Archive for March, 2009

Clover and Out

Posted in Science Politics, The Universe and Stuff with tags , , , , , , , , , on March 31, 2009 by telescoper

One of the most exciting challenges facing the current generation of cosmologists is to locate in the pattern of fluctuations in the cosmic microwave background evidence for the primordial gravitational waves predicted by models of the Universe that involve inflation.

Looking only at the temperature variation across the sky, it is not possible to distinguish between tensor  (gravitational wave) and scalar (density wave) contributions  (both of which are predicted to be excited during the inflationary epoch).  However, scattering of photons off electrons is expected to leave the radiation slightly polarized (at the level of a few percent). This gives us additional information in the form of the  polarization angle at each point on the sky and this extra clue should, in principle, enable us to disentangle the tensor and scalar components.

The polarization signal can be decomposed into two basic types depending on whether the pattern has  odd or even parity, as shown in the nice diagram (from a paper by James Bartlett)

The top row shows the E-mode (which look the same when reflected in a mirror and can be produced by either scalar or tensor modes) and the bottom shows the B-mode (which have a definite handedness that changes when mirror-reflected and which can’t be generated by scalar modes because they can’t have odd parity).

The B-mode is therefore (in principle)  a clean diagnostic of the presence of gravitational waves in the early Universe. Unfortunately, however, the B-mode is predicted to be very small, about 100 times smaller than the E-mode, and foreground contamination is likely to be a very serious issue for any experiment trying to detect it.

An experiment called Clover (involving the Universities of  Cardiff, Oxford, Cambridge and Manchester) was designed to detect the primordial B-mode signal from its vantage point in Chile. You can read more about the way it works at the dedicated webpages here at Cardiff and at Oxford. I won’t describe it in more detail here, for reasons which will become obvious.

The chance to get involved in a high-profile cosmological experiment was one of the reasons I moved to Cardiff a couple of years ago, and I was looking forward to seeing the data arriving for analysis. Although I’m primarily a theorist, I have some experience in advanced statistical methods that might have been useful in analysing the output.  It would have been fun blogging about it too.

Unfortunately, however, none of that is ever going to happen. Because of its budget crisis, and despite the fact that it has spent a large amount (£4.5M) on it already,  STFC has just decided to withdraw the funding needed to complete it (£2.5M)  and cancel the Clover experiment.

Clover wasn’t the only B-mode experiment in the game. Its rivals include QUIET and SPIDER, both based in the States. It wasn’t clear that Clover would have won the race, but now that we know  it’s a non-runner  we can be sure it won’t.

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**** Energy

Posted in Poetry, The Universe and Stuff with tags , , , , , on March 30, 2009 by telescoper

The phrase expletive deleted was made popular at the time of Watergate after the release of the expurgated tapes made by Richard Nixon in the Oval Office when he was President of the United States of America. These showed that, as well as been a complete crook, he was practically unable to speak a single sentence without including a swear word.

Nowadays the word expletive is generally taken to mean an oath or exclamation, particularly if it is obscene, but that’s not quite what it really means. Derived from the latin verb explere (“to fill out”) from which the past participle is expletus, the meaning of the word in the context of English grammar is  “something added to a phrase or sentence that isn’t strictly needed for the grammatical sense”.  An expletive is added either to fill a syntactical role or, in a poem, simply to make a line fit some metrical rule.

Examples of the former can be found in constructions like “It takes two to Tango” or “There is lots of crime in Nottingham”; neither  “it” nor “there” should really be needed but English likes to have something before the verb.

The second kind of use is illustrated wonderfully by Alexander Pope in his Essay on Criticism, which is a kind of guide to what to avoid in writing poetry. It’s a tour de force for its perceptiveness and humour. The following excerpt is pricelessly apt

These equal syllables alone require,
Tho’ oft the open vowels tire;
While expletives their feeble aid do join;
And ten low words oft creep in one dull line

Here the expletive is “do”,  and it is cleverly incorporated in the line talking about expletives, adding  the syllable needed to fit with a strict pentameter. Apparently, poets often used this construction before Pope attacked it but it quickly fell from favour afterwards.

His other prosodic targets are the “open vowels” which means initial vowels that produce an ugly glottal sound, such as in “oft” (especially ugly when following “Tho”). The last line is brilliant too, showing how using only monosyllabic “low” words makes for a line that plods along tediously just like it says.

It’s amazing how much Pope managed to fit into this poem, given the restrictions imposed by the closed couplet structure he adopted. Each idea is compressed into a unit of twenty syllables, two lines of ten syllables with a rhyme at the end of each. This is such an impressive exercise in word-play that it reminds me a lot of the skill showed by the best cryptic crossword setters. Needless to say I’m no more successful at writing poetry than I am at setting crossword clues.

After my talk in Dublin last Friday, somebody in the audience asked me what I thought about Dark Energy. There’s some discussion in the comments after my post on that too.

The Dark Energy is an ingredient added to the standard model of cosmology to reconcile  observations of a flat Universe with a matter density that seems too low to account for it.

Other than that it makes the  cosmological metric work out satisfactorily (geddit?), we don’t understand what Dark Energy means and would rather it wasn’t there.  Most people think the resulting model is inelegant or even ugly.

In other words, it’s an expletive…

Chelsea Bridge

Posted in Jazz with tags , , , , , , on March 29, 2009 by telescoper

When the great American songwriter Billy Strayhorn saw the beautifully evocative painting (left) by James McNeill Whistler of one of the bridges over the River Thames, it inspired him to write an equally evocative song to be performed by his longstanding musical collaborator and friend Duke Ellington. The song was written in 1941, but it was only years later that he realized that he had named it after the wrong bridge.

 

The painting was of Battersea Bridge; but he had named the song  Chelsea Bridge, a much less romantic location. Nevertheless, the tune quickly became a standard, and a feature for the band’s star saxophonist, Ben Webster who carried on playing it after he left Duke Ellington’s orchestra in 1943.

By all accounts Ben Webster was a drunken brute of a man but when he played ballads like this he produced music of great warmth and delicacy. In fact, his technique on the tenor sax would probably be called “wrong” by a teacher: he didn’t use his tongue properly on the reed so his notes had to be produced by much more lung power than “normal” players use. Instead of a clean attack, each note is wafted in on a sort of phoohing sound. The breathiness of his tone  is a consequence of this and, although he produced a huge volume which was good for playing in front of a big band like Ellington’s, it also made him unable to play well at faster tempos. His playing on slow ballads, though, was often exquisitely beautiful. Who says everyone has to be a speed merchant?

Ben Webster moved to Copenhagen in 1964 along with several other great Jazz musicians, to escape the racism and consequent lack of opportunity for black artists in  his homeland. He was buried in the part of Copenhagen called Nørrebro when he died in 1973. 

I am a fairly frequent visitor to Copenhagen – I’m going there again in June, in fact – and I did visit his grave once. There’s also a restaurant named after him in the city centre.

Anyway, here he is in in 1964 playing Chelsea Bridge with the marvellous Stan Tracey on piano who featured in a previous post of mine.

The Art of Sheep

Posted in Uncategorized with tags , on March 28, 2009 by telescoper

In case you’re wondering how people pass the time at the weekend here in Wales, get a load of this. It may be the strangest thing you’ve ever seen men do with sheep, but I think it’s wonderful. ..

Only in Wales!

Dublin Back

Posted in Art, Books, Talks and Reviews, Crosswords, The Universe and Stuff with tags , , , , on March 28, 2009 by telescoper

I’m just back from a flying visit to Dublin, where I gave a talk yesterday at a meeting of the Astronomical Science Group of Ireland (ASGI), an organization which promotes scientific collaborations between individuals and institutions on both sides of the border between Northern Ireland and the Republic of Eire. The venue for the twice-yearly meetings moves around both countries, but this time it was held in the splendid environment of Trinity College, Dublin.

It turned out to be an easy trip from Cardiff to Dublin and my first opportunity to try out Cardiff’s fine little airport. A small airline called Air Arann operates the route to Dublin from there, and it all went to schedule despite the plane having to struggle against a 70 mph head wind across the Irish sea. For our small propeller-driven plane, that made a signficant difference to the flying time.

Arriving in Dublin on Thursday I had time to have a nice dinner before settling in to my hotel in the Temple Bar region of the city. There’s a huge concentration of bars and nightclubs there and it’s a traditional area for Stag and Hen Parties. There was plenty of evidence of drunken debauchery going on into the early hours of the morning, which remind me of the way the Irish rugby fans carried on last weekend in Cardiff.

Anyway, the meeting itself was interesting with a wide range of talks most of which were given by PhD students. I enjoy meetings where the younger scientists are encouraged to speak; too many conferences involve the same people giving the same talk time after time. Solar Physics was particularly  well represented, and I learned quite a bit about about things that are far from my own province. 

There isn’t much actual cosmology done in Ireland (North or South) so my brief as invited speaker was to give an overview of the current state of the field for astronomers who are not  experts in cosmological matters. I therefore gave a summary of the concordance model which I’ve blogged about before and then made some comments about things that might point to a more complete theory of the Universe. I also mentioned some of the anomalies in the cosmic microwave background that I’ve also blogged about on here.

I usually use this piece of Hieronymus Bosch The Last Judgement to illustrate my feelings about the concordance model:

das_letzte_gericht

 

 
The top part represents the concordance cosmology. It clearly features an eminent cosmologist surrounded by postdoctoral researchers. Everything appears to be in heavenly harmony, surrounded by a radiant glow of self-satisfaction. The trumpets represent various forms of exaggerated press coverage.

But if you step back from it, and get the whole thing in a proper perspective, you realise that there’s an awful lot going on underneath that’s not so pleasant or easy to interptet. I don’t know what’s going down below there although the unfortunate figures slaving away in miserable conditions and suffering unimaginable torments are obviously supposed to represent graduate students.

The main point is that the concordance model is based on rather strange foundations: nobody understands what the dark matter and dark energy are, for example. Even more fundamentally, the whole thing is based on a shotgun marriage between general relativity and quantum field theory which is doomed to fail somewhere along the line.

Far from being a final theory of the Universe I think we should treat our standard model as a working hypothesis and actively look for departures from it. I’m not at all against the model. As models go, it’s very successful. It’s a good one, but it’s still just a model.

That reminds me of the school report I got after my first year at the Royal Grammar School. The summary at the bottom described me as a “model student”. I was so thrilled I went and looked up the word model in a dictionary and found it said “a small imitation of the real thing.”

Anyway, the talk went down pretty well (I think) and after a quick glass of Guinness (which definitely went down well) I was back to Dublin airport and home to Cardiff soon after that: Cardiff airport to my house was less than twenty minutes. I greatly enjoyed my short visit and was delighted to be asked to do a couple of seminars back there in the near future.

I was in a  good mood when I got home, which got even better when I found out that I won the latest Crossword competition in the Times Literary Supplement. And the prize isn’t even a dictionary. It’s cash!

Honoured amongst bloggers…

Posted in Uncategorized with tags , , , on March 25, 2009 by telescoper

I only have time for a quickie today as I have to spend this evening getting things together for my forthcoming trip to the Irish Republic for a talk in Dublin (which I’ll no doubt ramble on about when I get back).

I hear dark rumblings about the STFC financial crisis turning into a full-scale disaster owing to inept management, but I’ll refrain from going into details until it all becomes official. Suffice to say for now that, if you thought things were bad already, just watch this space…

Anyway, at least today brought some news that flattered my ego. Ian Douglas at the Daily Telegraph has seen fit to put this blog on his list of five great physics blogs. He’s obviously a man of great taste. Quite cute too. I’ll have to revise my opinion of the Daily Telegraph.

But no.

They have boring crosswords.

The Eightsome Reels

Posted in Crosswords, Literature with tags , on March 24, 2009 by telescoper

As an ardent cruciverbalist, I couldn’t resist posting this week’s Observer Crossword just to show you one of the interesting variations that Azed comes up with from time to time:

azed

It’s probably a bit small to read  the clues, or even the instructions, but the point to grasp is that the answers are all 8 letters long and they have to be fitted in the squares surrounding the corresponding number. The trouble is that you’re not told which square to start from, or whether the letters are to be entered clockwise or anticlockwise.

Hmmm.

The only way I know to start one of these puzzles is to solve several adjacent clues before entering them in the diagram and then see if I can find a way to fit them together on a bit of scrap paper. The structure of the diagram guarantees many checked letters (i.e. overlaps) between neighbouring answers so once you have a few then the subsequent ones get easier to fit in. These puzzles are usually difficult to start though.

Fortunately, however, in this one  I managed to get four  answers quite quickly:

2. As seen in bill fluctuating energy’s prone to fuse?

This is “liquable”, from “qua” meaning “as” in anagram of “bill”+e for energy, meaning able to melt.

3. Army regulation, devious blague open to dispute

Is clearly “arguable” (army regulation=ar+anagram of blague, “open to dispute” is the definition).

8. Easily duped once returning ball is eclipsed by Murray’s `gold’?

A little harder, but the word “once” suggests an obsolete spelling so the answer is “gullable” (“ball” backwards in “gule”, a Scottish form of “gold”, hence the reference to Murray).

9. Libel law curiously subject to decree?

Is “willable” (anagram of “libel law”; “subject to decree” being the definition).

With those four answers to fit in the squares around 2,  3, 8 and 9 I had plenty of checked letters and could find only one way to make it work. The remaining clues fell into place eventually, although it took me well over an hour to finish it on Sunday afternoon.

Nice puzzle though.

In the ongoing Azed competition for budding crossword cluers, I’m not doing so well. I did pick up a “highly commended” for my last clue, in competition No. 1918,  for the word PALAMPORE (a kind of Nepalese bedcover, don’t you know), but From the dizzying heights of 28th place, I’ve slipped down the table to 33rd.  Still, the winning clue for PALAMPORE was a real beauty:

Spread – array of two pages or a meal?

This involves an anagram of “pp+or a meal” with two different definitions of spread in the cryptic part. Very ingenious, and certainly better than my attempt (which I’m ashamed to include). Esteem to D.F. Manley, who wrote this clue and who is heading the Azed Honours Table for this year after 9 competitions.