Differentiating between modified gravity and dark energy

Arthur Lue, Román Scoccimarro, Glenn Starkman

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The nature of the fuel that drives today’s cosmic acceleration is an open and tantalizing mystery. We entertain the suggestion that the acceleration is not the manifestation of yet another new ingredient in the cosmic gas tank, but rather a signal of our first real lack of understanding of gravitational physics. By requiring that the underlying gravity theory respect Birkhoff’s law, we derive the modified gravitational force law necessary to generate any given cosmology, without reference to the fundamental theory, revealing modifications of gravity at scales typically much smaller than today’s horizon. We discuss how, through these modifications, the growth of density perturbations, the late-time integrated Sachs-Wolfe effect, and even solar-system measurements may be sensitive to whether today’s cosmic acceleration is generated by dark energy or modified gravitational dynamics, and are subject to imminent observational discrimination. We argue how these conclusions can be more generic, and probably not dependent on the validity of Birkhoff’s law.

    Original languageEnglish (US)
    JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
    Volume69
    Issue number4
    DOIs
    StatePublished - Feb 6 2004

    ASJC Scopus subject areas

    • Nuclear and High Energy Physics
    • Physics and Astronomy (miscellaneous)

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