Cosmological Neutrinos

TL;DR

This paper discusses the predicted existence and properties of a cosmic background of low-energy neutrinos, highlighting their abundance and impact on the universe's evolution in the context of hot big-bang cosmology.

Contribution

It provides an overview of the theoretical prediction of cosmological neutrinos and their significance in the early universe's structure formation.

Findings

Neutrinos are the second most abundant particles in the universe.

Their effects were significant during the early universe when they were relativistic.

The number density of cosmological neutrinos is comparable to that of cosmic background photons.

Abstract

Within the context of hot big-bang cosmology, a cosmic background of presently low energy neutrinos is predicted to exist in concert with the photons of the cosmic background radiation. The number density of the cosmological neutrinos is of the same order as that of the photons of the cosmic background radiation. That makes neutrinos the second most abundant particle species in the universe. In the early universe, when these neutrinos were highly relativistic, their effects in determining the ultimate structure and evolution of the universe were significant.