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Informal Pizza SeminarWhy I don't believe we live on a spacetime latticeGuy D. MooreMcGillQuantum field theory requires some kind of "cutoff" of the ultraviolet degrees of freedom. One cutoff which is frequently mentioned, both in the pure field theory context and in the context of quantum gravity, is a lattice (lattice gauge theory, simplicial quantum gravity). This is partly because lattice gauge theory has taught us that, even if there is a rotation-invariance violating lattice at small scales, the infrared (macroscopic) behavior can nevertheless be rotationally invariant.I will explain why this is true for Euclidean field theory - but NOT true in Minkowski spacetime, where we live. I then argue that violations of Lorentz invariance have severe infrared implications, and I present the best current constraints on Lorentz violation, which are extremely strong. At the end, I will present some new (unpublished) constraints on Lorentz violation.
Tuesday, November 25th 2003, 13:00
Ernest Rutherford Physics Building, room 326 |