Hints towards the Emergent Nature of Gravity

• Main Authors: Linnemann, Niels S, Visser, Manus R
• Format: Journal Article
• Language: English
• Published: 28-11-2017
• Subjects: Physics - General Relativity and Quantum Cosmology; Physics - High Energy Physics - Theory; Physics - History and Philosophy of Physics
• DOI: 10.48550/arxiv.1711.10503

A possible way out of the conundrum of quantum gravity is the proposal that
general relativity (GR) is not a fundamental theory but emerges from an
underlying microscopic description. Despite recent interest in the emergent
gravity program within the physics as well as the philosophy community, an
assessment of the theoretical evidence for this idea is lacking at the moment.
We intend to fill this gap in the literature by discussing the main arguments
in favour of the hypothesis that the metric field and its dynamics are
emergent. First, we distinguish between microstructure inspired from GR, such
as through quantization or discretization, and microstructure that is not
directly motivated from GR, such as strings, quantum bits or condensed matter
fields. The emergent gravity approach can then be defined as the view that the
metric field and its dynamics are derivable from the latter type of
microstructure. Subsequently, we assess in how far the following properties of
(semi-classical) GR are suggestive of underlying microstructure: (1) the
metric's universal coupling to matter fields, (2) perturbative
non-renormalizability, (3) black hole thermodynamics, and (4) the holographic
principle. In the conclusion we formalize the general structure of the
plausibility arguments put forward.