Ultimate fate of the universe

Theoretical scenarios for the end of the universe

The ultimate fate of the universe is a topic in cosmology that explores the possible scenarios for the end of the universe. These scenarios are based on the current understanding of the universe's expansion, the nature of dark energy, and the overall geometry of the universe.

Overview

The fate of the universe is determined by its density and the properties of dark energy. The universe's expansion rate, governed by the Friedmann equations, plays a crucial role in predicting its future.

Possible Scenarios

Big Freeze

The Big Freeze scenario, also known as the heat death, suggests that the universe will continue to expand indefinitely. As it expands, galaxies will drift apart, stars will burn out, and the universe will cool down to a state of maximum entropy, where no thermodynamic free energy is available to do work.

Big Crunch

Illustration of the Big Crunch scenario

The Big Crunch is a theoretical scenario where the expansion of the universe eventually reverses, leading to a contraction. In this scenario, the universe could collapse back into a singularity, potentially leading to a new Big Bang.

Big Rip

The Big Rip hypothesis posits that the universe's expansion accelerates to the point where galaxies, stars, planets, and eventually atomic particles are torn apart. This scenario depends on the properties of dark energy, particularly if it is a form of phantom energy with a equation of state parameter less than -1.

Big Bounce

The Big Bounce theory suggests that the universe undergoes a series of expansions and contractions. After a Big Crunch, a new Big Bang could occur, leading to a cyclic model of the universe.

False Vacuum Decay

In the false vacuum decay scenario, the universe could transition to a lower-energy state, causing a bubble of "true vacuum" to expand at the speed of light, altering the fundamental constants of nature and potentially destroying all structures in the universe.

Friedmann Universes

Diagram of Friedmann universes

The Friedmann universes are solutions to the Friedmann equations that describe different possible geometries of the universe:

• Closed universe: A universe with positive curvature that could lead to a Big Crunch.
• Open universe: A universe with negative curvature that expands forever.
• Flat universe: A universe with zero curvature that expands forever but at a decreasing rate.

Related pages

• Cosmology
• Dark energy
• Heat death of the universe
• Friedmann equations

References

• Peebles, P. J. E. (1993). Principles of Physical Cosmology. Princeton University Press.
• Weinberg, S. (2008). Cosmology. Oxford University Press.