Remember to look at the stars…
Stephen Hawking – a man who just didn't earn respect not for being a brilliant astrophysicist, but also for being one of the few people whose entire adult life was a constant fight against fearful odds. That story has been covered by the media extensively. Today, as a tribute towards this dreamer, we are sharing how his discovery of revolutionised our way of understanding one of the biggest cosmic concept: the black hole.
Space-time, a marriage made by the scientists of the last century, was one of the most elusive concepts back in the day. Just when Albert Einstein published his findings under the 'General Theory of Relativity', the very foundation of conventional classical physics shattered with a unified concept of spacetime. Sadly, Einstein himself couldn't ensure any exact solution to describe the true nature of the relationship between matter & energy vs spacetime. In 1916, a year later Einstein theorised General Theory of Relativity, Karl Schwarzschild found the first worth mentioning solution: that too for a point mass over all of space. Till today, the world recognises this as the solution for a black hole, one of the few exact solutions known even today. While in Schwarzschild's theory has some drawback: it assumed black holes to be static objects. But do you know who proved it wrong? It was Hawking; he was the first to prove that it wasn't a static cosmic holo. Stephen Hawking mathematically theorised Black holes radiate over time, and even more importantly, aren't completely black.
Now the question arises: if a black hole isn't so black, and if it's radiating, how? Black hole, being an astronomic vacuum according to prior theories, radiate? Finding the answer to this elusive question was probably the life-altering contribution of Hawking in the world of Physics. Let's try to explain what Hawking did in layman's term: we previously knew how to calculate, in quantum field theory, and understand the properties of empty space when it is very far away from any masses, like a black hole. Thanks to Hawking, for the first time, we could do this in curved space: within
a few radii of the event horizon. What he also observed was there was a marked difference in the behavior of the quantum vacuum when a mass was near.
When he ran through the math, he found the following properties:
* If you're far from the black hole, it looks like you get the thermal emission of blackbody radiation.
* Black hole's mass determines the temperature emission: the lower the mass, the higher the temperature.
* It follows Einstein's E = mc2 when radiating. The higher the rate of radiation, the faster the mass loss.
*Lastly and most importantly: as it loses mass, it shrinks and radiates faster.
These findings were revolutionary back in the day. It depicted a much clearer picture of humankind's overall understanding about black holes and how quantum fields behave in highly curved space. It opened up a new avenue altogether: the black hole information paradox. More importantly, it opens the door to additional subtleties that allowed scientists, for the first time, to take a proper peek under the hood of the universe and find out the effects of quantum gravity if there are any departures from the predictions of General Relativity. It has been nearly half a century but his findings remain one of the most revolutionary theory to explain black hole.