in Berkeley. Hey, Austin.

AUSTIN: Hello.

FLATOW: Hi there.

AUSTIN: Love the show. I have kind of been reading about particle physics, and I like to look at the pictures of the particles traveling to the detector. And there's always some that are spiral in these - well, sometimes there is one that are spiral in that - in those pictures. And I thought maybe you could tell me what would make a particle do that. I know that they put magnetic fields around the particle so they can see much they deflect. And I can see why they would go to one side or another. But I don't understand why a - what would make a particle spiral.

FLATOW: Yeah, yeah.

CARROLL: Well, this is good. I'm glad you liked looking at those pictures because that's what I was doing. I won't say how many years ago. But when I was 10 years old, sitting in the local public library, I loved books with these pictures of all the particles spiraling around in the bubble chambers and the cloud chambers. Typically, if you look at a picture from the Large Hadron Collider, you won't see the spirals because the particles are moving so fast, they don't get bent that much by the magnetic field.

But what happens is that, yes, if you put a charged particle in a magnetic field, it tends to go in a circle. But notice that it's leaving a track, right? So it's not just moving in the magnetic field. It's interacting with the matter that it's moving through. That's the only way you notice it, right? It's making bubbles or whatever it is that's just moving around. And that means it's losing energy. It's creating those bubbles. It's making the photons that make you see it. And so if it's losing energy as it goes in the circle, that circle is going to get smaller and smaller, and it's going to spiral in until it just stops moving in entirely.

FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR, talking with Sean Carroll, author of "The Particle at the End of the Universe." Did you build your own climate chamber when you were (unintelligible)?

CARROLL: I'm a theoretical physicist, Ira. You know that, right?


CARROLL: You don't want me building anything at all.

FLATOW: When I was a kid, the Scientific American used to have a little, you know, amateur scientist columns.


FLATOW: And I remember in the '60s when I was a teenager, there was one, how to build your own cloud chamber.


FLATOW: And I didn't build that one, but I built the other stuff that I could. I think that came in a few years after how to build your own laser but...

CARROLL: You know, I went in to the book project with an enormous amount of admiration for the experimental particle physicists who do build these things. And I came out with exponentially more admiration than I went in with. It's such an amazing accomplishment, how they built the LHC. I mean, one story I just like to tell is that they're digging a hole down to put an experiment underground and they hit ancient Roman ruins because they're building in France. And they had to stop for six months while the archeologists come in.

And they finally get moving again, and they hit a river, an underground river in their way. And the physicist went in with liquid nitrogen and froze the river so they could dig it out to keep building their hole and then let it all melt again. The river is still flowing. This is not stuff they teach you at grad school. But that's what it takes to be a good experimental physicist.

FLATOW: Yeah, you have to improvise, right?

CARROLL: Absolutely. The world is not set up for you to find out these things very easily. You need to work at it.

FLATOW: Would you ever think about changing careers or...




FLATOW: Not the handy...

CARROLL: (Unintelligible)

FLATOW: Not the handy guy.

CARROLL: I actually - one summer, when I was a young faculty member, I volunteered to be - to serve as an undergraduate researcher in the laboratory of another friend of mine who's an experimentalist. And he would not let me do it. He said, we're friends, and we wouldn't be friends after that. So that was my aborted career (unintelligible) experiment.

FLATOW: Would you be like one of those guys on the "Big Bang Theory" then?

CARROLL: There is something called the Pauli effect named after Wolfgang Pauli, the Nobel Prize-winning theoretical physicist. And the Pauli effect, it's not some, you know, deep principal quantum mechanics. It's that when Pauli would walk into a room, all the experiments would stop working. That would be me.

FLATOW: So we shouldn't call you Sheldon?

CARROLL: No. He's a...

FLATOW: He's a theoretic. But he lives with - yeah, he lives with some other guys who actually make the stuff.

CARROLL: He does. And, you know, there's that great line that, you know, it's a comedy show, right, OK? It's not the real world. So he walks into the lab and he sees all experimentalists and he says, hello there, Oompa-Loompas of science.

FLATOW: All right. Well, that's a good place to end, Sean. Oompa-Loompa.

CARROLL: None of my friends are going to be talking to me after this show. They're misquoting Sheldon here.

FLATOW: There you go. Sean Carroll, senior research associate in physics in the division of physics math and astronomy at Caltech, very nerdy place in Pasadena, author of the new book "The Particle at the End of the Universe." Happy Thanksgiving to you.

CARROLL: Thank you very much. Thanks, Ira.

FLATOW: ...and that turducken influence on our show today. Transcript provided by NPR, Copyright National Public Radio.