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What is Critical Physics?

My career included school physics, university physics, and the history of science. I taught A-level physics for 11 years in Nairobi, and for about 20 years in Oxford. I have also taught university physics and mathematics for about 15 years at Oxford Brookes University, and the history of physics and the history of mathematics for about 40 years at the University of Oxford.

It has taken me decades to discover my ‘true vocation’ in physics. It is not mathematical physics nor experimental physics nor the history of physics but what I term ‘critical physics’.

By the ‘critical physics’ I understand two forms of scholarship in physics:  

(a)    ‘The scholarship of definitions’. Rigorous definitions in physics are often the starting point of pedagogy or of theoretical research or of physical applications. As physics grows, improved definitions are sometimes required. The longer this renewal is postponed the weaker the foundations of physics.  Familiar terms such as ‘mass’, ‘energy’, ‘work’, ‘field’, ‘potential’, ‘vector potential’, the statistical concept of temperature,  ‘entropy’, and ‘enthalpy’,  and many more, are grasped intuitively and applied successfully, but not well understood. For example, the many conflicting definitions of the term ‘potential’ introduced in the 19th century continue to plague circuit theory today. It is extremely difficult to clarify and upgrade definitions and then to gain a consensus among professional physicists, but it is well worth while because it deepens physics and strengthens its foundations. Different skills are needed here, skills that were in plentiful supply in the 19th century, but not so prevalent today.


(b)   ‘Unfinished physics’: an examination of unfinished physics in foundational papers. It is often a matter of scientific fashion or industrial need or chance which aspects of the foundational work of Helmholtz, or Kelvin, or Maxwell, or Lorentz were developed by their successors. Sometimes deep ambiguities in their foundational papers have never been clarified. Sometimes the sheer weight of established tradition edges out later clarifications. And usually the missing or ambiguous physics is invisible today.  And this process is entirely innocent, with no suppression of information. Occasionally, it is the most difficult but at the same the most important concepts that remain undigested, such as Maxwell’s final theory of energy published in an obscure book two years before he died. Creativity by a great mind, in its historical context, may be lost if it is not properly understood. Such a recovery may give new life to significant areas of physics.  In my studies of the history of physics I have become frequently aware of this. Textbook after textbook have missed an important solution in the theory of magnetic energy proposed by Kelvin – because he did it so confusingly. There is a vast amount of research work to be done to complete the piecemeal and ambiguous developments of physics. And here I am looking only at classical physics. Deepening, clarifying and completing classical physics will have an inevitable an impact on quantum theory and relativity.

‘Critical physics’ is interdisciplinary in that it requires a rigorous understanding of the topic in question, in a style which the French call haute vulgarisation (accessible and scholarly and with a necessary minimum of formalism, acronyms and technical jargon); it should be sensitive pedagogically and it must be well informed historically.

Here are examples of what I call critical physics:

(a)  Maxwell, J C Matter and Motion (London: Society for Promoting Christian Knowledge. 1st ed. 1877)

(b) Roche, J ‘Introducing motion in a circle’

(c) Roche, J ‘What is momentum’? 

(d)  Roche, J ‘Axial vectors, skew-symmetric tensors and the nature of the magnetic field’

I plan to introduce more of these from time to time.

Through this page I hope to discover more like-minded ‘critical physicists’.

I will welcome and include studies of this sort into my webpage.

John Roche, Linacre College, Oxford.

Email: john.roche at linacre.ox.ac.uk

Copyright © John Roche 2014

This version: 25th June 2014


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