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Archive for February, 2017
For those of you who are interested, here are the slides I used for the 1st Annual Robert Grosseteste Lecture on Astrophysics/Cosmology, given at the University of Lincoln on Thursday 23rd February 2017.Follow @telescoper
A few months ago I blogged about the apparent “tension” between different measurements of the Hubble constant. Here is an alternative view of the situation, with some recent updates. The plot has thickened a bit, but it’s still unclear to me whether there’s really a significant discrepancy.
Anyway, here’s a totally unscientific poll on the issue! Do feel free to register your vote.
There has been some hand-wringing of late about the tension between the value of the expansion rate of the universe – the famous Hubble constant, H, measured directly from observed redshifts and distances, and that obtained by multi-parameter fits to the cosmic microwave background. Direct determinations consistently give values in the low to mid-70s, like Riess et al. (2016): H = 73.24 ± 1.74 km/s/Mpc while the latest CMB fit from Planck gives H = 67.8 ± 0.9 km/s/Mpc. These are formally discrepant at a modest level: enough to be annoying, but not enough to be conclusive.
The widespread presumption is that there is a subtle systematic error somewhere. Who is to blame depends on what you work on. People who work on the CMB and appreciate its phenomenal sensitivity to cosmic geometry generally presume the problem is with galaxy measurements. To people who work on local galaxies, the CMB value is…
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Twitter drew my attention this afternoon to a series of videos produced by the Royal Society designed to give teachers in schools some additional resources to encourage their pupils to do science experiments. They star the ubiquitous Professor Brian Cox, and they cover a wide range of science. You can see the whole playlist on Youtube here (although it is unfortunately back-to-front):
Although I ended up doing primarily theoretical work in my scientific career, there’s no question that ‘hands-on’ experiments played a big part in the development of my understanding of, especially, physics and chemistry. I remember vividly when I was about 12 years old doing a simple series of experiments in which we weighed out samples of chemical material of various types, then burned it somehow (usually over a bunsen burner) and weighed what was left. Commonsense based on experience with burning stuff like wood and paper is that the process reduces the amount of material so I expected the mass remaining at the end to be less than the initial mass. The first stuff that I did was a few grains of calcium. I couldn’t believe it when the residue turned out to weigh more than the stuff I started with. I was sure I was wrong and got quite upset for failing such an elementary practical exercise, but the same thing happened every time whatever the material.
Of course, the explanation is that the process going on was oxidation, and the calcium was actually combining with oxygen from the air to form an oxide. It did look as if some kind of destruction had happened, but the oxygen taken from the atmosphere had bonded to the calcium atoms and this increased the mass of the residue.
The teacher could have talked about this and explained it, but it wouldn’t have had anything like the impact on my understanding of discovering it for myself.
That’s a personal story of course, but I think it’s probably a widespread educational experience. These days few students seem to have the chance to do their own experience, either because of shortage of facilities or the dreaded ‘Health and Safety’ so I think any effort to encourage more teachers to allow their students to do more experiments is thoroughly worthwhile!Follow @telescoper
Today marks a very significant centenary in the history of music, specifically Jazz. Much of the origins and early development of Jazz is lost in the mists of time, but there is one point on which most music historians agree. The first commercial recording session that produced a record that nowadays is recognisable as Jazz happened exactly one hundred years ago today, on 26th February 1917, in the New York studios of the Victor label.
The band was called the ‘Original Dixieland Jass Band‘. A few months later they changed the “Jass” to “Jazz” and the name stuck. The Original Dixieland Jazz Band is usually referred by Jazz buffs as the ODJB.
Led by cornettist Nick LaRocca and clarinettist Larry Shields, the ODJB was a group of white musicians from in and around New Orleans who had picked up their musical ideas from listening to musicians there, including playing for the pioneering mixed-race band led by Papa Laine, before moving to Chicago which is where they were spotted by representatives of the Victor label. The rest, as they say, is history.
It’s worth emphasizing that 1917 was also a significant year for New Orleans itself, as that was the year that the red light district Storyville was shut down (as a threat to the health of the US Navy). Since Storyville had provided many of the opportunities for black musicians to work, its closure started a mass exodus to Chicago. That, and a desire among black musicians to leave the deeply racist South, is why most of the classic “New Orleans” Jazz records were actually made in Chicago.
Although they don’t represent the true origins of jazz, the ODJB were fine musicians who played with a great deal of pizzazz and were highly original and innovative. Audiences also found them great to dance to. The first single to be issued as a result of the historic first session was Livery Stable Blues. It was an instant hit and was followed by dozens more. As well as leading to fame and fortune for the ODJB, it paved the way for a century of Jazz on record.Follow @telescoper
I’m a bit late writing about this because the last two days have been very busy, but on Wednesday evening (22nd February) I went to a concert at St David’s Hall in Cardiff, featuring the Philharmonia Orchestra under the direction of Principal Conductor Esa-Pekka Salonen.
The first half of the programme featured two pieces by Beethoven, starting with a piece that was entirely new to me: his rarely heard concert overture Zur Namensfeier. It’s just a short piece (7 minutes long) and isn’t among Beethoven’s best compositions, but it did at least get the Philharmonia warmed up for the main event.
The Piano Concerto No. 5 (“Emperor”) wasn’t immediately popular when it was first performed in 1809 – perhaps because it was considered a bit grandiose – but is now firmly established as one of the pinnacles of the repertoire. The soloist was the superb Pierre-Laurent Aimard who gave us an electrifying performance, though I did feel that some of the transitions from soloist to orchestra could have been a little smoother.
The second half of the programme was devoted to a single work by Richard Strauss, for which the orchestra was augmented by the addition of brass and a larger percussion section.
For many people, the tone poem Also Sprach Zarathustra is irrevocably associated with Stanley Kubrick’s masterpiece 2001: A Space Odyssey as well as the BBC coverage of the Apollo moon landings. The opening section, representing sunrise (“as the individual enters the world, or the world enters the individual”), was memorably featured in both. Perhaps that association is why the opening section of this work sounds very modern, when it was actually written in 1896.
This is a spine-tingling piece to hear live, especially with the timpani, trumpets and splendid organ of St David’s Hall giving it everything. The principal percussionist was clearly loving every minute.
But the sunrise is only one section of nine and it’s a pity that it’s often the only part we get to hear. The other sections are rather more recognisably late-romantic, but they cover a huge range as Strauss expresses in music various aspects of the philosophy of Friedrich Nietzsche that inspired this piece.
The whole performance was brilliantly energised. Conductor Esa-Pekka Salonen got so carried away at one point that the baton slipped from his hand and flew into the First Violins. That’s definitely the first time I’ve seen that happen!
The concert ended to tumultuous applause: St David’s Hall wasn’t full, but the audience was very appreciative of an excellent performance.
Thankfully my journey back to Cardiff today was trouble-free. The trains from Lincoln to Nottingham and from Nottingham to Cardiff both ran to schedule and neither was at all overcrowded. In fact it was all rather pleasant.
I took this as we travelled along by the side of the River Severn
The Severn Bridge was visible in the distance but I’m not sure you can see it in the picture.
I used to make this journey quite often. I worked in Nottingham until the end of June 2007, after which I joined the staff of Cardiff University. It took some time to sell my house in Nottingham, however, so I didn’t fully relocate until the following year. In the meantime I rented a flat in Cardiff and travelled quite frequently to and fro to attend to the house in Nottingham.
I haven’t done that journey for about nine years. The area around Nottingham station has changed a bit in the intervening years, but I didn’t have time to see much else as I only had a brief wait for the connection to Cardiff.
When I did get back to Cardiff, I noticed during my walk home from the station through Sophia Gardens that the daffodils have appeared:
I realise that there’s not much about Astrophysics in this post, so I’ll mention that it’s exactly 30 years since the Supernova 1987a was detected (on 24th February 1987). Have a look here to see what’s been going on in the remnant over the years. It’s fascinating!
I remember the news of SN1987a very well. I was at Sussex at the time as a research student, and there was huge excitement primarily because neutrinos had been detected from the explosion – only a handful, but it was an important breakthrough.
Thirty years since the Supernova, almost ten years since I left Nottingham. Where does the time go?Follow @telescoper