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Department of Physics

The Cavendish Laboratory


The Present Cavendish

by Prof. Sir Brian Pippard 
from the booklet "A Hundred Years and More of Cambridge Physics".

A slate plaque in Free School Lane commemorates the first hundred years of the Cavendish, from its foundation by the first Cavendish Professor of Experimental Physics, James Clerk Maxwell, to the move of the Physics department to a green field site in West Cambridge. The name, made famous by Maxwell and his successors, was transferred and the original buildings are now the Old Cavendish Laboratory. Only those who never saw the conditions of work in the old buildings, overcrowded and often far from robust as to internal walls and floors, could deplore the sacrifice of rooms hallowed by J.J. Thomson and Rutherford in exchange for new quarters where their successors might stand a better chance of maintaining the great tradition.

This is not to imply that the choice was easy. Fears were expressed, both within the department and by many other members of the University, that teaching and research in Physics might become isolated from the rest of Science in Cambridge. Indeed, if there had been any reasonable chance that the Old Addenbroke's site would become available in the early Seventies, as was once envisaged, this would have been welcomed by all concerned as the ideal location for Physics, close to Engineering and Chemistry. As things have turned out it was lucky this plan was abandoned, and in any case the presence of Astronomy and Geophysics in West Cambridge has provided congenial neighbours. Separation from the other departments involved in the Natural Sciences Tripos has not proved as great a problem for the teaching as was feared by some, and as for the research it has thrived in a way that would have been impossible without the extra space now available. Finally, in justification of the move it must be remembered that the space vacated at the centre has allowed rehousing of other departments whose problems were hardly less acute. In the course of time it is to be hoped that the Cavendish will be joined in West Cambridge by others whose needs are still unsatisfied.

This, however, is very much in the future since there is no money coming in from Government sources for major building projects. Even in the late Sixties when the New Cavendish was being planned there were moments of grave doubt about the adequacy of the building grant, and this is reflected in two aspects of the buildings that eventually came into being: the cost was very low in comparison with earlier physics buildings elsewhere, and the hesitation that delayed the early stages of planning resulted in much more thorough discussion of the design than is usual with University buildings. This second point is worth stressing. The architects, Robert Matthew, Johnson-Marshall and Partners, were chosen for their notable work in the planning of York University, and by the time they arrived on the scene a building committee made up of members of the Department had already come to some conclusions about the desirable features of a physics laboratory. Even so, when a number of senior partners in the firm took up residence for a few days and talked to staff and students, they came back to the building committee with a battery of searching questions that the committee had not thought to ask themselves. As a result a clear view evolved about the organisation of a laboratory, especially the social organisation - who must have access to whom, who must be allowed to hide from public view, is it desirable for undergraduates to have free access to research laboratories etc. - the overall layout of the buildings reflects the outcome of these preliminary talks. The siting of the library, administration, stores and common room at the cross-roads to encourage chance meetings of people from different buildings; the embedding of Part II practical classes in the research areas; the open layout of the Mott building, with research groups clustered on two or three floors around a hall and staircase, visible to the passer-by yet not wholly exposed since the individual rooms that lead off the hall have their own privacy; these are all examples of the benefits of leisurely pondering on the issues, and they have resulted in a laboratory that has most notably achieved what was intended - scope for individual initiative, and incentive for workers in different groups to cooperate.

The Mott Building

The work on disordered materials in the Mott building exemplifies this point. Although the research groups that had developed separate, even competitive, identities in the old buildings still hold to their primal loyalties, with their own assistants, secretaries, workshops and darkrooms, there is much more exchange of ideas than hitherto between those in the Physics and Chemistry of Solids group whose primary interest is in the electrical behaviour of amorphous semiconductors, and those in (then) Metal Physics and Low Temperature Physics who are more concerned with the mechanical and thermal properties of glasses, both dielectric and metallic. One unfortunate consequence of shortage of funds, that the theoreticians who require less heavily serviced accommodation have to occupy the top floor instead of being mixed up among the experimenters, has not prevented valuable collaborations developing. The move away from well ordered crystalline solids towards the more difficult problems of disorder finds its parallels upstairs in the development of analytical and computational techniques for handling atomic groupings without the simplifications introduced by periodic structure. And catalysing the whole process, from a vantage point deeply embedded in the experimental areas, is the father-figure of disorder, as of so many other major advances in solid-state physics, Professor Mott himself.

At a time when we hear on every side how difficult it is to gain support for research it must be gratefully admitted that the Cavendish has nearly always been well treated by the University and the Research Councils, and in consequence has maintained an enviable range of modern equipment. Unfortunately, we are short of a most valuable commodity, technical experts dedicated to getting the best out of the highly sophisticated instruments and developing them still further. How to incorporate such people into the university structure is a country-wide problem for which no solution is yet in sight, but the obvious stimulus provided by those we have managed to attract encourages us to continue seeking means to appoint more.

It is one of the hazards of allowing the greatest freedom to first-class staff that their ideas may not always tally with conventional definitions of physics. It has long been Cavendish policy not to worry overmuch, provided the teaching does not suffer and the ideas are intellectually worthy. This policy, summed up in the motto "Physics is what physicists do", made the Cavendish thirty years ago the nursery of Molecular Biology, and then gave justification (if any were needed) for the presence of a thriving Energy Research Group whose techniques are nearer economics than physics. It is on the cards that some of the most popular research fields will fairly soon be priced out of the market, and a more liberal interpretation of what physics is about will then become commonplace; if so the Cavendish will find itself, as so often before, in the van of progress.