ABSTRACT
First let us review the classical description of radiation. It is most convenient to work in the transverse gauge in which the scalar potential φ(rt) vanishes and the vector potential A(rt) is divergence-free () https://www.w3.org/1998/Math/MathML"> ∇ ⋅ A ( r t ) = 0. https://s3-euw1-ap-pe-df-pch-content-public-u.s3.eu-west-1.amazonaws.com/9780429499265/ff9ae276-bf0f-4700-9154-eaa3ea82fbc6/content/eq1431.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
