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String Theory, Quantum Gravity and Locality
Published online by Cambridge University Press: 28 February 2022
Extract
In this talk, I'd like to explain a little bit about what string theory is, why theoretical physicists are so excited about it, and why I think that it will have a rather profound impact on some of our ideas about the structure of the physical world.
Let me begin by reviewing the way we think about quantum mechanical particles in a relativistic setting. The classical dynamics of the theory is specified by assuming that the action for a given particle trajectory is proportional to the relativistic interval traversed by the particle. If one sets up a canonical formalism with the variable parametrizing the particle trajectory playing the role of time, then one finds that the four-momentum of the particle is constrained, with the constraint just being the relativistic relation between the mass, energy, and three-momentum of a particle. The particle thus lives on a subspace of the full phase space, and one finds that on this subspace, the Hamiltonian for the system vanishes.
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- Part IV. Physics
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- Copyright © 1989 by the Philosophy of Science Association
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