Neutrino Hunters: The Thrilling Chase for a Ghostly Particle to Unlock the Secrets of the Universe - Hardcover

Jayawardhana, Ray

Hardcover

ISBN 10: 0374220638 ISBN 13: 9780374220631

Publisher: Scientific American / Farrar, Straus and Giroux, 2013

Synopsis

Winner of the Canadian Science Writers Association 2014 Science in Society Book Award
A Publishers Weekly Top 10 Science Book of the Season
A Book to Watch Out For, The New Yorker's Page-Turner Blog
A Los Angeles Times Gift Guide Selection
One of the Best Physics Books of 2013, Cocktail Party Physics Blog, Scientific American

Detective thriller meets astrophysics in this adventure into neutrinos and the scientists who pursue them

The incredibly small bits of matter we call neutrinos may hold the secret to why antimatter is so rare, how mighty stars explode as supernovae, what the universe was like just seconds after the big bang, and even the inner workings of our own planet.

For more than eighty years, adventurous minds from around the world have been chasing these ghostly particles, trillions of which pass through our bodies every second. Extremely elusive and difficult to pin down, neutrinos are not unlike the brilliant and eccentric scientists who doggedly pursue them.

In Neutrino Hunters, the renowned astrophysicist and award-winning writer Ray Jayawardhana takes us on a thrilling journey into the shadowy world of neutrinos and the colorful lives of those who seek them. Demystifying particle science along the way, Jayawardhana tells a detective story with cosmic implications―interweaving tales of the sharp-witted theorist Wolfgang Pauli; the troubled genius Ettore Majorana; the harbinger of the atomic age Enrico Fermi; the notorious Cold War defector Bruno Pontecorvo; and the dynamic dream team of Marie and Pierre Curie. Then there are the scientists of today who have caught the neutrino bug, and whose experimental investigations stretch from a working nickel mine in Ontario to a long tunnel through a mountain in central Italy, from a nuclear waste site in New Mexico to a bay on the South China Sea, and from Olympic-size pools deep underground to a gigantic cube of Antarctic ice―called, naturally, IceCube.

As Jayawardhana recounts a captivating saga of scientific discovery and celebrates a glorious human quest, he reveals why the next decade of neutrino hunting will redefine how we think about physics, cosmology, and our lives on Earth.

About this title

About the Author:

Ray Jayawardhana is a Professor and Canada Research Chair in Observational Astrophysics at the University of Toronto, where he also serves as Senior Advisor to the President on Science Engagement. His writing has appeared in The New York Times, The Economist, Scientific American, Astronomy, Muse, and more. He is the author of Strange New Worlds, a finalist for the Lane Anderson Award, one of Library Journal's best science books of 2011 and the basis of the CBC television documentary "The Planet Hunters". He lives in Toronto.

Excerpt. © Reprinted by permission. All rights reserved.:

ONE
THE HUNT HEATS UP
 
 
There he stood, wearing a red parka, Norwegian Prime Minister Jens Stoltenberg, on blindingly white snow against a clear blue sky, 9,000 feet above sea level, with the temperature hovering at minus 20 degrees Fahrenheit. “We are here today to celebrate one of the most outstanding achievements of mankind,” he bellowed out, as the sounds of flags flapping in the wind and snow crushing under a walker’s boots threatened to muffle his voice. His brief remarks over, with a couple of hundred workers, guests, and tourists watching, Stoltenberg unveiled a bust carved in ice, placed atop a waist-high column: “That’s the man!”
The ice sculpture bore the likeness of Stoltenberg’s legendary countryman Roald Amundsen. The low-key ceremony at the bottom of the world marked the centenary of Amundsen and four mates arriving at the South Pole on December 14, 1911, delivering historic glory to the young nation of Norway, which had become independent from Sweden a mere six years earlier. Fueled by relentless determination and aided by dogsleds, Amundsen’s team famously beat the ill-fated expedition led by the British naval officer Robert Falcon Scott by nearly five weeks, scoring what was undoubtedly a remarkable feat of terrestrial exploration.
Today the frozen wasteland where the fierce competition between Amundsen and Scott played out, with the pride of nations and the lives of heroes at stake, is a hotbed of activity for a different breed of explorers with more ethereal goals. Intrepid bands of scientists racing to unravel mysteries of life, our planet, and the universe are the ones laying claim to Antarctica now. In fact, the continent crawls with well over a thousand scientists and support personnel during the summer months. Geologists dig up ice cores and track the movements of glaciers for clues about climate change. Atmospheric scientists fly helium-filled balloons to measure stratospheric ozone, to complement the observations of satellites staring down from space. Paleontologists forage for fossils of creatures that were wiped out by the deadliest of known extinctions 250 million years ago. Biologists scour the dry valleys of Antarctica in search of organisms that thrive in extreme habitats. In early 2012, after many years of drilling, Russian researchers pierced through two miles of ice to reach Lake Vostok, a pristine subglacial reservoir shielded from sunlight and the wind for some 20 million years; they had hopes of encountering hitherto unknown life-forms.
Two years earlier, I got to experience what it was like to live and work on the ice when I went to Antarctica as a member of a meteorite-collecting expedition. We reached McMurdo Station, the American research center on the coast located near Scott’s 1902 landing site, by military transport plane from New Zealand. After a week of preparations, packing, and training, we then flew to a seasonal base camp, where, two by two, we boarded a Twin Otter plane on skis for the final leg of our journey. The small aircraft, operated by Canadian bush pilots, dropped us off on a remote ice field just five degrees from the Pole. That’s where eight of us—two women and six men—camped out in yellow, pyramid-shaped “Scott tents” for the next five bone-chilling weeks, cut off from the rest of the world except for a satellite telephone and the occasional drop-off of mail and supplies. This being the Antarctic summer, the Sun was always up, tracing a counterclockwise circle in the sky every twenty-four hours. There was no sign of life—human, animal, or plant—to be seen anywhere.
Day after day, if the winds were bearable, we went out on snowmobiles or on foot to search the nearby vast ice field and the moraines next to the hills for rocks that had fallen from space. Wrapped in big red parkas as well as thermal layers, bunny boots, neck warmers, gloves, goggles, balaclavas, and hats, we took care to avoid frostbite and crevasses during our excursions. It was easy to slip and fall on the rock-hard ice and hurt yourself badly. I slid off the Ski-Doo once, but thankfully the thick parka cushioned my fall. Others on the team also had minor mishaps, but we survived the cold, the tedium, and the isolation without any serious problems. In fact, we enjoyed the stark beauty of the landscape—the views from the tops of rocky peaks were especially magnificent—and found ways to entertain ourselves. By the expedition’s end, our team had collected a total of 900 meteorites, which are now available to researchers from around the world for a variety of studies. Our own reward was the remarkable experience itself—and the delightful Adélie and emperor penguins we encountered near McMurdo at the end of the season. My one regret is that I didn’t get to visit the South Pole, despite being so close to it.
The focus of activity at the Pole itself is decidedly extraterrestrial. These scientists seem to have taken to heart Marcel Proust’s adage that “the only true voyage of discovery … would not be to travel to new lands, but to possess other eyes.” The most striking part of their apparatus near the Pole is a 10-meter (33-foot) radio dish turned skyward, to map the feeble afterglow of the big bang. One of my Toronto colleagues, Keith Vanderlinde, spent most of the year 2008 taking care of this telescope; he survived the polar “night” that lasted for six months, temperatures that dipped to minus 100 degrees Fahrenheit, and the overwhelming sense of isolation, not to mention the short showers and the severe boredom. But the most ambitious, and unconventional, of the scientific instruments near the South Pole is buried permanently deep under the ice, and it looks down, not up. Its construction—or burial, to be more accurate—was completed just a year before the Amundsen centennial celebration. All that the visiting dignitaries could see aboveground was a rectangular office trailer on stilts, filled with cables and computers. There was little sign of what lay beneath but for the small flags that scientists had planted helpfully on the ice to mark its mammoth footprint.
IceCube is an observatory like no other. The glacial ice itself, transparent and cleared of air bubbles by extreme pressure at depths greater than a mile, serves the same purpose as the smooth primary mirror of a conventional astronomical telescope. Buried in it are 86 long steel cables standing vertically, with 60 basketball-size globes hanging on each at regular intervals. Every one of the 5,160 globes contains optical sensors and electronics. The sensors, called phototubes, act like lightbulbs in reverse: they collect light and generate electric signals. In the case of IceCube, these sensors scrutinize the subterranean ice for faint blue flashes that occasionally shimmer in the dark stillness. Whenever a sensor detects a flash, it sends a signal to computers on the surface.
The blue flickers mark the passage of elementary particles known as muons, which belong to the same family as electrons but are about two hundred times more massive. By combining signals from the different nodes of this deeply buried sensor network, physicists can trace a muon’s path in 3-D. But the researchers are not after the muons themselves. They are hunting for neutrinos, by far the most elusive and the weirdest of all known denizens of the subatomic world. These ghostly particles interact every once in a while with protons within ice molecules to release muons, thus betraying their presence as the muons in turn light up the ice. Since a newly created muon travels through ice along the same path as the incoming neutrino did, researchers can tell which direction the neutrino came from by examining the muon’s trail.
Neutrinos are elementary particles, just like electrons that buzz about atomic nuclei or quarks that combine to make protons and neutrons. They are fundamental building blocks of matter, but they don’t remain trapped inside atoms. Also unlike their subatomic cousins, neutrinos carry no electric charge, have a tiny mass, and hardly ever interact with other particles. A typical neutrino can travel through a light-year’s worth of lead without interacting with any atoms. Therein lies the snag: neutrinos are pathologically shy. Their severe reluctance to mingle makes these particles hard to pin down, so neutrino hunting is a tricky business. But every so often, a neutrino does collide with something, such as a proton inside a water molecule, essentially by accident. It is to raise the odds of accidental collisions, and thus to increase our chances of observing neutrinos, that scientists build extremely large detectors like IceCube.
You still can’t see neutrinos directly, but you can get a whiff of their presence from the clues they leave behind. On the rare occasions that neutrinos do interact with matter, they produce charged particles such as muons that physicists can detect with their instruments. But distinguishing neutrino signals from unrelated “noise” poses a challenge: cosmic rays, fast-moving particles that arrive from deep space, also produce muons, which might be confused with muons produced by neutrino interactions. Neutrino hunters place their equipment deep underground, or under a thick layer of ice, so that cosmic ray muons cannot get through. As Janet Conrad of the Massachusetts Institute of Technology explains, “If you’re trying to listen to a whisper, you don’t want a lot of noise around.”
Neutrinos are hard to catch, but they are also among the “most wanted” of all cosmic messengers for the secrets they hold about the nature of matter, the pyrotechnics of exploding stars, and the structure of the universe itself. Besides, in the words of theorist Boris Kayser of the Fermi National Accelerator Laboratory (Fermilab) near Chicago, which is home to several neutrino experiments, “If neutrinos didn’t exist, we wouldn’t be here.” He explains that “the Sun produces energy through nuclear reactions on which life on Earth depends, and those reactions could not occur without neutrinos.” Moreover, the nuclear burning in previous generations of stars, which produced the heavy elements necessary for life, would not have been possible without neutrinos, either. Therefore, he argues that “to make sense of the universe we need to understand neutrinos well.”
Thankfully, neutrinos are as ubiquitous as they are cagey. In fact, neutrinos are the most abundant matter particles in the universe. According to Hitoshi Murayama of the University of Tokyo and the University of California, Berkeley, there are a billion neutrinos for every atom in the universe. He contends that “their sheer number means they have an important role. The contribution of neutrinos to the cosmic energy budget is comparable to that of all the stars.” In fact, about a hundred trillion neutrinos produced in the nuclear furnace at the Sun’s core pass through your body every second of the day and night, yet they do no harm and leave no trace. During your entire lifetime, perhaps one single neutrino would interact with an atom in your body. Neutrinos travel right through the Earth unhindered, like bullets cutting through fog. Besides, the Earth’s bowels generate neutrinos, as radioactive elements decay, and so do collisions of energetic particles from space in the upper levels of the atmosphere. Cataclysmic deaths of massive stars set off tremendous bursts of neutrinos, which escape these sites of mayhem unscathed and bring us news of awesome celestial events millions of light-years away. Moreover, our planet is immersed in a sea of cosmic neutrinos, which sprang forth when the infant universe was barely two seconds old.
The bizarre traits of neutrinos have turned them into pop culture icons of sorts. As far back as 1960, John Updike celebrated them in a delightful poem published in The New Yorker. Titled “Cosmic Gall,” it described how neutrinos traverse the Earth as easily as dust bunnies travel down a drafty hall or light passes through a sheet of glass. Klaatu, a Canadian progressive rock band perhaps best remembered for false rumors that they were the Beatles recording under a pseudonym, described the same phantom behavior, of neutrinos passing right through our bodies without alerting us, in the lyrics of a 1976 song. Neutrinos have even starred as hipster characters in the animated television series Teenage Mutant Ninja Turtles.
Not surprisingly, references to neutrinos have also popped up on the popular sitcom The Big Bang Theory, in which two of the main characters are physicists. The show’s science consultant, David Saltzberg of the University of California, Los Angeles, is himself a physicist who works on neutrino telescopes, among other topics. In one scene, the co-lead Sheldon Cooper is fiddling with equations on a whiteboard in his office when his fellow physicist and roommate Leonard Hofstadter enters along with their engineer friend Howard Wolowitz. Sheldon exclaims, “Oh, there’s my missing neutrino. You were hiding from me as an unbalanced charge, weren’t you, you little subatomic Dickens?” Instead of acknowledging his friend’s greeting, he continues, “Here, look, look, I found my missing neutrino.” Howard responds drily, “Oh, good, we can take it off the milk cartons.”
Neutrinos have made numerous appearances in science fiction, of course, typically as the culprits behind strange or catastrophic events. In Robert J. Sawyer’s novel Flashforward, a burst of neutrinos from a dying star is responsible for making everyone lose consciousness briefly and see themselves as they would be some twenty-one years in the future. In Greg Bear’s Foundation and Chaos, a freak neutrino storm wipes out the rules that robots are programmed to follow (à la Isaac Asimov’s original Foundation series), resulting in complete mayhem. More recently, neutrinos were blamed for heating the Earth’s core, triggering ferocious earthquakes and floods, in the Hollywood disaster flick 2012 directed by Roland Emmerich.
Despite neutrinos’ quirky appeal as cultural icons, few people outside the physics community paid much attention to the science of real-life neutrinos until they made headlines recently for possibly breaking the cosmic speed limit set by Albert Einstein back in 1905. A large international collaboration of physicists known as OPERA (acronym for the unwieldy title Oscillation Project with Emulsion-tRacking Apparatus) made the startling announcement in a research paper posted online and at a press conference in late September of 2011. The particles appeared to travel faster than light between CERN, the European Organization for Nuclear Research and its Laboratory for Particle Physics in Geneva, Switzerland, and an underground detector 454 miles away in Gran Sasso, Italy, arriving 60 nanoseconds sooner than expected.
Despite the OPERA spokesman’s cautionary words, and skepticism from the vast majority of neutrino researchers, the news reverberated around the globe. Perhaps the commotion was not surprising given the astounding implications. If true, the finding would violate Einstein’s theory of special relativity, a cornerstone of modern physics. As Time magazine put it, “If the Europeans are right, Einstein was not just wrong but almost clueless.” Most physicists and journalists emphasized that the extraordinary claim required further investigation and independent verification. “If true, it is a result that would change the world. But that ‘if’ is enormous,” said The New York Times.
But all that hedging failed to rein in rampant speculations about superluminal voyages and grandiose visions of new physics. Suddenly jokes about neutrino time travel were everywhere. Some quipped that neutrinos had obeyed the law in Switzerland but broken the speed ...

About this edition

• Publisher: Scientific American / Farrar, Straus and Giroux
• Publication date: 2013
• ISBN 10: 0374220638
• ISBN 13: 9780374220631
• Binding: Hardcover
• Edition number: 1
• Number of pages: 256