You have to go back to the 1950s – before even I was born – for the last time my own team won the FA Cup, but they did win it three times in that decade, including in 1952 when they were watched at Wembley by the new Queen Elizabeth II. Sixty years on we’re approaching the Queen’s Diamond Jubilee, but I don’t think Her Majesty is watching. Neither am I, in fact, because the FA moved back the kick-off to 5.15 from the traditional 3pm. Sacrilege.
P.S. The score in the 1955 FA Cup Final was Newcastle United 3 Manchester City 1. Fans of Manchester United will be hoping that there’s a similar result in tomorrow’s Premiership match between the same two clubs!
I just found out this morning that this weekend sees the official opening of the Wales Coastal Path. This means that it’s now possible – if you have the time, the energy and sensible shoes – to walk the entire length of the Welsh coast. There’s a nice article here that picks out five particularly interesting stretches. One, around the Llyn Peninsula, is of particular interest to me because it includes this picture of ancient church of Saint Hywyn, which is almost on the beach in Aberdaron. The great Welsh poet R.S. Thomas was vicar here for a number of years.
Anyway, here’s a promotional video about the Wales Coastal Path, which gives an idea of some of the stunning views at various points around this beautiful country.
The paper, to appear in due course in Monthly Notices of the Royal Astronomical Society, describes a study of the positions and velocities of small satellite galaxies and other object around the Milky Way, which suggest the existence of a flattened structure orientated at right angles to the Galactic plane. They call this the “Vast Polar Structure”. There’s even a nifty video showing this arrangement:
They argue that this is is evidence that these structures have a tidal origin, having been thrown out in the collision between two smaller galaxies during the formation of the Milky Way. One would naively expect a much more isotropic distribution of material around our Galaxy if matter had fallen into it in the relatively quiescent way envisaged by more standard theoretical models.
Definitely Quite Interesting.
However, I was rather taken aback by this quotation by one of the authors, Pavel Kroupa, which ends the press release.
Our model appears to rule out the presence of dark matter in the universe, threatening a central pillar of current cosmological theory. We see this as the beginning of a paradigm shift, one that will ultimately lead us to a new understanding of the universe we inhabit.
Hang on a minute!
One would infer from this rather bold statement that the paper concerned contained a systematic comparison between the observations – allowing for selection effects, such as incomplete sky coverage – and detailed theoretical calculations of what is predicted in the standard theory of galaxy formation involving dark matter.
But it doesn’t.
What it does contain is a simple statistical calculation of the probability that the observed distribution of satellite galaxies would have arisen in an exactly isotropic distribution function, which they conclude to be around 0.2 per cent.
However, we already know that galaxies like the Milky Way are not exactly isotropic, so this isn’t really a test of the dark matter hypothesis. It’s a test of an idealised unrealistic model. And even if it were a more general test of the dark matter hypothesis, the probability of this hypothesis being correct is not what has been calculated. The probability of a model given the data is not the same as the probability of the data given the model. To get that you need Bayes’ theorem.
What needs to be done is to calculate the degree of anisotropy expected in the dark matter theory and in the tidal theory and then do a proper (i.e. Bayesian) comparison with the observations to see which model gives the better account of the data. This is not any easy thing to do because it necessitates doing detailed dynamical calculations at very high resolution of what galaxy like the Milky Way should look like according to both theories.
Until that’s done, these observations by no means “rule out” the dark matter theory.
I’ve always wanted to be at a live performance of the legendary 40 part motet Spem in Alium by Thomas Tallis, not only because it’s a gorgeous piece of music but also because I’ve always wondered what the conductor is supposed to do with his hands when there are so many independent parts. It’s such a complicated and demanding work, however, that opportunities to hear it live are rather limited. Last night’s concert at St David’s Hall by the Tallis Scholars (supplemented by a local choir; the Tallis Scholars number only ten singers) actually involved two performances of Tallis’ most famous work, first at the beginning and then again right at the end.
If you’ve never heard Spem in Alium before, then you really should make the effort. It’s an extraordinary piece of music in many different ways. Most writers focus on its complexity, but that shouldn’t make you think Tallis was just showing off when he wrote it, or distract you from the fact that it’s so very beautiful to listen to. The forty parts involved are divided into eight choirs, each of five voices. The piece starts with one voice from the first choir, and slowly evolves to incorporate all forty voices, waving each individual vocal line into a gorgeous musical tapestry. At times all the voices seem to be acting independently within the overall harmonic framework, at others the choirs act as the basic unit; there’s a wonderful passage, for example, when choirs throw phrases backwards and forwards between them. There are also moments when all the evolving parts come back into phase so that all voices sing the same words at the same time. The effect of this is indescribable; it sent cold shivers down my spine.
There is so much going on in this piece that it’s difficult to understand how Tallis managed to stop the different parts interfering destructively with each other, but Spem in Alium never dissolves into a shapeless melisma. As the piece unfolds, the various patterns that appear and disappear are always held in sharp focus. It’s a masterpiece, and although the large space of St David’s Hall probably isn’t ideal for performing a work like this, my long wait to hear a live performance of this masterpiece was well worth it.
The concert wasn’t just about Spem in Alium. The Tallis Scholars performed a number of other works on their own, including pieces by Tallis’ old mate William Byrd and part of one of my other favourite Tallis works, The Lamentations of Jeremiah. The programme called for various combinations of the singers drawn from the ten in the basic line-up, producing a wide range of texture and colour.
It was all extremely enjoyable, but my lasting memory will be the piece that started and ended the show. There’s so much to discover listening to Spem in Alium that the second performance of it that ended the concert made me want to hear a third straight away.
PS. One of the other pieces performed during the concert was Tallis’ Miserere, which aptly described Cardiff City’s performance at home to West Ham in their play-off semi-final which was being played at the same time as the concert!
Not unexpectedly, the European Space Agency announced yesterday that it’s next large mission will be the Jupiter Icy Moon Explorer (aka JUICE). There’s a piece in Physics World about the selection – and rejection of the other two contenders, NGO and ATHENA. Andy Lawrence has commented already on his own blog and is also quoted extensively in the Physics World article.
A lot of allegations are flying around about how the selection process was conducted, specifically relating to conflicts of interest. I don’t know any details, so I won’t comment on whether this is justified outrage or simply sour grapes.
Anyway, for what it’s worth, I think I agree with what Andy Lawrence says in the Physics World story in that the final decision was pretty inevitable after NASA’s decisions in the areas of gravitational waves and X-ray astronomy pulled the rug out from under the other contenders. I’ll also add that, although it’s far from my own specialism, I think JUICE looks like a very exciting mission. I wish it every success.
It just remains to be seen how long the recriminations will rumble on.
What was it that Ernest Rutherford said about science and stamp-collecting? It seems Shakespeare had much the same idea!
Study is like the heaven’s glorious sun, That will not be deep-search’d with saucy looks; Small have continual plodders ever won, Save base authority from others’ books. These earthly godfathers of heaven’s lights That give a name to every fixed star, Have no more profit of their shining nights Than those that walk and wot not what they are.
from Love’s Labour’s Lost (Act I, Scene I) by William Shakespeare.
P.S. “wot” in the last line is an archaic form of the verb “wit”, meaning “to know”; cf “I wot not what I ought to have braught” from A Midsummer Night’s Dream.
It has been brought to my attention that I haven’t done any of these for a while so I’ll attempt to re-start my series of Astronomy Look-alikes by pointing out that X-ray astronomer Martin Elvis bears a not inconsiderable likeness to former lead vocal artist of the popular beat combo Genesis, Peter Gabriel. I wonder if, by any chance, they might be related?
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In the Dark 