We all know that Stephen Hawking has worked
on some of the biggest questions about our cosmos.
But what are those ideas?
Black holes are incredibly dense objects
with such strong gravity that nothing,
not even light, can escape their pull.
Hawking worked with physicist Roger Penrose
to show that if you were able to travel to
the centre of a black hole,
you’d find something called a 'singularity'.
In a singularity so much matter is squashed
into such a small space that the force of
gravity becomes infinite.
Everything is crushed into a point
of infinite density, punching
a hole through the fabric of the universe,
and tearing up the rulebook of physics
as we know it. It's pretty frightening stuff.
You might think that a vacuum is empty.
But it's not. At least, not according to quantum theory.
It's fizzing with particles and anti-particles
that pop into existence from nowhere
and then disappear.
When this happens, at the edge of a black hole
one of the pair of particles can fall in,
leaving the other to escape.
This tiny stream of escaping particles
is known as, “Hawking radiation”.
Now, those particles that fell into the black hole,
they have a negative mass,
and cause the black hole to get smaller, and smaller,
until it disappears.
It will take a while,
in fact a very long while,
but in it's final moments
a black hole will explode with the energy
of a million nuclear bombs – leaving nothing behind.
So why is Stephen Hawking our most famous living scientist?
Well, he showed that at one point
everything in our universe was squeezed into a singularity,
which then exploded into the Big Bang,
eventually forming galaxies, stars, planets, you, me,
and everything in existence!
That was the beginning of our universe.
And I suppose the incredible thing is that he
came up with all these profound,
provocative insights without the convenience of being
able to write anything down.
He did it all by thought alone.