David S Walton
David S. Walton | |
|---|---|
| Alma mater | University of Newcastle |
| Known for | Ivor Catt |
| Scientific career | |
| Fields | Atomic physics, electromagnetic theory, digital electronics |
David S Walton is a British physicist, electronics engineer and teacher, known chiefly as a long-time collaborator of the British electronics engineer Ivor Catt. With Catt and Malcolm Davidson he formed the "Catt, Walton and Davidson" partnership, whose late-1970s articles and books challenged the conventional textbook treatment of Maxwell's displacement current and put forward a model of the capacitor as a transmission line.
Biography
Walton took his first degree in Physics at the University of Newcastle and remained there to carry out research in experimental atomic physics, leading to a PhD. His first teaching post was as a Lecturer in Physics at Trinity College Dublin, where he worked under the Nobel Prize winner E. T. S. Walton (no relation). At Trinity College he carried out research in electron time-of-flight spectroscopy and on anthracene scintillators.
He then left academic life to set up an electronics company, where he researched and published articles and a book on signal transmission and design issues in fast digital systems. This work led him on to the foundational concepts of electromagnetic theory. He subsequently worked for a multinational company and for a number of smaller companies, eventually running his own consultancy business in information technology; from 1999 to 2002 he was contracted to companies in Utrecht and Brussels to provide consultancy support for the management of their IT infrastructure.
In 2003 Walton made a complete career change and took up a physics teaching post at Emmanuel College, Gateshead, where he formally qualified as a teacher under the Graduate Teacher Programme. He taught at Emmanuel College for eight years before being appointed Head of Physics at Barnard Castle School in 2011.
Scientific contributions
Walton proposed that a capacitor is properly understood as a transmission line rather than as a lumped component. Working with Catt and Davidson on the theory and practice of high-speed digital logic, he argued that examination of the behaviour of the dielectric in a lumped capacitor shows displacement current to have no physical reality, and that in the absence of an ether there is no rationale for it. According to Catt's account, it was Walton who, in May 1976, first drew the conclusion "So that gets rid of displacement current" — a step central to what Catt later called "Theory C".
The group's arguments were set out in two articles in Wireless World: "Displacement current" (December 1978) and "The History of Displacement Current" (March 1979), both co-authored by Catt, Davidson and Walton. The articles provoked considerable controversy among electrical engineers and physicists.
Walton has also argued that Faraday's law and conservation of charge together imply the existence of electromagnetic energy travelling at a single fixed velocity with a determined relationship between the electric and magnetic fields, and that because the mathematics is reversible these two physical laws may be regarded as consequences of the nature of electromagnetic energy rather than the reverse. He has examined the anomalies, including the "Catt Anomaly", that arise when classical electrodynamics is applied to step propagation in a transmission line, and has proposed models of inductance and capacitance based on the transmission-line model.
In October 2013 Walton and Catt gave a joint seminar on electromagnetism at the Asynchronous Systems Laboratory, Newcastle University, presenting Theory C and its treatment of the transverse electromagnetic (TEM) wave, displacement current and unconventional models of the capacitor and the transmission line.
Publications
- Ivor Catt, David S. Walton and Malcolm Davidson, Digital Hardware Design, Macmillan, 1979. ISBN 0-333-25981-5
- Ivor Catt, David S. Walton and Malcolm Davidson, Digital Electronic Design, Volume 1, CAM Publishing, 1979. ISBN 0-906340-00-4
- Ivor Catt, Malcolm Davidson and David S. Walton, "Displacement current", Wireless World, December 1978
- Ivor Catt, Malcolm Davidson and David S. Walton, "The History of Displacement Current", Wireless World, March 1979