In his search for evidence of cosmic inflation, Duke Physics alum Jamie Bock (B.S. ’87) uses on-ground telescopes, high-altitude balloons, rockets, and satellites. Bock is a professor of physics at Caltech as well as a senior research scientist at the Jet Propulsion Laboratory (JPL). “Our groups build one-of-a-kind instruments to answer questions about the early universe,” he says.
Cosmic inflation is the rapid expansion theorized to have occurred just after the Big Bang. “Inflation does make observable effects in the universe,” Bock says, “and one way you can get at it is through measuring the polarization of cosmic background radiation.”
Bock was one of four principal investigators on the BICEP2 project, which aimed to do just that. BICEP2 made headlines twice in the last couple of years. First, in March 2014, BICEP2 scientists announced they had measured a polarization pattern in cosmic background radiation that was consistent with the presence of gravitational waves—ripples in Einstein’s space-time continuum that are predicted in certain models of inflation.
The second set of headlines came in February of this year when Bock and colleagues collaborated with scientists on the Planck project (a satellite mission of the European Space Agency) to present evidence that the polarization pattern was at least partially due to galactic dust. “The Planck data, which weren’t available until this year, showed that galactic dust emission was more polarized and more variable over the sky than previously modeled,” Bock says. However, he’s not convinced that dust is the only contributor to the polarization: “All we can say right now is at least 40% of the signal is associated with dust. Unfortunately, the remainder is instrument noise, mostly from Planck. It’s frustrating, but that’s simply the limit of what we can do today with the world’s best data.”
To better understand the polarization pattern and what it represents, follow-up work is underway on BICEP3, which like its predecessor, is a ground-based telescope located at the South Pole. “The error bars will go down as our experimental observations at higher and lower frequencies surpass the [earlier] data,” Bock says. “We’re now at the sweet spot for seeing an inflationary polarization signal. Cosmologists have been talking about testing this regime for the last two decades. In the next few years—or maybe less—we will find out the answer. That’s pretty exciting.”
Mary-Russell Roberson is a freelance science writer who lives in Durham.