# Whether an enormously large energy density of the quantum vacuum is catastrophic

## TL;DR

This paper examines the implications of the quantum vacuum's large energy density, discussing how renormalization techniques affect its perceived gravitational effects and questioning the observability of the bare cosmological constant.

## Contribution

It clarifies the role of renormalization in addressing the vacuum energy problem and argues that the large energy density may be nonobservable due to renormalization.

## Key findings

- Renormalization sets the cosmological constant to zero or a small value.
- Bare quantities in quantum field theory may be nonobservable.
- Gravitational effects of large vacuum energy might be unmeasurable.

## Abstract

The problem of an enormously large energy density of the quantum vacuum is discussed in connection with the concept of renormalization of physical parameters in quantum field theory. Using the method of dimensional regularization, it is recalled that the normal ordering procedure of creation and annihilation operators is equivalent to a renormalization of the cosmological constant leading to its zero and nonzero values in Minkowski space-time and in the standard cosmological model, respectively. It is argued that a frequently discussed gravitational effect, resulting from an enormously large energy density described by the nonrenormalized (bare) cosmological constant, might be nonobservable much like some other bare quantities introduced in the formalism of quantum field theory.