Archive for May, 2014

The Cake Equation

Posted in The Universe and Stuff with tags , , , on May 31, 2014 by telescoper

Yesterday being the last Friday of the month of May it was time for another tea-and-cake event in the School of Mathematical and Physical Sciences. These provide an opportunity for staff to get together and chat while demolishing a specially-themed cake. The cakes themselves are organized by the inestimable Miss Lemon and I never know what the theme is before the goods arrive, so I have to ad lib a short introduction (for just a minute, without repetition, hesitation, deviation or repetition) before cutting the cake.

As you will observe, this time the (Lemon Drizzle) cake was decorated with the Dirac Equation (which I consider to be the most beautiful equation in physics)..

On the Pulse of Morning

Posted in Poetry with tags , , on May 30, 2014 by telescoper

A Rock, A River, A Tree
Hosts to species long since departed,
Marked the mastodon.
The dinosaur, who left dry tokens
Of their sojourn here
On our planet floor,
Any broad alarm of their hastening doom
Is lost in the gloom of dust and ages.

But today, the Rock cries out to us, clearly, forcefully,
Come, you may stand upon my
Back and face your distant destiny,
But seek no haven in my shadow.

I will give you no more hiding place down here.

You, created only a little lower than
The angels, have crouched too long in
The bruising darkness,
Have lain too long
Face down in ignorance.

Your mouths spilling words
Armed for slaughter.

The Rock cries out today, you may stand on me,
But do not hide your face.

Across the wall of the world,
A River sings a beautiful song,
Come rest here by my side.

Each of you a bordered country,
Delicate and strangely made proud,
Yet thrusting perpetually under siege.

Your armed struggles for profit
Have left collars of waste upon
My shore, currents of debris upon my breast.

Yet, today I call you to my riverside,
If you will study war no more. Come,

Clad in peace and I will sing the songs
The Creator gave to me when I and the
Tree and the stone were one.

Before cynicism was a bloody sear across your
Brow and when you yet knew you still
Knew nothing.

The River sings and sings on.

There is a true yearning to respond to
The singing River and the wise Rock.

So say the Asian, the Hispanic, the Jew
The African and Native American, the Sioux,
The Catholic, the Muslim, the French, the Greek
The Irish, the Rabbi, the Priest, the Sheikh,
The Gay, the Straight, the Preacher,
The privileged, the homeless, the Teacher.
They hear. They all hear
The speaking of the Tree.

Today, the first and last of every Tree
Speaks to humankind. Come to me, here beside the River.

Plant yourself beside me, here beside the River.

Each of you, descendant of some passed
On traveller, has been paid for.

You, who gave me my first name, you
Pawnee, Apache and Seneca, you
Cherokee Nation, who rested with me, then
Forced on bloody feet, left me to the employment of
Other seekers- desperate for gain,
Starving for gold.

You, the Turk, the Swede, the German, the Scot…
You the Ashanti, the Yoruba, the Kru, bought
Sold, stolen, arriving on a nightmare
Praying for a dream.

Here, root yourselves beside me.

I am the Tree planted by the River,
Which will not be moved.

I, the Rock, I the River, I the Tree
I am yours- your Passages have been paid.

Lift up your faces, you have a piercing need
For this bright morning dawning for you.

History, despite its wrenching pain,
Cannot be unlived, and if faced
With courage, need not be lived again.

Lift up your eyes upon
The day breaking for you.

Give birth again
To the dream.

Women, children, men,
Take it into the palms of your hands.

Mold it into the shape of your most
Private need. Sculpt it into
The image of your most public self.
Lift up your hearts
Each new hour holds new chances
For new beginnings.

Do not be wedded forever
To fear, yoked eternally
To brutishness.

The horizon leans forward,
Offering you space to place new steps of change.
Here, on the pulse of this fine day
You may have the courage
To look up and out upon me, the
Rock, the River, the Tree, your country.

No less to Midas than the mendicant.

No less to you now than the mastodon then.

Here on the pulse of this new day
You may have the grace to look up and out
And into your sister’s eyes, into
Your brother’s face, your country
And say simply
Very simply
With hope
Good morning.

by Maya Angelou (4th April 1928-28th May 2014; Rest in Peace)


BICEP2: The Dust Thickens…

Posted in The Universe and Stuff with tags , , , , , , on May 29, 2014 by telescoper

Off to a day-long staff training event today so just time to post a quick update on the BICEP2 saga (see various posts on this blog). There’s a new paper on the arXiv today by Flauger, Hill and Spergel. The first part of its rather lengthy abstract reads:

BICEP2 has reported the detection of a degree-scale B-mode polarization pattern in the Cosmic Microwave Background (CMB) and has interpreted the measurement as evidence for primordial gravitational waves. Motivated by the profound importance of the discovery of gravitational waves from the early Universe, we examine to what extent a combination of Galactic foregrounds and lensed E-modes could be responsible for the signal. We reanalyze the BICEP2 results and show that the 100×150 GHz and 150×150 GHz data are consistent with a cosmology with r=0.2 and negligible foregrounds, but also with a cosmology with r=0 and a significant dust polarization signal. We give independent estimates of the dust polarization signal in the BICEP2 region using four different approaches. While these approaches are consistent with each other, the expected amplitude of the dust polarization power spectrum remains uncertain by about a factor of three. The lower end of the prediction leaves room for a primordial contribution, but at the higher end the dust in combination with the standard CMB lensing signal could account for the BICEP2 observations, without requiring the existence of primordial gravitational waves. By measuring the cross-correlations between the pre-Planck templates used in the BICEP2 analysis and between different versions of a data-based template, we emphasize that cross-correlations between models are very sensitive to noise in the polarization angles and that measured cross-correlations are likely underestimates of the contribution of foregrounds to the map. These results suggest that BICEP1 and BICEP2 data alone cannot distinguish between foregrounds and a primordial gravitational wave signal, and that future Keck Array observations at 100 GHz and Planck observations at higher frequencies will be crucial to determine whether the signal is of primordial origin. (abridged)

The foreground analysis done in this paper seems to me to be much more convincing that that presented in the original BICEP2 paper and it confirms that the data as presented can not discriminate between B-modes arising from a polarized foreground component and from the presence of primordial gravitational waves. As I’ve said before (several times now), the press hype surrounding this discovery was a bit premature and we have to wait for observations at other frequencies before a clearer picture emerges through the dust.

UPDATE: A new Nature News and Views Article contains a strong statement by David Spergel to the effect that BICEP2 provides no evidence either for or against the existence of primordial gravitational waves.

Uncertain Attitudes

Posted in Bad Statistics, Politics with tags , , , , on May 28, 2014 by telescoper

It’s been a while since I posted anything in the bad statistics file, but an article in today’s Grauniad has now given me an opportunity to rectify that omission.
The piece concerned, entitled Racism on the rise in Britain is based on some new data from the British Social Attitudes survey; the full report can be found here (PDF). The main result is shown in this graph:


The version of this plot shown in the Guardian piece has the smoothed long-term trend (the blue curve, based on a five-year moving average of the data and clearly generally downward since 1986) removed.

In any case the report, as is sadly almost always the case in surveys of this kind, neglects any mention of the statistical uncertainty in the survey. In fact the last point is based on a sample of 2149 respondents. Suppose the fraction of the population describing themselves as having some prejudice is p. For a sample of size n with x respondents indicating that they describe themselves as “very prejudiced or a little prejudiced” then one can straightforwardly estimate p \simeq x/n. So far so good, as long as there is no bias induced by the form of the question asked nor in the selection of the sample…

However, a little bit of mathematics involving the binomial distribution yields an answer for the uncertainty in this estimate of p in terms of the sampling error:

\sigma = \sqrt{\frac{p(1-p)}{n}}

For the sample size given, and a value p \simeq 0.35 this amounts to a standard error of about 1%. About 95% of samples drawn from a population in which the true fraction is p will yield an estimate within p \pm 2\sigma, i.e. within about 2% of the true figure. This is consistent with the “noise” on the unsmoothed curve and it shows that the year-on-year variation shown in the unsmoothed graph is largely attributable to sampling uncertainty; note that the sample sizes vary from year to year too. The results for 2012 and 2013 are 26% and 30% exactly, which differ by 4% and are therefore explicable solely in terms of sampling fluctuations.

I don’t know whether racial prejudice is on the rise in the UK or not, nor even how accurately such attitudes are measured by such surveys in the first place, but there’s no evidence in these data of any significant change over the past year. Given the behaviour of the smoothed data however, there is evidence that in the very long term the fraction of population identifying themselves as prejudiced is actually falling.

Newspapers however rarely let proper statistics get in the way of a good story, even to the extent of removing evidence that contradicts their own prejudice.

The 2014 Shaw Prize for Astronomy

Posted in The Universe and Stuff with tags , , , on May 27, 2014 by telescoper

So I came back to Brighton this morning after a nice long weekend in Cardiff. I took the 6.28 train via Southampton to avoid London and got to the University of Sussex in time to chair the University Human Resources Committee, the usual Chair being unwell. Anyway, all this means that I’ve been a bit busy this afternoon and also a bit tired all of which adds up to no time for a long post.

Fortunately, some nice news appeared to give me a topic for a very quick blog post. Earlier today the winners were announced for the 2014 Shaw Prize in Astronomy. This year’s award actually goes to three cosmologists, Daniel Eisenstein from Harvard, Shaun Cole from Durham  and John Peacock from Edinburgh. The prize of a cool $1Million goes 50% to Eisenstein; the other half is shared equally between Shaun and John. Nice to see another British success!

The citation reads

for their contributions to the measurements of features in the large-scale structure of galaxies used to constrain the cosmological model including baryon acoustic oscillations and redshift-space distortions.

It seems clear that John and Shaun were awarded their half of the prize because of their important work on the Anglo-Australian Two Degree Field Galaxy Redshift Survey (2dFGRS) and Daniel for leading a corresponding analysis of data derived from a survey of Luminous Red Galaxies from the Sloan Digital Sky Survey.

It’s a bit of a coincidence that baryon acoustic oscillations cropped up in this work, after my post last week about Sakharov Oscillations!

Anyway, congratulations to all three winners. No doubt they’ll be buying a few celebratory drinks for their colleagues in the very near future…



What Nigel Farage did not say on beards

Posted in Beards, Politics with tags , , , on May 26, 2014 by telescoper

In the aftermath of yesterday’s European election results, the great political question of the day is where precisely does UKIP stand on facial hair?

Kmflett's Blog

What Nigel Farage did not say on beards

UKIP leader Nigel Farage who is perpetually clean shaven is very probably a pogonophobe although as the equally perpetually hirsute Michael Rosen has pointed out to me, UKIP has some supporters with beards.

Accuracy on matters UKIP is not easy to achieve. The party itself is an unreliable guide and the BBC guided by the follicly challenged Nick Robinson isn’t much better.

However at the end of the week which saw a supposed quote from Farage about Muslims and beards to the effect that either the beard went or the wearer did and that beards should be no more than two inches in length achieve wide currency, a small attempt at accuracy can surely do no harm.

There is no absolute proof that Farage did not make these remarks. He has not denied them despite opportunities to do so

It is however…

View original post 198 more words

Moses und Aron

Posted in Opera with tags , , , , , on May 25, 2014 by telescoper

Last night I found myself once again in the Wales Millennium Centre in Cardiff Bay, the bank holiday weekend giving me enough breathing space to head back to Wales for a short break and take in an Opera.

As it turned out there was a rare treat on the menu: the first night of a new Welsh National Opera production of Moses und Aron by Arnold Schoenberg. It was well worth the trip from Brighton.

Schoenberg had only completed two of the three acts by the time of his death in 1951 so the Opera is unfinished. On the other hand the Biblical story of the Exodus is so familiar that it doesn’t matter too much that some is missing. But although the plot is well known the Opera gives it several new dimensions.

Moses is chosen by God to lead his people from captivity but he is deeply troubled by the difficulty of this task because of his old age and the ‘clumsiness of his tongue’. Moses’ brother Aron has a much easier way with words (and pictures) so they join forces and lead the Jews from captivity into the wilderness.

Moses has deep reservations about Aron’s freedom with the use of images and other gimmicks, with good reason. In Act 2 while Moses is away receiving the Ten Commandments and whatnot, leaving Aron in charge, Aron permits all kind of lewd and ungodly behaviour, all starting with his use of images to depict God. Upon Moses’ return all that comes to an end, but it has exposed an irreconcilable disagreement between the two brothers about what if anything of the divine can ever be expressed in words. Moses’ concept of God is absolute and unknowable, requiring faith rather than understanding; Aron is content to use the Method of Images.

I’m not qualified to go into the theology behind all this, but it did have some resonance with me as a scientist. How much of the truth of creation do we capture with our words and equations, or are they just images?

Anyway, back to the Opera. The staging was modern, Act I was a lecture room or conference centre. Moses appeared as an ageing professor and Aron as a sort of Teaching Assistant. The Israelites were depicted as rowdy and occasionally violent students. The set changed slightly in Act 2 to resemble a movie theatre, implying that Aron’s images were cinematic, presumably violent and pornographic.

Moses was played by the legendary Sir John Tomlinson. His deeply sonorous voice and compelling stage presence provided a perfect focus for the production. Aron was Mark Le Brocq, whose fine performance was all the more remarkable because he was understudy for Rainer Trost who was unwell; to pick up such a challenging part at a few hours’ notice can not be easy and he did wonderfully well. As always, the Chorus of Welsh National Opera were also excellent.

Schoenberg’s music for Moses un Aron is resolutely serialist, which will no doubt put some people off. I found it gripping and starkly beautiful, performed with consummate artistry by the Orchestra of Welsh National Opera under the direction of Lothar Koenigs.

All in all, yet another wonderful evening of music drama courtesy of WNO. Only two performances of Moses und Aron were planned for Cardiff this season; the other is next Friday (30th May). I’m glad that the Wales Millennium Centre was nearly full, as I hope WNO will continue putting on rare and challenging music like this. Unfortunately it seems the Arts Council have other ideas, and have just cut their grant to WNO. Fewer new productions and more revivals are in store from now on.