Physicist Brian Greene explains the Higgs Particle, also known as the "God Particle," and why you should care. The feat of finding such a particle, he says, is akin to "trying to hear a tiny, delicate whisper over the massive thundering din of a NASCAR race."
MS. BOONE: Okay, you could stand up for like 30 seconds. We're going to start with our next presenter. What? I'm not doing yoga. Ladies and gentlemen, can we get your attention please? It's fine if you want to go in and out, but if you could give us your attention.
The Washington Post calls our next speaker, the single-best explainer of abstruse ideas in the world today, it's my pleasure to introduce you to Brian Greene.
MR. GREENE: So thank you. It's a pleasure to be here with you this afternoon. In the early hours of July 4th, next Wednesday here in Aspen, there's going to be a press conference taking place in Geneva, Switzerland at CERN, the particle-collider in Geneva, where scientists are going to update the world on the search for the long-sought Higgs particle. This follows a previous announcement that you may recall back in December where the scientists gave preliminary evidence that this elusive Higgs particle had been found and around the world right now there are physicists who are eagerly anticipating that on Wednesday that earlier preliminary result will turn into a definitive result.
And we will have found the so-called "God particle." Or in the poetic words of Lynda Resnick, to quote from an e-mail that Lynda sent me last week, "Physicists have finally found God in little tiny particles." Now I should say at the outset that while the media loves this term, this name, the "God particle," since there is no connection to God or religion, we physicists don't really like this name at all. The term itself actually comes from Nobel laureate Leon Lederman, who says that the actual nickname that he coined for this cagey, elusive particle was the "Goddamn particle."
MR. GREENE: But he was writing a popular book on the subject at the time and the publishers convinced him that this wasn't the best title for the book, so he was willing to accept this shortened form. But putting names and nicknames to the side, we may be on the verge of a historic discovery. So what I want to do in the brief time that I have here is tell you a little bit about what's going on. And I'll do it in three parts. In part one, I'll tell you about what the Higgs particle is and how we've been looking for it.
In part two, I'll describe why this particle is so important to us physicists. And finally, in part three, I'll describe why you should care. Now, you'll know I put the "Why you should care?" part at the end because in the off chance that I don't convince you that you should care, the talk will basically be over any way.
Okay. Part one, what is the Higgs particle? Well, this story -- this part of the story begins with a seemingly simple sounding question which is where does the mass of elementary particles, electrons and quarks, where does their mass come from? I mean, we look around the world and all objects have mass which you can think of as the resistance which those objects offer to having their speed increased or decreased. Right?
So for example, imagine I have in my hand a baseball or a shot put, right? And I want to speed it up. And as I try to throw it, it offers resistance. I feel that resistance in my hand, in my arm, in my muscles and that resistance is the mass of that object. Similarly, if I had an elementary particle, an electron or a quark, if I try to push on it, it also would offer some resistance. That would be its mass, but the question is where does this resistance come from, where does the mass of the particles come from? Now, one answer that you could put forward is elementary particles have mass because they do. You can just say this is an intrinsic part of the way the universe is put together.
End of story. Now look, you can take that approach. But physicists don't find that kind of an answer satisfying. We don't like just-so stories. We want to find a mechanism by which particles acquire the mass which experiments reveal them to have. And in the 1960s, a group of physicists, working independently largely from one another, came up with just such a mechanism which over the decades has been most closely associated with the English physicist Peter Higgs. What I'd like to do is tell you about this Higgs mechanism for giving particles those mass.
Here's the idea -- here's Higgs' idea, here's how it goes. Higgs imagines that all of space is uniformly filled, suffused with an invisible substance, an invisible substance, sort of like an invisible molasses that permeates every nook and cranny of space. And the idea is that as a particle, like an electron, tries to move through this molasses, when you try to speed it up, its interaction with the molasses, the resistance that it feels as it tries to burrow through the molasses, that's what we interpret as the mass of the particle.
And in fact the idea is that different particles would have a different degree of stickiness which means they would experience a different amount of resistance as they try to borrow through this pervasive molasses, which would mean that these particles would all have different masses, which is just what the experiments show. So that's the basic idea according to this Higgs' proposal of how the elementary particles would acquire the mass that they do.
Now, to be sure this is a strange, peculiar sounding idea. Among other things it would rewrite the very meaning of nothingness, of empty space because it says that if you were to vacuum a region of space moving all of the matter down to the very last atom, it wouldn't be completely empty, at least not in the conventional sense. There'd still be this pervasive Higgs field, this Higgs' molasses which you can think of, therefore, as a kind of essentially un-removable occupant of space. Now, that may ring a bell for those of you who have studied anything about the history of science, is a long- discredited idea that sounds kind of similar, right, the ether, right? Sounds sort of like the ether. So scientists were not at first willing to jump on board this strange idea. In fact, the first paper that Higgs wrote on the subject, it was rejected by the journal to which he submitted it. But over time Higgs was able to convince the community of physicists, largely based upon theoretical considerations based in the math and I'm going to briefly summarize for you in just a little moment, he was able to convince physicists that this was the best explanation that we had for giving the particles the masses that they have.
So much so that when I began graduate school in the mid-1980s people spoke about this Higgs' idea with such confidence, such nonchalance that for many months I had no idea that it was hypothetical. But it was hypothetical back then and it is still hypothetical today, but that may all change on Wednesday as this idea may migrate to the arena of confirmed scientific fact. Now, how would that happen? How are we looking for this invisible Higgs field, this molasses that is meant to permeate all the space?
Here's the idea. There is this big accelerator in Geneva, the large Hadron Collider, about 18 miles around. And what happens in that collider is that protons are send cycling around the collider in opposite directions, near the speed of light, so fast that they can traverse that 18-mile race track more than 11,000 times each second. And these particles engage in head-on collisions.
Now the math suggest the idea is that if the Higgs' proposal is right, then when the particles collide, the energy of that collision can kind of jostle this Higgs' ocean, jiggle it, kind of flick off a little droplet of the Higgs' ocean. And that little droplet would be what we call the "Higgs particle."
Now, the scientists would not actually see the Higgs' particle itself because the mathematics shows that these particles are highly unstable. They quickly fall apart. They decay into more familiar particles, photons, electrons, and neutrinos. But the idea is that by playing a kind of CSI game, looking at the particles that are produced, scientists can reconstruct the process that gave rise to them and in that way be able to pinpoint that there was a Higgs' particle there. That's the idea that they are pursuing.
Now, framing it that way it sounds maybe kind of straightforward. But this is a monumental challenge to carry out this procedure. These protons are slamming together more than half-a-billion times each second. So to try to find this delicate little signature of this little Higgs' particle falling apart against this chaotic maelstrom of other particle processes that are taking place, well, that's like trying to hear a tiny, delicate whisper over the thundering, deafening din of a NASCAR race, terribly difficult to do.
But over the decades, physicists have developed techniques -- technology. They've built these enormous, mammoth detectors that surround the collision point and can capture all of the particles, the relentless splash of particles that are being sent out every second. Take that data, feed it in to some of the most powerful computers that exist which are running millions of lines of dedicated computer code in an effort to show that this Higgs idea, this Higgs particle is real. And this may result in a definitive discovery that we'll be looking for next Wednesday.
Now, that's what the Higgs' feel -- Higgs' particle idea is all about, how we're looking for it. Why do we physicists really care about this, or framed differently, why have we convinced governments around the world to spend $10 billion to build the Large Hadron Collider to look for this particle? Or framed in another way still, is this Higgs idea really progress or have we simply substituted for the earlier question "Why do particles have mass?" the new question "Why is there a Higgs field and a Higgs particle?"
Well, it is real progress. It takes a little bit of background to understand why. So let me quickly describe it for you. Back in the 1960s, when scientists were examining the output of the then most powerful particle colliders, they found that the blindingly chaotic and complex data that was emerging could only be understood using one key idea.
And that key idea is the idea of symmetry. Symmetry is an idea that we are, of course, all familiar with. It's a kind of pattern that exists between seemingly distinct entities. But when you realize the pattern, you see that they're part of a more complete and unified whole that's easier to describe. I mean, take my face, right? Cut it in half. This side is the mirror image of this side more or less. You put it together, it's a more unified whole.
Take a snowflake, right? A snowflake has 5 distinct points, but you can rotate the snowflake taking one point into another realizing that they are all part of a more unified whole. Take a sphere, a nice silver sphere. It's got many different points on the surface, but by rotating this sphere you can take one point at any other point and in that way you see that they are all part of a more unified whole which makes it easier to describe that object.
Similarly, the scientists found that when they were examining the data from the particle colliders, they found that the data itself fell into interesting patterns, symmetric patterns that guided them to equations, simple, elegant equations that could describe what was going on. But the problem is this, when they studied those equations in detail they found that if particles had mass, the
symmetry between the equations would be spoiled. They no longer wor. They'd fall apart.
There was a great tension between these beautiful equations on the one hand and the need to give particles a mass on the other. What Higgs showed is that you could have your cake and eat it too. And by that I mean if the mass of a particle comes from its interaction with an environmental influence, this Higgs ocean that surrounds us, then you can show that the equations can preserve their elegant symmetry and the particles can get their mass from this environmental effect. And with that, the standard model of particle physics was found.
The standard model particle physics is a simple, little equation. It can fit on a T-shirt, a simple equation that's able to describe all of the data coming from particle accelerators around the world. And by fitting on a T-shirt, I literally mean it can fit on a T- shirt. Alec (phonetic) and Sophia (phonetic), come up here one second. So here, on this T-shirt is the standard model of particle physics, okay? The first term here describes the nuclear and electromagnetic forces. These are the particles of matter. And this guy over here, this
Sophia, what is that symbol meant to describe?
SOPHIA: A Higgs field. MR. GREENE: A Higgs field. Yes, thank you very
MR. GREENE: And this term over here, what does that mean?
ALEC: A Higgs potential.
MR. GREENE: A Higgs potential. Thank you very much. You guys, head off over there.
MR. GREENE: And with that simple equation, we've been able to describe data with fantastic accuracy. And every feature of that equation has so far been experimentally confirmed except for the Higgs part of it, and that's what we're waiting to have happen on Wednesday. Now, that's one key reason why we are excited by
this. But in the last few minutes, let me describe one more key feature as well. That Higgs particle is not just another particle in a long list of existing particles. It has fundamentally different characteristics. You see, we have learned that every particle in the world, electrons, quarks, muons, neutrinos, all of the particles in the world spin around sort of like a top. Not exactly, but quantum-mechanically, it's not a bad way of thinking about it.
And they all spin at a particular rate dictated by the identity of the particle. So electrons and neutrinos and quarks, they all spin at a rate that we call spin-a-half. Photons and other force-carrying particles, they spin at a rate twice as big, that we call one. The Higgs would be the first particle of matter that has spin- zero, the first fundamental spin-less particle, a new kind of matter. And the reason why that's exciting for us, over
the past 30 years we have used the flexibility of those kinds of particles, the particles that don't spin, to put forward theories for a whole range of ideas, cosmological ideas for instance being primary among them because one of the issues in the Big Bang theory of cosmology is that the Big Bang says that way back in the beginning the universe went -- underwent this rapid expansion, right? We all have heard about this idea.
But the Big Bang mathematics leaves out something pretty important which is the Bang itself. It doesn't tell us what would have driven the outward expansion of space in the first place. Remarkably that kind of object, that kind of Higgs-like object, that kind of spin-less object, if you have enough of it in a little tiny region of space, you can show that it would yield the kind of repulsive gravitational push that would indeed drive everything apart, would indeed put a bang in the Big Bang.
That's a speculative idea. I wouldn't want to have it married to the announcement on Wednesday because Wednesday, if in fact this particle is found, that's bona- fide science. But over the course of 30 years, we've made use of that kind of a field so profoundly that if indeed it is confirmed that it exists, we will have at least some circumstantial evidence that many of the ideas that we have developed over decades that they are heading in the right direction. So let me finish by turning to my third part, why you should care. You don't necessarily have to care.
MR. GREENE: Right, I mean, maybe everything that I've said so far just so fires you up that you already care. That would be nice, but there's some people who just don't really care about these abstract, theoretical ideas, right? I have friends of that sort. You know, I've -- you know, frankly, my mother is like that.
MR. GREENE: Right? I mean she still wishes that I was a doctor. I tell her, well, I am a doctor. She says not that kind of doctor. You know it's this whole thing that just keeps on going. So she needs, and many others too, something more tangible. And I think a good way of thinking about a more tangible impact of this kind of detailed discovery and trying to understand the nature of the universe comes to us from an analogous historical discovery back in the 1920s and 1930s when the subject of quantum mechanics was discovered and experimentally confirmed.
Now, back then it could have felt that quantum mechanics was equally abstract and theoretical compared to the things that I'm talking about here today. But over the course of 80 years, a theory that began life by helping to understand molecules and atoms and subatomic particles -- that's what quantum mechanics is about -- has been parlayed, has been harnessed by science and technology to yield all manner of spectacular technological wonders, right?
Anything that has an integrated circuit relies upon quantum physics. It was quantum physics that allowed us to be able to manipulate electronics through tiny, little wires giving rise to personal computers, cell phones, medical technology that saves lives around the world all the time which is just to say a fundamental discovery can have a profound impact on the way that we live our lives. You just have to wait for theoretical discoveries to turn into practical applications. And the history of science shows that that is the pattern that typically happens.
Well, let me finish by giving you one final thought, maybe a more personal thought, on why these ideas about the Higgs are so important, so exciting. Back when I was in high school and I was taking my first physics class, the teacher set us a problem of a piece of chewing gum attached to a baseball and the ball was swinging and our challenge was to figure the motion of this ball as the chewing gum stretched and it swung back and forth like a pendulum.
I sat at my desk. It's not actually a hard problem to do. Anybody who takes a good course in physics I can do it. I solved the problem and I ran down the hall to my dad to show him, not because he cared about baseballs and chewing gum, but because of this idea that mathematics, a calculation that you do at your desk could describe something in the real world was such an amazing idea that mathematics can transcend so much of the world around us.I mean, today you've already heard interesting, important conversations about politics, about economics, conversations that affect millions, billions of people around the world, but I tell you all of it is transitory. It doesn't mean it's not important. But it's transitory. A 100 years from now, there'll be another set of problems, economic ones, environmental ones, political ones, and of course, we need to deal with them.
That's how we build the fabric of everyday life. But how exciting is it to sit at your desk and do a calculation that goes beyond everything that's transitory, calculations that might reveal fundamental features not about what happens here on earth, but about the entire universe, the entire universe. It's hard for me to imagine anything more thrilling than that. Thank you very much.