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General Relativity and Quantum Cosmology, gr-qc
Abstract:
For almost a century, the cosmological constant has been a mysterious object,
in relation to both its origin and its very small value. By using a
Bose-Einstein condensate analogue model for gravitational dynamics, we address
here the cosmological constant issue from an analogue gravity standpoint.
Starting from the fundamental equations describing a system of condensed
bosons, we highlight the presence of a vacuum source term for the analogue
gravitational field, playing the role of a cosmological constant. In this
simple system it is possible to compute from scratch the value of this
constant, to compare it with other characteristic energy scales and hence
address the problem of its magnitude within this framework, suggesting a
different path for the solution of this longstanding puzzle. We find that, even
though this constant term is related with quantum vacuum effects, it is not
immediately related to the ground state energy of the condensate. On the
gravity side this result suggests that the interpretation and computation of
the cosmological term as a form of renormalized vacuum energy might be
misleading, its origin being related to the mechanism that instead produces
spacetime from its pregeometric progenitor, shedding a different light on the
subject and at the same time suggesting a potentially relevant role of analogue
models in the understanding of quantum gravity.
