Inflation and Dark Matter from The Low Entropy Hypothesis and Modeling Mechanism of Modified Gravity

Abstract

The hypothesis of low entropy in the initial state of the universe usually explains the observed entropy increase is in only one time direction: the thermodynamic arrow of time. The Hamiltonian formalism is commonly used in the context of general relativity. The set of Lagrange multipliers are introduced in the formalism, and they are corresponding to the Hamiltonian constraints which are written in terms of "weak equality" - the equality is satisfied if the constraints hold. Follow the low-entropy hypothesis, we postulate a modeling mechanism - a weak equality (of modeling) that holds only on the subspace of the theory space of physical models defined by some modeling constraints. By applying the modeling mechanism, we obtain a specific model of modified gravity under specific modeling conditions. We derive a novel equation of modeling from the mechanism, that describes how different gravitational models emerge. The solution of the modeling equation naturally turns out to be the model of $R^2$-gravity (with additional terms) if ordinary matter is negligible. We also found that this mechanism leads to two models: large-field inflation and wave-like dark matter. Interestingly, the wave-like dark matter model is supported by the most recent observations of Einstein rings.

11 pages, Class. Quantum Grav (accepted on 21st Aug, 2024)

References in corpus (21)

• Modified Gravity and Cosmology
• f(R) theories
• Extended Theories of Gravity
• Axion Cosmology
• Wave Dark Matter
• Dark Matter from R^2-gravity
• Evolution of the Schrödinger--Newton system for a self--gravitating scalar field
• Cosmological Constraints on Bose-Einstein-Condensed Scalar Field Dark Matter
• Asymptotically Safe Inflation
• Inflation, Cosmic Perturbations and Non-Gaussianities
• Extended $f(R,L_m)$ gravity with generalized scalar field and kinetic term dependences
• Spontaneous Inflation and the Origin of the Arrow of Time
• Einstein rings modulated by wavelike dark matter from anomalies in gravitationally lensed images
• Asymptotically safe inflation from quadratic gravity
• Is dark matter a BEC or scalar field?
• Ghostly Galaxies as Solitons of Bose-Einstein Dark Matter
• On the problem of initial conditions for inflation
• The roots of scalar-tensor theory: an approximate history
• Minimally modified gravity with an auxiliary constraint: a Hamiltonian construction
• Is the Hypothesis About a Low Entropy Initial State of the Universe Necessary for Explaining the Arrow of Time?
• Does Inflation Provide Natural Initial Conditions for the Universe?