The linear optical response of the quantum vacuum

TL;DR

This paper demonstrates that the classical interpretation of vacuum polarization aligns with quantum electrodynamics, revealing the vacuum's properties as a Lorentz-invariant medium with a running fine structure constant.

Contribution

It provides a quantum electrodynamics-based explanation for vacuum polarization and clarifies the vacuum's role as a Lorentz-invariant medium with a variable coupling constant.

Findings

Vacuum polarization is consistent with QED.

The speed of light remains constant.

The fine structure constant varies with energy scale.

Abstract

We show that the interpretation of $\mathbf{D}=\varepsilon_{0} \mathbf{E}$ as vacuum polarization is consistent with quantum electrodynamics. A free electromagnetic field polarizes the vacuum but the magnetization and polarization currents cancel giving zero source current. The speed of light is a universal constant while the fine structure constant that couples the EM field to matter runs. In that sense, the quantum vacuum can be understood as a modern Lorentz invariant ether.