Archive for June, 2011

Whippin’ that Jelly

Posted in Jazz with tags , , on June 3, 2011 by telescoper

Summer has most definitely arrived. It’s a gorgeous day and most of the students have finished most of their examinations, so I’m sure will be taking a well-deserved break and enjoying the sunshine. It’s also Friday, and time, I think, for a little frivolity.

I’m indebted to young Miss Liggins for drawing my attention to this old record via Facebook. It’s by a relatively obscure swing band called the State Street Swingers, which was based in Chicago during the mid-1930s. From a technical point of view the musicians weren’t anything like as proficient as the leading bands of the Swing Era, especially in the horn section, so they usually tried to make up for their relatively limited abilities by playing for laughs behind various vocalists. It doesn’t say who it is on Youtube, but the singer sounds to me like Washboard Sam. He made a lot of records with other bands for the Vocalion label, which is what this one came out on, so that’s at least consistent with my hypothesis.

The State Street Swingers only ever recorded 14 tracks, most of them involving euphemistically raunchy titles, like this one, Whippin’ that Jelly. It may not be the most sophisticated music, but I hope it at least brings a smile to your face, as it does to mine every time I listen to it!

D+E+F+W=$500000

Posted in The Universe and Stuff with tags , , , , , , , on June 2, 2011 by telescoper

Just a quickie this fine summer morning to pass on the news – for those of you who haven’t heard yet – that this year’s Gruber Prize for Cosmology has been awarded to Marc Davis (Berkeley, USA), George Efstathiou (Cambridge, UK), Carlos Frenk (Durham, UK) and Simon White (Garching, Germany). This prestigious award is given for their pioneering work on the Cold Dark Matter model of structure formation, which included some of the first large-scale N-body computer simulations. The “Gang of Four” produced a number of papers during the 1980s that established the idea that galaxies form by hierarchical clustering from small initial fluctuations in a matter distribution dominated by massive collisionless non-baryonic particles, the most famous of their papers being pretty universally referred to as DEFW.

In fact, if you’ll forgive me going on a trip down memory lane, that paper, published in 1985, was one of the first papers I read when I started my research degree the same year at Sussex. It was back in the days when everyone seemed to use a VAX for big computing jobs and the simulations presented in that paper involved a mere 323 = 32768 particles. You could probably run that kind of simulation on a mobile phone these days!

This early work on Cold Dark Matter wasn’t the final word, of course. Subsequent observational evidence for an accelerating Universe resulting in our standard cosmological model being modifiel to include an additional (large) component of dark energy in addition to dark matter. Nevertheless, the core ideas presented by DEFW established the basic foundations of structure formation upon which the current standard model is built.

Incidentally, you can read an interesting account of the discovery of the accelerating universe here; a cosmologist by the name of “George F. Stathew” plays a prominent role in that piece and it’s curious I’ve never heard of him before now.

Each of the four winners gets a share of the $500000 Gruber Prize, i.e. in “normalized” terms, they get $125000 each. Why is it so controversial to suggest dividing citation counts the same way? The DEFW paper has about 1500 citations according to ADS, so I think it’s quite reasonable to award the authors 370-odd each towards their respective h-indices. That’s still a pretty good result by any bibliometric standard!

The four also get a Gold Medal each to wear at parties, although by my previous logic they should have to share one between them. Perhaps George might consider donating his to Arsenal Football Club, as their trophy cabinet is looking rather empty these days?

None of the winners are Australian undergraduates, so this award probably won’t be considered newsworthy by the mass media. Believe it or not, however, the Gruber Prize is held in even higher regard by cosmologists than the Templeton Prize, so I’d like to take this opportunity to congratulate them myself for their thoroughly well-deserved honour!

A Paradox of Galileo

Posted in Cute Problems with tags , , , on June 1, 2011 by telescoper

Going by the popularity of the little physics problem I posted last week, I thought some of you might be interested in this little conundrum which dates back to the 17th Century (to Galileo Galilei, in fact). It’s not a problem to which there’s a snappy answer, so no poll this time, but I think it’s quite a good one to think about – and please try to resist the temptation to google it!

The above figure shows a large circular wheel, which rolls from left to right, without slipping, on a flat surface, along a straight line from P to Q, making exactly one revolution as it does so. The distance PQ is thus equal to the circumference of the wheel.

Now, consider the small circle, firmly fixed to the larger circle with the two centres coincident. The small circle also makes one complete revolution as the wheel rolls, and  it travels from R to S. Similarly, therefore, the distance RS must be the circumference of the small circle.

Since RS is clearly equal to PQ it follows that the circumferences of the large wheel and the small circle must be equal!

Since the radii of the large and  small circles are different,  this conclusion is clearly false so what’s wrong with the argument?