The Information Paradox
Saturday, October 9, 2010 at 8:29AM
Vatche Sahakian in frosh, gravity, quantum, relativity

What would happen to you if you were to jump into a black hole... we have three possible answers to this, two from General Relativity, the other from String Theory. In all cases, your fate would not be something to look forward to. But for many physicists, this would actually be a great way to go!

A black hole is a hole in the fabric of space and time, a collapsed star that sucks in everything around it through its immense gravitational pull. We now know there are billions of these extreme objects scattered throughout our universe... so, what would happen to you if you were sucked into a large black hole? Einstein's theory of General Relativity, which predicts the existence of black holes, suggests the following outcome: as you approach the surface of the black hole - called the horizon - you wouldn't necessarily notice anything special. But as soon as you cross the horizon, you suddenly will realize that you cannot communicate with your relatives outside the black hole, even if you wanted to… Ironically, this is perhaps the only time you would want to talk to your relatives! As soon as you cross the horizon, you cannot escape from the black hole ever again; nothing can, not even messages in a bottle. You will continue to fall towards its center as the forces of gravity become stronger and stronger, and pulls your internal organs apart... no one outside will hear your screams... 

Now add to this Quantum Mechanics. Steven Hawking showed in the 1970's that a black hole actually evaporates! When quantum effects are taken into account, one finds that a black hole has a faint glow that slowly dumps the stuff it's made of into the outside world as random radiation! And there arises the Information Paradox... So, you jumped into the black hole and disappeared forever; does then the black hole evaporate into random radiation? if so, where have you gone? the information that is you, where is it? is a black hole a sink of information? This is deeply troubling, for physics and for psychology. We believe information cannot be lost, only change its form! The Information Paradox preoccupied theoretical physicists for decades... We now think we have a good answer to this puzzle from String Theory... stay tuned for another post that will help save your sanity... 

The accompanying lengthy video (5 parts) gives you a history of Hawking and the Information Paradox he proposed.

Article originally appeared on Physics feed for your imagination (
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