Maura McLaughlin
Department of Physics, West Virginia University
Einstein's Cosmic Ripples: Pursuing the Elusive Waves of Gravity
Maura McLaughlin is searching the northern sky hoping to detect something that has so-far eluded astrophysicists: the gravity ripples in spacetime predicted by Einstein but not yet found.
Those subtle waves have been calculated, conceptualized, theorized about and even blueprinted in detail over nearly 100 years, but despite the use of increasingly sensitive detectors no one has actual seen them. McLaughlin is on the case with a new approach. She's in no rush. If it takes five, 10 or 20 years, fine. Nothing ranks higher on the "to do" list for modern physics. Observing gravitational waves, or GWs, would cast light on the collapse of stars, the birth of black holes and the Big Bang itself.
It's a matter of nailing down the explanation of Einstein's four-dimensional spacetime, by detecting the distortions in that force of gravity that he theorized are set off by violent events like the collision of stars perhaps as distant as 300 million light-years, or several thousand galaxies, away.
McLaughlin, an assistant professor of physics at West Virginia University, and her team use pulsars as their starting point in the remote hills of West Virginia, home of the Green Bank Telescope. With pulsar measurements taken there and with the Arecibo telescope in Puerto Rico, they believe they can one day detect GWs. McLaughlin and her team are surveying the radio skies to detect more millisecond pulsars, which are incredibly precise celestial clocks. Gravitational waves will produce correlated disturbances in the arrival times of pulsars which can be detected by high-precision observations.
This is a different approach from that of two American observatories that make up the nearly $300 million experiment called LIGO, begun in the 1990's, in central Washington state and among the pines of Louisiana. LIGO, which stands for the Laser Interferometer Gravitational-Wave Observatory, is designed to detect gravity waves at the two distant sites, thus ruling out an earthquake or other local effect. Each lab sends laser beams down two identical arms that form a giant V in the countryside at each site. The beams travel 2.5 miles to mirrors, then home again. LIGO hopes a GW - a tiny movement indeed, much smaller than the nucleus of an atom - will rattle and stretch the arms, putting them out of sync, which a detector will record. So far, though, no waves.
"We think the waves exist, but it has always been an indirect measure," McLaughlin said. "We can observe stars that are in orbit around each other, and see that their orbits are shrinking and getting closer together in time. That's exactly in line with what Einstein predicted, and that's all good. The next step is detecting the gravity waves directly."
As a GW passes, the light travel times between Earth and all the pulsars will change slightly. "If we can measure these disturbances, we should be able to see this wave passing, this ripple in spacetime," McLaughlin said. "But it's tricky, because it's a very small effect."
McLaughlin became hooked on science as a schoolgirl in Oreland, Pa., reading science fiction, the works of Isaac Asimov, and the writings of the astronomer Carl Sagan and the physicist Stephen Hawking. She was at Penn State in the early 1990s when her career choice was settled by a research project at the Arecibo Observatory. "That was pretty cool," she says.
At Cornell, she earned her doctorate in physics, working on pulsars, and then moved on to the University of Manchester as an NSF math and physical sciences distinguished research fellow and as a postdoctoral research associate. She joined WVU in 2006.
The significance of detecting GWs is hard to overestimate. "It's a big deal, like a Nobel Prize-winning big deal, and would bring a massive increase in our understanding of the universe," McLaughlin said. "As we learn about sources of gravity waves, we will know about objects we can't see with visible light. We will gain a new window on the universe."
Maura McLaughlin's Teaching Plan
McLaughlin hopes to interest more undergraduate students in joining the search for pulsars and thus to help increase number of physics majors. The students will take part in surveys, including a drift scan, in which the telescope is stationary, and as the sky drifts by it takes in data. "We hope to get more students at WVU going into the introductory classes in astronomy, and actually processing data online, knowing exactly what a pulsar looks like," McLaughlin said.
She hopes to reach high-school students who are talented but never exposed to research. "It could be a big deal for them to do a little project like this," she said. One target is underrepresented rural youths and women at WVU. A few years ago she and her colleagues obtained an $800,000 NSF grant to create a Pulsar Search Collaboratory, which will bring 15 teachers and 30 students from across West Virginia to the Green Bank Observatory in summer to learn the basics and then continue to work on problems and stay in touch with WVU throughout the year. It follows her motto: "Students learn best when they need to learn."
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