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Survey of two-time physics

Bars, Itzhak (2001) Survey of two-time physics. Classical and Quantum Gravity, 18 (16). pp. 3113-3130. ISSN 0264-9381.

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Two-time physics (2T) is a general reformulation of one-time physics (1T) that displays previously unnoticed hidden symmetries in 1T dynamical systems and establishes previously unknown duality-type relations among them. This may play a role in displaying the symmetries and constructing the dynamics of little understood systems, such as M-theory. 2T-physics describes various 1T dynamical systems as different d-dimensional `holographic' views of the same 2T system in d + 2 dimensions. The `holography' is due to gauge symmetries that tend to reduce the number of effective dimensions. Different 1T evolutions (i.e. different Hamiltonians) emerge from the same 2T-theory when gauge fixing is done with different embeddings of d dimensions inside d + 2 dimensions. Thus, in the 2T setting, the distinguished 1T which we call `time' is a gauge-dependent concept. The 2T-action also has a global SO(d,2) symmetry in flat spacetime, or a more general d + 2 symmetry in curved spacetime, under which all dimensions are on an equal footing. This symmetry is observable in many 1T-systems, but it remained unknown until discovered in the 2T formalism. The symmetry takes various nonlinear (hidden) forms in the 1T-systems, and it is realized in the same irreducible unitary representation (the same Casimir eigenvalues) in their quantum Hilbert spaces. 2T-physics has mainly been developed in the context of particles, including spin and supersymmetry, but some advances have also been made with strings and p-branes, and insights for M-theory have already emerged. In the case of particles, there exists a general worldline formulation with background fields, as well as a field theory formulation, both described in terms of fields that depend on d + 2 coordinates. All 1T particle interactions with Yang-Mills, gravitational and other fields are included in the d + 2 reformulation. In particular, the standard model of particle physics can be regarded as a gauge-fixed form of a 2T-theory in 4 + 2 dimensions. These facts already provide evidence for a new type of higher-dimensional unification.

Item Type:Article
Additional Information:Copyright © Institute of Physics and IOP Publishing Limited 2001. Print publication: Issue 16 (21 August 2001); Received 16 October 2000; Published 1 August 2001 This research was partially supported by the US Department of Energy under grant number DE-FG03-84ER40168. The paper is based on lectures delivered at the Workshop on Strings, Branes and M-theory, CIT-USC Center, Los Angeles (March 2000); Second International School on Field Theory and Gravitation, Vit´oria, Brazil (April 2000); Quantization Gauge Theory and Strings, Moscow (June 2000); Non-perturbative Methods in Field and String Theory, Copenhagen (June 2000); M-theory and Dualities, Istanbul (June 2000).
Issue or Number:16
Record Number:CaltechAUTHORS:BARcqg01
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1328
Deposited By: Archive Administrator
Deposited On:10 Jan 2006
Last Modified:02 Oct 2019 22:42

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