A New Synthesis Slide 19 of 24

In the mid-seventies Stephen Hawking did a calculation that applied the rules of microscopic physics (quantum mechanics) to the region just outside the event horizon of a black hole. To everyone's amazement, his calculation revealed that black holes aren't black: they glow in the dark. Microscopic processes outside the black hole allow energy to leak out of the black hole, so that black holes literally evaporate by emitting radiation (light and heat). So this synthesis of microscopic physics with macroscopic physics (gravity and black holes) gave rise to a fascinating prediction: the evaporation of black holes. Unfortunately, as I suggested earlier, this prediction also revealed a serious dilemma (some call it a Paradox) which shows that our theories of the microscopic and macroscopic world are discordant, incompatible. In its simplest and most intuitive form this dilemma is called the ``Information Loss Paradox''.

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