Is it a dawn of new era in black holes?

Manasi Saraf Joshi
Sunday, 21 April 2019

April 10, 2019 was one of the important days for the scientist community across the world. On this day, the quest for over two decades ended after nearly 200 scientists from Event Horizon Telescope (EHT) were successful in capturing the first ever image of a black hole.

April 10, 2019 was one of the important days for the scientist community across the world. On this day, the quest for over two decades ended after nearly 200 scientists from Event Horizon Telescope (EHT) were successful in capturing the first ever image of a black hole.

A black hole is a mysterious place in space with such enormous mass and extreme gravity that nothing can escape it. Not even light. As light does not get out, black holes are invisible and thus get their name.

Dr Katherine Bouman, a 29 year-old post-doctoral fellow at Massachusetts Institute of Technology (MIT), received appreciation across the world for being instrumental in creating of the algorithm that helped produce this image.

““The image will not only throw open new research branches, but also opens up new ways to study these enigmas. The researchers already have the data on the black hole in our own galaxy as well. Going further, researchers will make efforts to get even more detailed pictures of these black holes, to measure their masses, spins even more accurately. These observations will allow them to test the general theory of relativity at its extreme limits. We will also be able to learn about how these black holes grow, how they can launch jets of material which shapes the formation and evolution of galaxies”,” said Surhud More, scientist working at Inter-University for Astronomy and Astrophysics (IUCAA).

The importance
This first image is for entire humanity to remember. It gives us a glimpse of the enigmatic black holes predicted by Einstein’s theory of general relativity. Until these new observation were made, we knew about black holes indirectly (for example, via their gravitational effects on stars, or the emission coming from the gas swirling a lot further around it, or through gravitational waves from mergers), Surhud added.

“But nobody had the resolution needed to see what the edge of a black hole really looks like. Of course, by definition no one can see exactly what is inside a black hole, and this image does not really tell us what is inside the black hole. It captures the light which just managed to skirt the black hole and escaped from it to us. This light marks something called ‘photon sphere’ boundary of the black hole. It is roughly 1.5 times the event horizon of the black hole. The photons on this boundary go in an orbit around the black hole. 

If this light was even a little bit closer to the black hole, it would have fallen into the black hole. Just to give you an idea of what it means for photons to go around a black hole: if you are at the photon radius of the black hole, then the light bouncing from the back of your head, can go around the black hole and travel towards the front.
 
This light travelling around the black hole will allow you to see the back of your head, ”he elaborated. 

“The size of this photon radius and this phenomenon is predicted by Einstein’s theory of general relativity. However, this phenomenon had never been directly observed before. This is as close it gets to seeing a black hole.
 
Nothing else has been ever observed to go around the black hole at such a close distance. That is the main significance of this discovery”, Surhud explained.

How close world is to understand the existence of the world?
Well, I am not sure the imaging of big black holes necessarily will directly tell us how the Universe came into existence. However, getting so close to the black hole can be useful to test interesting ideas of how we can marry the general theory of relativity and quantum mechanics. Any improved understanding of quantum gravity raises the hope to understand the very earliest stages of the Universe” Surhud said. But certainly it was a milestone.

What next?
The astronomers are now working to get more high resolution images of black holes and the findings will be published in The Astrophysical Journal.

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