One of the biggest paradoxes in physicstoday is one that sounds straight out of a science fiction novel.
What wouldhappen 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 iskeeping physicists up at night. There are currently two major theories fighting over this horrifyingscenario and the outcome of this battle could revolutionize the fundamentallaws of our universe. To begin to understand this controversy, we need to first understandwhat a black hole is. A black hole is aregion 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 formedin the early universe, soon after the big bang, most medium-sized black holes formwhen the center of a very massive star collapses in upon itself. For most of the past century, thescientific community thought that the extreme gravitational pull would crushall the matter that made up the black hole into a one-dimensional point, calleda 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 BritishColumbia, one of the pioneers in black hole quantum mechanics, helps to explainthe significance of this pull. Imagine sitting in a boat, carried along a riverthat leads towards a waterfall. If you are significantly far away from thecliff, you can easily row your boat to safety. But once you get far enoughdownstream, no matter how fast you row your boat in the opposite direction, youcannot 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 evenlight can escape. So, what would happen if youfell into a black hole? For years scientists thought they knew how youwould meet your end. Imagine falling into the black hole feet first. As yourfeet are closer to the black hole, they would feel a stronger gravitationalforce and will thus start to move faster than the rest of your body, causingyou to get stretched into a long noodle. Physicists call this process’spaghettification’.
Thespaghettification 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 whichcauses black holes to shrink in size and eventually evaporate completely. But there is a problem withthis idea. It violates one of the fundamental principles of quantum mechanics –information cannot be destroyed.