Archive for November, 2008

Lost in the City

Posted in Biographical, Poetry with tags , , on November 17, 2008 by telescoper

The second Friday of the month is the day of the regular “open” meeting of the Royal Astronomical Society (at 4pm) preceded by parallel discussion meetings on topics that vary from month to month. This month one of the sessions was organized in memory of Bernard Pagel, who died last year and whom I knew a little, so I decided to go to that.

I met Bernard Pagel when I started my DPhil at Sussex University in 1985. He taught one of the courses on the MSc Astronomy and we research students were required to attend his lectures. I have to say he wasn’t the best lecturer I’ve ever had; he always seemed unable to look at the class, which is a trait I find quite disconcerting. But he did reveal a wonderfully wicked sense of humour. When a visiting seminar speaker arrived late and after the seminar explained he had dozed off on the train and missed his stop, Bernard suggested that he must have been reading through his transparencies.

I left Sussex to move to London around about the time Bernard retired from his position at Sussex but he immediately took up a chair at NORDITA in Copenhagen where age restrictions were somewhat looser. I had been working for a while with Bernard Jones in Copenhagen so I next ran into Bernard Pagel when I visited there. I still found him a strange and rather distant man, but as often happens the ice was broken when a group of staff, students and visitors went to a nice concert in the Tivoli Concert Hall. If I remember correctly it was a Mozart violin concerto. Afterwards, Bernard let his guard down and talked in a much more relaxed way than I had known before and we became quite friendly thereafter. He was in fact a man with very wide interests outside his own sphere of eminence in astrophysical spectroscopy.

After the meeting was over, I went once more to the Athenaeum for dinner with the RAS Club. I was quite surprised when, after the meal, it was announced that I had written on my blog about my previous dinner there. I’m not convinced that everyone there knew what a blog actually is but maybe some of them have found their way here…

Although I got back home to Cardiff in good time on the last occasion I dined at the Club, I had already decided to go to the opera on Saturday night so didn’t have to rush off to make the last train. Walking back to Bloomsbury where I was staying on Friday and Saturday I suddenly realized that it as almost exactly ten years since I moved out of London to Nottingham. In fact I bought my house in Beeston on 13th November 1998 and commuted back to London for about a month, as my position in Nottingham didn’t start until 1st January 1999.

On Saturday morning I decided to behave like a tourist so I first went to the British Museum. I intended to see the new Babylon exhibition, but by the time I got there after a leisurely breakfast it had sold out for the day so I had to content myself with the permanent exhibits. I don’t think I ever went to the British Museum in all the time I lived in London, so it was interesting although I got completely lost.

I did get to see the Elgin Marbles but I still don’t know how to play. I also ended up in a room full of mummies, which is something I find quite distasteful. Although the mortal remains are incredibly old, they are still human bodies and I don’t like the way they are stuck in cases for people to gawp at. Call me sentimental but I think these should be returned to Egypt and laid to rest with some sort of dignity. I also think the Elgin Marbles should go back to Greece, but for different reasons. If we hand them back, we might actually get some votes in the Eurovision song contest for a change.

The rest of the day I wandered around a few of the dozens of bookshops that clutter the area between Charing Cross Road and Covent Garden, feeling all the time like a complete stranger to the city. So much has changed that it’s nearly impossible for me to believe that I ever actually lived there at all. In one shop I picked up a (very expensive) old book of poems by Shelley and found the following lines (written about Naples rather than London):

I stood within the city disinterred;
And heard the autumnal leaves like footfalls
Of spirits passing through the streets
;

I didn’t buy the book. My mood wasn’t helped by the gloomy light. Although it was quite warm for November, there was a curious purple tinge to the late afternoon which I found a bit unsettling.

On my way back I revisited an old tradition of mine of peering in through the window of one of the electrical goods shops on Tottenham Court Road to check the football results. When I was living in London I was usually out most of the day on weekends somewhere in the West End, so that was the only way to keep apprised of developments. Nowadays I don’t go out as much as I used to, so I find quieter ways of filling the gap between the end of Final Score and the start of Match of the Day that seems to me to symbolize middle age.

Then it was time to get to the Coliseum for the opera followed by supper with Joao and Kim at Belgo‘s where our table, ironically, was next to that of a dozen very raucous girls from Cardiff in town for a birthday celebration.

Boris Godunov

Posted in Music, Opera with tags , , on November 16, 2008 by telescoper

The production of Boris Godunov now playing at the Coliseum has had mixed reviews, largely because of the performance of Peter Rose as the tormented Tsar. I usually don’t find myself agreeing very much with what music critics say and I had been looking forward to English National Opera’s take on Mussorgsky‘s opera for some time. My trip to London this weekend gave me an excuse to see it for myself and form my own opinion.

The opera is based on a play by Pushkin which tells a story based on the historical figure who ruled Russian from 1598 until 1605. In the play, Boris Godunov only becomes Tsar after murdering the son Dmitriy of the previous Tsar, Ivan IV (“the terrible”) and is plagued with ghostly visions of the dead boy. His guilt drives him into madness and eventually to death, although in this production of the opera the audience doesn’t see how he dies.

In Tim Albery’s staging, the action is shifted forwards in time to pre-revolutionary Russia, with the costumes and designed hinting a time round about 1900. The production uses Mussorgsky’s original version of the opera which is not divided into acts, but spread across seven scenes (lasting about two hours and fifteen minutes) which are performed without an interval. The limitations of the minimalistic set are more than made up for by wonderful use of lighting at one point bathes the stage in gold and at another turns it into a chill Moscow streetscape.

The update of the period allows Albery to give this production a dimension that is entirely new. The ENO chorus deliberately conjures up the idea that revolution might be imminent. At several points the chorus appear in huge numbers on stage to be held at bay by only a few soldiers with rifles. This is a very effective device, especially since the chorus is in such good voice. The passion and attack of the mob is unleashed only sparingly but when it is it is very effective in providing a vocal backdrop to the developing plot.

Mussorgky’s music for Boris Godunov is romantic, richly textured, even lush in places and full of wonderful melodies. As you can imagine from the storyline it’s also rather dark and sombre, much of it in the basso profundo region.  That also goes for the singers: there is no conventional tenor role, though basses and baritones proliferate among the cast.

The one thing the music doesn’t have is a great deal of dramatic contrast, which I think must be why it appears to be difficult for the principals to bring their characters fully to life. It’s almost as if the opulence of the score holds them back. The other difficulty is that there are so many characters with not much time for the audience to get to know their personalities. Although they all sang well, I still felt they were strangers at the end. The one really outstanding performance in there was Brindley Sherratt (as the “chronicler” an old hermit called Pimen) who gave his character real depth and pathos.

And as for Boris himself? Was Boris good enough? I think Peter Rose actually sang very well and the limitations of his acting have been overemphasized by the critics. There aren’t that many opera singers who can act well, and he is certainly far from the worst I’ve seen. His voice is relatively light for a bass and he didn’t have the bottomless range that is really needed to get across the angst of the remorseful murderer.  In the scenes with Pimen (another bass) he generally suffered by comparison with his opposite number’s much richer sounds at the  low end of the register.

So, not for the first time, I am glad I ignored the critics and went ahead and bought my tickets for this. As it turned out I was sitting quite close to John Nettles (who plays Tom Barnaby in Midsomer Murders) and Jane Wymark (who plays his wife, Joyce,  in the same series). I half-expected there to be a murder during the performance.

When you’ve seen one planet….

Posted in The Universe and Stuff with tags on November 14, 2008 by telescoper

Rumours have been circulating for several days and now we have confirmation. The most exciting news in the history of the Universe! Planets exist

Well, actually, we knew that. We live on one. And anyway, the International Astronomical Union recently stipulated that planets could only be things orbiting the Sun.  Don’t ask me why. So the new things have to be called exoplanets. And over 300 hundred of these were known before today anyway.  A rose by any other name would smell as sweet, so we won’t worry about the taxonomy. But what’s the big deal?

2008111311What is different about the most recent observations, reported in today’s issue of Science, is that they involve direct detection (i.e. imaging) of exoplanets, not indirect inferences made by studying stellar wobbles. An example is shown here: the three red dots are the exoplanetary objects orbiting around the star HR 8799.

 Quite interesting.

But is every new detection of an exoplanet going to be hyped like this from now until doomsday? Or until the public gets thoroughly bored?  Might it not be better to wait until there’s a sufficiently large and unbiased sample that exoplaneticists can quit their stamp collecting and start doing some real science?

At least in cosmology nobody ever exaggerates the importance of their discoveries.

*cough*

Cerebral Asymmetry: is it all in the Mind?

Posted in Bad Statistics, Science Politics with tags , , on November 12, 2008 by telescoper

After blogging a few days ago about the possibility that our entire Universe might be asymmetric, I found out today that a short comment of mine about a completely different form of asymmetry has been published in the Proceedings of the National Academy of Sciences of New York.

Earlier this summer a paper by Ivanka Savic & Per Lindstrom concerning gender and sexuality differences in brain structure received widespread press coverage and the odd blog comment. They had analysed a group of 90 volunteers divided into four classes based on gender and sexual orientation: male heterosexual, male homosexual, female heterosexual and female homosexual.

They studied the brain structure of these volunteers using Magnetic Resonance Imaging and used their data to look for differences between the different classes. In particular they measured the asymmetry between left and right hemispheres for their samples. The right side of the brain for heterosexual men was found to be typically about 2% larger than the left; homosexual women also had an asymmetry, but slightly smaller than this at about 1%. Gay men and heterosexual women showed no discernible cerebral asymmetry. These claims are obviously very interesting and potentially important if they turn out to be true. It is in the nature of the scientific method that such results should be subjected to rigorous scrutiny in order to check their credibility.

As someone who knows nothing about neurobiology but one or two things about statistics, I dug out the research paper by Savic & Lindstrom and looked at the analysis it presents. I very quickly began to suspect there might be a problem. For each volunteer, the authors obtain measurements of the left and right cerebral volumes (call these L and R respectively). Each pair of measurements is then combined to form an asymmetry index (AI) as (L-R)/(L+R). There is then a set of values for AI, one for each volunteer. The claim is that these are systematically different for the different gender and orientation groups, based on a battery of tests including Analysis of Variance (ANOVA) and t-tests based on sample means.

Of course, it would be better to do this using a consistent, Bayesian, approach because this would make explicit the dependence of the results on an underlying model of the data. Sadly, the statistical methodology available off-the-shelf is of inferior frequentist type and this is what researchers tend to do when they don’t really know what they’re doing. They also don’t bother to read the health warnings that state the assumptions behind the results.

The problem in this case is that the tests done by Savic & Lindstrom all depend on the quantity being analysed (AI) having a normal (Gaussian) distribution. This is very often a reasonable hypothesis for biometric data, but unfortunately in this case the construction of the asymmetry index is such that it is expected to have a very non-Gaussian shape as is commonly the case for distributions of variables formed as ratios. In fact, the ratio of two normal variates has a peculiar distribution with very long tails. Many statistical analyses appeal to the Central Limit Theorem to justify the assumption of normality, but distributions with very long tails (such as the Cauchy distribution) violate the conditions of this Theorem, namely that the distribution must have finite variance. The asymmetry index is probably therefore an inappropriate choice of variable for the tests that Savic & Lindstrom perform. In particular the significance levels (or p-values) quoted in their paper are very low (of order 0.0008, for example, in the ANOVA test) which is surprising for such small samples. These probabilities are obtained by assuming the observations have Gaussian statistics, and they would be much lower for a distribution with longer tails.

Being a friendly chap I emailed Dr Savic drawing this problem to her attention and asking if she knew about this problem and the possible implications it might have for the analysis she had presented. If not, I offered to do an independent (private) check on the data to see how reliable the claimed statistical results actually were. I never received a reply.

Worried that the world might be jumping to all kinds of far-reaching conclusions about gay genes based on these questionable statistics, I wrote instead to the editor of the Journal Proceedings of the National Academy of Sciences of New York, Randy Schekman, who suggested I submit a written comment to the Journal. I did, it was accepted by the editorial committee, and it came out in the 11th November Issue. What I didn’t realise was that Savic & Lindstrom had actually prepared a reply and that this was published alongside my comment. I find it strange that I wasn’t told about this before publication but that aside, it is in principle quite reasonable to let the authors respond to criticisms like mine. Their response reveals that they completely missed the point of the danger of long-tailed distributions I mentioned above. They state that “when the sample size n is big the sampling distribution of the mean becomes approximately normal regardless of the distribution of the original variable“. Not if the distribution of the original variable has such a long tail it doesn’t! In fact, if the observations have a Cauchy distribution then so does the sampling distribution of the mean, whatever the size of sample. You can find this caveat spelled out in many places, including here. Savic & Lindstrom seem oblivous to this pitfall, even after I specifically pointed it out to them.

They also claim that a group size of n=30 is sufficient to be confident that the central limit theorem holds. A pity, then, that none of their groups is of that size. The overall sample is 90, but it is broken down into two groups of 20 and two of 25.

cerebral-asymmetry

(c) 2008 Academy of Sciences of New York

They also say that the measured AI distribution is actually normal anyway and give a plot (above). This shows all the AI values binned into one histogram. Since they don’t give any quantitative measures of goodness of fit, it’s hard to tell whether this has a normal distribution or not. One can, however, easily identify a group of five or six individuals that seem to form a separate group with larger AI values (the small peak to the right of the large peak). Since they don’t give histograms broken down by group it is impossible to be sure, but I would hazard a guess that these few individuals might be responsible for the entire result; remember that the entire sample has n only of 90.

More alarmingly, Savic & Lindstrom state in their reply that “one outlier” is omitted from this graph. Really? On what basis was the outlier rejected? The existence of outliers could be evidence of exactly the sort of problem I am worried about! Unless there was a known mistake in the measurement, this outlier should never have been omitted. They claim that the “recalculation of the data excluding this outlier does not change the results”. It find it difficult to believe that the removal of an outlier from such a small sample could not change the p-values!

In my note I made a few constructive suggestions as to how the difficulty might be circumvented, by Savic & Bergstrom have not followed any of them. Instead they report (without details of the p-values) having done some alternative, non-parametric, tests. These are all very well, but they don’t add very much if their p-values also assume Gaussian statistics. A better way to do this sort of thing robustly would be using Monte Carlo simulations.

The bottom line is that after this exchange of comments we haven’t really got anywhere and I still don’t know if the result is significant. I don’t really think it’s useful to go backwards and forwards through the journal, so I’ve emailed Dr Savic again asking for access to the numbers so I can check the statistics privately. In astronomy it is quite normal for people to make their data sets publically available, but that doesn’t seem to be the case in neurobiology. I’m not hopeful that they will reply, especially since they branded my comments “harsh” and “inappropriate”. Scientists should know how to take constructive criticism.

Their conclusion may eventually turn out to be right, but the analysis done so far is certainly not robust and it needs further checking. In the meantime I don’t just have doubts about the claimed significance of this specific result, which merely serves to illustrate the extremely poor level of statistical understanding displayed by large numbers of professional researchers. This was one of the things I wrote about in my book From Cosmos to Chaos. I’m very confident that a large fraction of claimed results in biosciences are based on bogus analyses.

I’ve long thought that scientific journals that deal with subjects like this should employ panels of statisticians to do the analysis independently of the authors and also that publication of the paper should require publication of the raw data. Science advances when results are subject to open criticism and independent analysis. I sincerely hope that Savic & Lindstrom will release their data in order for their conclusions to be checked in this way.

It’s no wonder that there is so much public distrust of science, when such important claims are rushed into the public domain without proper scrutiny.

For You

Posted in Music, Opera with tags , , , on November 12, 2008 by telescoper

I had divided loyalties this evening. Tonight was a special showing of Blast-The Movie, a documentary film about an experiment involving several Cardiff astronomers. The movie has had pretty good reviews, so I originally intended to join my colleagues this evening watching it in Cardiff University’s Julian Hodge Building.

However, only last weekend I found out that tonight was also going to be the night for the Welsh premier of For You, a brand new opera composed by Michael Berkeley and with a libretto by Ian McEwan. As an added bonus, both composer and writer were going to be around to talk about the piece beforehand, so I decided to break ranks and go off to the Sherman Theatre to watch this new production by Music Theatre Wales.

The pre-performance talk was very interesting in describing how the work came about and how the collaboration between Berkeley and McEwan worked out in practice (basically words first, music after). I’d read something about this already and the opera has also been premiered in London so I’d read some of the reviews. The Guardian liked the music but was less keen on the words; the Times was uniformly positive.

So how was it? I actually thought the libretto was very fine indeed: the plot is simple but ingenious and there are some nice comedic touches to counterpoint the darkness of the overall feel. The music was what didn’t really work for me. I felt Berkeley’s score was far too dense and fussy. There’s so much going on in some passages that it subtracts from rather than adds to the text. The vocal lines often have to battle through the rest of the music like shoppers on a busy saturday afternoon on Oxford Street. Sometimes less is more.

In the opening scene the composer Charles Frieth is taking a rehearsal, with him on stage conducting the orchestra in the pit. The tuning-up sounds are carefully scored – quite a challenge for a composer, I think – and it’s a very clever opening. This idea comes back whenever there’s a particularly manic episode (usually involving the deranged Polish maid Maria), the apparent cacophony from the orchestra mirroring psychological disorder on stage. That works well too, at least the first time. But this device is used so often that it begins to irritate. If you’ve read my piece about Charles Ives you’ll realise that I’m quite partial to a bit of dissonance here and there but even I find repeated extended doses rather indigestible.

But it’s not all like that. Although it is variable, the music does have some lovely moments, including a cheeky quotation from Mozart’s The Magic Flute.

The cast was pretty good too, especially since none of the characters are particularly likeable. Baritone Alan Opie was really good as Frieth and Amanda Collins sang wonderfully well as Maria (although she did overact quite a lot). The rest of the cast was solid rather than remarkable.

Overall, I’d say it was interesting rather than wonderful, but I’m definitely glad I went.

At the interval I went to the loo for a quick pee and as I was standing there answering the call of nature I realised that the composer was using the urinal next to me. That’s something you never get with Puccini….

Statistics

Posted in Music, Poetry with tags , , on November 11, 2008 by telescoper

Not many summers ago, in 2004, I spent an enjoyable day walking in the beautiful Peak District of Derbyshire followed by an evening at the opera in the pleasant spa town of Buxton, where there is an annual music festival. The opera I saw was A Turn of the Screw, by Benjamin Britten: a little incongruous for Buxton’s fine little Opera House which is decorated with chintzy Edwardiana and which was probably intended for performances of Gilbert & Sullivan comic operettas rather than stark tales of psychological terror. When Buxton’s theatre was built, in 1903, the town was a fashionable resort at which the well-to-do could take the waters and relax in the comfort of one of the many smart hotels.

Arriving over an hour before the opera started, I took a walk around the place and ended up on a small hill overlooking the town centre where I found the local war memorial. This is typical of the sort of thing one can see in small towns the length and breadth of Britain. It lists the names and dates of those killed during the “Great War” (1914-1918). Actually, it lists the names but mostly there is only one date, 1916.

The 1st Battalion of the Nottingham and Derbyshire Regiment (known as the Sherwood Foresters) took part in the Battle of the Somme that started on 1st July 1916. For many of them it ended that day too. Some of their names are listed on Buxton’s memorial. On the first day of this offensive, the British Army suffered 58,000 casualties as, all along the western front, troops walked slowly and defencelessly into heavy fire from machine guns that were supposed to have been knocked out by an artillery barrage that had been tragically ineffective. Rather than calling off the attack in the face of this slaughter, the powers that be carried on sending troops to their doom for months on end. By the end of the battle in November that year the British losses were a staggering 420,000, while those on the German side were estimated at half a million.

These numbers are beyond comprehension, but their impact on places like Buxton was measurably real. Buxton became a town of widows. The material loss of manpower made it impossible for many businesses to continue after 1918 and a steep economic decline followed. It never fully recovered from the devastation of 1916 and its pre-war posterity never returned.

And the carnage didn’t end on the Somme. As the “Great War” stumbled on, battle after battle degenerated into bloody fiasco. A year later the Third Battle of Ypres saw another 310,000 dead on the British side as another major assault on the German defences faltered in the mud of Passchendaele. By the end of the War on 11th November 1918, losses on both sides were counted in millions.

The First World War ended a long time ago, and there is now only one living survivor of the British trenches, but the tragedy that it was shouldn’t be forgotten and neither should the sacrifices made by those caught up in the slaughter. Every year, we have Remembrance Sunday (which passed yesterday) for which it is traditional to wear a poppy after John McCrae’s poem In Flanders Fields:

In Flanders fields the poppies blow
Between the crosses, row on row,
That mark our place; and in the sky
The larks, still bravely singing, fly
Scarce heard amid the guns below.

We are the Dead. Short days ago
We lived, felt dawn, saw sunset glow,
Loved and were loved, and now we lie
In Flanders fields.

Take up our quarrel with the foe:
To you from failing hands we throw
The torch; be yours to hold it high.
If ye break faith with us who die
We shall not sleep,
though poppies grow
In Flanders fields.

And tomorrow morning, at the 11th hour of the 11th day of the 11th month – when the guns fell silent 90 years ago – I will stand (as I always do) for the two minutes of silence observed across the country. Some people consider the wearing of a poppy and the observance of the two minutes’ silence to be celebrations of militarism. I don’t. I wear mine with respect for those who have made the ultimate sacrifice (on both sides, including non-combatants, and in all wars not just the “Great” one). As their deaths recede into the past, these rituals are needed to stop us seeing them as mere statistics. Each name on the war memorial at Buxton represents a human life extinguished and is evidence of the capacity for inhumanity which we all possess and from which we must not be allowed to hide.

For me the poppy also symbolises anger for those whose arrogance and mendacity has led us into wars that we should have avoided. I thank my lucky stars that I never had to live through conflict on the scale my grandparents’ generation had to face and curse those who have inflicted that fate on others. I quote another great First World War poet, Siegfried Sassoon (writing here in prose) whose words are as apt today as they were ninety years ago:

I have seen and endured the sufferings of the troops, and I can no longer be a party to prolonging these sufferings for ends which I believe to be evil and unjust. On behalf of all those who are suffering now I make this protest against the deception that is being practised on them; also I believe that I may help to destroy the callous complacency with which the majority of those at home regard the continuance of agonies which they do not share, and which they have not sufficient imagination to realize.

That could just as easily have been written about Iraq (2003) as Flanders (1917).

Benjamin Britten was the reason I went to Buxton that day in 2004 so its only fitting I should mention the moving performance of his War Requiem I listened to yesterday on the radio. This is a powerful work that interleaves the latin mass for the dead with poetry from the greatest of all the war poets, Wilfred Owen. This is his Anthem for Doomed Youth , which is set right at the beginning of the War Requiem, the references in the poem to church services adding tragic irony to his already powerful verse.

What passing-bells for these who die as cattle?
-Only the monstrous anger of the guns.
Only the stuttering rifles’ rapid rattle
Can patter out their hasty orisons.
No mockeries now for them; no prayers nor bells;
Nor any voice of mourning save the choirs,-
The shrill, demented choirs of wailing shells;
And bugles calling for them from sad shires.

What candles may be held to speed them all?
Not in the hands of boys but in their eyes
Shall shine the holy glimmers of good-byes.
The pallor of girls’ brows shall be their pall;
Their flowers the tenderness of patient minds,
And each slow dusk a drawing-down of blinds.

Wilfred Owen died in battle in 1918, aged 25, just a week before the armistice was signed. Another statistic.

A Lop-sided Universe?

Posted in Bad Statistics, Cosmic Anomalies, The Universe and Stuff with tags , on November 9, 2008 by telescoper

Over on cosmic variance, I found an old post concerning the issue of whether there might be large-scale anomalies in the cosmic microwave background sky. I blogged about this some time ago, under the title of Is there an Elephant in the Room?, so it’s interesting to see a different take on it. Interest in this issue has been highlighted by a recent paper by Groeneboom & Eriksen that claims to have detected asymmetry in the distribution of fluctuations in the data from the Wilkinson Microwave Anisotropy Probe (WMAP) inconsistent with the predictions of the standard cosmological model. If this feature is truly of primordial origin then it is an extremely important discovery as it will (probably) require the introduction of new physics into our understanding of cosmology, and that will be exciting.

It is the job of theorists to invent new theories, and it is not at all a problem that these bits of evidence have generated a number of speculative ideas. Who knows? One of them may be right. I think it is the job of theoreticians to think as radically as possible about things like this. On the other hand, it is the observational evidence that counts in the end and we should be very conservative in how we treat that. This is what bothers me about this particular issue.

elongatedThe picture on the left shows a processed version of the WMAP fluctuation pattern designed to reveal the asymmetry, with the apparent preferred direction shown in red. This map shows the variation of the across the whole sky, and the claimed result is that the fluctuations are a bit larger around the red dots (which are 180 degrees apart) than in the regions at right angles to them.

It’s a slight effect, but everything in the picture is a slight effect as the CMB is extremely smooth to start with, the fluctuations in temperature being only about one part in a hundred thousand. The statistical analysis looks to me to be reasonably solid, so lets suppose that the claim is correct.scan

The picture on the right (courtesy of NASA/WMAP Science Team) shows the scan strategy followed by the WMAP satellite on the same projection of the sky. The experiment maps the whole sky by spinning its detectors in such a way that they point at all possible positions. The axis of this spin is chosen in a particular way so that it is aligned with the ecliptic poles (out of the plane of the solar system). It is in the nature of this procedure that it visits some places more than others (those at the ecliptic poles are scanned more often than those at the equator), hence the variation in signal-to-noise shown in the map. You can see that effect graphically in the picture: the regions near the North and South ecliptic poles have better signal to noise than the others.

The axis found by Groeneboom & Eriksen is not perfectly aligned with the ecliptic plane but it is pretty close. It seems a reasonable (if conservative) interpretation of this that the detected CMB anomaly could be due to an unknown systematic that has something to do either with the solar system (such as an unknown source of radiation, like cold dust) or the way the satellite scans. The WMAP team have worked immensely hard to isolate any such systematics so if this is such an effect then it must be very subtle to have escaped their powerful scrutiny. They’re all clever people and it’s a fabulous experiment, but that doesn’t mean that it is impossible that they have missed something.

Many of the comments that have been posted on cosmic variance relating to this question the statistical nature of the result. Of course we have only one sky available, so given the “randomness” of the fluctuations it is possible that freakish configurations occur by chance. This misses the essentially probabilistic nature of all science which I tried to describe in my book on probability From Cosmos to Chaos. We are always limited by noise and incompleteness but that doesn’t invalidate the scientific method. In cosmology these problems are writ large because of the nature of the subject, but there is no qualitative difference in the interplay between science and theory in cosmology compared with other sciences. It’s just less easy to get the evidence.

So the issue here, which is addressed only partially by Groeneboom % Eriksen, is whether a lop-sided universe is more probable than an isotropic one given the WMAP measurements. They use a properly consistent Bayesian argument to tackle this issue and form a reasonably strong conclusion that the answer is yes. As far as it goes, I think this is (probably) reasonable.

However, now imagine I don’t believe in anistropic cosmologies but instead have an idea that this is caused by an unknown systematic relating in some way to the ecliptic plane. Following the usual Bayesian logic I think it is clear that, although both can account for the data, my hypothesis must be even more probable than a lop-sided universe. There is no reason why a primordial effect should align so closely with the ecliptic plane, so there is one unexplained coincidence in the lop-sided-universe model, whereas my model neatly accounts for that fact without any freedom to adjust free parameters. Ockham’s razor is on my side.

So what can we do about this? The answer might be not very much. It is true that, soon, the Planck Surveyor will be launched and it will map the CMB sky againat higher resolution and sensitivity. On the other hand, it will not solve the problem that we only have one sky. The fact that it is a different experiment may yield clues to any residual systematics in the WMAP results, but if it has a similar scan strategy to WMAP, even Planck might not provide definitive answers.

I think this one may run and run!

Amen

Posted in Jazz, Music with tags on November 8, 2008 by telescoper

A few days ago I put up a short clip of The Train and the River taken from the opening moments of the film Jazz on a Summer’s Day. This post contains the two last numbers to feature in the film, and the last one in particular is very very special.

At the 1958 Newport Jazz Festival, Mahalia Jackson (“The world’s greatest gospel singer”) played a lengthy set on the Sunday evening, and the whole concert is available on CD.  She wasn’t really a jazz singer, but she was born in New Orleans (in 1911) and her style developed in the shadow of both the jazz and blues traditions that had their origins in her home town.

Three tracks from her 1958 concert made it into the film. Two of them are the sort of exuberant up-tempo stompers typical of Southern gospel music; there’s something about that beat that sets your pulse racing and makes it almost impossible to resist clapping your hands on the off beat. A fine example is this highly locomotive rendition of Didn’t it Rain, a tune written by the world’s greatest composer  (“Trad”) which has the crowd of jazz fans leaping about in the aisles.

As you can hear, Mahalia Jackson’s voice is simply phenomenal.  She has so much power and emotional expressiveness that she is in a class on her own when it comes to this kind of music. In fact she gave singing lessons to the young Aretha Franklin, the one “soul “singer who came anywhere close to that quality of voice. But if you really want to hear music with from the soul, listen to Mahalia Jackson.

Although she had a number of hit records, Mahalia Jackson refused to sign for any major record label and performed throughout her life almost exclusively on gospel radio stations. I think she could easily have become a pop star if she had wanted to, but she saw her mission in life to communicate her faith to others through music. She also used a great deal of her earnings to help others by founding school bursaries and through other charitable works.

As in this concert, she usually performed with a backing band of piano, bass and organ but despite the lack of a drummer they build up a tremendous forward momentum.

Terrific though that track undoubtedly is, what comes next is truly sublime. The Lord’s Prayer is such a familiar piece of text to anyone brought up in the Christian tradition that it is difficult to imagine in advance of hearing this performance that it could be sung in such a way. The contrast between this and the previous track is immense, which makes it even more effective. This is no rumbustious rabble-rouser, just a simple and pure expression of her own deep religious faith. 

Almost as moving as her singing are the cuts to the audience reaction – the same people who were leaping about a few minutes earlier sit in deep and respectful contemplation. And who wouldn’t.. I’m not a religious man but there is certainly religious music that moves me very deeply, and this is a prime example.

Positive Vetting

Posted in Columbo with tags , on November 7, 2008 by telescoper
Columbo, reflecting on the meaning of existence

Columbo, reflecting on the meaning of existence

Today I took Columbo to his new vets. I was meaning to do this ages ago but I couldn’t find a convenient time during working hours to do take him there. Usually he hates going to the vets and adding in the fact that this was an entirely new place for him I was quite nervous about him getting a bit stressed.

As it turned out he was very perky this morning and I got him into his box quite easily (which makes a change). I turned up right on time at the vets for his 9am appointment and introduced him to the staff in reception. As always they remarked on what a big cat he is and how cute he looks. He has a particularly large head for a cat and he sometimes looks more like a teddy bear than a pussycat.

He’s had a bit of a tough week, especially on Wednesday with Bonfire Night fireworks going off all around my house until after 10pm. From my bedroom window I saw for free a magnificent display going on in Victoria Park which was very much better than the one I paid to see on Saturday. I kept Columbo indoors all evening, and he coped OK with the noise from the fireworks especially when I distracted him with his favourite brush. On the other hand, next door’s small yappy-type dog barked every time there was a significant explosion within earshot producing irritating sounds which neither I nor Columbo appreciated.

Surprisingly he didn’t look at all miserable in the vet’s reception and when I took him through to the consulting room he sat upright on the examining table with his ears pricked.  At other vets he usually moped around and tried to hide, which is a difficult task given his size.  This time he was quite comfortable during the quick examination at which he was pronounced fit and healthy.

One thing cats do when they’re nervous is to sweat from their paws (practically the only place they sweat from). Often when I’ve lifted Columbo from the vet’s table, wet pawprints have been left behind. Not this time, though.

The vet then wanted to take a blood sample in order to check his glucose levels. This has previously been the traumatic bit. The vet I saw today, however, had a different approach to all the others. Instead of taking a vial of blood from the throat area, which requires shaving the neck and introducing a needle into the big vein to draw the sample, this vet used a tiny needle to extract the merest dab from one of his ears. He certainly felt it, but it was all over in a flash. His blood glucose came out around 7 which is very good, considering that in stressful situations (like visits to the vets) the level usually rises.

As the vet typed up the notes and made out a prescription for more insulin, Columbo felt comfortable enough to take a little stroll around the room and explore a few of the interesting cupboards. I’ve never seen him so relaxed in such a situation before. I always imagined that the smells of other animals (some of which are in distress) is what affects him when he goes to the vet but although there were other cats waiting in reception, he wasn’t fazed at all.

Last thing was to weigh him. I’ve been trying to control his food to reduce his weight and it seems to be working slowly. This time he was down to about 6.35 kg. Still quite hefty, but heading in the right direction.

So then it was back into the box and out to reception. They had his insulin and needles in stock, present and correct, all ready for collection and, after I’d pocketed the gear, off we went. I was back home by 9.30. I let Columbo out of the box and, his excitement for the day over, he settled down to sleep on the sofa.

Parallel Lives

Posted in Music, The Universe and Stuff with tags , on November 6, 2008 by telescoper

I’ve just finished reading The Life of Charles Ives by Stuart Feder, which I bought some time ago with my Cambridge University Press author discount and I’ve had on my shelves without getting around to read it until this week. It’s a very interesting and informative biography of one of the strangest but most fascinating composers in the history of classical music.

Charles Ives was by any standards a daring musical innovator. Some of his compositions involve atonal structures and some involve different parts of the orchestra playing in different time signatures. He also wrote strange and wonderful piano pieces, including some which involved re-tuning the piano to obtain scales involving quarter-tones. Among this maelstrom of modern ideas he also liked to add quotations from folk songs and old hymns which gives his work a paradoxically nostalgic tinge.

His pieces are often extremely diffficult to play (so I’m told) and sometimes not that easy to listen to, but while he’s often perplexing he can also be exhilarating and very moving. Other composers might play off two musical ideas against each other, but Ives would smash them together and to hell with the dissonance. I think the wholeheartedness of his eccentricity is wonderful, but I know that some people think he was just a nut.. You’ll have to make your own mind up on that.

My favourite quote of his can be found scrawled on a hand-written score which he sent to his copyist:

Please don’t try to make things nice! All the wrong notes are right. Just copy as I have – I want it that way.”

But the point of adding this post to my blog was that in the course of reading the biography, it struck me that there is a strange parallel between the life of this controversial and not-too-well known composer and that of Albert Einstein who is certainly better known, especially to people reading what purports to be a physics blog.

For one thing their lifespans coincide pretty closely. Charles Ives was born in 1874 and died in 1954; Albert Einstein lived from 1879 to 1955. Of course the one was born in America and the latter in Germany. One inhabited the world of music and the other science; Ives, in fact, made his living in the insurance business and only composed in his spare time while Einstein spent most of his career in academia, after a brief period working in a patent office. Not everything Ives wrote was published professionally and he also rewrote things extensively, so it is difficult to establish exact dates for things especially for a non-expert like me. In any case I don’t want to push things too far and try to argue that some spooky zeitgeist acted at a distance to summon the ideas from each of them in his own sphere. I just think it is curious to observe how similar their world lines were, at least in some respects.

We all know that Einstein’s “year of miracles” was 1905, during which he published classic papers on special relativity, brownian motion and the photoelectric effect. What was arguably Ives’ greatest composition, The Unanswered Question, was completed in 1906 (although it was revised later). This piece is subtitled “A Cosmic Landscape” and it’s a sort of meditation on the philosophical problem of existence: the muted strings (which are often positioned offstage in concert performances) symbolize silence while the solo trumpet evokes the individual struggling to find meaning within the void. Here’s a fine performance of this work recorded at La Scala in Milan, in which the strings are onstage while the trumpet is in the audience. I love the way that at the end nobody seems to know if they have finished!

The Unanswered Question is probably Ives’ greatest masterpiece, but it wasn’t the only work he composed in 1906. A companion piece called Central Park in the Dark also dates from that year and they are sometimes performed together as a kind of diptych which offers interesting contrasts. While the former is static and rather abstract, the latter is dynamic and programmatic (in that it includes realistic evocations of night-time sounds).

Einstein’s next great triumph was his General Theory of Relativity in 1915, an extension of the special theory to include gravity and accelerated motion, which which came only after years of hard work learning the required difficult mathematics. Ives too was hard at work for the next decade which resulted in other high points, although they didn’t make him a household name like Einstein. The Fourth Symphony is an extraordinary work which even the best orchestras find extremely difficult to perform. Even better in my view is Three Places in New England (completed in 1914) , which contains my own favourite bit of Ives. The last movement, The Housatonic at Stockbridge is very typical of his unique approach, with a beautifully paraphrased hymn tune floating over the top of complex meandering string figures until the piece ends in a tumultuous crescendo.

After this period, both Einstein and Ives carried on working in their respective domains, and even with similar preoccupations. Einstein was in search of a unified field theory that could unite gravity with the other forces of nature, although the approach led him away from the mainstream of conventional physics research and his later years he became an increasingly marginal figure.

By about 1920 Ives had written five full symphonies (four numbered ones and one called the Holidays Symphony) but his ambition beyond these was perhaps just as grandiose as Einstein’s: to create a so-called “Universe Symphony” which he described (in typically bewildering fashion) as

A striving to present – to contemplate in tones rather than in music as such, that is – not exactly within the general term or meaning as it is so understood – to paint the creation, the mysterious beginnings of all things, known through God to man, to trace with tonal imprints the vastness, the spiritual eternities, from the great unknown to the great unknown.”

I guess such an ambitious project – to create an entirely new language of “tones” that could give expression to timeless eternity, a kind of musical theory of everything – was doomed to failure. Although Ives was an experienced symphonic composer he couldn’t find a way to realise his vision. Only fragments of the Universe Symphony remain (although various attempts have been made by others to complete it).

In fact, the end of Ives’ creative career was much more sudden and final than Einstein who, although he never again reached the heights he had scaled in 1915 – who could? – remained a productive and respected scientist until his death. Ives had a somewhat melancholic disposition and from time to time suffered from depression. By 1918 he already felt that his creative flame was faltering, but by 1926 the spark was extinguished completely. His wife, appropriately named Harmony, remembered the precise day when this happened at their townhouse in New York:

He came downstairs one day with tears in his eyes, and said he couldn’t seem to compose anymore – nothing went well, nothing sounded right.”

Although Charles Ives lived almost another thirty years he never composed another piece of music after that day in 1926. I find that unbearably sad, but at least a lot of his work is available and now fairly widely played. Alongside the pieces I have mentioned, there are literally hundreds of songs, some of which are exceptionally beautiful, and dozens of smaller works including piano and violin sonatas.

Although they both lived in the same part of America for many years, I don’t think Charles Ives and Albert Einstein ever met. I wonder what they would have made of each other if they had?

If you believe in the multiverse, of course, then there is a part of it in which they do meet. Einstein was an enthusiastic violinist so there will even be a parallel world in which Einstein is playing the Ives’ Violin Sonata on Youtube.