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

TL;DR

This paper proposes a novel mechanism based on low entropy and modeling constraints that leads to the emergence of modified gravity models, including $R^2$-gravity, and explains phenomena like inflation and wave-like dark matter.

Contribution

It introduces a new modeling mechanism using weak equality constraints that derives specific gravity models from fundamental principles.

Findings

Derives a novel equation of modeling for gravity.

Shows emergence of $R^2$-gravity under certain conditions.

Supports wave-like dark matter model with recent observations.

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.