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Milky Way's central black hole puts Einstein's theories to the test


An artistic visualization of the star S0-2 as it passes by the supermassive black hole at the galactic center, which has warped the geometry of space and time. As the star gets closer to the supermassive black hole, its light undergoes a gravitational redshift that is predicted by Einstein’s general theory of relativity. (National Science Foundation graphic by Nicolle R. Fuller)

University of California astronomers have tested Albert Einstein’s theories of relativity in the crucible of the monstrous black hole at the center of our Milky Way galaxy and found it rock solid. For now.

The team, led by UCLA astronomer Andrea Ghez, and with key analyses by UC Berkeley’s Jessica Lu, an assistant professor of astronomy, followed a star orbiting so close to the black hole that the light it gives off is affected by the black hole’s intense gravity. The effect, a gravitational redshift, matched exactly what Einstein’s theories of special and general relativity predict.

“The measurement of gravitational redshift around a supermassive black hole is really the beginning of a new era of testing general relativity,” said Lu, who began working with Ghez as a graduate student in 2003. “Our galactic center is a special place, a unique place, because we can study in detail the physics and astrophysics of a supermassive black hole. It is almost impossible to do that in any other galaxy.”  Read More