LIVINGSTON, La.—The rain began to fall as Joe Giaime and I scrambled down a lonely rise, back toward the observatory’s main building. It wasn’t so much rain as a hard mist, characteristic of the muggy weather southern Louisiana often sees in January when moisture rolls inland from the Gulf of Mexico. As gray clouds fell like a shroud over the loblolly pines all around us, Giaime mused, “Well, I guess you’ve already gathered that we’re in the middle of nowhere."
Middle of nowhere happens to be ground zero in the search for gravitational waves, which were first posited by Albert Einstein a century ago and may soon become one of the hottest fields in science. Livingston is remote in terms of geography, but as humans scan the heavens for gravitational waves this forest is practically the center of the physics universe.
Because of general relativity, we understand that large masses curve spacetime, kind of like standing in the middle of a trampoline distorts the fabric. When massive, dense objects in space accelerate, such as black holes or neutron stars, they create ripples in the fabric of spacetime. These ripples carry gravitational radiation away from the very massive objects, and the radiation then propagates through the Universe. This Louisiana observatory, the Laser Interferometer Gravitational-Wave Observatory or LIGO, exists to try to measure these subtle ripples.
The observatory has an educational center, and a few times a week yellow school buses from Baton Rouge or other nearby communities deliver hundreds of students to its front door. Giaime, a California Institute of Technology physicist who manages the lab and also a professor at Louisiana State University, says the most common question he gets is, "Why should we look for gravitational waves?" And it’s a good question, he says. The most simple answer is that it would help verify Einstein’s theory of general relativity, which in 1916 predicted the existence of curved spacetime.
Naturally there’s a deeper, better answer. The very objects that produce gravitational waves are the most energetic, wild, and interesting places in the Universe. Finding them would open new and never-before-realized windows into the universe. Genuine proof of gravitational waves could tell us about gravity at its strongest, like black holes. They could shine light on matter at its densest (ala a neutron star). And they could reveal new information about the largest explosions of the galaxy, like supernovae and the mergers of black holes and neutron stars. “These are the kinds of places we can probably only really learn about through gravitational waves,” Giaime explains.
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