Archive for chemistry

In Praise of Natural Sciences

Posted in Biographical, Education with tags , , , , on April 24, 2016 by telescoper

The other day I was chatting with some students in the Department of Physics & Astronomy at the University of Sussex. One thing that came up was the fact that I’m basing the material for my Second Year Theoretical Physics module on the notes I took when I was a second-year undergraduate student at Cambridge over thirty years ago. I mentioned that to counter suggestions that are often made that the physics curriculum has been excessively “dumbed down” over the years. It may have been elsewhere, of course, but not on my watch. In fact, despite the misfortune of having me as a lecturer, many of the students in my class are picking up things far faster than I did when I was their age!

Anyway, that led to a general discussion of the changing nature of university education. One point was that in my day there weren’t any four-year “Integrated Masters” degrees, just plain three-year Bachelors. Teaching was therefore a bit more compressed than it is now, especially at Cambridge with its shorter teaching terms. We teach in two 12-week blocks here at Sussex. Week 11 of the Spring Term is about to start so we’re nearing the finishing line for this academic year and soon the examinations will be upon us.

The other thing that proved an interesting point of discussion was that the degree programme that I took was the Natural Sciences Tripos That meant that I did a very general first year comprising four different elements that could be chosen flexibly. I quickly settled on Physics, Chemistry and  Mathematics for Natural Sciences to reflect my A-level results but was struggling for the fourth. In the end I picked the one that seemed most like Physics, a course called Crystalline Materials. I didn’t like that at all, and wish I’d done some Biology instead – Biology of Cells and Biology of Organisms were both options – or even Geology, but I stuck with it for the first year.

Having to do such a wide range of subjects was very challenging. The timetable was densely packed and the pace was considerable. In the second year, however, I was able to focus on Mathematics and Physics and although it was still intense it was a bit more focussed. I ended up doing Theoretical Physics in my final year, including a theory project.

My best teacher at School, Dr Geoeff Swinden,  was a chemist (he had a doctorate in organic chemistry from Oxford University) and when I went to Cambridge I fully expected to specialise in Chemistry rather tha Physics. I loved the curly arrows and all that. But two things changed. One was that I found the Physics content of the first year far more interesting – and the lecturers and tutors far more inspiring – than Chemistry, and the other was that my considerable ineptitude at practical work made me doubt that I had a future in a chemistry laboratory. And so it came to pass that I switched allegiance to Physics, a decision I am very glad I made. It was only towards the end of my degree that I started to take Astrophysics seriously as a possible specialism, but that’s another story.

As we are now approaching examination season I’ve been dealing with some matters in my role as External Examiner for Natural Sciences (Physics) at Cambridge, a position I have held since last year. It’s certaintly extremely interesting to see things from the other side of the fence, thirty years on since my finals. In particular I was struck last year by how many senior physicists there are at Cambridge who actually came as undergraduates expecting, like I did, to do Chemistry but also then switched. No doubt some moved in the opposite direction too, but the point is that the system not only allowed this but positively encouraged it.

Looking back, I think  there were great educational advantages in delaying  the choice of speciality the way a Natural Sciences degree did. New students usually have very little idea how different the subject is at university compared to A-level, so it seems unfair to lock them into a programme from Year 1. Moreover – and this struck me particularly talking to current students last week – a Natural Sciences programme might well prove a way of addressing the gender imbalance in physics by allowing female students (who might have been put off Physics at school) to gravitate towards it. Only 20% of the students who take Physics A-level are female, and that’s roughly the same mix that we find in the undergraduate population. How many more might opt for Physics after taking a general first year?

Another advantage of this kind of degree is that it gives scientists a good grounding in  a range of subjects. In the long run this could encourage greater levels of interdisciplinary thinking. This is important, since some of the most exciting areas of physics research lie at the interfaces with, e.g. chemistry and biology. Unfortunately, adminstrative structures often create barriers that deter such cross-disciplinary activities.



A-level Chemistry Examination (Paper 2) from 1981

Posted in Education with tags , , , on September 2, 2012 by telescoper

A few days ago I posted Paper 1 of the Chemistry A-level examination I took way back in 1981. Judging by the blog stats, that seemed to attract a bit of interest so I thought I’d follow it up with Paper 2 which, in contrast to the multiple-choice style of Paper 1, consists of longer questions and perhaps gives a better idea of whether anything has changed between then and now.

Anyway, as usual,  any comments from people who’ve done A-level Chemistry more recently would be very welcome through the Comments Box, e.g. is there anything  in this paper that you wouldn’t expect to see nowadays? Is it easier, harder, or about the same as current A-level Chemistry papers?

A-level Chemistry Examination Paper, Vintage 1981

Posted in Education with tags , , , on August 29, 2012 by telescoper

I don’t know how many followers of this blog are interested in Chemistry, but I thought I’d continue my irregular series of postings of old examination papers with my Chemistry A-level. This particular Paper was Paper 1 of 2 (although I did also take the “special” Paper 3). As you can see Paper 1 was of multiple-choice format, with 40 questions to answer in 75 minutes, which seems a bit stiff! Looking over the exam just now I can’t believe that there was a time when I actually knew this stuff. Nowadays I can only really do the first few questions – because they’re really physics – and I don’t even remember what most of the words mean in the other questions!

Anyway, as usual,  any comments from people who’ve done A-level Chemistry more recently would be very welcome through the Comments Box, e.g. is there anything  in this paper that you wouldn’t expect to see nowadays? Is it easier, harder, or about the same as current A-level Chemistry papers?

(Guest Post) Physics and Binary Creep

Posted in Education, Finance, Science Politics with tags , , , , , , on April 15, 2011 by telescoper

His Excel-lence (geddit?) Paul Crowther has been at it again, using his favourite packages sophisticated graph-plotting facilities to produce the interesting figures that go with another guest post….


Last week’s Times Higher Ed included a news item headlined ‘binary creep’, in which HEFCE were considering restricting support for PhD research students to universities of the highest research quality. Concerns were expressed in the article about a two stream future for universities – research intensives in the fast lane and ‘the rest’ in the slow lane. This reminded me of a recent Times Higher Ed interview with the former Commons’ Science and Technology Committee chairman, Lord (Phil) Willis. Lord Willis argued that the UK could probably sustain “no more than 30” universities with the capacity to attract the best global researchers and carry out world-class research, a view no doubt shared by ministers and civil servants within BIS. I should qualify the following line of thought by emphasising that this is not Government policy, although both stories reflect moves by funding agencies to further concentrate increasingly scarce resources on the highest ranked research universities. For example, in England HEFCE is expected to withdraw all quality-related (QR) support from 2* RAE research from 2012 onwards.

Mindful of the fact that in such a vision for the future, there would be a comparatively few, research intensive universities (`winners’) where would that leave the remainder (‘losers’), especially for physics? Research quality can be quantified in all manner of ways, but for simplicity I have adopted the Quality Index (QI) from Research Fortnight which provides a single mark out of 100 based on RAE quality profiles (4*:3*:2*:1* weighted 8:4:2:1). The chart below shows the  QI-ranked list of more-or-less all 120 UK universities who were rated in RAE 2008. It will come as no surprise to anyone that Oxbridge, LSE and Imperial top the rankings, closely followed by UCL and a few other high flyers, but beyond the top 10 perhaps more surprising there are no natural breaks in quality from Durham and QMUL in joint 11th place, to Bolton at 107th.

Thinking out loud about Willis’ assertion that the UK should not be spreading the jam more thinly than, say, the leading 30 universities, there would obviously be individual physics departments currently outside the top 30 which are ranked significantly higher than those within the top 30. To illustrate this, the chart also includes (in blue) physics QI scores for all teaching institutions that were assessed under the UOA 19 in RAE 2008. To blindly follow Lord Willis’ suggestion, 16 out of 42 institutions involved with physics research – comprising 37 per cent of all academic staff – would be clear losers. These would include one physics department raked within the top 10 (scoring 49) because its host institution is ranked 34th overall, while winners would include a department scoring 31, i.e. ranked 40th (out of 42) for physics, as a result of its university squeezing into the top 30. Chemistry – within the same RAE sub-panel as physics – reveals a broadly similar distribution, although there is perhaps a greater concentration of the highest research quality in the overall top 20, as the chart below illustrates.

Alternatively, if there is to be further concentration, one could argue that research funding should focus on, say, the top 20 physics departments regardless of the performance of their host institution. Indeed, already 80 percent of STFC spending goes to only 16 universities. Still, as RAE grades indicate, a strength of UK physics is the breadth of high quality research, with no natural break points until beyond 30th place in the rankings, as the final chart shows. Of course, RAE scores aren’t the sole criterion being discussed, with “critical mass” the other main driver. Due in large part to the big four, 70 per cent of physics academic staff submitted for RAE 2008 are in departments that are currently ranked in the top 20. Chemistry has a similar story to tell in the chart, albeit displaying a somewhat steeper QI gradient.

What might be the long-term consequences of a divergence between a small number of “research-facing” universities and the rest? It is apparent that if the number of physics departments involved in research were reduced by a third, some high quality research groups would be lost, regardless of precisely where the cleaver ultimately fell. Let’s too not forget that astrophysics represents the largest sub-field of physics from the last IOP survey, as measured in numbers of academics.

If policy makers don’t see anything fundamentally wrong with A-level physics being taught by teachers qualified, say, in biology, then they might too wonder whether physics degrees could be taught by academics lacking a physics research background? This might work for first year undergraduate courses, but thereafter isn’t more specialist knowledge needed that a research background most readily provides? How would the third of physics academics outside the top 30 universities react to the prospects of a teaching-only future? Many surely would consider jumping ship either to one of the chosen few or overseas, further decreasing the pool of those with research experience in the remaining physics departments. This is further complicated by the expected political desire that physics departments should be appropriately distributed geographically across England, Scotland, Wales and Northern Ireland.

As a final thought experiment, the fate of physics departments facing the prospect of a teaching-only future might also be binary in nature, either (a) whither and die, decreasing the range of institutions offering degrees in physics (or physical sciences, natural sciences etc.); perversely at a time when the Government are anxious to maintain the number of students studying Science, Technology, Engineering and Mathematics (STEM) subjects, or (b) thriving – free from the distractions of chasing dwinding research grants – by adapting to offer shorter duration physics degrees, described as “cheap and cheerful” by Dr David Starkey during the discussion on student fees on last Thursday’s Newsnight. To reiterate, it is not explicit Government policy to actively reduce the number of physics departments that receive research allocations, but this seems to be the general “direction of travel” in policy-makers speak, so I fear a rocky path ahead..


Flame Academy

Posted in Biographical, The Universe and Stuff with tags , , , , , , , on September 2, 2009 by telescoper

I heard on the radio this morning from that nice Mr Cowan that today is the anniversary of the start of the Great Fire of London which burned for four days in 1666. That provides for a bit of delayed synchronicity with yesterday’s post about the dreadful fires in the outskirts of Los Angeles and a similar conflagration in Athens (which now thankfully appears to be under control).

Fires are of course terrifying phenomena, and it must be among most people’s nightmares to be caught in one. The cambridge physicist Steve Gull experienced this at first hand when his boat exploded and caught fire recently. I’ll take this opportunity to wish him a speedy recovery from his injuries.

But frightening as such happenings are, a flame (the visible, light emitting part of a fire) can also be a very beautiful and fascinating spectacle. Flames are stable long-lived phenomena involving combustion in which a “fuel”, often some kind of hydrocarbon, reacts with an oxidizing element which, in the case of natural wildfires at any rate, is usually oxygen. However, along the way, many intermediate radicals are generated and the self-sustaining nature of the flame is maintained by intricate reaction kinetics.

The shape and colour of a flame is determined not just by its temperature but also, in a complicated way, by diffusion, convection and gravity. In a diffusion flame, the fuel and the oxidizing agent diffuse into each other and the rate of diffusion consequently limits the rate at which the flame spreads. Usually combustion takes place only at the edge of the flame: the interior contains unburnt fuel. A candle flame is usually relatively quiescent because the flow of material in it is predominantly laminar. However, at higher speeds you can find turbulent flames, like in the picture below!

Sometimes convection carries some of the combustion products away from the source of the flame. In a candle flame, for example, incomplete combustion forms soot particles which are convected upwards and then incandesce inside the flame giving it a yellow colour. Gravity limits the motion of heavier products away from the source. In a microgravity environment, flames look very different!

All this stuff about flames also gives me the opportunity to mention the great Russian physicist Yakov Borisovich Zel’dovich. To us cosmologists he is best known for his work on the large-scale structure of the Universe, but he only started to work on that subject relatively late in his career during the 1960s.  He in fact began his career as a physical chemist and arguably his greatest contribution to science was that he developed the first completely physically based theory of flame propagation (together with Frank-Kamenetskii). No doubt he used insights gained from this work, together with his studies of detonation and shock waves, in the Soviet nuclear bomb programme in which he was a central figure.

But one thing even Zel’dovich couldn’t explain is why fires are such fascinating things to look at. I remember years ago having a fire in my back garden to get rid of garden rubbish. The more it burned the more things  I wanted to throw on it,  to see how well they would burn rather than to get rid of them. I ended up spending hours finding things to burn, building up a huge inferno, before finally retiring indoors, blackened with soot.

I let the fire die down, but it smouldered for three days.


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