Vacuum Energy: Myths and Reality

TL;DR

This paper critically examines common myths about vacuum energy and the cosmological constant, arguing that many misconceptions are dispelled through thermodynamic considerations, making vacuum energy a plausible source of dark energy.

Contribution

It challenges prevailing myths about vacuum energy, providing a thermodynamic perspective that aligns the natural vacuum energy with observed dark energy levels.

Findings

Many myths about vacuum energy are incorrect when considering quantum ground state thermodynamics.

The natural value of vacuum energy aligns with observed dark energy despite zero-point energy divergences.

Vacuum energy is a plausible candidate for dark energy.

Abstract

We discuss the main myths related to the vacuum energy and cosmological constant, such as: ``unbearable lightness of space-time''; the dominating contribution of zero point energy of quantum fields to the vacuum energy; non-zero vacuum energy of the false vacuum; dependence of the vacuum energy on the overall shift of energy; the absolute value of energy only has significance for gravity; the vacuum energy depends on the vacuum content; cosmological constant changes after the phase transition; zero-point energy of the vacuum between the plates in Casimir effect must gravitate, that is why the zero-point energy in the vacuum outside the plates must also gravitate; etc. All these and some other conjectures appear to be wrong when one considers the thermodynamics of the ground state of the quantum many-body system, which mimics macroscopic thermodynamics of quantum vacuum. In particular, in spite of the ultraviolet divergence of the zero-point energy, the natural value of the vacuum energy is comparable with the observed dark energy. That is why the vacuum energy is the plausible candidate for the dark energy.