RICHLAND -- For the two dozen or so scientists and engineers gathered in the shrub-steppe desert east of Rattlesnake Mountain, south of the Hanford nuclear works, the task has been like trying to build a telescope from scratch on the wildly pitching deck of a ship in rough seas.
Except that it's not really a telescope so much as a unique device created to observe the cosmic signature of something scientists long considered impossible to detect -- if they believed in the phenomena at all.
Albert Einstein predicted their discovery in 1916 as part of his general theory of relativity, but even he had occasional doubts. It wasn't until recently, with the development of several new technologies, that it was considered remotely possible to look for evidence of these space tremors.
"It's an entirely new kind of exploratory enterprise," said Fred Raab, an atomic physicist and displaced New Yorker running the Hanford arm of a project known as the Laser Interferometer Gravitational Wave Observatory, or LIGO ("lie-go"). The other half of this wave antenna is 1,900 miles away in Livingston, La.
Given Einstein's ambivalence about the atomic bomb, which he had a part in developing but later condemned, it's perhaps fitting that one of his major predictions may some day be confirmed on the Hanford Nuclear Reservation.
LIGO gets switched on, sort of, in July.
"We expect it will be a long struggle to perfect the instrument," Raab cautioned. "Hundreds of things need to be just right to get the sensitivity we need. These are very, very sensitive measurements we're trying to achieve."
That's an understatement.
A gravity wave is best thought of as a space-quake, easiest to detect when produced by something big like a supernova (a star's explosive collapse), a black hole or the collision of two neutron stars.
A supernova at the center of the Milky Way would produce a massive gravity wave that despite its size would send only the tiniest of shudders through the page of a newspaper -- a flutter 10,000 times smaller than the diameter of an atomic nucleus.
Given that, consider the problem LIGO scientists have had in trying to build an instrument that can detect this unbelievably small signal among all the other "noise" on Earth -- from earthquakes to a truck rumbling by a mile away to the waves beating on the Pacific Coast some 300 miles away.
"The ocean waves on Earth create what's known as a microseism," said Raab.
This microseismic tremor passes through the planet about every eight seconds, he said, and also physically distorts the Earth. The scientists have had to build a computerized support system for LIGO that compensates for this by physically adjusting the instruments every eight seconds.
They also had to build in a compensating adjustment for the gravitational pull of the sun every day. Raab, an expert on precision measurements, explained that the surface of the Earth heaves up when the sun is overhead, so they also have to adjust for that -- but on the scale of millionths to trillionths of a meter, an unprecedented level of control.
And those are just a few of the more predictable problems.
Similar projects are getting under way around the world -- in Germany, Japan, Italy and Australia. The reason these projects are being done now is sort of a twist on the mountaineer's rationale for climbing: because the technology is finally there to make detecting a gravity wave possible.
Catching a wave
Why should anyone care?
For scientists, they know that whoever first detects a gravity wave is likely to win a Nobel Prize. For the general public, it may be harder to appreciate why such an uncertain venture is worth so much money. What good is relativity anyway, and why do we need to try to get a bead on gravity?
The theory of relativity says space and time and matter are all different manifestations of the same basic stuff, often referred to as "the fabric of space-time." Einstein's mathematical equation stating that energy and mass are different sides of the same coin likely sounded esoteric and impractical at first. But that was before E = mc2 led to such developments as nuclear power.
Gravity is the force produced by the clumps, distortions or movement within the fabric of space-time, usually depicted visually showing a massive object like the sun as a heavy ball dimpling the fabric of space-time.
There's no longer any question whether the theory of relativity is correct. Anyone who's ever fallen off a ladder certainly knows that gravity exists. But scientists still don't really know what gravity is made of or exactly how it works. After nearly a century of debate about the existence of gravity waves, several decades of attempts at detecting them and years of painstaking preparation in the design and construction of LIGO, the search will soon be on.
"This is one of the few (unsolved) problems in physics that's been around for almost a century," said Barry Barish, a physicist at Caltech and director of LIGO. "The prediction of gravitational waves is one of the most important features of Einstein's theory."
It's a fundamental new inquiry into the nature of the universe, said Barish, which means it is impossible to predict the course of discovery or its practical implications. But the history of such endeavors shows that these discoveries always significantly alter our lives and our knowledge.
"There's a whole side to the universe we don't have any other way to observe except by gravitational waves," said Kip Thorne, a Caltech theoretical physicist and one of the founders of LIGO.
Just as electricity has its electrons and light has its fundamental particles known as photons, gravity should also exist in particle form as "gravitons." But because of the nature of gravity, Thorne said, with our current technical abilities there is no way to actually detect such a fundamental particle as the ephemeral graviton.
Our best bet is to catch a wave.
"More than offering an additional window on space, gravity waves will provide a radically new perception," wrote Marcia Bartusiak, author of a book on the history of the search for gravity waves, "Einstein's Unfinished Symphony."
Proof is out there
The LIGO station at Hanford, as at the Livingston site, is shaped like an "L" with two pipeline-style concrete tunnels set at right angles to other -- one tunnel stretching out 2 1/2 miles to the northwest, the other 2 1/2 miles southwest.
Inside the tunnels, precise laser beams bounce back and forth in a near-perfect vacuum between equally precise mirrors held in place (and adjustable) by hair-thin steel wires and magnets.
"The instruments have to feel like they're in freefall in space," said Mike Zucker, an MIT physicist involved in the project.
The way the scientists hope to see the signal of a gravity wave is when the two lasers of LIGO, set at right angles to each other, interfere with each other in a particular manner. That's laser interferometry. It was Zucker's previous boss at MIT, the now-retired Rainier Weiss, who years ago convinced many in the scientific community that the technique could catch a gravity wave.
"He came up with the first coherent description of how it could work," Zucker said.
But a lot of technological advancements were required in lasers, mirrors, electronics and the design of isolation systems.
When a gravity wave strikes, the theory goes, it alternately stretches and compresses matter, space and time at the speed of light. The L-shape of LIGO means that one of the laser tubes will be stretched while the other one is being compressed, and then vice versa.
This should knock the two laser beams out of phase to the point where the passage of a gravity wave can be detected.
The twin LIGO in Louisiana was built to confirm the same signal -- the 1,900-mile separation reducing the chance of seeing identical "fake" waves produced by local noise.
"We know they exist," said Raab, adding that his confidence in Einstein's prediction doesn't necessarily translate into confidence the LIGO gang will get proof anytime soon.
It could be years, maybe many years, of tinkering and improving the system along with waiting for the right cosmic event before they catch a wave.