Hot Stuff, Looking Cool..

Posted in The Universe and Stuff with tags , , , , , on September 15, 2010 by telescoper

It’s nice for a change to have an excuse to write something about science rather than science funding, as a press release appeared today concerning the discovery of a new supercluster by Planck in collaboration with the X-ray observatory XMM-Newton.

The physics behind this new discovery concerns what happens to low-energy photons from the cosmic microwave background (CMB) when they are scattered by extremely hot plasma. Basically, incoming microwave photons collide with highly energetic electrons with the result that they gain energy and so are shifted to shorter wavelengths. The generic name given to this process is inverse Compton scattering, and it can happen in a variety of physical contexts. In cosmology, however, there is a particularly important situation where this process has observable consequences, when CMB photons travel through the extremely hot (but extremely tenuous) ionized gas in a cluster of galaxies. In this setting the process is called the Sunyaev-Zel’dovich effect.

The observational consequence is slightly paradoxical because what happens is that the microwave background can appears to have a lower temperature (at least for a certain range of wavelengths) in the direction of a galaxy cluster (in which the plasma can have a temperature of 10 million degrees or more). This is because fewer photons reach the observer in the microwave part of the spectrum that would if the cluster did not intervene; the missing ones have been kicked up to higher energies and are therefore not seen at their original wavelength, ergo the CMB looks a little cooler along the line of sight to a cluster than in other directions. To put it another way, what has actually happened is that the hot electrons have distorted the spectrum of the photons passing through it.

Here’s an example of the Sunyaev-Zel’dovich effect in action as seen by Planck in seven frequency bands:

At low frequencies (in the Rayleigh-Jeans part of the spectrum) the region where the cluster is looks cooler than average, although at high frequencies the effect is reversed.

The magnitude of the temperature distortion produced by a cluster depends on the density of electrons in the plasma pervading the cluster n, the temperature of the plasma T, and the overall size of the cluster; in fact, it’s propotional to n×T integrated along the line of sight through the cluster.

Why this new result is so interesting is that it combines very sensitive measurements of the microwave background temperature pattern  with sensitive measures of the X-ray emission over the same region of the sky. Plasma hot enough to produce a Sunyaev-Zel’dovich distortion of the CMB spectrum will also generate X-rays through a process known as thermal bremsstrahlung.  The power of the X-ray emission depends on the square of the electron density n2 multiplied by the Temperature T.

Since the Sunyaev-Zel’dovich and X-ray measurements depend on different mathematical combinations of the physical properties involved the amalgamation of these two techniques allows astronomers to probe the internal details of the cluster quite precisely.

The example shown here in the top two panels is of a familiar cluster – the Coma Cluster as mapped by Planck (in microwaves) and, by an older X-ray satellite called ROSAT, in X-rays. The two distributions have very similar morphology, strongly suggesting that they have a common origin in the cluster plasma.

The bottom panels show comparisons with the distribution of galaxies as seen in the optical part of the spectrum. You can see that the hot gas I’ve been talking about extends throughout the space between the galaxies. In fact, there is at least as much matter in the hot plasma as there is in the individual galaxies in objects like this, but it’s too hot to be seen in optical light. This could reasonably be called dark matter when it comes to its lack of optical emission, but it’s certainly not dark in X-rays!

The reason why the intracluster plasma is so hot boils down to the strength of the gravitational field in the cluster. Roughly speaking, the hot matter is in virial equilibrium within the gravitational potential generated by the mass distribution within the cluster. Since this is a very deep potential well, electrons move very quickly in response to it. In fact, the galaxies in the cluster are also roughly in virial equilibrium so they too are pulled about by the gravitational field. Galaxies don’t sit around quietly in clusters, they buzz about like bees in a bottle.

Anyway, the new data arising from the combination of Planck and XMM-Newton has revealed not just one cluster, but a cluster of clusters (i.e. a “supercluster”):

It’s early days for Planck, of course, and this is no more than a taster.
The Planck team is currently analysing the data from the first all-sky survey to identify both known and new galaxy clusters for the early Sunyaev-Zel’dovich catalogue, which will be released in January of 2011 as part of the Early Release Compact Source Catalogue. The full Sunyaev-Zel’dovich catalogue may well turn out to be the most enduring legacy of the Planck mission.


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De Juribus Unum

Posted in Biographical with tags , , on September 14, 2010 by telescoper

I got home from work this evening and found an ominous Manilla envelope among my mail. I assumed that it was a tax demand, since a lot of people seem to be getting them these days. But it wasn’t. It was a Jury Summons, requiring me to attend for Jury Service at Cardiff Law Courts, one of the fine civic buildings in Cathays Park, at a date in November 2010. I was relieved (that it wasn’t a tax demand) but also strangely excited. I’ve never actually done Jury Service, you see, and I quite enjoy the odd courtroom drama on the telly. Since I don’t actually have any lectures this semester I think I might as well get it over with, rather than asking for a deferral.

Incidentally, Question F on the form upon which one has to reply to the Jury Summons asks (sic):

Do you currently have, or have had in the past, any disorder or disability of the mind?

Do you think if I correct their grammar they’ll think I’m a busybody and let me off?

Anyway, in anticipation of the forthcoming excitement, I thought I’d post this clip from one of my favourite old movies, 12 Angry Men, starring the great Henry Fonda which delivers an object lesson in how to deal with prejudice.

I’m sure the real thing is nothing like this, of course. The only true tale I can remember was a former colleague of mine who was on a Jury that acquitted a young man of being a drug dealer on the grounds that the quantity of marijuana he was carrying was so small it must have been for his personal use only. The amount concerned was 12 ounces…..

Any readers with other juristic anecdotes to share? If so, you know where to put them. (I mean, in the comments box.)


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Smalltown Boy

Posted in Biographical, Music with tags , , , , on September 13, 2010 by telescoper

This time of year always fills me with nostalgia. All the talk of new students arriving, taking their first steps on a new life away from home, reminds me of the time many years ago when got on the train in Newcastle and made the long journey to Cambridge with most of my belongings in suitcases. No-one in my family had ever gone to university before I went to Cambridge – and  none have gone since, if truth be told!

I’d only been to Cambridge once before (for the interview). When I got there, after several hours’ travel, and sat down in the room in Magdalene College that had been allocated to me, I felt someone (possibly me) had made a terrible mistake and there was no way I would ever feel like I belonged there.

In fact, I’m now feeling second-order nostalgia, because one of my very first blog posts, almost two years ago, was about that trip. I remember sitting in the garden writing it just as I remember sitting in my new room in Cambridge all those years ago thinking “What on Earth am I doing here?”.

Having set  off on a sentimental journey, I might as well complete it with this  track from Bronski Beat which – for reasons which I hope are obvious – completes the sense of wistfulness. This was released in 1984, a  couple of years after I left home, but I’ve never been one to let mere chronology get in the way of self-indulgence.

The Invisible Ma(so)n

Posted in Science Politics with tags , on September 12, 2010 by telescoper

I couldn’t resist sharing this little item I saw on the back page of the last issue of Research Fortnight:

WHERE’S KEITH? Once upon a time STFC chief executive
Keith Mason could be seen out and about, taking flak
in public for all manner of woes. But Research Fortnight
can’t help noticing that he has been remarkable only
by his absence recently. No site visits, no photo ops, no
community chit chats. He is due to stand down in March
2012, but how should we interpret his low profile in the
meantime? Surely no one can have built up that much
unused holiday?

On the other hand, the last time the Chief Executive of the Science and Technology Facilities Council (STFC) got involved in a Comprehensive Spending Review (in 2007), the outcome for his organization could hardly have been described as positive. Perhaps other members of the STFC Executive have decided to send him on a fact-finding mission to the Outer Hebrides in order to stop him messing up the negotations this time?


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Star-gazer

Posted in Poetry, The Universe and Stuff with tags , , on September 11, 2010 by telescoper

Forty-two years ago (to me if to no one else
The number is of some interest) it was a brilliant starry night
And the westward train was empty and had no corridors
So darting from side to side I could catch the unwonted sight
Of those almost intolerably bright
Holes, punched in the sky, which excited me partly because
Of their Latin names and partly because I had read in the textbooks
How very far off they were, it seemed their light
Had left them (some at least) long years before I was.

And this remembering now I mark that what
Light was leaving some of them at least then,
Forty-two years ago, will never arrive
In time for me to catch it, which light when
It does get here may find that there is not
Anyone left alive
To run from side to side in a late night train
Admiring it and adding noughts in vain.

(written in 1963, by Louis MacNeice)


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Astronomy Look-alikes, No. 40

Posted in Astronomy Lookalikes, The Universe and Stuff with tags , , , on September 10, 2010 by telescoper

Obviously someone else has already noticed the remarkable similarity between the structure of the human brain and that revealed by computer simulations of the large-scale structure of the Universe.

Does this mean that dark matter is really just all in the mind?


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Astronomy Photographer of the Year

Posted in Art, The Universe and Stuff with tags , , , on September 10, 2010 by telescoper

Amidst the doom and gloom of spending cuts and Ministerial incompetence we’re sometimes liable to forget what it’s all about. Last night provided us with a reminder, in the form of the Astronomy Photographer of the Year competition held at the National Maritime Museum (site of the Royal Observatory at Greenwich). There’s a varied selection of gorgeous entries on today’s Guardian, but this stunning image by Tom Lowe was the overall winner. Congratulations to him!


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Student Grants and/or Research Loans

Posted in Politics, Science Politics with tags , , , on September 9, 2010 by telescoper

I’m still a bit depressed after the events I blogged about yesterday. Some days you wonder why you bother, and this has been one of them. However, at least it’s got me rattled enough to stand back and think about the state of the UK university system in more general terms so I thought I’d jot down an idea which is probably barking mad, but has been at the back of my mind for some time.

The basic point is that universities essentially do two things, teaching and research. However, when you think about it, there’s a fundamental inconsistency in the way these are funded. It seems to me that correcting this anomaly could significantly improve  both the main benefits  universities contribute to the UK economy.

First, research. I wrote yesterday about using taxpayer’s money to fund research in universities:

If it’s going to pay off in the short term it should be funded by private investors or venture capitalists of some sort. Dragon’s Den, even. When the public purse is so heavily constrained, it should only be asked to fund those things that can’t in practice be funded any other way.

I’ve just remembered that a similar thing was said in in the Times Higher recently, in a piece about the new President of the Royal Astronomical Society:

Notwithstanding the Royal Academy of Engineering’s “very unfortunate” recent submission to the government spending review – which argued that the need to rebalance the UK economy required public spending to be concentrated on applied science – Professor Davies is confident he can make a good case for spending on astrophysics to be protected.

Research with market potential can already access funding from venture capitalists, he argued, while cautioning the government against attempting to predict the economic impact of different subjects.

This is pretty much the opposite of what the Treasury thinks. It wants to concentrate public funds in projects that  can demonstrate immediate commercial potential. Taxpayer’s money used in this way ends up in the pockets of entrepreneurs if the research succeeds and, if it doesn’t,  the grant has effectively been wasted. My proposal, therefore, is  to phase out research grants for groups that want to concentrate on commercially motivated research and replace them with research loans. If the claims they make to secure the advance are justified they should have no problem repaying it  from the profits they make from patent income or other forms of exploitation. If not, then they will have to pay back the loan from their own funds (as well as being exposed as bullshit merchants). In the current economic situation the loans could be made at very low interest rates and still save a huge amount of the current research budget for higher education. Indeed after a few years – suggest the loans should be repayable in 3-5 years, it would be self-financing. I think a large fraction of research in the Applied Sciences and Engineering should be funded in this way.

The money saved by replacing grants  to commercially driven research groups with loans could be re-invested in those areas where public investment is really needed, such as pure science and medicine. Here grants are needed because the motivation for the research is different. Much of it does, in fact, lead to commercial spin-offs, but that is accidental and likely to appear only in the very long term. The real motivation of doing this kind of research is to enrich the knowledge base of the UK and the world in general. In other words, it’s for the public good. Remember that?

Most of you probably think that this is a crazy idea, but if you do I’ll ask you to now think about how the government funds teaching in universities and ask yourself why research is handled in such a  different way.

Way back in the mists of time when I was a student, I didn’t have to pay fees and even got a maintenance grant from the government that was more-or-less sufficient to live on. That system changed so that students don’t get grants any more, but may qualify for loans. They also have to pay a contribution to their fees, but the government still pays an amount directly to the university on their behalf.

This change of policy happened because the (then) Labour government wanted to boost the rate of participation in universities, but didn’t think the taxpayer should pay the whole cost. The logic goes that the students benefit from their education, e.g. in terms of increased earnings over their working lifetime, so they should pay a contribution to it.

The problem with all this is that it has led to a huge increase in enrolment on degree courses in “vocational” areas such as Leisure & Tourism, Media Studies, and Business while traditional courses, such as those in STEM disciplines, providing the sort of rigorous intellectual training that is essential for many sectors of the economy, have struggled to keep up. This is partly because subjects like Mathematics and Physics are difficult, partly because they are expensive, and partly because the UK school system has ceased to function as preparation for such courses.

I’m by no means against universities supplying training in vocational subjects, but because these are the areas where the primary beneficiary is indeed the student, I don’t think the government should subsidise them as much as the more rigorous courses that we really need to encourage the brightest students to take up.

The fix I’d propose for this within the current tightly constrained budget is to cut government funding for vocational subjects and use the money to subsidise those courses contributing to the intellectual wealth of the country. I don’t mean just science, incidentally, I think we have a big problem with participation many other areas, such as modern languages. The best students – in chosen areas – should not only get their fees paid, they should also get maintenance grants as in the old days. Students should not be prevented from doing, e.g., a Business studies degree, or from doing anything without a state scholarship, but should understand that they have to pay for it.

If it’s fair to ask students to contribute to their teaching, it’s fair to ask commercial companies to pay for the research that they exploit. Just as student grants should be re-introduced for certain disciplines, so should research loans be introduced for others. You know it makes sense.

However, if you want to tell me why it doesn’t, via the comments box, please feel free!


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Unravelling Cable

Posted in Politics, Science Politics with tags , , , , , , , on September 8, 2010 by telescoper

I woke up this morning with the Vince Cable Blues, owing to an item on the BBC News concerning a speech by the Secretary of State for Business, Innovation and Skills that clearly signals that the forthcoming Comprehensive Spending Review will entail big cuts to the UK’s science budget.

It was a depressing way to start the day, but I for one wasn’t particularly surprised by the news. We all know big cuts are coming, the only remaining questions are “how big?” and “where?”. However, when the text of the speech was released, I was shocked by what it revealed about the Secretary of State’s grasp of his brief.  Read it for yourself and see if you agree with me.

Vince Cable: Out of his Depth

Of course there are the obligatory  platitudes about the quality of the UK’s scientific research, a lot of flannel about the importance of “blue skies” thinking, before he settles on the utilitarian line favoured by the Treasury mandarins who no doubt wrote his speech for him: greater concentration of research funding into areas that are “theoretically outstanding” (judged how?) or “commercially useful” (when?). In fact one wonders what the point of this speech was, as it said very little that was specific except that the government is going to cut science. We knew that already.

For what it’s worth I’ll repeat my own view that “commercially useful” research should not be funded by the taxpayer through research grants. If it’s going to pay off in the short term it should be funded by private investors or venture capitalists of some sort. Dragon’s Den, even. When the public purse is so heavily constrained, it should only be asked to fund those things that can’t in practice be funded any other way. That means long-term, speculative, curiosity driven research. You know, science.

So was Cable’s speech was feeble-minded, riddled with clichés, and totally lacking in depth or detail? Yes.  Was it surprising? No.

What was surprising, at least to me, is Cable’s deliberate use of spurious numbers to back up his argument. For example,

Its is worth noting in the last RAE 54 per cent of submitted work was defined as world class and that is the area where funding should be concentrated.

This appears to be what Cable  was referring to when he stated on the BBC Radio 4 Today Programme that  “45% of research grants were not of excellent standard”.

For one thing, there’s a difference between a research grant and the money allocated by HEFCE through the Research Assessment Exercise (RAE); more about that in a moment. Moreover, at least in England,  RAE funding is only allocated to grades 3* and 4* anyway, so the concentration he talks about is already happening. The comment is made all the more meaningless, however, because the 54% was actually imposed on the assessment panels anyway; they were told to match the outcome of their deliberations to a target profile. The figure quoted is therefore hardly an objective measure of the quality of scientific research in the UK.

When it comes to research grants – usually obtained from one of the Research Councils, such as the Science and Technology Facilities Council (STFC) scientists apply for funding and their proposals are assessed by panels. In the case of STFC I can assure every one that the only proposals funded are those graded excellent, and there isn’t anything like enough money to fund all the proposals graded that way. Further cuts will simply mean that  even more excellent research will have to be scrapped, and even more excellent scientists will  go abroad.

This basic misunderstanding convinces me that Vince Cable is completely out of his depth in this job. That’s very unfortunate because it means he will probably be susceptible to manipulation by the dark side (i.e. the anti-science lobby in Whitehall). Already  someone – most likely a Civil Service mandarin with an axe to grind – seems to have  duped him into thinking that 45% of  taxpayer’s money funds mediocre research. What with him already singing so enthusiastically from the Treasury hymn sheet, I fear they have got him exactly where they want him. Rarely has a new arrival in the Whitehall jungle gone native so quickly.

Another remark of his that was quoted today is that “the bar will have to be raised somewhat” in terms of  science funding.  At the next General Election I hope the British people, especially those foolish enough to opt for the Liberal Democrats last time, will “raise the bar” when it comes to deciding who is worthy of their vote. I’m sure of one thing, though. The fraction of British politicians who are “mediocre” is an awful lot higher than 45%.


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Twenty20

Posted in Cricket with tags , , , , , on September 8, 2010 by telescoper

Just a quick post to share a picture taken at  last night’s Twenty20 International in Cardiff between England and Pakistan. We had the entire spectrum of Welsh weather to contend with, but the worst of yesterday’s rain was over well before the match started and the SWALEC stadium, just ten minutes’ walk from my house, was a fine sight under a variety of peculiar cloud formations and the floodlights, as you can tell  from the picture I took on my phone.

Pakistan won the toss and batted first, but didn’t make a very good fist of it and were bowled out for a mere 89 from their 20 overs. England had a little wobble during the run chase but in the end won comfortably by 6 wickets.

Unfortunately, the crowd numbered only a few thousand so the atmosphere was a bit flat and Pakistan’s poor showing with the bat made it all a bit of anti-climax, but it was still a good way to precede a nice curry. I’ve heard various theories as to why the attendance was so poor, but I think it’s pretty obvious: at £45  for a game whose format ensures it can last no longer than about three hours,  tickets for this match were just too expensive. I think the authorities should think again about their pricing strategy.


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