Check out this dramatic and slightly alarming picture of a huge filament emanating from the surface of the Sun, courtesy of NASA’s Solar Dynamics Observatory. The filament is about 700,000km long, apparently – that’s an entire Solar Radius. It’s expected to collapse back into the Sun at some point, an event which should be rather exciting! For more details see here.
Even better, here’s a close-up animation.
It reminds me a bit of that Balrog thing in The Lord of the Rings that gave Gandalf such a good run for his money.
Of Heaven or Hell I have no power to sing, I cannot ease the burden of your fears, Or make quick-coming death a little thing, Or bring again the pleasure of past years, Nor for my words shall ye forget your tears, Or hope again for aught that I can say, The idle singer of an empty day.
But rather, when aweary of your mirth, From full hearts still unsatisfied ye sigh, And, feeling kindly unto all the earth, Grudge every minute as it passes by, Made the more mindful that the sweet days die– –Remember me a little then I pray, The idle singer of an empty day.
The heavy trouble, the bewildering care That weighs us down who live and earn our bread, These idle verses have no power to bear; So let em sing of names rememberèd, Because they, living not, can ne’er be dead, Or long time take their memory quite away From us poor singers of an empty day.
Dreamer of dreams, born out of my due time, Why should I strive to set the crooked straight? Let it suffice me that my murmuring rhyme Beats with light wing against the ivory gate, Telling a tale not too importunate To those who in the sleepy region stay, Lulled by the singer of an empty day.
Folk say, a wizard to a northern king At Christmas-tide such wondrous things did show, That through one window men beheld the spring, And through another saw the summer glow, And through a third the fruited vines a-row, While still, unheard, but in its wonted way, Piped the drear wind of that December day.
So with this Earthly Paradise it is, If ye will read aright, and pardon me, Who strive to build a shadowy isle of bliss Midmost the beating of the steely sea, Where tossed about all hearts of men must be; Whose ravening monsters mighty men shall slay, Not the poor singer of an empty day
As the argument about increased tuition fees for English universities intensifies in the run-up to Thursday’s debate in the House of Commons, the Welsh Assembly Government last week announced that fees for students in Wales would rise to a basic level of £6000 per year, with a possible increase to £9000 “in certain circumstances”.
I’m a bit surprised that the WAG made this announcement in advance of the vote in Westminster, as it seems to me to be by no means certain that England will introduce the post-Browne system that Wales is copying. If the increased fee measure for England doesn’t get through Parliament then Welsh universities will find themselves out on a limb.
More generally, I find it extremely disappointing that there seems to be absolutely no independent thinking going on in Wales about Higher Education funding. The responsibility for this is devolved to the WAG, but time and time again it simply copies what the English are doing. What’s the point of having devolution if you haven’t got politicians willing and able to be different from the Westminster crowd?
One thing that Welsh Assembly Minister Leighton Andrews did announce that isn’t the case in England is that students domiciled in Wales would be protected from any tuition fee rise by a new system of grants, meaning that the Welsh Assembly will pick up the tab for Welsh students. They will still have to pay the existing fee level of £3290 per annum, but the WAG will pay the extra (between about £3K and £6K). This is good news for the students of course, but the grants will be available to Welsh students not just for Welsh universities but wherever they choose to study. Since about 16,000 Welsh students are currently at university in England, this means that the WAG is handing over a great big chunk (at least 16,000 × £3000 = £48 million) of its hard-earned budget straight back to England. It’s a very strange thing to do when the WAG is constantly complaining that the Barnett formula doesn’t give them enough money in the first place.
What’s more, the Welsh Assembly grants for Welsh students will be paid for by top-slicing the teaching grants that HECFW makes to Welsh universities. So further funding cuts for universities in Wales are going to be imposed precisely in order to subsidise English universities. This is hardly in the spirit of devolution either!
English students wanting to study in Wales will have to pay full whack, but will be paying to attend universities whose overall level of state funding is even lower than in England (at least for STEM subjects whose subsidy is protected in England). Currently about 25,000 English students study in Wales compared with the 16,000 Welsh students who study in England. If the new measures go ahead I can see fewer English students coming to Wales, and more Welsh students going to England. This will have deeply damaging consequences for the Welsh Higher Education system.
It’s very surprising that the Welsh Nationalists, Plaid Cymru, who form part of the governing coalition in the Welsh Assembly, have gone along with this strange move. It’s good for Welsh students, but not good for Welsh universities. I would have thought that the best plan for Welsh students would be to keep up the bursaries but apply them only for study in Wales. That way both students and institutions will benefit and the Welsh Assembly’s budget will actually be spent in Wales, which is surely what is supposed to happen…
POSTCRIPT: Leighton Andrews’ speech to the Welsh Assembly can be seen here.
It’s cold and rainy outside so I thought I’d indulge myself by posting a bit of music. When I was in Oxford last week I was treated to a glass or two of wine after my seminar and during the conversation I was mildy castigated by Pedro Ferreira for not posting enough “modern jazz”, and especially not enough Ornette Coleman. I explained that I always feel like I’m cheating when I just put up a bit of music without actually writing something about it at the same time, and I especially feel that way about pieces that some people might find a bit challenging.
Anyway, I went through my collection just now and found the pioneering album Change of the Century which is well represented on Youtube (and not cursed by the copyright mafia), so here we go…
Coleman’s music must have sounded strange and dissonant for listeners in the late 1950s but it was soon assimilated and became part of the language of jazz from the 1960s onwards. This album dates from 1959, right at the start of his acceptance as a major artist. This album is actually also one of his most listenable LPs and contains a number of tunes which are catchy and even singable. There are obvious overtones of Charlie Parker throughout, but Ornette is already introducing some novel features, especially the use of suspended rhythmic figures which Miles Davis was to call the “stopping and swinging” approach to improvisation.
The album also features Don Cherry on trumpet, Billy Higgins on drums and the superb Charlie Haden on bass so it’s by no means a solo vehicle for Ornette Coleman’s alto saxophone. Indeed, some of the most exciting moments in the album belong to the intricate alto-trumpet unison passages, which are so complicated but played with unbelievable accuracy by the musicians. The following track, simply called Free, provides good examples.
Ornette Coleman’s playing, though, is truly remarkable: agile, constantly moving and full of nervous energy, but also bursting away from the constraints of the bar lines and sometimes taking ideas over the boundary between one chorus and the next. In this respect he was fortunate to have Haden and Higgins playing behind him because they seem to be able to sense the direction of these spontaneous departures, giving the music a close-knit unity which sets it apart from so many other groups recorded at the same time.
If you’re interested in modern jazz you really should get this album. It’s consistently brilliant. As a taster, here’s the track called Free, which is my favourite.
Don Cherry and Billy Higgins are sadly no longer with us, but Ornette Coleman is still going strong. I hope to post some reflections on his later work in due course.
At the end of day two of the Second Ashes Test between England and Australia, England were 317 for 2 in response to Australia’s 245 all out. Cook is 136 not out and Petersen 85 not out. Going well for England down under in the heat of Adelaide, I’d say. Australian captain Ricky Ponting seems to be hoping for help from above..
..although, given that this is in Australia, surely his hands are actually pointing downwards?
Donning my community service hat, I’ll just pass on some important news from the Science and Technology Facilities Council (STFC) concerning Astronomy research grants. The message is contained in an email that has been circulated concerning the new grant system and you can also find it at Paul Crowther’s website here. I urge all astronomers to read the text in full. I believe separate instructions are going out to particle physics and nuclear physics groups concerning their grants.
Detailed guidance on how to apply the consolidated grants is not yet available.
A lot of questions remain to be answered, such as how on Earth people are going to be able to write a big proposal in the short time available when there are as yet no proper instructions, how groups with several existing grants will go about consolidating them when they all have different start and end dates, how the consolidated grants will be assessed, etc.
Also, it is now clear that results of the existing grant round (for grants due to start in April 2011) will not be forthcoming until January at the earliest, so that Swindon Office will be trying to sort out the new system at the same time as trying to complete the last round of the old one.
The combinations of delays to this round with the hasty implementation of a drastically different scheme for the next round is bound to cause a lot of problems both for STFC staff and researchers wanting to apply for grants, not to mention the Astronomy Grants Panel (of which I am a member).
The main purpose of this change is to save administrative costs at STFC, but it seems to me the main effect will be transfer an increased burden to universities, at least in the short term. Once again everything’s being done by the seat of the pants, with a complete lack of joined-up thinking.
Please don’t shoot the messenger, or anyone else on the AGP!
There’s a thing going around on Facebook which purports to be a list of the 100 “best” books rated by the BBC Book Club. I’m a bit confused by this because the list actually published by the BBC Book Club is rather different. Apparently the BBC thinks that most people have read only 6 of them anyway. Anyway, I’ve put the list here and marked the ones I’ve read in bold. I am interested to see how many my discerning readers have read, so please count the ones you have read and answer the quick poll.
In order to count you have to have read the whole book, not just bits!
1 Pride and Prejudice – Jane Austen
2 The Lord of the Rings – JRR Tolkien
3 Jane Eyre – Charlotte Bronte
4 Harry Potter series – JK Rowling
5 To Kill a Mockingbird – Harper Lee
6 The Bible
7 Wuthering Heights – Emily Bronte
8 Nineteen Eighty Four – George Orwell
9 His Dark Materials – Philip Pullman
10 Great Expectations – Charles Dickens
11 Little Women – Louisa M Alcott
12 Tess of the D’Urbervilles – Thomas Hardy
13 Catch 22 – Joseph Heller
14 Complete Works of Shakespeare
15 Rebecca – Daphne Du Maurier
16 The Hobbit – JRR Tolkien
17 Birdsong – Sebastian Faulks
18 Catcher in the Rye – JD Salinger
19 The Time Traveler’s Wife – Audrey Niffenegger
20 Middlemarch – George Eliot
21 Gone With The Wind – Margaret Mitchell
22 The Great Gatsby – F Scott Fitzgerald
24 War and Peace – Leo Tolstoy
25 The Hitch Hiker’s Guide to the Galaxy – Douglas Adams
27 Crime and Punishment – Fyodor Dostoyevsky
28 Grapes of Wrath – John Steinbeck
29 Alice in Wonderland – Lewis Carroll
30 The Wind in the Willows – Kenneth Grahame
31 Anna Karenina – Leo Tolstoy
32 David Copperfield – Charles Dickens
33 Chronicles of Narnia – CS Lewis
34 Emma -Jane Austen
35 Persuasion – Jane Austen
36 The Lion, The Witch and the Wardrobe – CS Lewis
37 The Kite Runner – Khaled Hosseini
38 Captain Corelli’s Mandolin – Louis De Bernieres
39 Memoirs of a Geisha – Arthur Golden
40 Winnie the Pooh – A.A. Milne
41 Animal Farm – George Orwell
42 The Da Vinci Code – Dan Brown
43 One Hundred Years of Solitude – Gabriel Garcia Marquez
44 A Prayer for Owen Meaney – John Irving
45 The Woman in White – Wilkie Collins
46 Anne of Green Gables – LM Montgomery
47 Far From The Madding Crowd – Thomas Hardy
48 The Handmaid’s Tale – Margaret Atwood
49 Lord of the Flies – William Golding
50 Atonement – Ian McEwan
51 Life of Pi – Yann Martel
52 Dune – Frank Herbert
53 Cold Comfort Farm – Stella Gibbons
54 Sense and Sensibility – Jane Austen
55 A Suitable Boy – Vikram Seth
56 The Shadow of the Wind – Carlos Ruiz Zafon
57 A Tale Of Two Cities – Charles Dickens
58 Brave New World – Aldous Huxley
59 The Curious Incident of the Dog in the Night-time – Mark Haddon
60 Love In The Time Of Cholera – Gabriel Garcia Marquez
61 Of Mice and Men – John Steinbeck
62 Lolita – Vladimir Nabokov
63 The Secret History – Donna Tartt
64 The Lovely Bones – Alice Sebold
65 Count of Monte Cristo – Alexandre Dumas
66 On The Road – Jack Kerouac
67 Jude the Obscure – Thomas Hardy
68 Bridget Jones’s Diary – Helen Fielding
69 Midnight’s Children – Salman Rushdie
70 Moby Dick – Herman Melville
71 Oliver Twist – Charles Dickens
72 Dracula – Bram Stoker
73 The Secret Garden – Frances Hodgson Burnett
74 Notes From A Small Island – Bill Bryson
75 Ulysses – James Joyce
76 The Inferno – Dante
77 Swallows and Amazons – Arthur Ransome
78 Germinal – Emile Zola
79 Vanity Fair – William Makepeace Thackeray
80 Possession – AS Byatt
81 A Christmas Carol – Charles Dickens
82 Cloud Atlas – David Mitchell
83 The Color Purple – Alice Walker
84 The Remains of the Day – Kazuo Ishiguro
85 Madame Bovary – Gustave Flaubert
86 A Fine Balance – Rohinton Mistry
87 Charlotte’s Web – E.B. White
88 The Five People You Meet In Heaven – Mitch Albom
89 Adventures of Sherlock Holmes – Sir Arthur Conan Doyle
90 The Faraway Tree Collection – Enid Blyton
91 Heart of Darkness – Joseph Conrad
92 The Little Prince – Antoine De Saint-Exupery
93 The Wasp Factory – Iain Banks
94 Watership Down – Richard Adams
95 A Confederacy of Dunces – John Kennedy Toole
96 A Town Like Alice – Nevil Shute
97 The Three Musketeers – Alexandre Dumas
98 Hamlet – William Shakespeare
99 Charlie and the Chocolate Factory – Roald Dahl
100 Les Miserables – Victor Hugo
Any opinions on great books not on the list welcome through the comments box!
Posted in Uncategorized on December 3, 2010 by telescoper
I couldn’t resist reposting this. It’s hilarious.
(Note: this post is `just for fun;' no premeds, doctors, researchers, or nobel laureates were meant to be offended in the writing of this post.) The bane of many American physics grad students is teaching introductory physics to premed students. Due to the nature of med school admissions, one ends up with classrooms full of students who cannot afford to get anything less than an A+++ if they hope to make it to (Ivy League) Med School. Further, du … Read More
Not for the first time in my life I find myself a bit of a laughing stock, after blowing my top during a seminar at Cardiff yesterday by retired Professor Mike Disney. In fact I got so angry that, much to the amusement of my colleagues, I stormed out. I don’t often lose my temper, and am not proud of having done so, but I reached a point when the red mist descended. What caused it was bad science and, in particular, bad statistics. It was all a big pity because what could have been an interesting discussion of an interesting result was ruined by too many unjustified assertions and too little attention to the underlying basis of the science. I still believe that no matter how interesting the results are, it’s the method that really matters.
The interesting result that Mike Disney talked about emerges from a Principal Components Analysis (PCA) of the data relating to a sample of about 200 galaxies; it was actually published in Nature a couple of years ago; the arXiv version is here. It was the misleading way this was discussed in the seminar that got me so agitated so I’ll give my take on it now that I’ve calmed down to explain what I think is going on.
In fact, Principal Component Analysis is a very simple technique and shouldn’t really be controversial at all. It is a way of simplifying the representation of multivariate data by looking for the correlations present within it. To illustrate how it works, consider the following two-dimensional (i.e. bivariate) example I took from a nice tutorial on the method.
In this example the measured variables are Pressure and Temperature. When you plot them against each other you find they are correlated, i.e. the pressure tends to increase with temperature (or vice-versa). When you do a PCA of this type of dataset you first construct the covariance matrix (or, more precisely, its normalized form the correlation matrix). Such matrices are always symmetric and square (i.e. N×N, where N is the number of measurements involved at each point; in this case N=2) . What the PCA does is to determine the eigenvalues and eigenvectors of the correlation matrix.
The eigenvectors for the example above are shown in the diagram – they are basically the major and minor axes of an ellipse drawn to fit the scatter plot; these two eigenvectors (and their associated eigenvalues) define the principal components as linear combinations of the original variables. Notice that along one principal direction (v1) there is much more variation than the other (v2). This means that most of the variance in the data set is along the direction indicated by the vector v1, and relatively little in the orthogonal direction v2; the eigenvalue for the first vector is consequently larger than that for the second.
The upshot of this is that the description of this (very simple) dataset can be compressed by using the first principal component rather than the original variables, i.e. by switching from the original two variables (pressure and temperature) to one variable (v1) we have compressed our description without losing much information (only the little bit that is involved in the scatter in the v2 direction.
In the more general case of N observables there will be N principal components, corresponding to vectors in an N-dimensional space, but nothing changes qualitatively. What the PCA does is to rank the eigenvectors according to their eigenvalue (i.e. the variance associated with the direction of the eigenvector). The first principal component is the one with the largest variance, and so on down the ordered list.
Where PCA is useful with large data sets is when the variance associated with the first (or first few) principal components is very much larger than the rest. In that case one can dispense with the N variables and just use one or two.
In the cases discussed by Professor Disney yesterday the data involved six measurable parameters of each galaxy: (1) a dynamical mass estimate; (2) the mass inferred from HI emission (21cm); (3) the total luminosity; (4) radius; (5) a measure of the central concentration of the galaxy; and (6) a measure of its colour. The PCA analysis of these data reveals that about 80% of the variance in the data set is associated with the first principal component, so there is clearly a significant correlation present in the data although, to be honest, I have seen many PCA analyses with much stronger concentrations of variance in the first eigenvector so it doesn’t strike me as being particularly strong.
However, thinking as a physicist rather than a statistician there is clearly something very interesting going on. From a theoretical point of view one would imagine that the properties of an individual galaxy might be controlled by as many as six independent parameters including mass, angular momentum, baryon fraction, age and size, as well as by the accidents of its recent haphazard merger history.
Disney et al. argue that for gaseous galaxies to appear as a one-parameter set, as observed here, the theory of galaxy formation and evolution must supply at least five independent constraint equations in order to collapse everything into a single parameter.
This is all vaguely reminiscent of the Hertzsprung-Russell diagram, or at least the main sequence thereof:
You can see here that there’s a correlation between temperature and luminosity which constrains this particular bivariate data set to lie along a (nearly) one-dimensional track in the diagram. In fact these properties correlate with each other because there is a single parameter model relating all properties of main sequence stars to their mass. In other words, once you fix the mass of a main sequence star, it has a fixed luminosity, temperature, and radius (apart from variations caused by age, metallicity, etc). Of course the problem is that masses of stars are difficult to determine so this parameter is largely hidden from the observer. What is really happening is that luminosity and temperature correlate with each other, because they both depend on the hidden parameter mass.
I don’t think that the PCA result disproves the current theory of hierarchical galaxy formation (which is what Disney claims) but it will definitely be a challenge for theorists to provide a satisfactory explanation of the result! My own guess for the physical parameter that accounts for most of the variation in this data set is the mass of the dark halo within which the galaxy is embedded. In other words, it might really be just like the Hertzsprung-Russell diagram…
But back to my argument with Mike Disney. I asked what is the first principal component of the galaxy data, i.e. what does the principal eigenvector look like? He refused to answer, saying that it was impossible to tell. Of course it isn’t, as the PCA method actually requires it to be determined. Further questioning seemed to reveal a basic misunderstanding of the whole idea of PCA which made the assertion that all of modern cosmology would need to be revised somewhat difficult to swallow. At that point of deadlock, I got very angry and stormed out.
I realise that behind the confusion was a reasonable point. The first principal component is well-defined, i.e. v1 is completely well defined in the first figure. However, along the line defined by that vector, P and T are proportional to each other so in a sense only one of them is needed to specify a position along this line. But you can’t say on the basis of this analysis alone that the fundamental variable is either pressure or temperature; they might be correlated through a third quantity you don’t know about.
Anyway, as a postscript I’ll say I did go and apologize to Mike Disney afterwards for losing my rag. He was very forgiving, although I probably now have a reputation for being a grumpy old bastard. Which I suppose I am. He also said one other thing, that he didn’t mind me getting angry because it showed I cared about the truth. Which I suppose I do.
Just a quick post to commemorate the record-breaking First Test of the Ashes series between England and Australia in Brisbane that finished yesterday. It was notable for a number of reasons, including Australian bowler Peter Siddle’s hat-trick in England’s first innings, and some fine batting by Mike Hussey and Brad Haddin in Australia’s first innings, but chiefly for an extraordinary fightback by England’s batsmen in their 2nd innings which took them to an amazing 517 for 1 declared from a situation in which they might well have folded. Well played Messrs Strauss, Cook and Trott for all getting centuries and saving the game.
The way the press have been going on about the result you’d think England had won, but it was only a draw. There’s a long way to go – another four Tests to be precise – before the fate of the Ashes is decided. Still, England have already done better than they did last time they played an Ashes series in Australia. They lost that one 5-0!
I thought I’d post this little poem by Simon Rae to mark the occasion. There wasn’t that much evidence of high-quality spin bowling in the First Test, but A Red Ball Spins is more about the fact that although it might be winter here and the domestic season long over, somewhere in the world there’s always cricket, lovely cricket…
A red ball spins, a swallow’s flight, That every generation follows From rituals first performed in meadows To epic Tests in packed arenas.
Shadows signal the close of play Then slip through turnstiles into light: Another match, another day. Around the world the red balls spins.
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In the Dark 