What are black holes?

Black holes are one of the most peculiar and fascinating things that no science geek could stop talking about. It has baffled the greatest minds of the world and continues to do so. But what if we told you that the story of black holes began way before in the 1700s? Even before Einstein’s prediction in the 1900s?

What is a black hole?

Yes, the black hole was conceptualized more than a century before Einstein’s prediction by an English rector named John Michell. His ‘dark star’ was rubbished then, but it did stand the test of time. Especially with the prediction of black holes by Albert Einstein in 1916 in his relativity theory.

Now, although Einstein predicted it in his theory, Schwarzschild developed the idea of black holes through the general relativity theory. But even he had to wait for another half a century before a physical black hole could be discovered through x-ray telescopes. Are you piqued enough to wonder what these black holes are?

Well, black holes are regions in our galaxy that are so dense with an immense gravitational pull that nothing can escape these overwhelming black pits. The gravity is so strong that it can bend light and warp time. Anything that ventures into the black hole would be pulled in to be stretched and compressed in what is today known as spaghettification. Are you curious as to how these interesting beings came about?

How are Black Holes formed?

As of today, there are three different types of black holes known – stellar, intermediate, and supermassive black holes. And each has a different story of origin.

One of the most accepted origins of black holes is when stars near their death, they collapse or fall into themselves. When the stars are small, they usually take the form of white dwarfs or neutron stars. But what happens to a larger star?

The collapse of a large star leads to the formation of stellar black holes. Even though we say that these are the smallest black holes, mind you, they are packed with mass that is three times bigger than that of the Sun. They continue to swallow the particles and objects around them, eventually growing in size.

Stellar back holes are sprinkled across the galaxies. Can you believe that our Milky Way alone has a few million stellar black holes? Contrary to them, supermassive black holes form the center of almost every galaxy. The one that crowns our Milky Way is called Sagittarius X. However, theorists are yet to conclude how these are formed – a major problem being their age.

Some of them emerged only a 690million years after the Big Bang. It might sound like a lot, but in galaxy language, it’s just a blink of an eye. Not at all enough for a star to collapse and grow to have a mass that is billions of times bigger than the Sun. Speculations range from the merge of many stellar black holes to large gas clouds to clusters of dark matter.

Up until recently, these were the only two sizes that existed for astronomers. The discovery of one in the arm of one of the spiral galaxies – the intermediate black holes (IMBH), changed that.

“Astronomers have been looking very hard for these medium-sized black holes,” said co-author of the 2014 paper on IMBH, Tim Roberts in a statement “There have been hints that they exist, but the IMBHs have been acting like a long-lost relative that isn’t interested in being found.” Although, playing hard to get, astronomers believe that these could exist in dwarf galaxies, growing into supermassive black holes in the future.

What do Black Holes look like?

Black holes consist of three layers: the outer and inner layer of the event horizon and the singularity.

The event horizon is what we can call the mouth of the black hole. Once anything passes an event horizon, it cannot escape at all – not even light. The inner region of the black hole, the single point in space-time where the concentration of mass exists is called singularity.

Having said the above, we cannot directly see black holes, as light doesn’t pass through them This is why we had to wait for x-ray telescopes to finally unearth them in our galaxies.  Instead, we infer or detect their presence through electro-magnetic rays, effects on the matter nearby, and the light emitted when matter accelerates towards the black hole.

The fascination behind black holes never seems to end. They continue to capture mankind’s wildest imaginations. They unravel themselves layer by layer every once in a while, astonishing us, stupefying us. And isn’t that what takes Science forward? We just never know what groundbreaking discovery awaits us next.














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