Archive for October 1, 2013

Why the Universe is (probably) not rotating

Posted in Cosmic Anomalies, The Universe and Stuff with tags , , , , , on October 1, 2013 by telescoper

Just a quick post to point you towards a nice blog post by Jason McEwen entitled Is the Universe rotating? It’s a general rule that if  an article has a question for a title then the answer to that question is probably “no”, and “probably no” is indeed the answer in this case.

The item relates to a paper by McEwen et al whose abstract is given here:

We perform a definitive analysis of Bianchi VII_h cosmologies with WMAP observations of the cosmic microwave background (CMB) temperature anisotropies. Bayesian analysis techniques are developed to study anisotropic cosmologies using full-sky and partial-sky, masked CMB temperature data. We apply these techniques to analyse the full-sky internal linear combination (ILC) map and a partial-sky, masked W-band map of WMAP 9-year observations. In addition to the physically motivated Bianchi VII_h model, we examine phenomenological models considered in previous studies, in which the Bianchi VII_h parameters are decoupled from the standard cosmological parameters. In the two phenomenological models considered, Bayes factors of 1.7 and 1.1 units of log-evidence favouring a Bianchi component are found in full-sky ILC data. The corresponding best-fit Bianchi maps recovered are similar for both phenomenological models and are very close to those found in previous studies using earlier WMAP data releases. However, no evidence for a phenomenological Bianchi component is found in the partial-sky W-band data. In the physical Bianchi VII_h model we find no evidence for a Bianchi component: WMAP data thus do not favour Bianchi VII_h cosmologies over the standard Lambda Cold Dark Matter (LCDM) cosmology. It is not possible to discount Bianchi VII_h cosmologies in favour of LCDM completely, but we are able to constrain the vorticity of physical Bianchi VII_h cosmologies at $(\omega/H)_0 < 8.6 \times 10^{-10}$ with 95% confidence.

For non-experts the Bianchi cosmologies are based on exact solutions of Einstein’s equations for general relativity which obey the condition that they are spatially homogeneous but not necessarily isotropic. If you find that concept hard to understand, imagine a universe which looks the same everywhere but which is pervaded by a uniform magnetic field: that would be homogeneous (because every place is identical) but anisotropic (because there is a preferred direction – along the magnetic field lines). Another example of would be s a universe which is, for reasons known only to itself, rotating; the preferred direction here is the axis of rotation. The complete classification of all Bianchi space-times is discussed here. I also mentioned them and showed some pictures on this blog here.

As Jason’s post explains, observations of the cosmic microwave background by the Wilkinson Microwave Anisotropy Probe (WMAP) suggest  that there is something a little bit fishy about it: it seems to be have an anomalous large-scale asymmetry not expected in the standard cosmology. These suggestions seem to be confirmed by Planck, though the type of analysis done for WMAP has not yet been performed for Planck. The paper mentioned above investigates whether the WMAP asymmetry could be accounted for by one particular Bianchi cosmology, i.e. Bianchi VII_h. This is quite a complicated model which has negative spatial curvature, rotation (vorticity) and shear; formally speaking, it is the most general Bianchi model of any type that includes the standard Friedmann cosmology as a special case.

The question whether such a complicated model actually provides a better fit to the data than the much simpler standard model is one naturally answered by Bayesian techniques that trade off the increased complexity of a more sophisticated model  against the improvement in goodness-of-fit achieved by having more free parameters.  Using this approach McEwen et al. showed that, in simple  terms, while a slight improvement in fit is indeed gained by adding a Bianchi VII_h component to the model,  the penalty paid in terms of increased complexity means that the alternative model is not significantly more probable than the simple one. Ockham’s Razor strikes again! Although this argument does not definitively exclude the possibility that the Universe is rotating, it does put limits on how much rotation there can be. It also excludes one possible explanation of the  peculiar pattern  of the temperature fluctuations seen by WMAP.

So what does cause the anomalous behaviour of the cosmic microwave background?

I have no idea.

Return of the Bad Penny Blues

Posted in Jazz, Music with tags , , , on October 1, 2013 by telescoper

So, it’s October again. What happened to September? Anyway, looking back through my archive this morning I discovered that exactly five years ago today I posted a tribute to the legendary Humphrey Lyttelton. I still miss Humph greatly so thought I’d indulge myself by posting the piece again with a few small updates. Well, they say a Bad Penny always comes back….

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I knew I could’t blog for long without writing something about a great hero of mine, the inimitable Humphrey Lyttelton, better known to his many fans as “Humph”. He died earlier this year (on April 25 2008, at the age of 86) of complications following a heart operation. News of his death came as a massive shock to me, as it had never really occured to me that one day he would be no more. Tributes to him in the media were unsurprisingly glowing in their admiration.

In later years, Humph was best known as the chairman of the long-running radio comedy show I’m Sorry I Haven’t a Clue, subtitled “The Antidote to Panel Games” in which his gravelly but perfectly elocuted voice, schoolmasterish manner and impeccable comic timing proved the perfect foil to the antics of Barry Cryer, Tim Brooke-Taylor, Graeme Garden and many other contributors. I hope I get the chance to say a bit more about this programme in due course, as I treasure my collection of recordings of shows that still make me laugh at the umpteenth listening.

But Humph had many other strings to his bow. He was a talented cartoonist and a gifted writer, and also hosted the BBC Radio programme “The Best of Jazz” on Radio 2 for forty years, counting the great John Peel among his legions of listeners. I owe a special debt to Humph for this programme as I listened to it religiously every monday night at 9pm during my teenage years. He would open the show with “This his Humphrey Lyttelton here, with the best part of an hour of jazz between now and five to ten”. His theme tune then was Wanderlust, recorded by a subset of Duke Ellington’s orchestra with the great saxophonist Coleman Hawkins appearing as a guest and contributing a truly magnificent tenor solo near the end of the piece.

Through Humph I discovered most of the music I still listen to on a daily basis, jazz from the classic era of Louis Armstrong and Jelly Roll Morton, through the swing era of Duke Ellington, Benny Goodman and Count Basie, the postwar bebop period of Charlie Parker, Dizzy Gillespie and Thelonious Monk, Miles Davis and John Coltrane, then modernists like Ornette Coleman, Sam Rivers, Archie Shepp and onto the avant-garde of the time. Humph loved all kinds of jazz, and he communicated his encyclopedic knowledge a style flavoured by a dry sense of humour. I never met him in person, but I would have loved the chance to thank him for helping nurture in me a passion for all that wonderful music.

Humph was also a fine Jazz trumpeter and bandleader in his own right. When my father was at school in the 1950s, the Lyttelton band was the leading “traditional Jazz” band in Britain. Humph had played with many of the greats, including Louis Armstrong and Sidney Bechet, and won their admiration for his trumpet-playing.

My dad had become a Lyttelton fan at School and it was this that persuaded him to take up playing the drums. He joined the RAF for his national service, and he had the opportunity to play with various bands then and later on when he went back into civvy street. He was a life long admirer of Humph and eventually got to play with him at the Corner House in Newcastle but not until the 1990s. He told me it was one of the proudest moments of his life, although he had been so nervous he didn’t really play very well. Here’s a photograph of this occasion:

In the late 1940s Humph’s band had started to record a series of 78rpm records for the Parlophone label, starting with a lovely version of “Maple Leaf Rag” and stretching to over a hundred titles. Among these tracks was one record that actually made it into the Top 20 of the British pop charts in 1956, admittedly at Number 19, but nevertheless that’s no mean feat for a Jazz record. I should point out that this was long before my birth, but I remember hearing the track many times around the house when I was young.

The Bad Penny Blues was written by Humphrey Lyttelton and the hit recording features a quartet drawn from his band which, by the mid-1950s, had gravitated to a more mainstream jazz style, away from the “traddy” sound favoured by most contemporary jazz outfits. Indeed, he had incurred the wrath of many conservative fans by daring to include a saxophonist, the brilliant but eccentric Bruce Turner, in his outfit. Bad Penny Blues, though, featured only Humph on trumpet, Johhny Parker on piano, Stan Greig on drums and Jim Bray on bass. It was only recorded as an afterthought because it went down well at live gigs at Humph’s Jazz Club the HL Club (which later became the 100 Club, at 100 Oxford Street.)

But the real key to the success of this record was a young man by the name of Joe Meek. Starting out as a sound engineer at the Parlophone studios, Meek had quickly established an excellent reputation and in this case he was asked to take over the whole production of the record. According to Humph, they were slightly concerned at what he was doing with the microphones before they made the take but after it was done they all went home and left Meek to do some tinkering with the sound before cutting the disk. In those days, recording techniques were relatively crude and there generally wasn’t much in the way of post production, especially in jazz.

When he heard the final record, Humph was shocked. For one thing, Meek had close-miked all the instruments, including the drums – something which wasn’t generally done with jazz records for fear of (a) drowning out the rest of the band and (b) exposing the clumsiness of the drummer, the latter being a particularly problem. As Humph said, his band always sounded like the rhythm section was wearing diving boots. For this reason the drums were usually recorded with a distant mike and generally hidden in the ensemble playing. But in this case it worked out very well. Stan Greig used brushes on this track and his playing served beautifully both to propel and to punctuate the performances of the other musicians.

But it wasn’t the drums that so disturbed Humph. Meek had also fiddled with the double bass and with the left hand boogie-woogie figures of Johnny Parker’s piano, fattening them out and changing the balance to bring them right up in the final mix. He also compressed the overall sound so that the bass lines seem to press in on both the piano’s right hand and the growling muted trumpet lead, tying them closer to Greig’s insistent drum patterns and creating an unusually dense sound. The result is an intense, driving feel, with a dark undertone that is quite unlike any other jazz record of its period and redolent with the atmosphere of a smoky jazz club. I love it, especially the moment when Humph’s trumpet takes over from the piano solo. With a timely kick from the drums and against the backdrop of those bluesy thumping bass lines the band finds another gear and they build up a fine head of steam before riffing their way into the fade.

Here is the original 78rpm single:

Humph didn’t like the way the record had been put together, but it was an instant hit. He later joked that he hated it all the way to the bank.

Joe Meek went on to produce several classic pop records, generating many ideas that were later used by Phil Spector, but ultimately he became a tragic figure. Such commercial success as he achieved didn’t really last and he sank into debt, depression and paranoia. A gay man in an era in which homosexuality was still illegal, he became a victim of blackmail and was questioned by the police for alleged encounters with rent boys. He committed suicide in 1967 at the age of 37.

The Bad Penny Blues went on to be the “inspiration” behind Paul Macartney’s Lady Madonna, a Beatles track which has a lot of the same notes in it and also borrows the same overall feel. I can’t put it more subtly than that. George Martin, who produced the Beatles’ track, was actually in charge of the Parlophone studio at the time Bad Penny Blues was recorded…

And Humph went on to live another 52 years, bringing music and laughter to millions.

To end with, here’s a link to a later version of the tune recorded by a more recent manifestation of Humph’s band, probably in the 1980s. Note the way his technique involved the use of his eyebrows! I may be wrong, but I think the pianist on this performance is Mick Pyne and the bass is played by Dave Green. I can’t really make out the drummer.