One of the biggest paradoxes in physics
today is one that sounds straight out of a science fiction novel. What would
happen if you fell into a black hole? Rest assured, the answer to this bizarre question is that you would die
– that is not up for discussion. But it is how exactly you would die that is
keeping physicists up at night. There are currently two major theories fighting over this horrifying
scenario and the outcome of this battle could revolutionize the fundamental
laws of our universe.
To begin to understand this controversy, we need to first understand
what a black hole is. A black hole is a
region in space where the force of gravity is so strong that even light is not able to escape. Although some black holes are thought to have formed
in the early universe, soon after the big bang, most medium-sized black holes form
when the center of a very massive star collapses in upon itself.
For most of the past century, the
scientific community thought that the extreme gravitational pull would crush
all the matter that made up the black hole into a one-dimensional point, called
a singularity which is not only incredibly massive, but also incredibly dense.
The closer you are to this point, the stronger the gravitational attraction is.
An analogy inspired by William G. Unruh of the University of British
Columbia, one of the pioneers in black hole quantum mechanics, helps to explain
the significance of this pull. Imagine sitting in a boat, carried along a river
that leads towards a waterfall. If you are significantly far away from the
cliff, you can easily row your boat to safety. But once you get far enough
downstream, no matter how fast you row your boat in the opposite direction, you
cannot escape the pull of the water. For black holes, this ‘point of no return’
is called the event horizon and it is the place beyond which nothing, not even
light can escape.
So, what would happen if you
fell into a black hole? For years scientists thought they knew how you
would meet your end. Imagine falling into the black hole feet first. As your
feet are closer to the black hole, they would feel a stronger gravitational
force and will thus start to move faster than the rest of your body, causing
you to get stretched into a long noodle. Physicists call this process
spaghettification idea satisfied scientists until 1974, when Hawking dropped a bombshell.
He proposed what is now a widely accepted idea about the nature of black holes.
that black holes emit particles in the form of Hawking radiation which
causes black holes to shrink in size and eventually evaporate completely.
But there is a problem with
this idea. It violates one of the fundamental principles of quantum mechanics –
information cannot be destroyed.