Sheldon Cooper, top nerd on "The Big Bang," jokes about neutrinos. So did John Updike in the witty short poem "Cosmic Gall," printed in 1960 in the New Yorker. But Canadian astrophysicist Ray Jayawardhana suggests we take them seriously indeed in "Neutrino Hunters: The Thrilling Chase for a Ghostly Particle to Unlock the Secrets of the Universe."
Neutrinos are elementary particles with no charge and a mass so infinitesimal that a "typical neutrino can travel though a light-year's worth of lead without interacting with any atoms," Jayawardhana writes. They are harmless to humans, zipping through us at a rate of many trillion per second, day and night.
The author's spry and readable primer moves briskly through 80 years of particle physics. Aside from the venerable E=Mc2, there is nary an equation to furrow the poor reader's brow. "For an active scientist, it is not always easy to find the time to write for a broad audience," Jayawardhana confides in his Acknowledgments, "but it can be rewarding and fun."
That unintentionally funny line could be lifted from "The Big Bang" script, but Jayawardhana — "Ray Jay" to his friends — has impeccable credentials. He grew up in Sri Lanka, studied at Yale and Harvard universities and taught at the universities of Michigan and California at Berkeley before landing the research chair in Observational Astrophysics at the University of Toronto. He is a strong explainer, as his two earlier books attest — "Star Factories" and "Strange New Worlds: The Search for Alien Planets and Life Beyond Our Solar System."
Jayawardhana likes to go big, and this time he does so by going extremely small, into the weird realm of subatomic particles. He begins in a cool place, Antarctica, site of IceCube, a stupendous neutrino observatory sunk more than a mile below the polar surface. Completed in December 2010, IceCube strings 5,160 optical sensors along a grid of 86 sunken cables. If the sensors pick up a signature blue flash in the silent darkness, that's evidence of a neutrino in a rare collision with a proton in an ice molecule. The IceCube schematic tucked onto Page 8 depicts it alongside a to-scale Eiffel Tower, a puny dwarf next to this $270-million neutrino-seeking array.
The author is ecstatic about IceCube, one of several massive neutrino-hunting contraptions scattered below lakes and inside mines and mountains around the globe. (They are buried to cut down on the cosmic ray clutter that interferes with finding neutrinos.) In a guest article this month in the Boston Globe, Jayawardhana exalts that IceCube is finding about "one energetic neutrino originating beyond our galaxy every month."
For physicists, these particles "at least a million times lighter than electrons" are harbingers from violent reaches of the universe, helping refine our scenarios for exploding, dying stars. The chapter that covers the excitement around a Feb. 23, 1987, supernova near the Tarantula Nebula is nicely narrated, explained from the perspectives of multiple scientists, confirmed via simultaneous neutrino detection in Japan (11 flashes) and a salt mine near Cleveland (eight flashes).
Neutrinos, Jayawardhana explains, have put an important chink in the standard model of particle physics. Early theorists and the cheeky poet Updike assumed they had zero mass, a calculation that turned out to be false. This and the discovery that these particles oscillate among three types means that "neutrino physics has transformed from a sleepy backwater twenty years ago, when only a handful of scientists paid any attention, to a thriving hub of activity, with over a thousand researchers actively studying these shadowy particles."
At times, "Neutrino Hunters" gives off a bit of Readers Digest condensation in, say, the hurried passage on Marie and Pierre Curie. It can also exhibit an odd padding, digressing pointlessly in its section on the 2011 Tohoku earthquake in Japan. Why tell us that the mother of an unharmed Canadian physics grad student couldn't find him for a few hours, given the loss of life in the quake and tsunami?
Still, Jayawardhana brings a welcome frankness as he explores all we don't know about his topic— which is, as he might say, the fun part.
Long manages the Anisfield-Wolf Book Awards for the Cleveland Foundation.
The Thrilling Chase for a Ghostly Particle to Unlock the Secrets of the Universe
Scientific American/Farrar, Straus & Giroux: 256 p.p., $27
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