• Corpus ID: 118906703

Twenty Years of Debate with Stephen

@article{Susskind2002TwentyYO,
  title={Twenty Years of Debate with Stephen},
  author={Leonard Susskind},
  journal={arXiv: High Energy Physics - Theory},
  year={2002}
}

• L. Susskind
• Published 3 April 2002
• Physics
• arXiv: High Energy Physics - Theory

This is my contribution to Stephen Hawking’s 60th birthday party. Happy Birthday Stephen! 1 Crisis and Paradigm Shift Stephen, as we all know, is by far the most stubborn and infuriating person in the universe. My own scientific relation with him I think can be called adversarial. We have disagreed profoundly about deep issues concerning black holes, information and all that kind of thing. At times he has caused me to pull my hair out in frustration – and you can plainly see the result. I can assure you that when we began to argue more than two decades ago, I had a full head of hair. I can also say that of all the physicists I have known he has had the strongest influence on me and on my thinking. Just about everything I have thought about since 1980 has in one way or another been a response to his profoundly insightful question about the fate of information that falls into a black hole [1]. While I firmly believe his answer was wrong, the question and his insistence on a convincing answer has forced us to rethink the foundations of physics. The result is a wholly new paradigm that is now taking shape. I am deeply honored to be here to celebrate Stephen’s monumental contributions and especially his magnificent stubbornness. The new paradigm whose broad outlines are already clear involves four closely related ideas which I will call Horizon Complementarity (also known as Black Hole Complementarity ) [2, 3] , the Holographic Principle [4, 5], the Ultraviolet/Infrared connection [6] and the counting of black hole microstates [7, 8, 9, 10, 11]. Each has had strong support from the mathematics of string theory. We have also learned that certain lessons derived from quantum field theory in a fixed background can lead to totally wrong conclusions. For example quantum field theory gives rise to an ultraviolet divergent result for the entropy in the vicinity of a horizon [12, 13] and a volume’s worth of degrees of freedom in a region of space. Another misleading result of quantum field theory is that increasingly large energy and momentum scales are equivalent to progressively smaller distance scales. Finally quantum field theory in a black hole background inevitably leads to the loss of quantum coherence from the vantage point of a distant observer [1]. 2 Stephen’s Argument for Coherence Loss Let’s begin with the issue of coherence loss. Begin by drawing the Penrose diagram for black hole formation. Let us think of it as a background on which we can study conventional quantum field theory. Now let’s add some additional particles which for simplicity are