Archive for August, 2022

A Day for Celebrations

Posted in Biographical, Education, Maynooth with tags , on August 31, 2022 by telescoper

It’s quite a busy day today. I spent a slice of of this morning attending the Autumn Examination Board (online). Students taking repeat exams will get their results on Friday which, coincidentally, is the same day that this year’s Leaving Certificate Examinations will come out.

I have one major task to finish today, completing the revisions of a paper to get it ready to resubmit. I’ve been struggling with this over the last few days but I think only minor changes are left to do so I should get it done after lunch. I’ll be at the Irish National Astronomy Meeting tomorrow (Thursday) and Friday so I’d like to get that done before that.

I already have two causes for celebration today. The first is that my first Maynooth PhD student’s first paper has now hit the arXiv. The second is that today is the last day of my three-year as Head of the Department of Theoretical Physics. As I wrote on the occasion of my appointment:

It’s about three years now since I stepped down as Head of School at the University of Sussex at which point I didn’t imagine I would be stepping up to be Head of Anything again, but to be honest this position has a smaller and much better defined set of responsibilities than the one I used to hold so I’m actually quite looking forward to it.

The idea that the job would have “a smaller and much better defined set of responsibilities” turns out to have been one of the worst miscalculations of my life, entirely for reasons outside the Department and not only because of the pandemic. Suffice to say that it’s been a difficult three years. I have to say though that the staff and students in the Department have been great to work with over this period, and their support is the only thing that made the job bearable. I will of course be continuing to work with them as a teacher and researcher and will do the best I can to support my replacement, assuming the University management gets around to appointing a successor, which it has yet to do despite having many months to do so.

Now, to finish revising that paper.

Fair Play for PhD Researchers

Posted in Maynooth with tags , on August 30, 2022 by telescoper

I thought I’d use the medium of this blog to share a petition aimed at increasing the stipends of PhD students in Ireland. The background to this petition, described on this blog here, is that in June the Government of Ireland introduced a new scheme in which a select group of students would receive a stipend of €28k per annum for PhD. The justification for this amount from the Government itself is that it corresponds to an appropriate level of paper. It seems to me to be entirely logical that if this is the appropriate level of pay, then all PhD stipends should be increased to this level with immediate effect.

As the petition site says:

We maintain that the current PhD stipend is insufficient on several accounts. All of Ireland, especially Dublin, has a cost of living crisis driven by increasing rents and rising inflation. The costs are even higher for non-EU researchers, who have to pay for health insurance and residence permits each year.

The Central Statistics Office (CSO) reported an approximate 9.1% inflation of prices1 in the last year, which means that the current (average) stipend of €18.5k has the same purchasing power as a €17k stipend pre-inflation, when current first-year PhD researchers accepted their roles.

I hope that not only other PhD students and academic staff at Maynooth and beyond will sign this petition. It is particularly important for the we academic staff to show solidarity with research students as we head into a possible industrial dispute ourselves.

You can find the petition here.

The Notional Lottery

Posted in Biographical, Education, Maynooth with tags , , on August 29, 2022 by telescoper

On Friday evening I got an email to tell me I’d won a prize on the Euromillions lottery. My excitement was short-lived, however, as I discovered on checking my ticket that my winnings amounted to the princely sum of €5, not the jackpot of nearly €100 million.

As regular readers of this blog might know, I play the Euromillions every week. I use the same numbers each time and always stake the minimum amount (€2.50) . Some think it is strange, but I see it partly as one of those little rituals we all invent for ourselves and partly as a small price to pay for a little frisson of excitement when the numbers are drawn.

But I do sometimes wonder what on Earth I would do if I won the huge jackpot prize. I have no dependents. I don’t have a car and have no interest in getting one, especially a fancy one. I don’t need a bigger house, or a yacht, or a private jet.  Frankly, there’s nothing that I would really want to buy that I couldn’t buy already. It’s not that I have a huge salary, just that I’m not exactly very materialistic. I would of course pay of my mortgage, but that wouldn’t make much of a dent in €100 million!

Would I quit my job? Would I quit teaching? If you had asked me those questions a decade ago I would have said a firm “no” but now I’m not so sure. If I could ditch the admin stuff, I would of course do so. I still enjoy teaching and research, though. On the other hand I’m pushing sixty now, and my departure from a paid position would open up opportunities for someone younger. I might carry on in some voluntary arrangement if this were possible.

So what would I do with the money? I think what I would probably do is set up some sort of philanthropic foundation to give most of it to good causes, including the arts and sciences; the latter would include a big donation to arXiv.

One thing I wouldn’t do would be to give the money directly to universities, as any donation would be swallowed up by the central coffers and most of it would probably just be wasted on management salaries and vanity projects instead of education and research. I suppose if I set up a foundation I could give grants directly to researchers and students for specific purposes bypassing the top layer.

Anyway, all this is notional because I only won €5. Maybe next week…

The Week Ahead

Posted in Biographical, Maynooth with tags , , , , , on August 28, 2022 by telescoper

I’m aware that tomorrow (Monday 29th August) is a Bank Holiday across the Irish Sea, but here on the Emerald Isle we had our August Bank Holiday at the start of the month so tomorrow I’ll be working. Among the important events to take place next week is the final Examination Board of 2021/2 on Wednesday morning at which we see all the results of all the students not just those from our Department. After that final check the marks will be released to students on Friday 2nd September and they’ll be able to discuss their situation with staff on Consultation Day which is Tuesday of next week (6th September).

The term of my appointment as Head of the Department of Theoretical Physics ends on Wednesday August 31st. I did try to step down a year ago. Here is what I wrote then:

Over the last few days, in an exhausted and demoralized state, I have been looking back over the best part of two years I have been Head of the Department of Theoretical Physics at Maynooth University – most of which has coincided with the Covid-19 pandemic. Frankly, I have found the burden of administration on top of the heavy teaching load required of me to be unmanageable. Because we are a very small Department teaching a full degree course, all of us have to teach many more modules than is reasonable for for staff who are expected to do research as well. I had to teach five modules* last academic year; that would have been bad enough even without having to do everything online and without the additional and frequently onerous duties associated with the Head of Department. There is no prospect of that burden decreasing for the foreseeable future.

For reasons which now escape me I agreed to carry on for one more year until the end of the three-year term to which I was appointed. I regret that “the burden”, far from decreasing, has continued to increase, to the extent that last year we had to cope with staff shortages too.

As it happens I will be spending Thursday and Friday at the Irish National Astronomy Meeting which this year is at the historic Dunsink Observatory (just outside Dublin and not far from Maynooth). I was last there on a trip to Dublin many years ago so I am looking forward to seeing it again as well as listening to the talks. The programme seems very broad and varied, so it should be interesting. The last one of these I attended in person was in Armagh in 2019, before Covid intervened and meetings became virtual. I’m not giving a talk this time, so hopefully it will be a fairly relaxed occasion.

Knowing that I was due to step down as HoD on 31st August I booked a week’s annual leave the following week (5th-9th September inclusive). I have had very little opportunity to take holidays over the past three years, so I am looking forward to a little bit of peace and quiet before the academic term starts. Before that, however, I have two research papers which are almost finished and which I’d really like to submit by Wednesday (and another which will have to wait until I return from leave). I’ve had little time to do research over the last three years either.

This year’s Leaving Certificate results are due out on Friday 2nd September and first-round CAO offers go out on Thursday 8th August. There will then be a scramble to allocate places, but I shall be blissfully out of the way for at least part of that. I will of course be back for the start of teaching (for returning students on 19th September and for new students on 26th September). As I have mentioned before that there is a serious student accommodation crisis in Ireland which will probably disrupt the studies of many students. I have yet to hear of any steps that my institution is taking to mitigate the looming disaster. It’s going to be a very challenging Semester, even without being Head of Department.

Oh, and on Monday I will be attending a virtual briefing about the plans from my Union (IFUT) to ballot its members for industrial action, of which more anon….

Sizes, Shapes and Minkowski Functionals

Posted in mathematics, The Universe and Stuff with tags , , , , on August 27, 2022 by telescoper

Before I forget I thought I would do a brief post on the subject of Minkowski Functionals, as used in the paper we recently published in the Open Journal of Astrophysics. As as has been pointed out, the Wikipedia page on Minkowski Functionals is somewhat abstract and impenetrable so here is a much simplified summary of their application in a cosmological setting.

One of things we want to do with a cosmological data set to characterize its statistical properties to compare theoretical predictions with observations. One interesting way of doing this is to study the morphology of the patterns involved using quantitative measures based on topology.

The approach normally used deals with Excursion Sets, i.e. regions where a field exceeds a certain level usually given in terms of the rms fluctuation or defined by the fraction of space above the threshold. The field could, for example, be the temperature field on the CMB Sky or the density field traced by galaxies. In general the excursion set will consist of a number of disjoint pieces which may be simply or multiply connected. As the threshold is raised, the connectivity of the excursion set will shrink but also its connectivity will change, so we need to study everything as a function of threshold to get a full description.

One can think of lots of ways of defining measures related to an excursion set. The Minkowski Functionals are the topological invariants that satisfy four properties:

  1. Additivity
  2. Continuity
  3. Rotation Invariance
  4. Translation Invariance

In D dimensions there are (D+1) invariants so defined. In cosmology we usually deal with D=2 or D=3. In 2D, two of the characteristics are obvious: the total area of the excursion set and the total length of its boundary (perimeter). These are clearly additive.

In order to understand the third invariant we need to invoke the Gauss-Bonnet theorem, shown in this graphic:

The Euler-Poincare characteristic (χ) is our third invariant. The definition here allows one to take into account whether or not the data are defined on a plane or curved surface such as the celestial sphere. In the simplest case of a plane we get:

As an illustrative example consider this familiar structure:

Instead of using a height threshold let’s just consider the structure defined by land versus water. There is one obvious island but in fact there are around 80 smaller islands surrounding it. That illustrates the need to define a resolution scale: structures smaller than the resolution scale do not count. The same goes with lakes. If we take a coarse resolution scale of 100 km2 then there are five large lakes (Lough Neagh, Lough Corrib, Lough Derg, Lough Ree and Lower Lough Erne) and no islands. At this resolution, the set consists of one region with 5 holes in it: its Euler-Poincaré characteristic is therefore χ=-4. The change of χ with scale in cosmological data sets is of great interest. Note also that the area and length of perimeter will change with resolution too.

One can use the Gauss-Bonnet theorem to extend these considerations to 3D by applying to the surfaces bounding the pieces of the excursion set and consequently defining their corresponding Euler-Poincaré. characteristics, though for historical reasons many in cosmology refer not to χ but the genus g.

A sphere has zero genus (χ=1) and torus has g=1 (χ=0).

In 3D the four Minkowski Functionals are: the volume of the excursion set; the surface area of the boundary of the excursion set; the mean curvature of the boundary; and χ (or g).

Great advantage of these measures is that they are quite straightforward to extract from data (after suitable smoothing) and their mean values are calculable analytically for the cosmologically-relevant case of a Gaussian random field.

Here endeth the lesson.

Open Access USA

Posted in Open Access with tags , , on August 26, 2022 by telescoper

There was an important announcement yesterday about Open Access from the Office of Science & Technology Policy at the White House which I picked up from Twitter. Here is a summary:

More detailed documents can be found here and here.

The principle that research that is funded by the public should be available to the public is one of the foundations of Open Access publishing and it is laudable to see this enforced more strictly. Previously journals were able to keep articles behind a paywall for an embargo period, just withholding access for up to a year. The deadline for ending this practice is December 31st 2025. I would have made it sooner, but at least it has not been kicked into the very long grass.

The problem that I can see with the policy is that it will probably involve researchers having to pay thousands of dollars in article processing fees associated with the “Gold” Open Access of the form offered by commercial publishers. When the summary says “without cost” it means “without cost to the reader”. The way it will work is that these costs are transferred to the authors. The publishers will still gather their profits.

It will take stronger policies than this to break the stranglehold of the academic publishing cartels. It is more likely in my view that radical change will emerge from the grass roots, as researchers find novel ways of publishing their work without handing huge dollops of cash to profiteers.

The ABC of A-levels

Posted in Biographical, Education, Rugby with tags , , , on August 25, 2022 by telescoper

Yesterday I was having a bit of a clear-out of my office at home ahead of the new teaching term when I came across the above clipping at the back of a box of old papers. It’s from the Newcastle Evening Chronicle in 1981 and it shows the number of A-levels passed that summer by pupils at the Royal Grammar School in Newcastle, which I went to.

I don’t know why I’ve kept this for so long, neither do I know why the local paper felt important to list this information. It probably isn’t allowed to publish such things these days owing to Data Protection regulations but it did so routinely back then. I think it’s OK to publish it now because it has been in the public domain, technically speaking, for over 40 years. The Chronicle also published O-level passes with names, and I have the list with me in it from 1979.

A few things struck me about this list. One is that, while I can put faces to many of the names, there are many to which I can not. Indeed some of the names don’t ring any bells at all. I’m sure I’ve been forgotten by most people in the list too! When I arrived at the school in 1974 I was assigned to a “House” called Eldon along with about 30 other boys. In the first year we were placed at desks in our classroom in alphabetical order. Obviously the first people I got to know were those sitting in adjacent desks. It’s interesting that seven years on, the two names preceding mine in the list above were also in Eldon and had been sitting next to me on the very first day I arrived and they are among the few people from RGS that I am still in regular contact with.

The Sixth Form (two years, “Lower 6th” and “Upper Sixth” to coincide with the length of the A-level course) was divided into Arts and Sciences. The Arts are listed first in alphabetical order, then the Sciences. I was in the latter group. My 4 A-levels were Mathematics, Further Mathematics, Physics & Chemistry. I also did two special papers, in Physics and Chemistry. After A-levels, along with about 20 of the people on the above list, I stayed on for a “7th term” to do the Cambridge Entrance Examination, and the rest is history.

I also note that very few of us had only a single first initial like me. That’s a Coles family trait. My Dad always said that you only use one name so why have extras?

One final comment. Near the bottom of the list you will see the name “J M Webb”. That name is not to do with the James Webb of Space Telescope fame, but Jonathan Webb did go on to play Rugby for England. I didn’t know him well at school because, as well as being separated by alphabetical considerations, he was in a different House (Horsley if I remember correctly).

New Publication at the Open Journal of Astrophysics

Posted in Open Access, The Universe and Stuff with tags , , , , , , , , , on August 24, 2022 by telescoper

It’s time once again for me to announce another new paper at the Open Journal of Astrophysics. The new paper, published yesterday, is the 12th paper in Volume 5 (2022) and the 60th in all. The latest publication is entitled “Minkowski Functionals in Joint Galaxy Clustering & Weak Lensing Analyses” and the authors are Nisha Grewal, Joe Zuntz and Tilman Tröster of the Institute for Astronomy in Edinburgh and Alexandra Amon of the Institute of Astronomy in Cambridge. The paper is in the folder marked Cosmology and Non-Galactic Astrophysics.

Incidentally, Dr Alexandra Amon is the winner of this year’s Caroline Herschel Lectureship in Astronomy, so congratulations to her for that too!

The new paper is about the application of topological characteristics known as Minkowski Functionals to cosmological data. This approach has been used in the past to study the pattern cosmic microwave background temperature fluctuations; see e.g. here for one of my forays into this way back in 2008. Now there are more high-quality datasets besides the CMB so there are more opportunities to use this elegant approach. Perhaps I should do a blog post about Minkowski Functionals? Somewhat to my surprise I can’t find anything on that topic in my back catalogue here In The Dark

Anyway, here is a screen grab of the overlay which includes the  abstract:

 

 

You can click on the image to make it larger should you wish to do so. You can find the accepted version of the paper on the arXiv here.

How big were the biggest galaxies in the early Universe?

Posted in Biographical, Cardiff, The Universe and Stuff with tags , , , , , , , on August 23, 2022 by telescoper

Once upon a time (over a decade ago when I was still in Cardiff), I wrote a paper with PhD student Ian Harrison on the biggest (most massive) galaxy clusters. I even wrote a blog post about it. It was based on an interesting branch of statistical theory called extreme value statistics which I posted about in general terms here.

Well now the recent spate of observations of high-redshift galaxies by the James Webb Space Telescope has inspired Chris Lovell (who was a student at Cardiff back in the day then moved to Sussex to do his PhD and is now at the University of Hertfordshire) and Ian Harrison (who is back in Cardiff as a postdoc after a spell in the Midlands), and others at Cambridge and Sussex, to apply the extreme value statistics idea not to clusters but to galaxies. Here is the abstract:

The basic idea of galaxy formation in the standard ΛCDM cosmological model is that galaxies form in dark matter haloes that grow hierarchically so that the typical size of galaxies increases with time. The most massive haloes at high redshift should therefore be less massive than the most massive haloes at low redshift, as neatly illustrated by this figure, which shows the theoretical halo mass function (solid lines) and the predicted distribution of the most massive halo (dashed lines) at a number of redshifts, for a fixed volume of 100 Mpc3.

The colour-coding is with redshift as per the legend, with light blue the highest (z=16).

Of course we don’t observe the halo mass directly and the connection between this mass and the luminosity of a galaxy sitting in it is likely to be complicated because the formation of the stars that produce the light is a rather messy process; the ratio of mass to light is consequently hard to predict. Moreover we don’t even have overwhelmingly convincing measurements of the redshifts yet. A brief summary of the conclusions of this paper, however, is that is some of the big early galaxies recently observed by JWST seem to be a big too big for comfort if we take their observed properties at face value. A lot more observational work will be needed, however, before we can draw definite conclusions about whether the standard model is consistent with these new observations.

The Death of Michael Collins

Posted in History with tags , , , , on August 22, 2022 by telescoper
Michael Collins in full dress uniform, pictured a few days before his death.

Today marks the centenary of the death of Michael Collins during the Irish Civil War. The event was marked by a ceremony yesterday at Béal na Bláth, where Collins was shot in the head and killed by a sniper on 22nd August 1922. He was 31 years old.

The Civil War had erupted over the the Anglo-Irish Treaty with the pro-Treaty National Army (of which Collins was Commander-in-Chief) fighting against anti-Treaty forces. Opponents of the Treaty felt that the Irish Free State it created fell far short of the Republic they had fought for during the War of Independence. In particular the Treaty required an Oath of Allegiance to the British Crown, which many Republicans found totally unacceptable.

On 22nd August, with Free State forces gaining the upper hand, Collins was travelling through County Cork with a convoy including an armoured car, when it was ambushed by soldiers of the anti-Treaty IRA. Instead of trying to escape, the convoy stopped and a gunfight developed during which Collins was shot dead. He was the only fatality. There was no official inquiry into the events at Béal na Bláth and nobody knows for sure who fired the fatal shot. The death of Michael Collins, following the death a few days earlier of Arthur Griffith, was a big setback for the leadership of the Free State and the already bitter Civil War descended into cycle of atrocities and reprisals. The fighting was to grind on until May 1923.