Expanding Universe: slowdown or speedup?

TL;DR

This paper reviews various theoretical approaches to understanding the accelerated expansion of the universe, including dark energy, modified gravity, and holographic principles, highlighting their implications and differences.

Contribution

It provides a comprehensive overview of existing models explaining cosmic acceleration, emphasizing the fundamental and novel perspectives involved.

Findings

Multiple models can account for acceleration

Dark energy remains a leading explanation

Holographic principles offer new insights

Abstract

The kinematics and dynamic interpretation of the cosmological expansion is reviewed in a widely accessible manner with emphasis on the acceleration aspect. Virtually all the approaches that can in principle account for the accelerated expansion of the Universe are reviewed, including dark energy as an item in the energy budget of the Universe; modified Einstein equations; and, on a fundamentally new level, the use of the holographic principle.