Archive for March, 2017

Recycled Bach

Posted in Music with tags , , , , , , on March 31, 2017 by telescoper

I had the office to myself this morning so I was listening to Essential Classics presented by Rob Cowan on BBC Radio 3 earlier on. During the course of the programme he pointed out that Johann Sebastian Bach was not averse to a bit of recycling and gave the following example. I’m sure that everyone has heard of Bach’s Mass in B Minor (BWV232), which is widely regarded as one of the greatest works ever composed in the entire history of music.

However, although this work is often depicted as a kind of culmination of Bach’s career as a composer and it wasn’t completed until 1749 (the year before Bach’s death), many sections were in fact recycled from much earlier compositions.

For example, give a listen to this. It is the Aria Ach, bleibe doch, mein liebstes Leben from the Cantata Lobet Gott in seinen Reichen (BWV11), often called the Ascension Oratorio, which was first performed in 1735. Apart from the fact that it sets a different text in a different language – the B Minor Mass is a setting of the complete `Ordinary’ of the Latin mass – and there are one or two musical differences here and there, this is instantly recognizable as an earlier incarnation of the sublime Agnus Dei from the B Minor Mass..

Oh, and if you’ve got half an hour to spare you could watch this video of a sparkly and sprightly performance of the entire cantana.

 p.s. It’s Bach’s birthday today: he was born on March 31 1685.

 

 

A Question of Equilibrium

Posted in Cute Problems with tags , on March 30, 2017 by telescoper

It’s been quite a while since I’ve been able to find time to post any items in the cute problems folder, and I don’t have much time today either, but here’s a quickie. You may well find this a lot harder than it looks at first sight. At least I did!

An isolated system consists of two identical components, each of constant heat capacity C, initially held at temperatures T1 and T2 respectively. What is the maximum amount of work that can be extracted from the system by allowing the  two components to reach equilibrium with each other?

As usual, answers through the comments box please. There is no prize, even if you’re right.

 

 

We’ll Be Together Again

Posted in Jazz, Politics with tags , , , , , on March 29, 2017 by telescoper

So, we’ve come to it at last.

At 12.30 BST the Prime Minister’s letter invoking Article 50 of the Lisbon Treaty will be delivered to the President of the European Council, Donald Tusk. This will begin the process by which the United Kingdom leaves the European Union. It also begins the process of dismantling the United Kingdom itself. Scottish independence is now an inevitability as is, probably on a slightly longer timescale, the reunification of Ireland.

I am sad beyond words that this country has taken this path to self-destruction, but can only hope that we eventually see sense and change or mind at some point in the next two years, or return to the fold at some later stage.

No artist was better at conveying a sense of tragedy and loss through their music than Billie Holiday, and here’s a track by her that perfectly expresses my feelings at this bleak time:

No tears, no fears
Remember there’s always tomorrow
So what if we have to part
We’ll be together again

 

 

The Threepenny Opera

Posted in Biographical with tags , on March 28, 2017 by telescoper

Yesterday’s announcement of the launch of a new 12-sided pound coin reminded me of the old three-penny bit, which had the same number of sides but a different composition and overall design.

Threepenny bit

The old coin had been around since the 16th century, but was phased out when the United Kingdom switched to decimal currency back in 1971. Youngsters won’t remember the old currency, but a pound used to be divided into 20 shillings, each of which was 12 `old’ pence. A threepenny bit was therefore worth 1/80 of a pound sterling. Other old coins of note were the tanner (sixpence), the shilling (one bob) and the half-crown (‘two and six’, i.e. two shillings and sixpence). There was also a penny (which was a rather large coin), the halfpenny and even the farthing (half a halfpenny). Pound coins didn’t exist in those days, only pound notes. There were also `ten bob’ notes, corresponding to half a pound, which converted to 50p coins on decimalization.

Tomorrow the Prime Minister of the United Kingdom will trigger Article 50 of the Lisbon Treaty which will begin our country’s regression into the past. I can’t help feeling that it won’t be long until go back to the old money too.

Anyway, I have specific memories of the threepenny bit because once, when I was little, I swallowed one and had to go to hospital. Don’t ask me how or why this happened. I didn’t feel particularly unwell but they did an X-ray and there it was, bold as brass, in all its dodecagonal glory. I don’t remember the eventual emergence of the coin but when we went back to the hospital a few days later it had vanished from the radar. Nature had clearly taken its course.

That little episode wasn’t as funny as my cousin Gary, who once had to go to hospital because he got a marble stuck up his nose. In Newcastle the word for a a marble is a `liggy’, by the way. I was with Gary when this happened (!) and ended up going along to casualty with him. He was in some discomfort as we sat in the waiting room, then a rather burly nurse came in. She looked at him carefully, then raised her right hand and delivered a resounding smack on the back of his head, whereupon the liggy stotted out across the floor. Job done.

Is there a kinematic backreaction in cosmology?

Posted in The Universe and Stuff with tags , , , , , on March 28, 2017 by telescoper

I just noticed that a paper has appeared on the arXiv with the confident title There is no kinematic backreaction. Normally one can be skeptical about such bold claims, but this one is written by Nick Kaiser and he’s very rarely wrong…

The article has a very clear abstract:

Kaiser

This is an important point of debate, because the inference that the universe is dominated by dark energy (i.e. some component of the cosmic energy density that violates the strong energy condition) relies on the assumption that the distribution of matter is homogeneous and isotropic (i.e. that the Universe obeys the Cosmological Principle). Added to the assumption that the large-scale dynamics of the Universe are described by the general theory of relativity, this means that we evolution of the cosmos is described by the Friedmann equations. It is by comparison with the Friedmann equations that we can infer the existence of dark energy from the apparent change in the cosmic expansion rate over time.

But the Cosmological Principle can only be true in an approximate sense, on very large scales, as the universe does contain galaxies, clusters and superclusters. It has been a topic of some discussion over the past few years as to whether the formation of cosmic structure may influence the expansion rate by requiring extra terms that do not appear in the Friedmann equations.

Nick Kaiser says `no’. It’s a succinct and nicely argued paper but it is entirely Newtonian. It seems to me that if you accept that his argument is correct then the only way you can maintain that backreaction can be significant is by asserting that it is something intrinsically relativistic that is not covered by a Newtonian argument. Since all the relevant velocities are much less than that of light and the metric perturbations generated by density perturbations are small (~10-5) this seems a hard case to argue.

I’d be interested in receiving backreactions to this paper via the comments box below.

Data-Intensive Physics and Astrophysics

Posted in Biographical, Education with tags , , , , on March 27, 2017 by telescoper

One of the jobs I’ve got in my current position (which is divided between the School of Physics & Astronomy and the Data Innovation Research Institute) is to develop new teaching activities, focussing on interdisciplinary courses involving a Data Science component. Despite the fact that I only started work developing them in September last year the first two such courses have been formally approved and are now open for admission of new students to begin their courses in September 2017. That represents a very fast-track for such things as there are many hurdles to get over in preparing new courses. Meeting the deadlines hasn’t been easy, which is largely why I’ve been whingeing on here about workload issues, but we’re finally there!

The two new courses are both at Masters (MSc) level and are called Data-Intensive Physics and Data-Intensive Astrophysics and they are both taught jointly by staff in the School of Physics and Astronomy and the School of Computer Science and Informatics in a kind of major/minor combination.

The aim of these courses is twofold.

One is to provide specialist postgraduate training for students wishing to go into academic research in a ‘data-intensive’ area of physics or astrophysics, by which I mean a field which involves the analysis and manipulation of very large or complex data sets and/or the use of high-performance computing for, e.g., simulation work. There is a shortage of postgraduates with the necessary combination of skills to being PhD programmes in such areas, and we plan to try to fill the gap with these courses.

The other aim is to cater for students who may not have made up their mind whether to go into academic research, but wish to keep their options open while pursuing a postgraduate course. The unique combination of physics/astrophysics and computer science will give those with these qualifications the option of either continuing or going into another sphere of data-intensive research in the wider world of Big Data.

We’ll be putting out some official promotional materials for these courses very soon, but I thought I’d mention them here partly because it might help with recruitment and partly because I’m so relieved that they’ve actually made it into the prospectus.

 

Tim Garland Electric Quartet

Posted in Jazz with tags , , , on March 27, 2017 by telescoper

Time for  a quick report on a superb concert I attended on Friday evening, at the Royal Welsh College of Music and Drama, by the Tim Garland Electric Quartet. I don’t get to hear anything like as much live jazz as I would like to, but did manage to get my act together in time for this one.

The band consisted of Tim Garland (tenor & soprano saxophones and bass clarinet, Jason Rebello (keyboards), Ant Law (acoustic and electric guitars) and Asaf Sirkis (drums and other percussion). Although named the ‘Electric Quartet’ it turned out to have a larger acoustic component than I expected, because Jason Rebello had clearly taken a shine to the splendid grand piano that had been provided and did much of his work on that rather than the synthesizers and other electronica he had brought with him. I think the music we heard therefore had a different flavour from similar concerts they have been doing around the country, echoing the words of Shelly Manne (about jazz musicians): “We never play anything the same way once.”

Here’s a little intro to the band I found on Youtube:

As well as being a very fine soloist and bandleader, Tim Garland is also a prolific composer and many of the pieces played at this concert were his own original compositions. My favourites of these were the hauntingly evocative Tyne Song (written in celebration of the town of my birth, which brought a tear to my eye) and The Eternal Greeting , which is from the band’s latest album One. They also played lovely versions of two familiar jazz standards, Good Morning Heartache (made famous by Billie Holiday) and the Miles Davis & Bill Evans classic Blue in Green. The programme was very varied, with middle-eastern, classical and flamenco influences, as well as the Jazz/Rock Fusion of the 80s, and the overall standard of music exceptionally high and with a wonderful sense of freshness and sponteneity. Tim Garland also introduced each number in a very engaging and laid-back way, pointing out little items of interest about the music.

I loved every minute and it served to remind me how much I love to hear live jazz. I must make more of an effort to get to concerts. And if you haven’t had the chance to hear this band, do go and hear them – they’re terrific!

At the end of the gig, as an added bonus, the members of the band appeared in the foyer to sign CDs. I had the chance to thank them for the wonderful performance and also now have a signed CD of Songs to the North Sky.