So Alastair Cook has resigned from his post as Captain of the England (and Wales) Cricket team, having been skipper for 59 test matches since 2012. After their drubbing in India this is hardly surprising, but I hope he finds his form and continues as an opening batsman. He’s only 32 so should have a few more years in him.
When he started as captain I felt that he was far too cautious, something perhaps he inherited from his predecessor Andrew Strauss. I think he got marginally better as time went by, but I always felt he didn’t have sufficient presence on the field to be a great team leader and too often let things drift when England were fielding. Anyway, I don’t want to be too harsh – he did lead England to two Ashes victories!
Farewell, then, Alastair Cook. But who should take his place? Is it the youngster, Joe Root? Or should Geoffrey Boycott come out of retirement to wield his stick of rhubarb in the corridor of uncertainty once more?
Some say the world will end in fire, Some say in ice. From what I’ve tasted of desire I hold with those who favor fire. But if it had to perish twice, I think I know enough of hate To say that for destruction ice Is also great And would suffice.
I have lately posted a number of classic boogie woogie and blues performances by the great Jimmy Yancey. Here’s a piece that’s related but really very different, recorded in 1944 by a musician not usually associated with boogie woogie at all, Errol Garner, who was 23 when this track was made. The story I heard about this is that the studio bosses leant on the young and impressionable pianist to do play some things that he wasn’t keen on, including a bit of boogie woogie. Eventually Garner acceded to their request, and produced what I think is a minor masterpiece called Boogie Woogie Boogie. Note the way he doesn’t stick to the same left-hand figures throughout the track which makes this much more varied than most recordings in this genre. I particularly like the transition at about 1:35 where it all goes a bit “Batman”! It also has a distinctively dark minor-key feel to it, which is rather atmospheric.
An interesting bit of local cosmology news has been hitting the headlines over the last few days. The story relates to a paper by Yehuda Hoffman et al. published in Nature Astronomy on 30th January. The abstract reads:
Our Local Group of galaxies is moving with respect to the cosmic microwave background (CMB) with a velocity1of VCMB = 631 ± 20 km s−1and participates in a bulk flow that extends out to distances of ~20,000 km s−1 or more2,3,4. There has been an implicit assumption that overabundances of galaxies induce the Local Group motion5,6,7. Yet underdense regions push as much as overdensities attract8, but they are deficient in light and consequently difficult to chart. It was suggested a decade ago that an underdensity in the northern hemisphere roughly 15,000 km s−1 away contributes significantly to the observed flow9. We show here that repulsion from an underdensity is important and that the dominant influences causing the observed flow are a single attractor — associated with the Shapley concentration — and a single previously unidentified repeller, which contribute roughly equally to the CMB dipole. The bulk flow is closely anti-aligned with the repeller out to 16,000 ± 4,500 km s−1. This ‘dipole repeller’ is predicted to be associated with a void in the distribution of galaxies.
The effect of this “void in the distribution of galaxies” has been described in rather lurid terms as “Milky Way being pushed through space by cosmic dead zone” in a Guardian piece on this research.
If you’re confused by this into thinking that some sort of anti-gravity is at play, then it isn’t really anything so exotic. If the Universe were completely homogeneous and isotropic – as our simplest models assume – then it would be expanding at the same rate in all directions. This would be a pure “Hubble flow“, with galaxies appearing to recede from an observer with a speed proportional to their distance:
But the Universe isn’t exactly smooth. As well as the galaxies themselves, there are clusters, filaments and sheets of galaxies and a corresponding collection of void regions, together forming a huge and complex “cosmic web” of large-scale structure. This distorts the Hubble flow by inducing peculiar motions (i.e. departures from the pure expansion). A part of the Universe which is denser than average (e.g. a cluster or supercluster) expands less quickly than average, a part which is less dense (i.e. a void) expands more quickly than average. Relative to the global expansion rate, clusters represent a “pull” and voids represent a “push”. That’s really all there is to it.
The difficult part about this kind of study is measuring a sufficient number of peculiar motions of galaxies around our own to make a detailed map of what’s going on in the local velocity field. That’s particularly hard for galaxies near the plane of the Milky Way disk as they tend to be obscured by dust. Nevertheless, after plugging away at this for many years, the authors of the Nature paper have generated some fascinating results. It seems that our Galaxy and other members of the Local Group lie between a dense supercluster (often called the Shapley concentration) and an underdense region, so the peculiar velocity field around us has an approximately dipole structure.
They’ve even made a nice video to show you what’s going on, so I don’t have to explain any further!
Today, 2nd February 2017, is Time to Talk Day, which means that it’s time for the nation’s biggest conversation about mental health.
One in four adults and one in ten young people will experience a mental health problem every year. Talking about it doesn’t have to be difficult but can make a big difference. It’s easy to have a conversation about mental health, and it could change someone’s life (including yours). You don’t have to be an expert to help: sometimes just asking how they are is all you need to do to help someone who’s having a hard time.
Here’s a little video about Time to Talk Day:
For more information on how to get involved see here.
It has been a very busy day today but I thought I’d grab a few minutes to rant about something inspired by a cosmological topic but that I’m afraid is symptomatic of malaise that extends far wider than fundamental science.
The other day I found a news item with the title Study reveals substantial evidence of holographic universe. You can find a fairly detailed discussion of the holographic principle here, but the name is fairly self-explanatory: the familiar hologram is a two-dimensional object that contains enough information to reconstruct a three-dimensional object. The holographic principle extends this to the idea that information pertaining to a higher-dimensional space may reside on a lower-dimensional boundary of that space. It’s an idea which has gained some traction in the context of the black hole information paradox, for example.
There are people far more knowledgeable about the holographic principle than me, but naturally what grabbed my attention was the title of the news item: Study reveals substantial evidence of holographic universe. That got me really excited, as I wasn’t previously aware that there was any observed property of the Universe that showed any unambiguous evidence for the holographic interpretation or indeed that models based on this model could describe the available data better than the standard ΛCDM cosmological model. Naturally I went to the original paper on the arXiv by Niayesh Ashfordi et al. to which the news item relates. Here is the abstract:
We test a class of holographic models for the very early universe against cosmological observations and find that they are competitive to the standard ΛCDM model of cosmology. These models are based on three dimensional perturbative super-renormalizable Quantum Field Theory (QFT), and while they predict a different power spectrum from the standard power-law used in ΛCDM, they still provide an excellent fit to data (within their regime of validity). By comparing the Bayesian evidence for the models, we find that ΛCDM does a better job globally, while the holographic models provide a (marginally) better fit to data without very low multipoles (i.e. l≲30), where the dual QFT becomes non-perturbative. Observations can be used to exclude some QFT models, while we also find models satisfying all phenomenological constraints: the data rules out the dual theory being Yang-Mills theory coupled to fermions only, but allows for Yang-Mills theory coupled to non-minimal scalars with quartic interactions. Lattice simulations of 3d QFT’s can provide non-perturbative predictions for large-angle statistics of the cosmic microwave background, and potentially explain its apparent anomalies.
The third sentence (highlighted) states explicitly that according to the Bayesian evidence (see here for a review of this) the holographic models do not fit the data even as well as the standard model (unless some of the CMB measurements are excluded, and then they’re only slightly better)
I think the holographic principle is a very interesting idea and it may indeed at some point prove to provide a deeper understanding of our universe than our current models. Nevertheless it seems clear to me that the title of this news article is extremely misleading. Current observations do not really provide any evidence in favour of the holographic models, and certainly not “substantial evidence”.
The wider point should be obvious. We scientists rightly bemoan the era of “fake news”. We like to think that we occupy the high ground, by rigorously weighing up the evidence, drawing conclusions as objectively as possible, and reporting our findings with a balanced view of the uncertainties and caveats. That’s what we should be doing. Unless we do that we’re not communicating science but engaged in propaganda, and that’s a very dangerous game to play as it endangers the already fragile trust the public place in science.
The authors of the paper are not entirely to blame as they did not write the piece that kicked off this rant, which seems to have been produced by the press office at the University of Southampton, but they should not have consented to it being released with such a misleading title.
After the annual last-minute rush to file my tax return by the deadline (which is midnight today, 31st January), I can now relax not only because the job is finished, but also because it confirms that I am due a rebate (as indeed I was last year).
Anyway, thinking about the 31st January deadline made me remember that it was precisely four years ago, on 31st January 2013, that I left Cardiff University to take up a post at the University of Sussex. On that occasion I had to rush to finish marking a big stack of exams and finish packing the books in my office before signing the work of art I had left on my whiteboard and heading off.
I didn’t think then that in four years I would be back in Cardiff, but then I didn’t think a lot of things would happen that have happened in that time. I don’t regret my decision to resign, but I do find myself from time to time wondering how things are going back at Sussex and how things might be now had I decided to stay there. I’ve been so busy I’ve only been back once to Brighton since I left last summer. I must put that right. Perhaps I’ll have a holiday there in the spring.
Last night I joined in a protest in Cardiff against Donald Trump’s executive order curtailing the US refugee programme and suspending the right of entry to the USA to people with perfectly valid documentation who were born in Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen. In effect, it’s a Muslim Ban. Coincidentally, the Muslim countries exempted from the order include Saudi Arabia, Egypt and the United Arab Emirates are all places where Trump has business interests.
This unconscionable and unconstitutional order has led to detentions and forced deportations in clear violation of the Geneva convention. There’s a Naturepiece giving some examples of scientists it has affected, to illustrate the damage done already. I find it a disgrace that our government has failed to voice its disapproval of this order, and I’m apparently not alone. Despite just a day’s notice, thousands turned out for protests across the United Kingdom, including Cardiff, where we assembled at about 6.30pm near the statue of Aneurin Bevan on Queen Street.
Despite the pouring rain the numbers built up impressively until the street became very crowded. It wasn’t very easy to count the people there but I’m very confident that they numbered well over a thousand. That’s not as large as the demonstration in London that happened at the same time, but it’s a start.
There were some speeches and chanting and lots of witty signs and we marched up and down Queen Street making an enjoyable noise. It was all very good-humoured, but behind it all was a deep sense of alarm that the President of the United States of America has revealed himself to be nothing but a fascist. Yes, I mean a fascist -that’s precisely what he is. More and more people are going to come to that conclusion over the next few weeks and months and if and when he ever does come to the United Kingdom on a State Visit, there’ll be demonstrations against him. Our political masters may be prepared to sell this country to Trump, but I don’t think ordinary people will stand for it.
This speech, delivered by Sir Ian McKellen at the Cambridge Union a couple of years ago, is from the play Sir Thomas More and is widely attributed to William Shakespeare. It’s from Act 2 Scene 4, at which point in the drama Thomas More (who was then London’s Deputy Sheriff) is called upon to put down an anti-immigration riot in the Parish of St Martin Le Grand, that took place on 1st May 1517. In reality More’s intevention wasn’t effective, and it took the arrival of 5000 troops to disperse the mob.
As well as being powerful for many other reasons, this speech especially fascinating because a hand-written manuscript (thought to be by Shakespeare himself) survives and is kept in the British Library.
The backdrop to this story is that, between 1330 and 1550 about 64,000 immigrants from all across Europe came to England in search of better lives. Locals blamed them for taking their jobs and threatening their culture. Tensions reached breaking point in 1517 and a mob armed with stones, bricks, bats, boots and boiling water attacked the immigrants and looted their homes. Five hundred years on, and we still haven’t learned.
Here is the text of the speech. As you will see, it basically amounts to the argument “do as you would be done by”, but it is much more powerful when performed by an actor, so do watch the clip too!
Grant them removed, and grant that this your noise
Hath chid down all the majesty of England;
Imagine that you see the wretched strangers,
Their babies at their backs and their poor luggage,
Plodding to the ports and coasts for transportation,
And that you sit as kings in your desires,
Authority quite silent by your brawl,
And you in ruff of your opinions clothed;
What had you got? I’ll tell you: you had taught
How insolence and strong hand should prevail,
How order should be quelled; and by this pattern
Not one of you should live an aged man,
For other ruffians, as their fancies wrought,
With self same hand, self reasons, and self right,
Would shark on you, and men like ravenous fishes
Would feed on one another….
Say now the king Should so much come too short of your great trespass As but to banish you, whither would you go? What country, by the nature of your error, Should give you harbour? go you to France or Flanders, To any German province, to Spain or Portugal, Nay, any where that not adheres to England, Why, you must needs be strangers: would you be pleased To find a nation of such barbarous temper, That, breaking out in hideous violence, Would not afford you an abode on earth, Whet their detested knives against your throats, Spurn you like dogs, and like as if that God Owed not nor made not you, nor that the claimants Were not all appropriate to your comforts, But chartered unto them, what would you think To be thus used? this is the strangers case; And this your mountainish inhumanity.
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In the Dark 