One of the coldest places on Earth is in a soon-to-be-destroyed missile bunker beneath Eastern Washington's Rattlesnake Ridge — a spot where the equation for Sir Isaac Newton's famous law of gravitational attraction is being tested.
According to Newton's original formula, a gravitational force between two objects equals the mass of one multiplied by the mass of the other — all divided by the square of the distance between the two objects. Then all that is multiplied by an esoteric, hard-to-describe number that physicists call "Big G."
In 1916, Albert Einstein made sure Newton's law fit into his theory of relatively, which contends that gravity is only a manifestation of curvatures in space-time. But what if Newton's math does not match reality? And if Newton is off, would Einstein be off?
"We physicists, we're skeptical of every theory," explains physicist Paul Boynton of the University of Washington.
Actually, Einstein's concept of gravity — building on Newton's work — is just one of more than a half dozen theories of gravity floating around. Most were unveiled in the past 50 years, each harder to understand than the math for Einstein's theory.
Meanwhile, pieces of the universe don't neatly fit Einstein's and Newton's arithmetic. The expansion of space does not quite fit the current formulas. Some distant stars are moving faster than our current calculations say they should. Photons and hydrogen clouds in deep space are not behaving as our math predicts. The two Pioneer spacecraft, launched in the early 1970s and now beyond the edge of our solar system, are slowing down more quickly than we can account for.
In 1974, physicist Daniel Long of Washington State University published a report on a tabletop experiment in which he questioned the validity of Newton's law of gravitational attraction. His results, prompted skepticism of Newton's law in the physics world, but have since languished for decades.
"The question remains. If we dig deeper, maybe we'll find something," explains Riley Newman, a physicist at the University of California at Irvine.
Enter Boynton, his assistant Michael Moore (who recently left for other work), and two University of California Irvine physicists — Newman and Eric Berg. Gravity has fascinated them for decades — a nerdy intellectual desire to figure out how the universe works at its hidden levels. These days the now-trio spends a good portion of their time experimenting with it.
"We understand gravity so little. It's difficult to study . . . If we understand it 100 years from now, that might lead to new technologies," Berg said.
Berg and Newman point out that pie-in-the-sky theorizing like Long's can sometimes lead to practical projects much later. Einstein's E equals M times C squared, scratched on a chalkboard, later led to the atomic bomb and nuclear power. Early 20th century work in quantum mechanics can be linked to advancements in the transistor radio, after its invention in the 1950s. Einstein's theory of gravity increases the accuracy of GPS systems by helping correct the time factors in their calculations.
Their drive to expand their understanding of gravity brought the trio to Eastern Washington's Hanford nuclear reservation 17 years ago, where the scientists set up an underground lab to work on experiments to test Newton's mathematical formula.
Western Hanford is part of a Cold War security buffer zone for the plutonium factories in the center of the reservation. The massive Rattlesnake Ridge dominates the area — a huge expanse of land home to sagebrush, elk, and coyotes. For the most part, the ridge is fenced off and completely isolated — only a few people are allowed in at designated times.
At the base of the ridge is an underground Cold War Nike Ajax missile bunker that protected the site from potential Soviet attacks in the 1950s and 1960s. This is where Boynton, Newman, and Berg conduct their experiments. A Cold War attack-related status board still hangs in the two-story deep chamber.
The basic approach to gravity research is to set up a measuring device in an environment void of every conceivable thing that could affect the measurements, including Newton's definition of gravity. With this level of control, any new wrinkle in the measurements could be some type of previously-undetected non-Newtonian feature of gravity.
Gravity experiments must be conducted in as perfect a vacuum as possible. To ensure accuracy, the experiment location should be affected by as few ground vibrations as possible, with no nearby ground water to disrupt the surrounding gravitational attractions. That translates to an isolated, dry spot — a bill the Rattlesnake Ridge bunker fits perfectly.
"Anyone within 50 yards of our [underground lab] place is a problem. Vehicles can cause disturbances at larger distances," Boynton said.
Extreme cold is also vital to the team's gravity research, because it slows molecules enough that their movements will not affect the experiment's measurements. To maintain the right conditions, the group's experiment is housed in a vacuum chamber within a complex, 10-foot-tall, 2-foot-wide thermos bottle. The bottle is cooled to a chilling 451.6 degrees Fahrenheit below zero — 4.5 degrees Celsius above "Absolute Zero" — using liquid helium. The helium's slow evaporation means it requires replacement every six days — the only time people are allowed near or in the bunker.
Within the vacuum, a small funny-looking object slowly twists on a string-like filament — 200 seconds for a complete twist and return to its original position. Over and over and over again, as a big weight slowly rotates around the tube full of liquid helium.
The team is looking for infinitessimally small variations in timing. If the speed of the twisting object wobbles by even 5 billionths of a second, it would be a significant clue that Newton's formula for gravitational attraction — around since 1687 and memorized by generations of high school science students — might have to be rethought.
In 2012, the three researchers hope to finish crunching their data and write a report. But the fate of future high school science students studying Newton's law will not be resolved for a long, long time.
Other scientists will write pro and con scholarly papers in response to the trio's results and conclusions. If the trio finds that Newton's formula does not match the experiment's reality, their conclusion won't become accepted in the world of physics until other researchers duplicate the experiment elsewhere and get similar results.
But if the trio's data does not show the hunted-for 5-billionths-of-a-second deviation, it could mean two different things: Either Newton's formula holds up or his formula cannot be disproved with current technology.
Maybe more precise equipment would be needed to find a real-world anomaly in the formula. Maybe the potential anomaly lurks somewhere below the observable level; on a plane that scientists cannot see yet.
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