Electromagnetic and gravitational radiation from massless particles

TL;DR

This paper shows that classical physics cannot fully describe electromagnetic and gravitational radiation from massless particles, highlighting the need for quantum theory especially for high-frequency components.

Contribution

It demonstrates the limitations of classical theory in describing radiation from massless particles and emphasizes the importance of quantum effects and quantization of gravity.

Findings

Classical formulas diverge for massless particles' radiation.

Quantum electrodynamics predicts finite power for massless charges.

Classical gravity fails to describe radiation from massless particles, suggesting quantization is necessary.

Abstract

We demonstrate that full description of both electromagnetic and gravitational radiation from massless particles lies outside the scope of classical theory. Synchrotron radiation from the hypothetical massless charge in quantum electrodynamics in external magnetic field has finite total power while the corresponding classical formula diverges in the massless limit. We argue that in both cases classical theory describes correctly only the low-frequency part of the spectra, while the total power diverges because of absence of the UV frequency cutoff. Failure of description of gravitational radiation from massless particles by classical General Relativity may be considered as another appeal for quantization of gravity apart from the problem of singularities.