4,947 research outputs found

    String and M-theory: answering the critics

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    Using as a springboard a three-way debate between theoretical physicist Lee Smolin, philosopher of science Nancy Cartwright and myself, I address in layman's terms the issues of why we need a unified theory of the fundamental interactions and why, in my opinion, string and M-theory currently offer the best hope. The focus will be on responding more generally to the various criticisms. I also describe the diverse application of string/M-theory techniques to other branches of physics and mathematics which render the whole enterprise worthwhile whether or not "a theory of everything" is forthcoming.Comment: Update on EPSRC. (Contribution to the Special Issue of Foundations of Physics: "Forty Years Of String Theory: Reflecting On the Foundations", edited by Gerard 't Hooft, Erik Verlinde, Dennis Dieks and Sebastian de Haro. 22 pages latex

    M-Theory (the Theory Formerly Known as Strings)

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    Superunification underwent a major paradigm shift in 1984 when eleven-dimensional supergravity was knocked off its pedestal by ten-dimensional superstrings. This last year has witnessed a new shift of equal proportions: perturbative ten-dimensional superstrings have in their turn been superseded by a new non-perturbative theory called {\it MM-theory}, which describes supermembranes and superfivebranes, which subsumes all five consistent string theories and whose low energy limit is, ironically, eleven-dimensional supergravity. In particular, six-dimensional string/string duality follows from membrane/fivebrane duality by compactifying MM-theory on S1/Z2×K3S^1/Z_2 \times K3 (heterotic/heterotic duality) or S1×K3S^1 \times K3 (Type IIAIIA/heterotic duality) or S1/Z2×T4S^1/Z_2 \times T^4 (heterotic/Type IIAIIA duality) or S1×T4S^1 \times T^4 (Type IIAIIA/Type IIAIIA duality).Comment: Version to appear in I.J.M.P.A. References added; typographical errors corrected; 25 pages Late

    M-history without the M

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    A review of the book "A Brief History of String Theory: From Dual Models to M-Theory" by Dean RicklesComment: 6 pages latex. Book review commissioned by Contemporary Physic