Time and space, frequency and wavevector: or, what I talk about when I talk about propagation
arXiv:1408.0128
Abstract
The existence of waves with negative frequency is a surprising and perhaps controversial claim which has recently been revisted in optics and for water waves. Here I explain a context within which to understand the meaning of the "negative frequency" conception, and why it appears in some cases.
6 pages, 3 figures