[Paper Review] Cyclic anamorphic cosmology

Anna Ijjas|arXiv (Cornell University)|Oct 9, 2016

Cosmology and Gravitation Theories3 citations

TL;DR

This paper proposes a cyclic anamorphic cosmology by adapting a classically stable, non-singular bounce to connect an Einstein gravity contracting phase with an anamorphic smoothing phase. The key contribution is demonstrating that the anamorphic scenario—originally designed for a single contraction-to-expansion transition—can be extended into a fully cyclic model, resolving initial conditions problems without requiring a beginning in time.

ABSTRACT

Cyclic models of the universe have the advantage of avoiding initial conditions problems related to postulating any sort of beginning in time. To date, the only known viable examples of cyclic models have been ekpyrotic. In this paper, we show that the recently proposed anamorphic scenario can also be made cyclic. The key to the cyclic completion is a classically stable, non-singular bounce. Remarkably, even though the bounce construction was originally developed to connect a period of contraction with a period of expansion both described by Einstein gravity, we show here that it can naturally be modified to connect an ordinary contracting phase described by Einstein gravity with a phase of anamorphic smoothing. The paper will present the basic principles and steps in constructing cyclic anamorphic models.

Motivation & Objective

• To extend the anamorphic scenario, originally a single-cycle model, into a fully cyclic cosmological framework.
• To address the initial conditions problem in cosmology by eliminating the need for a beginning in time.
• To demonstrate that a non-singular, classically stable bounce can connect Einstein gravity contraction with anamorphic smoothing.
• To establish the feasibility of cyclic behavior in anamorphic models through a consistent dynamical framework.

Proposed method

• Adapting a previously developed non-singular bounce mechanism originally designed for ekpyrotic-like transitions to connect contraction under Einstein gravity with an anamorphic phase.
• Modifying the bounce construction to ensure compatibility with the anamorphic smoothing mechanism, which involves a specific form of scalar field dynamics.
• Employing a dynamical framework where the bounce smoothly transitions from a contracting phase governed by Einstein gravity to a phase of anamorphic smoothing.
• Ensuring classical stability of the bounce to prevent quantum instabilities or singularities in the cyclic evolution.
• Using effective field theory techniques to describe the transition across the bounce while preserving the anamorphic smoothing mechanism.
• Verifying that the cyclic structure remains consistent with the original anamorphic scenario’s ability to generate scale-invariant perturbations.

Experimental results

Research questions

• RQ1 Can the anamorphic scenario be extended into a cyclic cosmological model through a non-singular bounce?
• RQ2 How can a stable bounce connect a phase of Einstein gravity contraction with an anamorphic smoothing phase?
• RQ3 Does the cyclic anamorphic model preserve the initial condition avoidance and scale-invariant perturbation generation of the original anamorphic scenario?
• RQ4 What are the dynamical and stability conditions required for such a cyclic transition to be classically viable?
• RQ5 Is the bounce mechanism compatible with both the contracting phase and the anamorphic phase without introducing singularities or instabilities?

Key findings

• A non-singular, classically stable bounce can successfully connect a contracting phase governed by Einstein gravity with a phase of anamorphic smoothing.
• The cyclic anamorphic model avoids initial conditions problems by eliminating the need for a beginning in time.
• The bounce mechanism is adaptable to the anamorphic scenario, enabling a cyclic evolution without violating the dynamics of the anamorphic smoothing phase.
• The model maintains the key feature of generating scale-invariant perturbations, consistent with observations.
• The cyclic structure is dynamically stable and consistent with effective field theory descriptions across the bounce.
• The framework demonstrates that anamorphic cosmology is not limited to single-cycle models but can be extended into a fully cyclic cosmological scenario.