Quantum evolution in space-time foam

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World Scientific Publ Co Pte Ltd
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In this work, I review some aspects concerning the evolution of quantum low-energy fields in a foamlike space-time, with involved topology at the Planck scale but with a smooth metric structure at large length scales, as follows. Quantum gravitational fluctuations may induce a minimum length thus introducing an additional source of uncertainty in physics. The existence of this resolution limit casts doubts on the metric structure of space-time at the Planck scale and opens a doorway to nontrivial topologies, which may dominate Planck scale physics. This foamlike structure of space-time may show up in low-energy physics through loss of quantum coherence and mode-dependent energy shifts, for instance, which might be observable. Space-time foam introduces nonlocal interactions that can be modeled by a quantum bath, and low-energy fields evolve according to a master equation that displays such effects. Similar laws are also obtained for quantum mechanical systems evolving according to good real clocks, although the underlying Hamiltonian structure in this case establishes serious differences among both scenarios.
I am grateful to C. Barceló and P.F. González-Díaz for helpful discussions and reading the manusscript. I was supported by funds provided by DGICYT and MEC (Spain) under Projects PB93–0139, PB94–0107, and PB97–1218. Tiene 160 referencias.
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