Archive for July, 2017

The Beard and Hat-Trick Test

Posted in Beards, Cricket with tags , , , on July 31, 2017 by telescoper

I’ve just arrived where I shall be for the next two weeks (of which more anon), but I couldn’t resist noting today’s remarkable finale of the Third Test between England and South Africa, which ended with Moeen Ali taking the last three wickets in consecutive balls. A hat-trick, no less. Quite a spectacular ending for the 100th Test Match played at the Oval.

I was so excited by Moeen’s performance that I tweeted about it and ended up on the BBC website with this analysis:

Fame at last!

The `inimitable Keith Flett’ didn’t need any encouragement from me to write a blog post pointing out that Moeen is the first England player with a beard ever to take a Test hat-trick.

Incidentally, there were quite a few comments on social media about the timing of Joe Root’s declaration, mainly arguing that he’d waited too long. I certainly wouldn’t have declared unless and until England had a lead of 450+, so thought he got it about right. More importantly, his team won with plenty of time to spare.

It’s been a truly topsy-turvy series so far, with England thumping South Africa at Lord’s and the Oval, but losing heavily at Trent Bridge in between. I wonder what will happen in the final test, at Old Trafford?

Probably it will rain…

Advertisements

They called it Passchendaele

Posted in History, Poetry with tags , , , , on July 31, 2017 by telescoper

Pass

One hundred years ago today, on 31st July 1917, the Third Battle of Ypres began. The battle, often called the Battle of Passchendaele, staggered on until November with hundreds of thousands of troops killed. The Allied assault on Ypres was ultimately intended to break through the German lines and capture submarine bases on the Belgian coast. That objective was not reached, and territorial gains were limited to just a few miles at terrible cost in suffering and death.

David Lloyd George, Prime Minster at the time, wrote in his memoirs:

Passchendaele was indeed one of the greatest disasters of the war … No soldier of any intelligence now defends this senseless campaign …

Others have argued that the Battle of Passchendaele had the important strategic role of taking pressure of the French army further South, which was so close to breaking point that mutinies were breaking out. Although the casualties on both sides were unsustainable, the German High Command knew that American reinforcements would soon enter the fray, and that if they were to win the War it would have to be with a knockout blow the following year. The German offensive of 1918 made substantial inroads through the Allied lines, even threatening Paris, until it was eventually halted and turned into a full-scale retreat.

Whatever the military outcome of the Battle, there is no question about the scale of the suffering of the troops (many of whom, at this stage of the War, were conscripts). The area in which the action took place was mainly low-lying, with a water table just a couple of feet below the surface. The myriad of small streams ditches, and drainage channels that had been developed over centuries to turn it into farmland, were destroyed by heavy shelling so the soldiers had to contend with heavy mud, often strewn with body parts and deep enough to drown in, as described by Siegfried Sassoon in his poem Memorial Tablet:

Squire nagged and bullied till I went to fight,
(Under Lord Derby’s Scheme). I died in hell—
(They called it Passchendaele). My wound was slight,
And I was hobbling back; and then a shell
Burst slick upon the duck-boards: so I fell
Into the bottomless mud, and lost the light.

At sermon-time, while Squire is in his pew,
He gives my gilded name a thoughtful stare:
For, though low down upon the list, I’m there;
‘In proud and glorious memory’ … that’s my due.
Two bleeding years I fought in France, for Squire:
I suffered anguish that he’s never guessed.
Once I came home on leave: and then went west…
What greater glory could a man desire?

Whenever I read about the terrible events of past wars, the important thing (to me) is not strategy or objectives but the suffering  that had to be endured by ordinary soldiers. It’s important to remember things like Passchendaele to remind ourselves how lucky we are to be living in a time of relative peace. The way the world is heading, however, I worry that may soon be coming to an end. Lest we forget? Far too many people have already forgotten.

P.S. Among those killed in action on the first day of Passchendaele was Welsh poet Hedd Wyn, whom I wrote about here.

P.P.S. The troops shown in the picture above are in fact Australian gunners: the picture was taken in October 1917.

 

 

Building Baby Universes

Posted in Books, Talks and Reviews, The Universe and Stuff with tags , on July 29, 2017 by telescoper

I’m going to be off on some travels soon, but before I go I’ll take the opportunity for a spot of gratuitous self-promotion. The next (August) edition of Physics World contains a review by yours truly of the book A Big Bang in a Little Room: The Quest to Create New Universes by Dr Zeeya Merali.

The above illustration accompanies the article but to find out any more you’ll have to read Physics World! 

Euclid’s Flagship Simulation

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

 

Credit: J. Carretero/P. Tallada/S. Serrano for ICE/PIC/U.Zurich and the Euclid Consortium Cosmological Simulations Science Working Group.

The above image is taken from the world’s largest simulated galaxy catalogue, which has been constructed to help prepare for the  forthcoming Euclid space mission. The image actually shows only a small part of the full Euclid Flagship mock galaxy catalogue, which contains more than 2 thousand million galaxies distributed over the 3-dimension cosmological volume that Euclid will survey. Synthetic galaxies in this simulation mimic with great detail the complex properties that real sources display: ranging from their shapes, colours, luminosities, and emission lines in their spectra, to the gravitational lensing distortions that affect the light emitted by distant galaxies as it travels to us. The simulation is large enough to allow full `light-cone’ effects to be taken into account, as the look-back time to the edge of the Euclid survey volume is long enough for significant evolution to have occurred; according to the standard cosmological model, the time taken for light to travel from redshift z=2.3 to now is about 10.8 billion years, a significant fraction of the age of the Universe.

`Mock’ catalogues like this are needed to plan large observational programmes, whether using space missions or ground-based facilities, and to help prepare the data analysis strategies and tools needed to deal with the real data when it arrives. They can also be used to make excellent images for PR and outreach purposes.

The use of the word `simulation’ always makes me smile. Being a crossword nut I spend far too much time looking in dictionaries but one often finds quite amusing things there. This is how the Oxford English Dictionary defines SIMULATION:

1.

a. The action or practice of simulating, with intent to deceive; false pretence, deceitful profession.

b. Tendency to assume a form resembling that of something else; unconscious imitation.

2. A false assumption or display, a surface resemblance or imitation, of something.

3. The technique of imitating the behaviour of some situation or process (whether economic, military, mechanical, etc.) by means of a suitably analogous situation or apparatus, esp. for the purpose of study or personnel training.

So it’s only the third entry that gives the meaning intended to be conveyed by the usage in the context of cosmological simulations. This is worth bearing in mind if you prefer old-fashioned analytical theory and want to wind up a simulationist!

In football, of course, you can even get sent off for simulation…

The 1967 Sexual Offences Act

Posted in History, LGBT with tags , , on July 27, 2017 by telescoper

1967 act

Just a short post to note that today is the 50th anniversary of the day that the Sexual Offences Act (1967) received the Royal Assent (27th July 1967). This Act partially decriminalised sex between two male adults provided both were over the age of 21 at the time. I’ve emphasised `partially’ because the number of prosecutions of men for consensual sexual acts actually went up in the years following this law. It was not until 2000 that the Sexual Offences (Amendment) Act 2000 equalised that age of consent at 16 for both homosexual and heterosexual behaviours throughout the United Kingdom. The 1967 Act was problematic in many ways, but it was a start…

CMB Spectral Distortions Revisited

Posted in Biographical, The Universe and Stuff with tags , , , , , , , , , on July 27, 2017 by telescoper

While uploading some bibliographic information for bureaucratic purposes yesterday I noticed that an old paper of mine had recently attracted a number of citations. The paper was written while I was a postdoctoral research fellow in the Astronomy Centre at the University of Sussex in 1990, but not published until 1991 by which time I had moved to Queen Mary College (as it was then called). The citation history of this article is actually quite interesting:

You can see that it was cited a bit immediately after publication, then endured a long spell from 1997 to 2012 in which nobody seemed interested in it, then experienced something of a revival. It currently has a total of about 49 citations, which doesn’t exactly make it a classic in a field which is extremely active, but it’s nice to see it hasn’t been forgotten entirely.

Here is the abstract of the paper:

As the abstract makes clear we wrote this paper in response to a measurement of the spectrum of the cosmic microwave background radiation by the FIRAS instrument on the satellite COBE that had demonstrated that it was extremely well fitted by a Planck spectrum, with little room for any deviation away from a perfect black-body shape. Here’s the measured curve from COBE and some other experiments at the time:

The accuracy of the fit allows one to place limits on any process happening in the early Universe that might produce a distortion of the spectrum. There are a number of things that could do this. Any energy released in the early Universe takes time to thermalise, i.e. for the radiation field and the matter to come into thermal equilibrium via Compton scattering, double Compton scattering and Bremsstrahlung. Imperfect thermalisation produces a spectrum which doesn’t quite match the Planck curve.

Two types of distortion are possible, both introduced in classic papers from 1969 and 1970 by Rashid Sunyaev and Ya. B. Zel’dovich. One type is called a y-distortion (which corresponds to photons being shifted from low frequency and the other is called a μ-distortion, which is described by inserting a chemical potential term to the usual Planck formula for the black-body spectrum. Observational limits on both forms of distortion are very tight : |y|<1.5 ×10-5; |μ|<1.5 ×10-5, which places stringent limits on any energy release, including that which would arise from the dissipation of primordial acoustic waves (which is what John and I concentrated on in the paper).

So why did interest in this get revived a few years ago? The answer to that is that advances in relevant technology have now made it possible to think about an experiment that can measure much smaller spectral distortions than has hitherto been possible. A proposal for an experiment, called PIXIE, which includes such a measurement, is described here. Although spectral distortions are only a secondary science goal for PIXIE, it could push down the upper limits quoted above by a factor of 1000 or so, at which level we should expect to see departures from the Planck curve within the standard model, which would be a very important test of basic cosmological theory.

That all depends on whether PIXIE – or something like it – goes ahead.

 

Par scores in T20 cricket

Posted in Cricket with tags , , on July 26, 2017 by telescoper

So last night Glamorgan won a Natwest T20 Blast match against Gloucestershire by 25 runs having batted first and scored 176 off their 20 overs. Glamorgan are now top of the `South Division’, despite having three games rained off. They play second-placed Surrey on Friday. Weather permitting.

Anyhow, last night when I saw the result I got to wondering what the par score is for a first innings in Twenty20 (i.e. median score for a winning side batting first).  Would you have expected them to win with a score of 176? The answer – and the answers to many other questions – can be found in this interesting post.

P.S. If you can’t be bothered to read the post, the median winning score for men’s T20 matches is about 164 so Glamorgan had a better-than-even chance of winning after their first innings.

Strike Rate

I haven’t blogged for the last two weeks – partly because life has been busy, but also because I’ve struggled to come up with anything to say that provides particular insights about individual BBL or WBBL matches that are being played. I will return to this, and will continue to post key stats about various matches on the Strike Rate twitter account.

In this post, I’m posting my analysis of ‘par scores’ for T20, and how they vary between the men’s and women’s game, and in different parts of the world. This is useful for understanding what sort of score can be expected in particular conditions.

Par scores are calculated as run rates, which can be converted into total scores by multiplying by 20. This is more useful than raw total scores, since not all innings last for the full 20 overs. When a team wins in the second innings…

View original post 759 more words