The Ends of Earth, and Beyond

Essay / by Anil Ananthaswamy /

To answer the most pressing questions about the origins of the universe, scientists must retreat to isolated pinnacles in the Andes or the South Pole. Anil Ananthaswamy follows in their footsteps in his new book.

Credit: ESO/Y. Beletsky

Well before I started researching and writing The Edge of Physics, I harbored a curious desire to visit telescopes and monasteries. Metaphorically linked by their status as lonely outposts atop faraway mountains, they held an irresistible allure. My fascination morphed into a book about journeys to the remote locations that host the telescopes, detectors and experiments at the cutting-edge of physics and cosmology. But it was only on the last of these trips to the ends of the Earth, standing beside a telescope high up in the Himalayas and staring at a nearby monastery, that I realized the full import of these extreme locations for physics.

One defining characteristic of modern civilization is noise. We normally associate noise with sound, but to scientists and engineers who work with delicate instruments, it can mean a whole host of things. It’s the glare of light pollution, or the invisible cacophony of radio waves—emanating from mobile phones, TV transmissions, airplanes, even power lines—or ambient radioactivity. There’s even the slew of secondary particles created by the constant bombardment of Earth’s upper atmosphere by cosmic rays, for which, of course, humans are not to blame.

Most of us are unaware of such noise, but to physicists these are an anathema, a curse. These varieties of noise can obscure the faint signals from the distant cosmos, including the cosmic microwave background, which is the radiation left over from the big bang, or they can overwhelm the search for dark matter that is thought to make up 90 percent of the matter in the universe. Where’s a physicist to hide?

As it turns out, they trudge off to build telescopes in the Atacama Desert high in the Chilean Andes, a region blessed with dry air and clear, dark skies. Thanks to a paucity of people and an enlightened government that enforces laws limiting light pollution, the Atacama offers unparalleled views of the Milky Way and beyond. Or they head to Siberia, where the depths of the world’s largest body of fresh water, Lake Baikal, provide a unique sanctuary. More than a kilometer of water shields their submerged instruments, which are hunting for neutrinos from outer space, from cosmic rays. The crystal clarity of Lake Baikal is also important. Neutrinos, when they hit water, disappear in a flash of blue light, and it’s this light that the physicists are after. Were Lake Baikal to become polluted and murky, we’d lose a valuable resource for tracking down particles that may be our best window to the universe at high energies.

Sometimes, the physicists are forced underground to escape the constant pitter-patter of cosmic rays on the Earth’s surface. Deep inside mines, including the abandoned iron mine in Soudan, Minnesota, experimenters listen for the faint “ping” of hypothetical dark matter particles hitting exquisitely engineered detectors. These detectors are protected by half-a-mile or more of rock above, allowing physicists to build experiments sensitive enough to mount a search for elusive dark matter.

The hunt for quieter and quieter sites for astronomy and cosmology has even led physicists to the unlikeliest of places: the South Pole. The high altitude, combined with cold, dry air and a thin atmosphere, is a boon for telescopes (both water vapor and dense, warm layers of the lower atmosphere can smudge the light from distant galaxies, limiting our ability to see deep into space). Antarctica, despite the cold and high winds, also turns out to be an ideal location to launch gigantic long-duration balloons that carry telescopes almost to the edge of space, a vantage point to study everything from the curvature of spacetime to the presence of primordial antimatter.

Sometimes, no place on Earth can suffice. For example, detailed study of the cosmic microwave background—which is at a temperature of 2.75 Kelvin, just a smidgen above absolute zero—is best done from space. Even low-Earth orbit is too close, because our planet’s thermal radiation can make a mockery of our best efforts at cooling. So physicists have ventured a million miles from Earth, to a secluded place in deep space where spacecraft use the Earth as a shield against the Sun and observe the cosmos. It must be really quiet and cold out there.

But space is an expensive place to do research. And so it became clear to me—while standing on one of the hills that dotted the 14,000-feet-high Hanle Valley in the Indian Himalayas, gazing out at the 400-year-old Hanle Monastery proudly perched on an adjacent hill—that we have to protect our pristine outposts. From the Atacama Desert in Chile to Lake Baikal in Siberia to the South Pole, these far-flung regions are naturally quiet, where the noise of the modern world is merely a distant drumbeat. The monks had chosen mountaintops for a similar reason, to reduce the reverberations of a noisy outer life so that they could probe the depths of their inner lives. Our telescopes and detectors need such quiet too. If we destroy these places, with pollution or because of changes in climate, we might end up with a planet whose inhabitants will be unable to look clearly into the universe to answer questions about our own origins. We’ll be like monks who cannot fathom deeper mysteries because of a noisy mind.

Anil Ananthaswamy is a consulting editor for New Scientist and a contributor to National Geographic News. Check out the Edge of Physics site here.

Originally published March 2, 2010

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