You have to be smart enough for your name to become intelligence. So it’s not exactly shocking that many of Albert Einstein’s theories have been supported by observable evidence. Einstein wins another posthumous victory – a new study of the black hole in the center of our galaxy (yet) confirms the theory of general relativity.
In 1915, Einstein published his theory of general relativity, which made many predictions about the nature of the universe. Relativity has led scientists to rethink many things, including the nature of Mercury’s orbit around the sun. A month after Einstein’s work was published, Karl Schwarzschild developed the first solutions of Einstein’s field equations to describe an orbital rotation now known as the Schwarzschild precession. Mercury has a slight precession due to the mass of the sun, and something orbiting a black hole should have a much more extreme version. Scientists now have good evidence that this is the case.
In the center of our galaxy hides a supermassive black hole known as Sagittarius A * (pronounced Sagittarius A star). A star known as S2 orbits Sagittarius A * every 16 years, but the nature of its orbit is a true sensation of mind. For decades, astronomers have used S2’s elliptical orbit, which is 15 times larger than the sun, to test various elements of general relativity. For example, confirm gravitational red shifts as predicted by theory. It turns out that the orbit does not remain static – it revolves around the rosette-shaped black hole (think spirograph) indicating a Schwarzschild precession.
The team analyzed S2 using the SINFONI and NACO adaptive optics instruments from the Very Large Telescope (VLT) of the European Southern Observatory. In 2017, they added the beam combining instrument called GRAVITY to the mix, which helped refine the observations and show a clear Schwarzschild precession. The distinctive orbital changes seen in S2 are the result of the incredible mass possessed by Sagittarius A *. Essentially, the intense gravity of the black hole distorts space-time and makes S2’s orbit move.
General relativity has been confirmed over and over again, so no one expected it to be the nail in his coffin. That said, general relativity has its limits. Problems such as quantum gravity and dark energy seem to exist outside the model of general relativity. We will need new physics to fully explain the universe, but Einstein made many predictions more than a century ago.
Best image credit: ESO (public domain)