Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)

By Jérôme Martin. 2012

827 citations recorded by the source corpus.

Abstract This article aims at discussing the cosmological constant problem at a pedagogical but fully technical level. We review how the vacuum energy can be regularized in flat and curved space–time and how it can be understood in terms of Feynman bubble diagrams. In particular, we show that the properly renormalized value of the zero-point energy density today (for a free theory) is in fact far from being 122 orders of magnitude larger than the critical energy density, as often quoted in the literature. We mainly consider the case of scalar fields but also treat the cases of fermions and gauge bosons which allows us to discuss the question of vacuum energy in super-symmetry. Then, we discuss how the cosmological constant can be measured in cosmology and constrained with experiments such as measurements of planet orbits in our solar system or atomic spectra. We also review why the Lamb shift and the Casimir effect seem to indicate that the quantum zero-point fluctuations are not an artifact of the quantum field theory formalism. We investigate how experiments on the universality of free fall can constrain the gravitational properties of vacuum energy and we discuss the status of the weak equivalence principle in quantum mechanics, in particular the Colella, Overhauser and Werner experiment and the quantum Galileo experiment performed with a Salecker–Wigner–Peres clock. Finally, we briefly conclude with a discussion on the solutions to the cosmological constant problem that have been proposed so far.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/294e86f0a804063953c9e6eeb6e821a0a5b806aa

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Citations in the corpus

Dynamical systems applied to cosmology: Dark energy and modified gravity (2017, methodology): “For more details we refer the reader to the classic reviews of Weinberg (1989, 2000), and more recent reviews by Carroll (2001), Martin (2012) and Padilla (2015).”
Hubble Tension: The Evidence of New Physics (2023, background): “The fundamental problem with the former is that there is a large discrepancy between the observations and theoretical expectations of Λ [24,26,29,30].”
HUBBLE PARAMETER MEASUREMENT CONSTRAINTS ON THE REDSHIFT OF THE DECELERATION–ACCELERATION TRANSITION, DYNAMICAL DARK ENERGY, AND SPACE CURVATURE (2016, background): “In addition, the binned H(z) 1 For reviews of this picture, as well as of the alternate modified gravity scenario, see Ratra & Vogeley (2008), Weinberg et al. (2013), Martin (2012), Joyce et al. (2016), and references therein.”
Trans-Planckian issues for inflationary cosmology (2012, background): “We may conjecture that the back-reaction of IR modes thus leads to a dynamical relaxation mechanism for a bare positive cosmological constant [122] (for a recent review on the cosmological constant problem, see [126]).”
Born–Infeld inspired modifications of gravity (2017, background): “One of the challenges is the cosmological constant problem, posing a naturalness problem due to the giant mismatch between its observed value and the radiative contributions from known massive particles to the vacuum energy [361, 292, 249].”
A systematic approach to generalisations of General Relativity and their cosmological implications (2018, background): “the cosmological constant problem [7, 8], representing the largest discrepancy between theoretical predictions and observations in all of science.”
Observational probes of cosmic acceleration (2012, background): “For a detailed discussion in the context of contemporary particle theory, see the review by Martin (2012).”
Dark Energy in Light of Multi-Messenger Gravitational-Wave Astronomy (2018, result): “Such a cosmological constant (CC) term is perfectly consistent with present observations but notoriously disagrees with theoretical expectations for the vacuum energy (Weinberg, 1989; Martin, 2012).”