Seeing a Black hole

These are exciting times ! Scientists have presented the first-ever image of a black hole.

The data for this image was captured in 2017, but ti took the agency 2 years to transport and process the data to generate the image. A network of 8 radio telescopes in different countries , including the south pole, captured information simultaneoulsy, and the data itself was transported on hard drives. The data captured was radiowave imaging, so there was no colour. They chose a bright orange color just to look good.

The image shows the shadow of the black hole at the center of the galaxy M87, a massive galaxy in the Virgo galaxy cluster 55 million light-years away. Its mass is 6.5 billion times that of the Sun. It took a worldwide collaboration of telescopes, the Event Horizon Telescope (EHT), in order to find it.

This is not really a “picture” of a black hole, and the shadow does not denote the black hole’s event horizon. Instead, you’re seeing the effects of gravity on the radio waves emitted from matter surrounding the black hole in a slightly larger region around the black hole’s event horizon. Gravity warps the shape of spacetime itself, deflecting some of the light in the region and generating an eerie circular shadow.

But it’s a groundbreaking observation, and another important proof of the theory of gravity that physicists use as a guide to the universe, Albert Einstein’s theory of general relativity.

Black holes have long served as a theoretical exercise. But astronomical observations in the past 60 years have increasingly demonstrated that there are objects in the Universe whose gravitational field is so intense that it warps spacetime such that light cannot escape beyond a point of no return, called the event horizon. Thanks to a world-side collaboration, is the closest image ever taken to the event horizon itself, near-direct evidence of the black hole’s existence.

Black holes as a theory are a consequence of trying to solve the equations of Albert Einstein’s theory of general relativity for a spherical, non-rotating system. However, it was the work of physicist David Ritz Finkelstein in 1958 that determined what black holes would look like in space: points of no return for light. We already had lots of indirect evidence of black holes’ existence—we’ve seen gravitational waves, predicted perfectly by mass turned into energy after the utterly inconceivable collision between a pair of black holes each a few dozen times the mass of the Sun. We’ve seen jets of particles spew forth from galactic centres that are far more energetic than those that come from collisions at our highest-energy physics experiment, the Large Hadron Collider. Technically, the EHT data is indirect evidence as well, but it’s about as close to direct evidence as we’ve had thus far.

It all started with Einstein. And Hawking.