Black holes have even rattled the great Albert Einstein. The physicist was stunned when his equations predicted the existence of singularity in the densest objects of the universe. Singularity in physics is the point where the density is infinite, the volume is zero and the gravity is infinite. As Nobel laureate Kip Thorne said, "This [singularity] is the place where even the laws of physics collapse! "Even the light can not escape the attraction of black holes, making these celestial objects both fascinating and frustrating for study.
Until recently, we had only seen abstract visualizations of a black hole of artists. Thanks to the Event Horizon Telescope (EHT), we now have a picture of reality – a supermassive black hole at the center of the Messier 87 (M87) galaxy, 50 million light-years away.
"It's fantastic to be able to record a black hole at close range. What the EHT has achieved is unbelievable, "says Edward Witten, pioneer of mathematics and theoretical physics at the Institute of Advanced Study at Princeton, USA.
Einstein's general theory of relativity transformed both spatially and temporally into a smooth space-time continuum. Mass was conceived as waves (or curvature) on this space-time substance. When the mass approaches infinity and the volume approaches zero, the supermassive object twists space-time so that even light can not escape. This is the basic science that underlies black holes.
"Now that I know what's in the center of M87, I'll be even more shocked to see this galaxy next time," said Detlef Koschny, senior astrophysicist at the European Space Agency's headquarters, Netherlands System.
The boundary of a black hole is called an "event horizon". Objects that go beyond the event horizon are lost in the fuzzy vortex of space-time; hence the term "point of no return".
"I do not think I expected a close picture of a black hole in my life. The view is remarkable, not least the uncanny distortion of space-time in an intense gravitational field. It clearly shows that Einstein's general theory of relativity actually works, "commented Robert Massey, managing director of the Royal Astronomical Society, London. "I suspect that the team will soon be posting a picture of a black hole near our own Milky Way galaxy, and perhaps even more ambitious targets. We may soon see a collapsed star not far from the sun. We could even imagine that we will visit him in the distant future, "adds Massey, an advocate of international scientific collaboration and public engagement.
From Stephen Hawking's pioneering work we know that black holes are not completely black. They are able to emit plasma jets and create particle-antiparticle pairs near the event horizon. As matter approaches the event horizon, it forms a circling disk due to the gravity of the black hole. Lumps of matter grind together, generating massive friction and releasing enormous amounts of energy. By spinning, the disk is warmed up, as juices in hot-mix machines become hotter. Therefore, matter near the event horizon shines brightly, with heat equal to hundreds of stars. This bright glow was mapped by the EHT network of eight radio telescopes.
"Because of the horizon, the shadow of the horizon should appear like a dark disk against the background of the illuminated photons (created from the matter that accumulates on the hole). To locate the sharp boundary of the shadow, it is essential to understand the dynamics of the accretion matter extremely close to the horizon, "explains Tapas Kumar Das, a top theoretical physicist at the Harish Chandra Research Institute in Allahabad.
"We have developed a general relativistic model for the accretion structure that theoretically allows us to track the dynamics of accretion material extremely close to the horizon. Our work will be helpful in understanding the effects of the black hole spin on the shape of the event horizon, "adds Das, who is the only scientist in India working on black hole silhouette techniques.
The legendary Indian physicist S. Chandrasekhar was the first to formulate the mass of dying stars that might collapse into a black hole or not. In star astrophysics, this is called Chandrasekhar limit and is about 1.4 solar mass. Normally, stars that exceed this mass limit develop into black holes.
"For humanity to achieve the highest spiritual pursuit of science, scientists across borders have collaborated to give a face to the theoretical foundations (almost a century ago) of S. Chandrasekhar and Albert Einstein," explains Murthy Gudipati, a senior astrophysicist at NASA-JPL, USA.
This historical event undoubtedly enriches and enhances our understanding of black holes and their dynamics. On a more sublime level, this study gives us clues to the basic nature of gravity, energy, matter, space, time, space-time geometry, and so forth.
The dazzling image of a black hole is a glimpse into the deepest and darkest fundamental secrets of our universe – literally, scientifically and metaphorically. As Shakespeare once said, there is a "method in addition" [singularity] Madness".
The author is an Indian astrophysicist and scientific writer in the UK