About black holes that are neither holes nor so black

Dr Irengbam Mohendra Singh *

Yuri Gagarin, the Russian cosmonaut, who first made the journey into the space in 1961, observed: "What a beauty, I saw clouds and their light shadows on the distant dear Earth [...] "The water looked like darkish, slightly gleaming spots [...] When I watched the horizon, I saw the abrupt, contrasting transition from the Earth's light-coloured surface to the absolutely black sky. I enjoyed the rich coloured spectrum of the earth." That was the bird's eye view of the Earth from space.

Nothing to me is more puzzling than the science of cosmology. GK Chesterton put it: "The cosmos is about the smallest hole that a man can hide in." Astronomers have over the centuries struggled to explain the heavens with varying degrees. They couldn't all be correct.

The Greek astronomer and mathematician Eratosthenes (275-195 BCE) used the Sun to measure the size of the round Earth. Another like him but more famous, Ptolemy (90-168 CE) set up a solar system where the stars and planets revolved around the Earth, incorrectly though. The Polish astronomer Copernicus (1473-1543 CE) got in big trouble for correctly proposing a solar system that involved the Earth revolving around the Sun. The Danish astronomer Kepler (1571-1630 CE) determined that planets travelled around the Sun, not in circles but in ellipses.

I often marvel at their brain. No one who changed the world beginning from Aristotle, Copernicus, through Galileo, Newton to Einstein and Hawking, had an IQ under 130. For reference, an average medical Student's IQ is about 120.

Legend has it that Einstein's IQ was 160. So is Stephen Hawking's. These two intellectual giants who gave so much to the world about cosmology had similar atheistic view of the origin of cosmos as in the Indian Rigveda, written late, about 1,000 BCE.

The Sanskrit hymn of creation called Nasadiya Sukta (Rigveda 10:1290) in the 'Indian cosmology and the origin of the Universe' was translated by AL Balsam in English. The 6th stanza describes: "But after all, who knows, and who can say where it all came, and how creation happened? The Devas (gods) themselves are later than creation, so who knows truly whence it has arisen?"

I read Stephen Hawking's book, A Brief History of time ( 2005), while researching for my book, Quest Beyond Religion (2006). In it for the first time, I came across theories of the Big Bang and the Black Hole. Hawking's book was immensely popular as he wrote it with wit, clarity and directness with concerns for the lay people. He is undoubtedly the most famous scientist, which is surpassed by his cameo roles as a celebrity. These two theories are not Hawking's originals. He just made them popular.

I read Hawking's BBC Reith lecture that he delivered in 2016, about the existence of Black Holes that challenged Einstein's space-time and the theory of general relativity. Einstein said large objects distort space-time that is almost flat, and around them, the distortion causes smaller objects to slide towards it, like a ball on a trampoline. This sliding of small objects is what he calls 'gravity'.

Hawking argues that if the curves in space-time become deeper, and eventually infinite as in a black hole, Einstein's gravity of space-time will cease to apply. I couldn't hardly agree more, from the Newtonian end of the spectrum of gravity.

The lesson in science is that at every stage of discovery it is a bit more complicated than the one we knew. Twelve years after Einstein published his theory of general relativity, a Belgian Catholic priest, George Lemaitre in 1927, first proposed the theory of "the Cosmic Egg Exploding at the moment of the Creation", which became known as the "Big Bang theory" when it was coined sarcastically as the 'Big bang theory' in a 1949 BBC broadcast by the English astronomer Fred Hoyle, who didn't agree with Lemaitre.

Albert Einstein's claimed in 1939, that stars couldn't collapse under gravity because matter couldn't be compressed beyond a certain point. One American astronomer John Wheeler didn't agree at that time. He brought the idea of the "black hole story." In his publications in the 1950s and 1960s, Wheeler emphasised that many stars would eventually collapse and the collapsed stars would become "wormholes"(1957). He introduced the term "black hole" in 1967.

So what is a black hole? A black hole to me, is the strangest object found in the cosmos. It is an intensely curved space-time that scientists can't actually see, but they know it exists from the tremors it sends when stars that get too close to it get torn apart and sucked in. A big scientific breakthrough occurred when scientist very recently, felt such tremors known as 'gravitational waves' from the collision between two black holes that occurred more than a billion years ago, about which I wrote in an earlier column.

Astonishingly, Einstein first predicted black holes in 1916 with the general theory of relativity. But the credit goes to Wheeler, who first discovered a black hole in 1971. A black hole is believed to be an intensely curved Einstein's space-time. It has three "layers": the outer, the inner 'event horizon' and the singularity. The boundary around its mouth is the continuing 'event horizon'. This is where gravity is just strong enough to drag light into the black hole, but light can't escape because of the tight gravitational pull. Therefore, the region around the black hole is a dark disk.

Light rays that pass a little further away don't get caught but do get bent by the black hole's gravity, following Einstein's theory of general relativity. The inner region of the black hole, where its mass lies, is known as "singularity" (see below).

Current theories envisage that there is a black hole in every galaxy in the Universe. Certainly, there is a supermassive black hole in our galaxy, known as Sagittarius A with a mass of about four million times that of the Sun at the centre of our Milky Way galaxy. Though they sound unreal, astronomers can study its precise measurements from the effect it has on small groups of stars known as S2, orbiting such a supermassive black hole, roughly 26,000 light years from the Earth.

Scientists can observe material that is sometimes drawn towards a black hole, ricochets off the event horizon and is hurled outwards, rather than being sucked in into the maw. Bright powerful jets of material at near-relativistic speed (a velocity approaching the speed of light) can be seen "burped" out of a black hole to great distances, although the black hole itself cannot been seen.

In astrophysics, most stars during their lifetime over billions of years, can support themselves against their own gravity from collapsing by the opposing internal thermal pressure, caused by nuclear reactions of converting hydrogen into helium. Eventually the stars do run out of nuclear fuel, when they start to contract. In a few stars, they may be able to hold themselves and turn into 'white dwarfs'.

When a uniform spherical star cannot be supported by outward pressure produced by its nuclear fusion, It would contract to a single point of infinite density, called a 'singularity'. This theory does not refer not only to the end of a star, but also to the starting-point of the entire universe. Hawking worked on this mathematically to earn his global recognition with the theory of Big Bang.

So, a black hole is a singularity ie a dimensionless point where all matter pulled into it is concentrated with an infinite density, where space-time does not exist, as it's the point of infinite curvature of space-time. So space-time breaks down at the singularity, where the curvature of space-time is indefinite and marks the end of time. This is what Einstein found so objectionable.

Hawking calculated in 1974 that, according to quantum mechanics black holes are not that dark. They are not prisons from which things can't get out, both in this universe and possibly to another as baby cosmoses. He quoted the French scientist Pierre-Simon Laplace, who two hundred years ago, formulated that the laws of science determine the evolution of the universe (scientific determinism).

Hawking contrasting with Laplace, claims: "In determinism, the predictability of the universe breaks down with black holes. If information were lost in black holes, we won't be able to predict the future, because a black hole can emit any collection of particles. It was therefore very important to determine whether information was really lost in black holes, and whether in principle, it could be recovered.

Laplace to me, was more famous for his reply to Napoleon Bonaparte who asked him: how God fitted into this picture [theory]? He replied: "Sir, I have no need for that hypothesis."

I believe, once scientists understand what is inside this event horizon we would be closer to the origin of the universe and whether there are many cosmoses in space. Scientist may even need a new theory of gravity and a new theory of space-time. Proving the point, here's the latest news about black holes (January 2018).

Researchers at NASA, observed evidence, with the Chandra X-ray Telescope and Hubble Space Telescope, of two "burps" of high energy particles emanating from the Supermassive black hole at the centre of the galaxy SDSS J1354+1327.