What Weinberg and others have done is to make the error of embedding this argument into one that first mentions some version of the antrhopic principle. This is correct reasoning, and it agrees with observation. Therefore we predict that the cosmological constant could not have been too large. "Too large positive Lambda interferes with galaxy formation. Here is how it goes: We start with a theory of structure formation that tells us As it is added to an already correct argument, the anthropic principle plays no role in the actual scientific argument. To an already correct argument is then added mention of the anthropic principle. The subtle point is that their arguments have embedded in them correct arguments having to do only with what we observe. I show that the argument of Weinberg and others are incorrect. I'll start with one of the main arguments I make. Smolin's publication of "Scientific alternatives to the anthropic principle" and his summary of the arguments, written at Susskind's request. His contributions to physics include the discovery of string theory, the string theory of black hole entropy, the principle of "black hole complementarity," the holographic principle, the matrix description of M-theory, the introduction of holographic entropy bounds in cosmology, the idea of an anthropic string theory "landscape." Leonard Susskind's Edge Bio Page LEONARD SUSSKIND, the discoverer of string theory, is the Felix Bloch Professor in theoretical physics at Stanford University. He is the author of The Life of The Cosmos and Three Roads to Quantum Gravity. In 2001, he became a founding member and research physicist of the Perimeter Institute for Theoretical Physics, in Waterloo, Canada. LEE SMOLIN, a theoretical physicist, is concerned with quantum gravity, "the name we give to the theory that unifies all the physics now under construction." More specifically, he is a co-inventor of an approach called loop quantum gravity. Edge draws attention to the larger context of intellectual life.īelow are the original email pieces, followed by the final letters presented side-by-side. The constant shifting of metaphors, the intensity with which we advance our ideas to each other - this is what intellectuals do. And finally it's a good example of what Edge is all about, where contributors share the boundaries of their knowledge and experience with each other and respond to challenges, comments, criticisms, and insights. While this is a conversation written by physicists for physicists, it should nonetheless be of interest for Edge readers as it's in the context of previous Edge features with the authors, it's instructive as to how science is done, and it's a debate that clarifies, not detracts. This was the opening salvo of an intense email exchange between Susskind and Smolin concerning Smolin's argument that "the Anthropic Principle (AP) cannot yield any falsifiable predictions, and therefore cannot be a part of science".Īfter reading several postings by each of the physicists, I asked each if (a) they would consider posting the comments on Edge, and (b) if they would write a new, and final "letter".īoth agreed, but only after a negotiation: (1) No more than 1 letter each (2) Neither sees the other's letter in advance (3) No changes after the fact. Recently, I received a copy of an email sent by Leonard Susskind to a group of physicists which included an attached file entitled "Answer to Smolin".
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