by Sean Carroll
Wilson answered with equal directness: “No, sir, I don’t believe so.”
We can imagine that Pastore was a bit taken aback by this answer; presumably he expected to hear a song and dance about how Fermilab played a crucial role in keeping up with the Soviets, the kind of argument that was trotted out for all kinds of purposes in that era. He asked if there was really nothing at all, to which Wilson simply replied, “Nothing at all.” But you don’t get to be senator without being at least a little stubborn, so Pastore tried a third time, just to ensure he had heard correctly: “It has no value in that respect?”
Wilson was no dummy; he realized he was expected to provide a little bit more if he wanted Congress to fund his ambitious but esoteric endeavor, but he refused to back off from his original point. His answer is one of the most-remembered quotes in the long history of scientists trying to explain why they do what they do:
It has only to do with the respect with which we regard one another, the dignity of man, our love of culture. It has to do with: Are we good painters, good sculptors, great poets? I mean all the things we really venerate in our country and are patriotic about. It has nothing to do directly with defending our country except to make it worth defending.
Big Science is not cheap. The Large Hadron Collider has cost about $9 billion, almost all of which came ultimately from taxes collected in countries around the world. The people who paid that money have a right to know what they are getting for their investment. It’s the duty of the scientific community to be as honest and convincing as possible about the rewards of basic research.
Some of those rewards come in the form of technological breakthroughs. But ultimately, those are not the most important rewards; what matters most is the knowledge that is brought back to us by these extremely ambitious experiments.
Not everyone agrees. Steven Weinberg, who has been a tireless advocate for investment in basic science, recalls a telling anecdote.
During the debate over the SSC, I was on the Larry King radio show with a congressman who opposed it. He said that he wasn’t against spending on science, but that we had to set priorities. I explained that the SSC was going to help us learn the laws of nature, and I asked if that didn’t deserve a high priority. I remember every word of his answer. It was “No.”
It’s not an uncommon attitude. But it’s an impoverished perspective, one that misses the bigger picture. Basic science might not lead to immediate improvements in national defense or a cure for cancer, but it enriches our lives by teaching us something about the universe of which we are a part. That should be a very high priority indeed.
When do I get my jet pack?
None of which is to say that we wouldn’t like to have useful technological applications of the work being done in modern particle physics. Scientists are quick to point out that basic research—scientific investigation carried out purely for its own sake, rather than in pursuit of immediate applications—has very often ended up having enormously practical implications, even if they were unanticipated at the time. From electricity to quantum mechanics, the pages of history are strewn with ideas that once were abstract and impractical, only to later become central to technological progress. As a result, whenever new scientific discoveries are made, people want to know: When do I get my jet pack?
Can we imagine that something similar will be the fate of research at the LHC? As Yogi Berra once said, making predictions is hard, especially about the future. However, we can admit that what we find at the LHC might have a very different character from the fundamental physics of previous centuries. It’s possible that any particles we discover at the LHC will literally never be put to good use in practical devices.
That’s not just pessimism; it flows from the particular kinds of things we might hope to discover. When Benjamin Franklin was studying electricity or Heinrich Hertz was producing radio waves, they weren’t creating things that didn’t already exist in the world. Electricity and radio waves are all around us, even if we discount all the artificial sources of them. Scientists in that era were learning to manipulate mysterious features of the readily accessible world, and it’s not surprising that the knowledge they discovered later became technologically useful. At the LHC, by contrast, we are literally creating particles that don’t exist in our everyday environments. There are good reasons for that. The particles are typically very massive, so it requires an enormous amount of energy to make them. And they are either very weakly interacting, so it’s hard to capture or manipulate them (like neutrinos), or they are extremely short-lived, so they decay before they can be put to much good use.
Take the Higgs boson as an example. It’s not easy to make a Higgs boson—the only way we know is to have a particle accelerator several miles long. We can certainly imagine technological improvements that would give you a pocket-size device able to reach such high energies; nobody has any idea how to do it, but it doesn’t violate the laws of physics. But even if you had a handy iHiggs boson producer, what would it be good for? Every Higgs you make decays in less than a zeptosecond. It’s hard to imagine any application of those bosons that wouldn’t be carried out more efficiently by some other kind of particle.
This argument isn’t airtight, of course. Muons are unstable particles, and they have found potential technological applications, from catalyzing nuclear fusion to searching for hidden chambers in pyramids. But the muon has a lifetime of about one millionth of a second, much longer than a Higgs boson. Neutrinos are stable but weakly interacting, and some farsighted folks have imagined using them for communication purposes. If we were feeling especially expansive, we might imagine discovering dark-matter particles that could find similar uses. It’s not a place I would recommend investing a lot of money, however.
Warp drive and levitation
Because the Higgs boson is responsible for giving particles mass, people sometimes wonder whether mastering its properties will allow us to make things lighter or heavier. Or worse. The day after the July 4 announcement of the Higgs discovery, Canada’s National Journal printed a bold headline: HIGGS BOSON FIND COULD MAKE LIGHT-SPEED TRAVEL POSSIBLE, SCIENTISTS SAY. None of the scientists quoted in the article said anything of the sort, but I suppose it’s possible that some scientists somewhere did say that at some point in time.
Using the Higgs to make things lighter or even massless is pretty much a nonstarter, for a few reasons. Most obvious, the large majority of the mass in ordinary objects doesn’t come from the Higgs; it comes from the strong-interaction energy inside protons and neutrons. But more important, it’s not really the Higgs boson that gives mass to the quarks and charged leptons, it’s the Higgs field lurking in empty space. If you wanted, for example, to change the mass of an electron, it’s not a matter of shooting Higgs bosons at it; you would have to change the value of the background Higgs field.
That’s easier said than done. For one thing, while we can imagine changing the Higgs field, we have no idea how to actually do it. For another, it would require an absurd amount of energy. Let’s imagine that we figured out a way to displace the Higgs field from its regular value (246 GeV) all the way to zero, inside some small but macroscopic volume of space. The usual value the Higgs field has is the state of minimum energy it can be in; pushing it back to zero means that our small volume is now packed with energy. From E = mc2, that means it has mass. A quick calculation reveals that a region the size of a golf ball, inside of which the Higgs field is displaced to zero, would have approximately the same mass as the entire earth. If we were to make it much bigger than that, there would be so much mass inside a small space that the whole volume would collapse to make a black hole.
Finally, even if you somehow managed to turn off the Higgs field in, say, your body, it’s not just that you would suddenly become lighter. Certain elementary particles would become lighter—the electrons and quarks—and the broken symmetry of the weak interaction would be restored. As a result, the atoms and molecules in your body would fall into completely different configu
rations, mostly just disintegrating altogether and releasing a huge amount of energy. Decreasing the Higgs field wouldn’t put you on a diet; it would make your body explode.
So, don’t be looking forward to Higgs-powered levitation devices anytime soon. On the other hand, it remains entirely possible that new discoveries at the LHC will lay the groundwork for future applications in ways we can’t currently anticipate. Even if that’s not why we pursue them.
Spinoffs
Research in particle physics often does lead to very tangible benefits. Those benefits usually take the form of spinoffs—new technologies that were developed to help meet the challenges posed by the experimental effort itself, rather than direct applications of finding new particles.
The most obvious example is the World Wide Web. Tim Berners-Lee, working at CERN, pioneered the Web when he was trying to develop ways to make it easier for particle physicists to share information. Now it’s hard to imagine our world without it. Nobody ever suggested funding CERN because some day they would invent the WWW; it’s just a matter of putting smart people into an intense environment with daunting technological challenges, and reaping the benefits from what comes out.
There are many other similar examples. The need for uniquely powerful magnets in particle accelerators has led to noticeable advances in superconducting technology. The ability to manipulate particles has had applications in medicine, food sterilization and testing, and other areas of science such as chemistry and biology. The durable and high-precision detectors that appear in particle experiments have found uses in medicine, radiation testing, and security. The incredible demands on computing power and information transfer between particle physicists have led to advances in computer technology. The list is very long, but the lesson is very clear: Money spent on searching for esoteric particles doesn’t just slide down the drain.
It’s hard to quantify exactly how efficient it is to invest in fundamental research. Studies by economist Edwin Mansfield suggested that, for society as a whole, it is a wise investment indeed. Mansfield argues that public spending on basic science yields an average return of 28 percent, which almost anyone would be thrilled to get out of their investment portfolio. A number like that is suggestive at best, because the details depend greatly on what industries are studied and what counts as “basic science.” But it reinforces the anecdotal impression that, at the cutting edge of science, even the most nonapplied research yields impressive dividends.
The most important spinoff of basic research isn’t technological at all—it’s the inspiration that science provides for people of all ages. Who knows when a certain child is going to hear a news story about the Higgs boson, become intrigued by science, start studying, and end up as a world-class doctor or engineer? When society puts some small fraction of its wealth into asking and answering big questions, it reminds us all of the curiosity we have about our universe. And that leads to all sorts of good places.
The future of particle physics
Weinberg’s ornery congressman aside, most people are willing to admit that learning the laws of nature is a worthwhile project. It’s reasonable to ask, however, precisely how much we think it’s worth. The fate of the Superconducting Super Collider weighs heavily on anyone who contemplates the future of particle physics. We live in an era in which money is tight, and expensive projects need to justify themselves. The LHC is an amazing accomplishment and will hopefully hum along for many years to come, but at some point we will have learned everything it has to teach us. What then?
The problem is that, while the overwhelming majority of worthwhile scientific projects are much less expensive than high-energy particle accelerators, there are certain questions that can’t be addressed without such a machine. The LHC cost roughly $9 billion, and it has given us the Higgs boson and, hopefully, will give us much more in the future. If we were limited to spending only $4.5 billion on that project, we wouldn’t have discovered half a Higgs boson or taken twice as long; we simply would have found nothing. Making new particles requires high energies and substantial luminosities, which require a large amount of precision equipment and expertise, which cost money. Hanging over all the jubilation for the wonderful performance of the LHC is the very real possibility that it may be the last high-energy accelerator built in our lifetimes.
There is no shortage of plans for possible next steps forward, if the money can be found. The LHC itself could be upgraded to higher energies, although that seems like a stopgap solution. More attention has been focused on the possibility of a new linear collider (in a straight line, rather than a ring), which would collide electrons and positrons. One proposal has been dubbed the International Linear Collider (ILC), which would be more than twenty miles long and reach energies of either 500 GeV or 1 TeV.
That sounds like less energy than the LHC, which might seem like a step backward, but electron-positron colliders work in a different mode from that of hadron colliders. Rather than throwing as much energy as possible into collisions and seeing what comes out, electron-positron machines are ideal for precision work, which can be achieved by aiming at precisely the energy required to produce a specific new particle. Now that we believe the Higgs is at 125 GeV, it provides a tempting target for physics at a linear collider.
Cost estimates for the ILC range anywhere from $7 billion to $25 billion, and possible sites have been explored in Europe, the United States, and Japan. The project would clearly require major international collaboration and necessitate as much political acumen as experimental physics know-how. An alternative proposal, the Compact Linear Collider (CLIC), has been developed at CERN. It would actually be shorter but reach higher energies through the use of innovative (and therefore riskier) technologies. In 2012, studies for the two competing projects were brought together under a single umbrella. The new leader of the combined effort will be Lyn Evans, who didn’t get to enjoy much of a retirement after stepping down from heading the LHC team. It will be Evans’s job to decide on the most promising technology for moving forward, as well as to juggle the competing interests of different countries who would love to host a new collider (but don’t want to pay for it).
One of the persistent themes you hear when talking to anyone who has been involved with the LHC is the inspirational success of its international collaboration. Scientists and technicians of many different nationalities and ages and backgrounds have come together to build something larger than themselves. If our larger society can summon the willpower to put substantial resources into new facilities, the future of particle physics is bright. But for that to happen, scientists have to convey the interest and importance of what they do. We can’t sell particle physics on the basis that it might someday cure Alzheimer’s or lead to portable teleportation devices. We have to tell the truth: We want to discover how nature works. How much that’s worth is for the human race as a whole to decide.
Wonder
Interviewing my fellow physicists for this book, I was struck by how many were fascinated by the arts before they eventually turned to science. Fabiola Gianotti, Joe Incandela, and Sau Lan Wu all studied art or music when they were young; David Kaplan was a film major.
It’s not a coincidence. Even though our quest to understand how nature works often leads to practical applications, that’s rarely what gets people interested in the first place. Passion for science derives from an aesthetic sensibility, not a practical one. We discover something new about the world, and that lets us better appreciate its beauty. On the surface, the weak interactions are a mess: The force-carrying bosons have different masses and charges, and different interaction strengths for different particles. Then we dig deeper, and an elegant mechanism emerges: a broken symmetry, hidden from our view by a field pervading space. It’s like being able to read poetry in the original language, instead of being stuck with mediocre translations.
I was recently helping out with a TV show that was trying to explain the Higgs boson. When you do TV, words never suffice; you need com
pelling images. If you’re trying to explain subatomic phenomena, the only way to get compelling images is to reach for an analogy. So here’s what I came up with: Imagine little robots scooting about on the floor of a vacuum chamber. Each robot is equipped with a sail, but the sails come in all different sizes, from fairly large to quite small. We first film the robots when the chamber has been evacuated; they all move at the same speed, since the sails are completely irrelevant when there’s no air for them to feel. But then we let the atmosphere into the chamber and film them moving again. Now the robots with tiny sails still move quickly, while those with large sails are much more sluggish. Hopefully the analogy is clear. The robots are particles, and the sails are their couplings to the Higgs field, which is represented by the air. In a vacuum, where there is no air, the robots are all symmetric and move at the same speed. Filling the chamber with air breaks the symmetry, just like the Higgs field does. You could even draw an analogy between sound waves in the air and the Higgs particle.
Since I’m a theoretically minded person myself, nobody wants to put me in charge of robots, so I consulted with some of my colleagues at Caltech in engineering and aeronautics. When I explained what we wanted to do, the response was universal: “I have no idea what the Higgs boson is, or whether that’s a good analogy, but it sounds awesome.”
At heart, science is the quest for awesome—the literal awe that you feel when you understand something profound for the first time. It’s a feeling we are all born with, although it often gets lost as we grow up and more mundane concerns take over our lives. When a big event happens, like the discovery of the Higgs boson at the LHC, that childlike curiosity in all of us comes to the fore once again. It took thousands of people to build the LHC and its experiments and to analyze the data that led to that discovery, but the accomplishment belongs to everyone who is interested in the universe.