Cyclic model

Lore & Background

This puzzling situation remained until the early 21st century when dark energy provided new hope for a consistent cyclic cosmology. It describes a universe exploding into existence repeatedly over time, with two parallel orbifold planes colliding periodically in a higher-dimensional space. Dark energy corresponds to a force between the branes, solving the monopole, horizon, and flatness problems. Other cyclic models include conformal cyclic cosmology by Roger Penrose, loop quantum cosmology predicting a quantum bridge between contracting and expanding branches, and a model by Nikolai Gorkavyi involving black hole mergers and gravitational waves. Cyclic models regained attention by the mid 2020s when tensions between Lambda-CDM model predictions and DESI mapping observations regarding dynamic dark energy left the possibility of a Big Bounce open.

Reader's Guide

Cyclic models represent a significant alternative to the standard Big Bang cosmology, offering a way to avoid a singular beginning and end to the universe. The resurgence of interest in cyclic models in the mid 2020s, driven by tensions in Lambda-CDM and DESI observations, underscores their enduring relevance. These models challenge the notion of a unique Big Bang and propose a universe that may be eternal, with each cycle providing a complete history. Their legacy lies in pushing the boundaries of theoretical cosmology and offering testable predictions for future observations.

Did You Know?

• The Steinhardt–Turok model proposes that two parallel orbifold planes collide periodically in a higher-dimensional space.
• The Baum–Frampton model assumes phantom energy with an equation of state parameter w < -1.