The future of black hole science
“There is, monks, an inter-cosmic void, an unrestrained darkness, a pitch-black darkness, where even the light of the sun & moon — so mighty, so powerful — doesn’t reach.”
– Andhakara Sutra, Maha Wagga, Sanyuktha Nikaya
These are the words of Lord Buddha who explains about a pitch black darkness residing in the cosmos. What could it be? It took nearly 2500 years since the Buddha for humans to understand all about it. In 1915 Albert Einstein revolutionized the scientific world by putting forward a new theory about gravity: The General Relativity. He hypothesized that space and time create what he called space-time continuum and objects with mass cause this space-time to curve affecting the motion of light and matter near it. First verifications of this bizarre hypothesis came in 1919 by Arthur Eddington who took pictures of stars close to the sun during a total solar eclipse in South Africa and showed that the position of stars very close to the sun has been shifted by an amount predicted by the new theory. However, this prediction of the bending of light close to a massive object is one of the least astounding ones. Digging deep into Einstein’s theory, a German physicist named Karl Schwarzschild predicted that if an object has sufficient density its gravity could be so intense that even light would not escape from it. These were called “dark stars” or “gravitationally collapsed objects” and in the early 60s, the term “black holes” were coined. In the early 21st century these black holes were merely a mathematical curiosity of scientists. The math behind Einstein’s general relativity drove these scientists into making astounding claims about the properties of black holes. For example, the rate at which time flows would decrease as one approaches a black hole and freezes at the boundary of the black hole known as the event horizon. The matter that falls into a black hole will never escape, however, a black hole can be evaporated via a process called Hawking radiation, which can take billions or even trillions of years.
There are black holes with masses ranging from a few to billions of solar masses. Ones with a few solar masses (known as stellar mass black holes) are formed when stars die in an explosion known as a supernova. The other type of black holes (known as supermassive black holes) can be found in the centers of galaxies and assumed to be resulted by the merger of millions of stellar mass black holes. Last few years have been busy years for scientists involved in these exotic objects for two reasons. In 2016 the first ever detection of “gravitational waves” was reported by the LIGO observatory in the USA. It detected the “stretching” and “squashing” of the space-time by these gravitational waves that are generated by the merger of two stellar-mass black holes that were orbiting one another. In this year the first ever photograph of a supermassive black hole was published by scientists of the event horizon telescope. It was a result of combining data from multiple telescopes around the world. This method enabled scientists to build an equivalent telescope as large as the earth itself.
Einstein’s theory of general relativity was proved to be correct without a doubt (again) with these observations mentioned above. However, that doesn’t stop scientists from predicting and trying to observe many other phenomena related to black holes. One of the most important questions that modern physicists fail to answer is the relation between the quantum nature of particles and gravitation. And also there is the conundrum of “wormholes” that predicts the ability to travel through space and time by jumping into a black hole. With the addition of new observatories to the LIGO instrument (proposed to be built in India) and with additional telescopes added to the Event Horizon telescope and with quite a few more space telescopes that will go into orbit during the next decade, we can expect much more scientific breakthroughs in the coming years.