Einstein's general theory of relativity passes the blackhole test
Despite being over a 100 years old, Albert Einstein's general theory of relativity has passed yet another test with flying colors. A team of scientists, upon concluding a 26-year-long study, has come to the conclusion that Einstein's general theory of relativity holds true, even when subjected to the crucial blackhole test. Not a physics buff? Don't worry, we'll explain.
The idea behind the recent test of Einstein's general theory of relativity was to find out whether the theory, which otherwise holds true, works in extreme environments such as those around blackholes. The study involved observing a star, S2, as it passed through the intense gravitational field exerted by the supermassive blackhole, Sagittarius A*, at the centre of the Milky Way.
For starters, Sagittarius A* is around 4 million times more massive than the Sun, and the gravity it produces is so strong that it makes stars (much bigger and heavier than the Sun) orbit around it at break-neck speeds. S2, happened to be one of the stars orbiting Sagittarius A*, and the Very Large Telescope in Chile was able to observe it in action.
The Very Large Telescope caught S2 whipping around Sagittarius A* at an astonishing velocity of 8,000km/s, despite being separated by a distance equivalent to 120 times the distance between the Earth and the Sun. Observations revealed that light from S2 was stretched to longer wavelengths owing to Sagittarius A*'s extreme gravitational pull, exactly like the "gravitational redshift" predicted by Einstein in his general theory.
Gravitational redshift, as predicted by Einstein, is a phenomenon wherein light's wavelength gets drawn out and shifts towards the red end of the spectrum when photons climb out of a gravity well, like that of a blackhole. It had never been observed under intense gravity.
The technicalities apart, the confirmation that Einstein's theories hold perfectly true even in the most extreme conditions, goes a long, long way in increasing humanity's understanding of the fundamental physical laws of the universe. Additionally, according to Frank Eisenhauer from Germany's Max Planck Institute of Extraterrestrial Physics (MPE), the findings have also opened the door to further studies of the physics of blackholes.