Broadening Horizons

Beyond the straight and narrow of their disciplines, there is far more that should form part of what every PhD student is exposed to during their doctoral (and indeed post-doctoral) years. I was reminded of this fact when I attended a symposium last week in my department, as part of the Winton Programme on Sustainability,  which touched on many different aspects of energy efficiency. Entitled ‘Energy Efficiency…the physical limits’, it was an excellent day covering a wide range of topics and (I was pleased to see) including a significant biological component; when the programme was first set up I was concerned the emphasis might remain wholly synthetic. Here I will focus on two contrasting issues from the talks, both of which illustrate the breadth of coverage that I felt was so powerful for the mixed audience. This included students and professors from many disciplines (and also incuding David Harding,  the ex-physicist who now runs Winton Capital Management and  whose generous donation to the department of £20M allowed the Winton Programme to be set up). The full programme can be found here.

I was particularly impressed by the first talk, feeling it was just the sort of thing students should hear (and there were a great number of them in the audience) to contextualise their own specific field of research, but probably rarely do. It was given by Malcolm Keay of the Oxford Institute for Energy Studies and set the scene excellently for the detailed technical talks that came later. A flavour of his talk can be found in this presentation from his web pages although this obviously isn’t the set of slides he used last week.

A central theme of his talk is what I’ve now learned is known as the Jevons Paradox, namely that if you increase the efficiency with which you use some resource(in this case energy) you tend to increase the amount used. I hadn’t known this was the correct term to use, but an obvious example is what happens with improvements in technology for our computer and TV screens. As we have moved away from the old-fashioned CRT tubes to flat screen LCD devices, so the screens have got bigger and bigger. Had the screens stayed the same size, the efficiency would indeed have led to reduction in energy consumption. Instead, by substantially increasing screen size the energy use has, on the contrary, increased substantially overall.  Jevons  (1835-1882) was clearly a man ahead of his time, a British political economist before such people really existed (and probably before the label had been coined), who came to a realisation of the paradox which now bears his name by considering the use of coal. He noted that the improved design of steam engines pioneered by James Wat , markedly more efficient than Newcomen’s original designs, had led to a vast expansion of their use so that as a consequence coal consumption soared.

Keay took a much more modern example for his talk, that of efficient air conditioning (specifically with reference to the US). Because air conditioning is now efficient and (relatively) cheap, many more people choose to live in the hotter parts of the US; they live in houses that don’t have the traditional thick adobe walls of the south and west, because those were built to aid cooling and this is no longer seen as necessary;  as a consequence the thermal insulation of these new thin-walled houses is poor. These people live in sprawling urban conurbations (he used the example of Atlanta compared with Barcelona, cities with comparable populations but the former covers 26 times the land area) and hence need to use far more fuel for transportation to get them to their place of work, schools and shops. So, from introducing that first step of more efficient air conditioning as a luxury for a few, the many now use it to live in energy-inefficient houses with an energy-intensive lifestyle due to the nature of the cities they live in. Only if US fuel tax rises substantially is any reversal of this pattern of behaviour likely to be seen, with a consequent benefit from the original increased efficiency on the total energy resource needed.

For the average student in the audience studying new materials for photovoltaic devices or trying to further miniaturise some transistor design, I hope this was as startling as informative. It isn’t sufficient to be clever, one must also understand where what one is doing fits into the larger picture and for me this talk of Keay’s set the scene excellently for what came later. It certainly got me thinking about a whole bunch of stuff which I’d never mentally pulled together before.

In our training (these days I hesitate to use the word education with respect to what we provide for PhD students) we put an increasing emphasis on innovation and entrepreneurial skills. Important stuff, but we should not lose sight of the fact that beyond the invention, creation and construction that may add up to innovation, there are many additional factors that need to be considered before a product ‘makes’ it. I’m not talking here about talking to venture capitalists or successfully setting up a spin-out company, but the more political aspects. It’s not just the funding of the actual research that matters, but the economic models on which decisions to move ahead or not are based, and the consequences of different courses of action. Factoring Jevons paradox into this is probably not immediately relevant, but the other facts and figures Keay gave about what genuinely constitutes efficiency when it comes to carbon emissions (although he never actually used the phrase whole life analysis) most certainly are; keeping our students well-informed on the bigger picture should never be forgotten.

The other talk from the symposium I’d like to highlight briefly as being particularly thought-provoking, was that by Simon Laughlin  on ‘What makes brains efficient?’. Simon is a Cambridge University Zoologist who has primarily researched Drosophila brains. I got to know him originally through standing at the primary school gate – I distinctly remember a discussion with him about the new BBSRC when the Research Councils were reconfigured back in the 1990s – rather  than through science (after all my knowledge about Drosophila brains is distinctly limited). But he has always been interested in interdisciplinary aspects of his science. His talk was particularly well pitched for this audience, taking the mechanics of the brain function and relating it to those terms that would be familiar to physical scientists. For instance:

• chemical circuitry is good for Boolean operations whereas electrical signals are much faster and good for long distance transmission, whilst also being much more energy intensive;
• the brain operates very close to the noise (Landauer)  limit, just a factor of two or so above it. It is highly miniaturised, with about 3 km of neurones per cubic mm;
• the brain uses sparse coding, sorting information into parallel low rate lines and sending the minimum information necessary because speed and precision are energetically expensive.

He illustrated all these points beautifully and by carefully positioning his biological facts in a framework familiar to the physicists in the audience, he was able to put his key messages across succinctly and clearly. It was an excellent demonstration of how to give such a cross-disciplinary talk, and it was only possible because he has been in dialogue with the community for so many years he knows what messages work, whilst still being able to put across his key biological findings.

I highlight these two talks because they both provided different types of insight from the standard fare of semiconductor physics, quantum efficiencies (even if in the context of purple bacterial photosynthesis), FET’s, MOSFET’s and other acronyms and the limits of microfabrication one might have expected from the Symposium’s title. For me it was the wide diversity of topics which made the day so stimulating, but which reminded me of the importance not only of the actual style of delivery for talks, but also of ensuring the context of one’s work is always clear. We shortchange our students if all we offer them are the technicalities without the overarching framework.