Stochastic Spacetime and Brownian Motion of Test Particles |
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Authors: | Email author" target="_blank">L?H?FordEmail author |
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Institution: | (1) Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, Massachusetts, 02155 |
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Abstract: | The operational meaning of spacetime fluctuations is discussed. Classical spacetime geometry can be viewed as encoding the
relations between the motions of test particles in the geometry. By analogy, quantum fluctuations of spacetime geometry can
be interpreted in terms of the fluctuations of these motions. Thus, one can give meaning to spacetime fluctuations in terms
of observables which describe the Brownian motion of test particles. We will first discuss some electromagnetic analogies,
where quantum fluctuations of the electromagnetic field induce Brownian motion of test particles. We next discuss several
explicit examples of Brownian motion caused by a fluctuating gravitational field. These examples include lightcone fluctuations,
variations in the flight times of photons through the fluctuating geometry, and fluctuations in the expansion parameter given
by a Langevin version of the Raychaudhuri equation. The fluctuations in this parameter lead to variations in the luminosity
of sources. Other phenomena that can be linked to spacetime fluctuations are spectral line broadening and angular blurring
of distant sources. |
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Keywords: | Brownian motion spacetime fluctuations |
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