题目：A simple derivation of the electromagnetic field of an arbitrarily moving charge

摘要：
The expression for the electromagnetic field of a charge moving along an arbitrary trajectory is
obtained in a direct, elegant, and Lorentz invariant manner without resorting to more complicated
procedures such as differentiation of the Liénard-Wiechert potentials. The derivation uses arguments
based on Lorentz invariance and a physically transparent expression originally due to Thomson for
the field of a charge that experiences an impulsive acceleration.

文献：H. Padmanabhana, Am. J. Phys. 77 (2), February 2009.

讲这个内容之前，你最好先简单综述一下电动力学中的标准处理。