New Imaging Technology Could Enable Scientists to Test Theory of Relativity

Two weeks ago, a team of international astronomers, including researchers from the Harvard-Smithsonian Center for Astrophysics (CfA), published a report that could corroborate Einstein’s 100-year-old theory of general relativity, around which the entire modern model of physics has taken shape.

“All in a day’s work,” joked Sheperd S. Doeleman, MIT Haystack Observatory assistant director and CfA research assistant.

Doeleman and several other CfA affiliates utilized a global array of telescopes to measure a black hole’s “point of no return,” or the innermost boundary past which all matter is irretrievably lost to gravity.

This technology could permit scientists to one day capture an image of a black hole, which would represent the first step towards testing Einstein’s theory of relativity.

“What I find so exciting about it is that we are probing a region of universe where Einstein tells us what we should see,” Doeleman said. “We’re thinking about asking the question: was Einstein right? If there is a place where Einstein’s theory could break down, my money is on its being near a black hole.”

Einstein’s theory of relativity proposes the existence of black holes, infinitesimal regions in space where the pull of gravity is so strong that no matter, not even light, can escape.

Black holes form the center of most galaxies, including the Milky Way, according to report co-author and CfA engineer Jonathan Weintroub.

About 10 percent of these black holes emit jets of radioactive particles at very high speeds.

Tracing the origin of the jet enables scientists to locate the boundary of the black hole’s region of gravitational pull, known as its event horizon.

“It marks the point at which not even light can escape the gravitational pull,” Weintroub said. “It’s not really a point of no return. It’s more of a sphere of no return.”

Unlike the black hole at the center of our galaxy, the black hole at the heart of distant galaxy Messier 87 produces these radioactive particles, and was chosen as the focus of this CfA research.

The technology employed in this study, known as the Event Horizon Telescope, simulates the magnifying effects of an earth-sized telescope by scattering an array of powerful telescopes around the globe. The readings from these telescopes are centralized in a super computer located in the MIT Haystack Observatory.

Doeleman developed a means of broadening the bandwidth of the telescope to increase the resolution of M87’s image. With three telescopes stationed in California, Arizona, and Hawaii, Doeleman and his fellow researchers effectively measured the event horizon of M87.

While Doeleman and Weintroub worked largely on the engineering and execution, astronomy professor and Director of CfA’s Institute for Theory and Computation (ITC) Avi Loeb collaborated with former ITC student Avery E. Broderick to analyze the data.

“It’s a very exciting time to be in data analysis game,” said Broderick, who teaches physics and astronomy at the University of Waterloo.

Although the small number of stations in the EHT currently limits imaging capabilities, the researchers hope to expand the array to more continents by 2015 to effectively produce an image of a black hole, Loeb said.

“That image would appear on the cover of textbooks everywhere,” Loeb said. “I’m just happy to live at such a time where we have the technology to make these leaps.”