The Pace of Modern Technology

In 1946, J. H. E. Griffiths published in Nature the first account of an experimental observation of the phenomenon of ferromagnetic resonance. Naturally enough this paper elicited little interest from electrical engineers, nor did the theoretical work of C. Kittel and D. Polder published during the next three years which gave a quantitative explanation of Griffith's experiment. Now, however, approximately eight years after Polder's rather complete theoretical paper on ferromagnetic resonance this issue of an engineering journal is devoted exclusively to the practical ramifications of this first experimental observation. Many of the devices referred to in this issue are beyond the development stage and are already in widespread use in microwave systems, Although the delay between research and development and between development and production usually seems interminably long to those most actively associated with the development of engineering devices, it appears, in retrospect at least, that in this case the progress has been almost astounding. In fact, it is illuminating to go back to the beginning of the electronic era and look at the basic experiments which led to the development of the vacuum tube in order to see how our technological timetable has been greatly compressed during the last fifty years.