The first sign that Albert Einstein’s
theory of gravity was correct has made a repeat appearance, this time near a supermassive
In 1915, Einstein realized that his
newly formulated general theory of relativity explained a weird quirk in the
orbit of Mercury. Now, that same
effect has been found in a star’s orbit
of the enormous black hole at the heart of the Milky Way, researchers with the
GRAVITY collaboration report April 16 in
Astronomy & Astrophysics.
The star, called S2, is part of a
stellar entourage that surrounds the Milky Way’s central black hole. For
decades, researchers have tracked S2’s elliptical motion around the black hole.
The researchers previously had used observations of S2 to identify a different
effect of general relativity, the reddening of the star’s light due to what’s
called gravitational redshift (SN: 7/26/18).
Now, they’ve determined that the ellipse
rotates over time, what’s known as Schwarzschild precession. That precession is
the result of the warping of spacetime caused by massive objects, according to
general relativity. A similar precession in Mercury’s orbit had stumped scientists before Einstein came along (SN: 4/11/18).
While physicists have never found a case
where general relativity fails, they are searching for any cracks in the theory
that could help lead to a new, improved theory of gravity. The new study
confirms that Einstein’s theory checks out once again, even in the intense
gravitational environment around a supermassive black hole.