Archive for February, 2011

Astronomy Look-alikes, No. 48

Posted in Astronomy Lookalikes with tags , on February 28, 2011 by telescoper

Is it possible that Professor of Astrophysics and Cosmology at the University of Cambridge Anthony Lasenby might be related to the late Quentin Crisp?


Who is the best actor not to win an Oscar?

Posted in Uncategorized with tags , , on February 28, 2011 by telescoper

Waking to the news that Colin Firth won the Best Actor Oscar for his role as George VI in The King’s Speech, I thought it would be fun to consider outstanding acting performances that for one reason or another didn’t win an Oscar.

My nomination is for Sean Connery’s spellbending performance as Brother William of Baskerville in The Name of the Rose (a “palimpsest” of Umberto Eco’s novel of the same title). In fact you can watch the whole film (in pieces) on Youtube:

Other nominations through the comments box please!


Crossing Words

Posted in Crosswords with tags , , , on February 27, 2011 by telescoper

It’s been a while since I posted anything about crosswords, so the fact that I saw my name in today’s Observer gives me an excuse to do so now.

First, I was delighted to get another point for a Very Highly Commended (VHC) clue in the ongoing Azed clue-setting competition. The latest competition puzzle was Azed No. 2019. This was an interesting one, incorporating a variation on the “Plain” Azed puzzle in that the 12 by 12 square grid was actually divided vertically into two rectangular puzzles side-by-side. Clues for each half of the resulting “Right & Left” puzzle were run together, usually without punctuation, and with either side coming first. Solvers had to determine the location of the join between the clues, solve each part, and then figure out which side of the puzzle the answers had to go. I think it was a very enjoyable puzzle, with Azed’s skill strongly in evidence not only in constructing the clues but also in disguising the splices.

The two words for which clues were invited for the competition were OVERAWE and HENOTIC; the latter is a fairly unfamiliar term, defined in the puzzle as “tending to unify”. The clue that won me a VHC was

Cow or ewe cooked with odd bits of veal serving to make one nice hot stew?

Here I’m using “cow” as a definition of “OVERAWE”, with subsidiary anagram of OR+EWE+VA (odd bits of VEAL), with “cooked” as an anagram indicator; “serving to make one” defines HENOTIC, clued with another anagram NICE+HOT, with anagram indicator “stew”. I think it’s an easy clue, but I was quite pleased at the way the two halves run into each other to  produce a reasonable surface reading. Above all, I think it’s fair – no superfluous words and no dodgy syntax.

Anyway, I’ve now got 3 VHC mentions this year, which is as many as I’ve ever won in the annual competition,  so if I can just get one more it will be a personal best. There are 5 puzzles remaining this year, so maybe I’ll manage it!

A few weeks ago I won a prize in the Everyman crossword competition – also in the Observer. This is a much more straightforward puzzle than Azed and I usually do it more as a warm-up exercise than anything else but still post the completed grid off every week. One day last week I came home from work to find a note from DHL saying that they’d left a package with my next-door neighbour. It turned out to be a package of Penguin books: a Concise English Dictionary; a Concise Thesaurus; a Dictionary of Proverbs; a Dictionary of English Idioms; and the Penguin Book of Facts (a kind of encyclopedia). Anyone who’s been to my house knows that I have no shortage of dictionaries already, but I’m pleased with the others.

I finished this week’s Everyman just before starting to write this post. For the second week running there’s a clue formed by an indirect anagram. In this instance it is:

End of game inventor reviewed (2-4)

The answer is NO-SIDE (the signal indicating the end of a rugby match). The subsidiary indication is an anagram of EDISON (“inventor”). This is called an indirect anagram because the letters to be formed into the anagram do not actually appear in the clue. Most British setters frown upon this type of clue, not because they are hard – the one above certainly isn’t difficult to solve – but because they aren’t Ximenean and are therefore unfair.  Azed would certainly never countenance such a clue, though an increasing number of setters – especially those for the Grauniad – seem to adopt a much more libertarian approach.


`Difficult to Defend’

Posted in Education, Finance with tags , , on February 26, 2011 by telescoper

My copy of the Times Higher arrived a little late this week, so I’ve only just seen the latest evidence that the Westminster government’s plans for English Higher Education are degenerating into farce.

For a start it seems that the government made a serious error in believing that the Office For Fair Access (known to its few friends as OFFA) actually doesn’t have the legal authority to impose fee levels on universities. The government had assumed that they would be able to prevent all universities charging the maximum £9K allowed under the new rules. But they can’t.

Since the increased tuition fee is being offset by cuts of up to 80% in teaching budgets it’s no surprise that universities want to maximise the income from fees. Oxford, Cambridge, Imperial College and UCL have all already indicated that they will go for the maximum, which isn’t surprising since these are among the leading universities in the country. It may be that some universities, perhaps from the ex-Poly sector, might try to go for the `pack ’em high and sell ’em cheap’ approach to undergraduate degrees, but a more challenging issue is what the middle-grade universities will do. Will they try to compete on price, or will they fear that charging less than £9K will get them branded as second-rate?

However, if all universities charge £9K – which has always seemed to me to be the most likely outcome – then this costs the government much more than it anticipated, because it has to provide a much higher amount in loans. David Willetts has argued that the £9K limit is `difficult to defend’, claiming that despite the cuts a fee of this size would lead to a 40% increase in teaching resource. This isn’t actually true because universities will have to devote a large slice of the fee income to supporting less-well-off students and they are also being hit by huge cuts in capital funding, which will have to be made up some way. Methinks Willett’s famous two brains might have got their wires crossed.

Whether the £9k level is defensible or not, the government appears powerless to stop universities charging it, so is threatening to penalise research grants or to cut the number of student places if too many try it. This looks like panic to me.

The current state of British Higher Education policy is difficult to defend in other ways too. In among the figures spun out by Willetts is one that reveals that 80% of UK students are in subjects outside the area of Science, Technology, Engineering and Mathematics (STEM), which attract a lower level of central funding than STEM disciplines. However, the differential is not as large as you might think: there’s only a factor two between the lowest band (D, including Sociology, Economics, Business Studies, Law and Education) and the STEM band B (including my own subject, Physics). The real difference in cost is much larger than that, and not just because science subjects need laboratories and the like.

To give an example, I was talking last week to a student from a Humanities department at a leading University (not my employer). Each week she gets 3 lectures and one two-hour seminar, usually run by a research student. That’s it for her contact with the department. In my School, a typical student can expect around 20 contact hours per week including lectures, exercise class, laboratory sessions, and a tutorial (usually in a group of four). The vast majority of these sessions are done by full-time academic staff, not PDRAs or PhD students, although we do employ such folks in laboratory sessions and for a very small number of lectures. It doesn’t take Albert Einstein to work out that 20 hours of staff time costs a lot more than 3, and that’s even before you include the cost of the laboratories and equipment needed to teach physics. In the current system, however, students pay the same fee for STEM and non-STEM subjects.

This situation not only works as a powerful disincentive for a university to invest in expensive subjects, such as physics, but also rips off arts students who are given very little teaching in return for their fee. It is fortunate for this country that scientists working in its universities show such dedication to teaching as well as research that they don’t try to do what our cousins in the arts do. I sense a growing consensus, however, that we’re being ripped off too.

I suppose it could be argued that the big cuts in teaching grant in England do something to redress this anomaly, as the central funding element for Arts & Humanities subjects is cut to zero in the new funding regime. On the other hand, however, if universities do charge £9K for all subjects then the differential between arts and sciences will turn out to be lower than 2:1, as the central funding element for STEM subjects is far less than £9K. On the other other hand, if STEM subjects were to charge a higher fee than the others then demand would probably collapse.

To get another angle on this argument, consider the comments made by senior members of the legal profession who are concerned about the drastic overproduction of law graduates. Only about half those doing the Bar Professional Training Course after a law degree stand any chance of getting a job as a lawyer in the UK. Contrast this with the situation in science subjects, where we don’t even produce enough graduates to ensure that schools have an adequate supply of science teachers. The system is completely out of balance.

I don’t see anything in the post-Browne era that will alter this ridiculous situation. STEM subjects will continue to be strangled and universities will continue to overproduce graduates in other areas. Somebody has to get a grip. I doubt the Westminster government is capable of doing this. It has already delayed its planned White Paper on Higher Education, providing yet another indication that it has completely lost the plot.

Or maybe it’s making a complete botch of the situation deliberately, as part of a cunning plan to encourage universities to go private?


A First Problem in Astrophysics

Posted in Education, The Universe and Stuff with tags , , , , on February 25, 2011 by telescoper

When I first arrived at Cambridge University (nearly 30 years ago) to begin my course in Natural Sciences, eventually leading to a specialism in Physics, one of the books we were all asked to buy was the Cavendish Problems in Physics. One of the first problems I had to solve for tutorial work was from that collection, and I have been setting it (in a slightly amended form) for my own students ever since I started lecturing. I thought I’d put it up here because I think there might be a few budding theoretical astrophysicists who’ll find it interesting and because it provides a simple refutation of a crazy theory that has been doing the rounds on Twitter all morning.

I like this problem because it involves a little bit of lateral thinking, because not all the information given seems immediately relevant to the question being asked, but you can get a long way by just writing down the pieces of information given and thinking about how you might use simple physical ideas to connect them to the answer.

If you haven’t seen this problem before, why not have a go?

Using only the information given in this Question, estimate the ratio of the mean densities of the Earth and Sun:

i) the angular diameter of the Sun as seen from Earth is half a degree

ii) the length of 1° of latitude on the Earth’s surface is 100km

iii) the length of a year is 3×107 seconds

iv) the acceleration due to gravity at the Earth’s surface is 10 m s-2.

HINT: You do not need to look up anything else, not even G!

The answer you should get is that the mean density of the Earth is something like 3.5 times that of the Sun, although the information given in the question isn’t all that accurate.

In fact the mean density of the Earth is about 5500 kg per cubic metre, and that of the Sun is about 1400 kg per cubic metre; the average density of the Sun is just 40% higher than water, which is perhaps surprising to the uninitiated….

The density of solid iron on the other hand is about 7900  kg per cubic  metre, and even higher than that if it is compressed…

UPDATE: I’ve added my Solution.


Astronomy Look-alikes, No. 47

Posted in Astronomy Lookalikes with tags , on February 25, 2011 by telescoper

Not many people know that the “A” in Professor John A Peacock actually stands for “Acker” (i.e. Peacock is aka Bilk), although it’s clear the reason he’s not better known as a clarinettist is his failure to wear the appropriate form of hat.

I’ve also included a recording of the man himself playing a medley of his hit, Stranger on the Shore, accompanied by a selection of photographs of Cardiff Bay:

John A Peacock

Acker Bilk


Astronomy Look-alikes, No. 46

Posted in Astronomy Lookalikes with tags , , on February 24, 2011 by telescoper

I recently received an anonymous tipoff (from Haley Gomez) drawing attention to the remarkable similarity in visual appearance between esteemed Plumian Professor of Astronomy and Experimental Philosophy at the University of Cambridge Rob Kennicutt and the Muppet Show’s resident comedian Fozzie Bear. I hear they sound similar too! I wonder if by any chance they might be related?

Fozzie Bear


Annual Appraisal

Posted in Biographical with tags , on February 24, 2011 by telescoper

Today’s the day. My annual Staff Appraisal with the Big Boss. I’ve filled in the forms and am ready to go. I expect it will go pretty much like this, except without the beards.


In February

Posted in Biographical, Poetry with tags , , on February 23, 2011 by telescoper

Another busy day – mainly filled with form-filling but also including a tutorial and a meeting of our cosmology discussion group – and tonight, for the second week running, I’m off to a lecture at Cardiff Scientific Society. This time it’s by our own Haley Gomez entitled Smoking Supernovae. And here am I trying to give up!

Anyway, I’m going to do what I usually do when I haven’t got time for a proper post and that is put up a bit of poetry. Appropriate for the time of year, in hopeful anticipation of the forthcoming spring, I offer you this (from a poem entitled In February written by Alice Meynell).

Rich meanings of the prophet-Spring adorn,
Unseen, this colourless sky of folded showers,
And folded winds; no blossom in the bowers;
A poet’s face asleep in this grey morn.
Now in the midst of the old world forlorn
A mystic child is set in these still hours.
I keep this time, even before the flowers,
Sacred to all the young and the unborn


Which side (of the Einstein equations) are you on?

Posted in The Universe and Stuff with tags , , , , , , on February 22, 2011 by telescoper

As a cosmologist, I am often asked why it is that people talk about the cosmological constant as if it were some sort of vacuum energy or “dark energy“. I was explaining it again to a student today so I thought I’d jot something down here so I can use it for future reference. In a nutshell, it goes like this. The original form of Einstein’s equations for general relativity can be written

R_{ij}-\frac{1}{2}g_{ij}R = \frac{8\pi G}{c^4} T_{ij}.

The precise meaning of the terms on the left hand side doesn’t really matter, but basically they describe the curvature of space-time and are derived from the Ricci tensor R_{ij} and the metric tensor g_{ij}; this is how Einstein’s theory expresses the effect of gravity warping space. On the right hand side we have the energy-momentum tensor (sometimes called the stress tensor) T_{ij}, which describes the distribution of matter and its motion. Einstein’s equations can be summarised in John Archibald Wheeler’s pithy phrase: “Space tells matter how to move; matter tells space how to curve”.

In standard cosmology we usually assume that we can describe the matter-energy content of the Universe as a uniform perfect fluid, for which the energy-momentum tensor takes the simple form

T_{ij} = -pg_{ij} +\left(p+\rho c^2\right) U_i U_j,

in which p is the pressure and \rho the density; U_i is the fluid’s 4-velocity.

Einstein famously modified (or perhaps generalised) the original equations by adding a cosmological constant term \Lambda to the left hand side thus:

R_{ij}-\frac{1}{2}g_{ij}R -\Lambda g_{ij} = \frac{8\pi G}{c^4} T_{ij}.

Doing this essentially modifies the description of gravity, or appears to do so because it happens to be written on the left hand side of the equation. In fact one could equally well move the term involving \Lambda to the other side and absorb it into a redefined energy-momentum tensor, \tilde{T}_{ij}:

R_{ij}-\frac{1}{2}g_{ij}R = \frac{8\pi G}{c^4} \tilde{T}_{ij}.

The new energy-momentum tensor needed to make this work is of the form

\tilde{T}_{ij}=T_{ij}+ \left(\frac{\Lambda c^{4}}{8 \pi G} \right) g_{ij}= -\tilde{p} g_{ij} +\left(\tilde{p}+\tilde{\rho} c^2\right) U_i U_j


\tilde{p}=p-\frac{\Lambda c^4}{8\pi G}

\tilde{\rho}=\rho + \frac{\Lambda c^4}{8\pi G}

So the cosmological constant now looks like you didn’t modify gravity at all, but created an additional contribution to the pressure and density of the original fluid. In fact, considering the correction terms on their own it is clear that the cosmological constant acts exactly like an additional perfect fluid contribution with p=-\rho c^2.

This is just one simple example wherein a modification of the gravitational part of the theory can be made to look like the appearance of a peculiar form of matter. More complicated versions of this idea – most of them entirely speculative – abound in theoretical cosmology. That’s just what cosmologists are like.

Over the last few decades cosmology has suffered an invasion by been stimulated and enriched by particle physicists who would like to understand how such a mysterious form of energy might arise in their theories. That at least partly explains why, in one sense at least,  modern cosmologists prefer to dress to the right.

Incidentally, another interesting point is why people say such a fluid describes a cosmological “vacuum” energy. In the cosmological setting, i.e. assuming the fluid is distributed in  a homogeneous and isotropic fashion then the energy density of the expanding Universe varies with (cosmological proper) time according to

\dot{\rho}=-3\left(\frac{\dot{a}}{a}\right) \left(\rho + \frac{p}{c^2}\right)

so for our strange fluid, the second term in brackets vanishes and we have \dot{\rho}=0. As the universe expands, normal forms of matter and radiation get diluted, but the energy density of this stuff remains constant. It seems to me to be quite appropriate for a vacuum to something which, no matter how hard you try,  you can’t dilute!

I hope this clarifies the situation.