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What lies beyond the Higgs boson?


The Compact Muon Solenoid, or CMS, is one of the main experiments at the Large Hadron Collider. In his forthcoming book on the LHC, "The Particle at the End of the Universe," Caltech physicist Sean Carroll recounts the story of how an underground river had to be frozen to put the 50-foot-high detector into its cavern.

Now that a "Higgs-like particle" has been detected at Europe's Large Hadron Collider, is the hard part of the $10 billion quest for new physics finished? No. Way. The hard part — and, most physicists would say, the fun part — is just beginning. Caltech theoretical physicist Sean Carroll explains why in a new book, and on tonight's episode of our "Virtually Speaking Science" talk show.

You can tune in the program at 9 p.m. ET (6 p.m. PT / SLT) via the BlogTalkRadio website, or you can join the live audience in the Stella Nova Auditorium in the Second Life virtual world. If you miss the show, never fear: Like all our previous hourlong shows, tonight's program is being archived on BlogTalkRadio as well as on iTunes.

The physics of subatomic particles isn't exactly Carroll's comfort zone. He's more at home with big topics such as cosmic inflation, the accelerating universe, the arrow of time and extra dimensions. But that just means Carroll is able to fit the scientific view of the universe at its smallest scales into the bigger picture, writing in a style that's accessible to folks who wouldn't otherwise know their boson from a fermion in the ground.

Sean Carroll via Google+

Sean M. Carroll is a senior research associate in the physics department at the California Institute of Technology.

Carroll was at Europe's CERN particle physics center when the big reveal was made in July — which means his forthcoming book about the search for the Higgs boson, "The Particle at the End of the Universe," will touch on the human story as well as the history and the science behind the quest. Carroll is also at work on a special for PBS' "Nova" documentary series, due to air early next year.

If you're looking for a preview of the book and the TV show, as well as a preview of what lies ahead on the frontiers of physics, don't miss tonight's show. If you're looking for some extra background on the Higgs quest, check out "The Higgs Boson Made Simple." And to get ready for the program, give a look to this edited transcript of the Q&A I conducted with Carroll on Tuesday:

Cosmic Log: What was it that led you to write about the LHC and the Higgs quest? Is this something that you've been working on at your day job?

Sean Carroll: "No, it's actually not. To be very honest, the book was not my idea. It was the publisher's idea. I'd been following the very exciting search for the Higgs boson. We live-blogged the startup of the LHC, and we certainly followed the tantalizing seminars that were given in December of 2011 when they found a little bit of evidence for it. We were all excited, but the idea of writing a book about it had not occurred to me until my publisher suggested it."

Q: Well, now that you've gotten into the subject, do you find that it does relate to your day job?

A: "In the book, I explain a little bit more of the physics behind the Higgs boson than is usually explained. It's funny, because I tried to concentrate mostly on the experiment, and the stories of human beings building the experiment, and their struggles. But my heart is really in gauge theories and spontaneous symmetry breaking and all the fun physics behind that. So I certainly improved my understanding of all those things while struggling to figure out how to explain them the best. It's not actually what I'm working on, in terms of research right now. But who knows? That's something that absolutely can happen."

Q: Is there something you've found that maybe you didn't previously realize, because you're coming at this from the outside?

A: "I really hope that I've conveyed a sense of the enormous task that the experimentalists and the engineers set themselves by creating this monstrosity that we call the LHC. One story out of many: When they were digging the hole in the ground to put the CMS experiment into, they found that there was an underground river between the surface and the 300-foot level where they were going to put it. The way they got around that was to freeze the river. They pumped down liquid nitrogen, froze the water, dug out the ice, put down the experiment, sealed in the tunnel and then let the water unfreeze again. Now the river flows over the experiment. How do you anticipate something like that? That's the kind of challenge that the builders faced."

Q: And you were there for the payoff. What was the mood like when physicists announced that they had found what looks like the Higgs boson? How has the mood changed since then?

A: "It's a tremendous mixture of emotions, because there have been very few announcements in physics that have been anticipated for quite this long. We knew exactly what it was as soon as we had it.  When we discovered the accelerating universe, for example, people didn't expect it. Therefore, some people are skeptical, and say 'you've got to find more data.' Whereas the Higgs was something that's been expected since 1967, roughly. Getting it is an accomplishment, but you also exhale a little bit, right? You've been holding your breath, because you've been looking for so long, and you think, 'What if it's not there? Will we have to start over again?'

"Now that we have it, we need to think very carefully about where it takes us. We're hoping that the Higgs boson is not just the end of one era, but the beginning of the next one. We hope to find a whole bunch of new particles beyond the Standard Model." 

Watch Higgs Boson Revealed on PBS. See more from NOVA.

Q: Since the subtitle of your book is 'How the Hunt for the Higgs Boson Leads Us to the Edge of a New World,' can you talk about what that new world will look like, and what it might mean?

A: "We know that the Standard Model of particle physics fits all the data we have here on Earth. On the other hand, it's not the final answer. It's inelegant in various ways, and it doesn't fit the data that we have from the sky. There's no dark matter in the Standard Model. We need to move beyond the Standard Model if we want to have a full understanding. The Higgs boson is the final piece of the Standard Model puzzle, but it's also a different kind of particle than all the other ones.


"One of the ways in which it's different is, it's a bit more sociable than the other particles. It tends to want to interact fairly readily with all the other kinds of particles. So, it's very possible that we'll discover what dark matter is indirectly, through the Higgs boson. The Higgs particle can mediate an interaction between ordinary matter and dark matter. By studying the properties of the Higgs boson, we can infer the properties of new particles that we haven't discovered yet. So it's great that we found it, but really, the fun's just begun."

Q: What are some of the other deep questions that could be answered at the LHC?

A: "One of the things about 'selling' experimental physics is that people will say, 'OK, you want $9 billion to build this accelerator — what is it going to buy?' We don't know. If we knew, we wouldn't need to build it. Now, at least the LHC has found one thing, and that one particle has generated a great deal of excitement. Thank God we have that. But certainly we're nowhere near satisfied. We're hoping to find something more.

"The thing we'd like to find more than anything else is supersymmetry. If supersymmetry is there, then in principle, there are double the number of particles that we already know lurking around somewhere. But it's hard. We haven't found it yet. And supersymmetry may not be part of nature, so we have to be open to whatever actually exists out there in the world. We'd like to know what the dark matter is. That's a particle that we know has to be there. It may or may not be detectable at the LHC, but we have a good shot at it.

"More than anything else, we'd like to be surprised. We'd like to find something we haven't even been looking for."

Q: Then there are those standard questions: 'What good is all this? What's in it for non-scientists? Will there be a new energy source, or a new gizmo?' How do you deal with those questions?

A: "I talk about that a lot, in fact. The whole final chapter of the book is devoted to exactly that question. I try to be honest. There might be new gizmos that come out of this, or other technological spin-offs. But that's not why we built the Large Hadron Collider. It's not for the gizmos. It's for the discoveries. It's for figuring out the fundamental laws of nature.

"The case that scientists need to make is that if we want to continue developing this skill that we've been working on for the last 2,500 years, it's worth knowing how the universe works. It's worth spending billions of dollars over the course of several decades on something that might not give us any gizmos, that might not cure malaria.

"We're not going to build a better iPhone. We're just going to figure out how reality works. And we should try to make the case that that's worth the money."

Send questions for Carroll in advance by tweeting with the hashtag #AskVS ... then tune in "Virtually Speaking Science" on BlogTalkRadio or join us in Second Life at 9 p.m. ET (6 p.m. PT/SLT) tonight. The show will be archived on BlogTalkRadio as well as iTunes.

Previous episodes of "Virtually Speaking Science":

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.