R.I.P. Richard Bower

Posted in Biographical, R.I.P., The Universe and Stuff with tags , , , , on January 10, 2023 by telescoper

I was shocked and saddened this weekend to hear of the death from cancer of Professor Richard Bower of Durham University. Richard was a leading light in the Institute for Computational Cosmology (ICC) at Durham, though his research interests spanned observational and theoretical studies of galaxy and cluster formation as well as numerical studies. 

I heard the sad news via social media and there have many tributes to and personal reminiscences of Richard have been circulated from friends, colleagues and former students, including this lovely one by Josh Borrow. I’m sure there will be official obituaries in due course that do justice to Richards personality and achievements in teaching and research; I’ll add links when I see them.

If I can add a personal note, I only worked on one project with Richard, about thirty years ago while I was still at Queen Mary & Westfield College in London. Doing the project was tremendous fun – so much so that the paper we ended up writing bears little relation to what we thought it would be like when we started. We were both young then – I think Richard was about a year younger than me – and both had a tendency to fly off at tangents, but fortunately we were working with two responsible adults (Carlos Frenk and Simon White) who kept us in order. I think the paper we wrote is a nice one, but the real point is that the whole experience was so enjoyable that it was not only formative experience for me from an intellectual point of view but also left me with very fond memories. Whenever we met subsequently, which happened fairly frequently and conferences and on panels and the like, we always talked about what a great time that was. It’s hard to accept we’ll never have that conversation again.

I send heartfelt condolences to Richard’s family, friends and colleagues, both past and present, and in Durham and elsewhere. was an irrepressible and irreplaceable character who will be greatly missed by the entire cosmological community.

Rest in peace, Richard Bower.

Putting girls off Physics

Posted in Education, mathematics, Maynooth, Politics with tags , , on January 9, 2023 by telescoper

I see that Katharine Birbalsingh has resigned from her job as UK Government commissioner for social mobility. Apparently she feels she was “doing more harm than good”. If only the rest of the Government had that level of self-awareness.

I wrote about Katharine Birbalsingh last year, and her departure gives me the excuse to repeat what I said then. Birbalsingh is Head of a school in which only 16% of the students taking physics A-level are female (the national average is about 23%) and tried to explain this by saying that girls don’t like doing “hard maths”.

..physics isn’t something that girls tend to fancy. They don’t want to do it, they don’t like it.

Gender stereotyping begins at school, it seems.

There is an easy rebuttal of this line of “reasoning”. First, there is no “hard maths” in Physics A-level. Most of the mathematical content (especially differential calculus) was removed years ago. Second, the percentage of students taking actual A-level Mathematics in the UK who are female is more like 40% than 20% and girls do better at Mathematics than boys at A-level. The argument that girls are put off Physics because it includes Maths is therefore demonstrably bogus.

An alternative explanation for the figures is that schools (especially the one led by Katharine Birbalsingh, where the take-up is even worse than the national average) provide an environment that actively discourages girls from being interested in Physics by reinforcing gender stereotypes even in schools that offer Physics A-level in the first place. The attitudes of teachers and school principals undoubtedly have a big influence on the life choices of students, which is why it is so depressing to hear lazy stereotypes repeated once again.

There is no evidence whatsoever that women aren’t as good at Maths and Physics as men once they get into the subject, but plenty of evidence that the system dissuades then early on from considering Physics as a discipline they want to pursue. Indeed, at University female students generally out-perform male students in Physics when it comes to final results; it’s just that there are few of them to start with.

Anyway, I thought of a way of addressing gender inequality in physics admissions about 8 years ago. The idea was to bring together two threads. I’ll repeat the arguments here.

The first is that, despite strenuous efforts by many parties, the fraction of female students taking A-level Physics has flat-lined at around 20% for at least two decades. This is the reason why the proportion of female physics students at university is the same, i.e. 20%. In short, the problem lies within the school system.

The second line of argument is that A-level Physics is not a useful preparation for a Physics degree anyway because it does not develop the sort of problem-solving skills or the ability to express physical concepts in mathematical language on which university physics depends. In other words it not only avoids “hard maths” but virtually all mathematics and, worse, is really very boring. As a consequence, most physics admissions tutors that I know care much more about the performance of students at A-level Mathematics than Physics, which is a far better indicator of their ability to study Physics at University than the Physics A-level.

Hitherto, most of the effort that has been expended on the first problem has been directed at persuading more girls to do Physics A-level. Since all UK universities require a Physics A-level for entry into a degree programme, this makes sense but it has not been very successful.

I believe that the only practical way to improve the gender balance on university physics course is to drop the requirement that applicants have A-level Physics entirely and only insist on Mathematics (which has a much more even gender mix). I do not believe that this would require many changes to course content but I do believe it would circumvent the barriers that our current school system places in the way of aspiring female physicists, bypassing the bottleneck at one stroke.

I suggested this idea when I was Head of the School of Mathematical and Physical Sciences at Sussex, but it was firmly rejected by Senior Management because we would be out of line with other Physics departments. I took the view that in this context being out of line was a positive thing but that wasn’t the view of my bosses so the idea sank.

In case you think such a radical step is unworkable, I give you the example of our Physics programmes in Maynooth. We have a variety of these, including Theoretical Physics & Mathematics, Physics with Astrophysics, and Mathematical Physics and/or Experimental Physics through our omnibus science programme. Not one of these courses requires students to have taken Physics in their Leaving Certificate (roughly the equivalent of A-level) though as I explained in yesterday’s post, Mathematics is a compulsory subject at Leaving Certificate. The group of about first-year 130 students I taught this academic year is considerably more diverse than any physics class I ever taught in the UK, and not only in terms of gender…

I contend that the evidence suggests it’s not Mathematics that puts female students off Physics, a large part of it is A-level Physics.

Mathematics for All?

Posted in Education, mathematics, Maynooth, Politics with tags , , on January 8, 2023 by telescoper
Random maths stuff to scare Simon Jenkins.

One of the things I noticed in the news from the UK last week was PM Rishi Sunak’s suggestion that all school students in England should study mathematics to age 18. I’ve emphasized in England because responsibility for education is devolved to the governments of Scotland, Wales and Northern Ireland so what the Prime Minister on this matter says has no bearing outside England.

Anyway, two of the obvious fundamental problems with Sunak’s proposal are:

  1. How will making mathematics a compulsory subject at age 16-18 fit within the current system of A-levels, in which most students study only three subjects?
  2. Who is going to teach all the extra lessons required when there is already a shortage of STEM teachers?

I’m not sure of the extent to which Sunak has thought through this plan. I suspect it’s nothing more than the usual sort of half-baked idea that his type of politician likes to float in order to distract attention away from serious problems elsewhere (e.g. NHS, the economy, strikes, etc). The suggestion has generated a wide range of responses, including from the Guardian’s resident idiot Simon Jenkins who, as usual, misses the point spectacularly when he writes:

Like many of my generation, I did basic and advanced maths to age 16. This embraced complex algebra, trigonometry, quadratic equations, differential calculus, the use of logarithms and old-fashioned slide rules. I cannot recall ever using one jot of it, all now forgotten. 

I’m tempted to suggest that if Simon Jenkins hadn’t forgotten what he’d learnt at school he might write less garbage, but I won’t. I also studied these things to age 16 and, because I chose a career in science, I have used all of them (except slide rules, which were obsolete, but including logarithms). Of course not everyone will feel the same.

I should however point out that as well as Mathematics and science subjects I also studied Geography, History, French, Latin, and English Literature to O-level (which I took at age 16). I don’t think I have ever “used” any of these since, but I do not for one minute regret having studied them. In my opinion education is not just about the acquisition of things to use, but represents a way of opening the mind up to a range of different ways of thinking. Mathematical reasoning is not the only way of thinking but it is important, as is the process involved in learning another language. As I have written on this blog many times before, education is not just about “skills training”: it’s about expanding the mind.

Putting most of Simon Jenkins’s childish rant to one side, there is a serious point buried in it. What Sunak seems to want to achieve is increased levels of basic numeracy which does not require the fluency in trigonometry or differential calculus. The question then is what has gone wrong with the education of a student who hasn’t acquired that knowledge by the age of sixteen? I’d suggest that indicates as significant failing of the pre-16 education system, which is therefore what needs to be fixed. Remedial action in post-16 education is at best a sticking-plaster solution, when more fundamental reform is required.

I feel obliged to point out, however, that here in Ireland, Mathematics is indeed a compulsory subject up to age 18 at least for those students who take the Leaving Certificate. This plays a role here similar to that of GCE A-levels in the UK, but most students take 7 subjects rather than just three. Mathematics is compulsory (as are English and Irish). All subjects can be taken at Ordinary or Higher level in the Leaving Certificate and Mathematics can also be taken at Foundation level (as can Irish).

Last Semester I was involved in teaching Mathematical Physics to a class of about 130 first-year students at Maynooth University. Most of these students are doing our General Science degree, entry to which requires just Ordinary level mathematics and one science subject at Leaving Cert.

The great strength of the Leaving Certificate, which it shares with the International Baccalaureate, is its breadth. I think having English as a compulsory subject for everyone is just as positive as the Mathematics requirement. The concentration of subjects at A-level can work very well for students who know what they want to do after School – as it did with me – but there are dangers involved in pigeonholing students at age 16. A broader education does not put so much pressure on students to decide so young.

Moving to something more like the Leaving Certificate addresses Item 1. at the start of this piece, but Item 2. remains an issue for England as it does in Ireland. In reality the choice for many students is restricted not by the examination system by the lack of specialist teachers in schools, especially (not not only) in STEM subjects. The problem there is that the pay and working conditions for teachers in state schools are not commensurate with their importance to society. I don’t see Sunak showing any inclination to change that situation.

New Publication at the Open Journal of Astrophysics

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , on January 7, 2023 by telescoper

Continuing the process of catching up with business at the Open Journal of Astrophysics, here is the first paper of 2023. This one was accepted before Christmas but the final version only appeared on arXiv after the holiday and was published officially on 4th January 2023.

The latest paper is the first paper in Volume 6 (2023) as well as the 66th in all. It’s yet another in the Cosmology and Non-Galactic Astrophysics folder.

The latest publication is entitled “It takes two to know one: Computing accurate one-point PDF covariances from effective two-point PDF models“. This is a British-French-German collaboration led by Cora Uhlemann of Newcastle University with co-authors  Oliver Friedrich, Aoife Boyle, Alex Gough, Alexandre Barthelemy, Francis Bernardeau, and Sandrine Codis.

This is such an interesting paper that we discussed it at our cosmology journal club at Maynooth University a while ago when it first appeared on arXiv and reading it again since then has suggested a nice project to me!

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 officially accepted version of the paper on the arXiv here.

Nollaig na mBan

Posted in Irish Language, Literature with tags , , , on January 6, 2023 by telescoper

Today is January 6th, which is Epiphany in the Church calendar, Twelfth Night, usually the day the Christmas decorations came down when I was a kid, and here in Ireland a day known as Nollaig na mBan (Women’s Christmas).  You can read more about the origin of this Irish tradition here.

This allows me an excuse to be a grammar bore yet again. The Irish word for “woman” is bean, which has the plural form Ban; na  is the corresponding definite article. However, in the phrase  Nollaig na mBan, “women” is in the genitive case (Christmas of the women) and the B therefore undergoes lenition to become m. This sort initial consonant mutation is very common in the Irish language. Instead of being pronunced “ban” the word for women is therefore spoken as “man”. Fortunately, the written language is kind in that it leaves the unmodified consonant in place, hence mBan.

I was also reminded today that 6th January (in 1914) was the date of the gathering described in James Joyce’s wonderful short story The Deadthe last, the longest, and the best of the collection Dubliners, which I thoroughly recommend if you haven’t read it yet. It’s an ideal gateway into Joyce’s writing:

Nollaig na mBan shona daoibh go léir!

Fifty Years of Gravitation

Posted in The Universe and Stuff with tags , , on January 5, 2023 by telescoper

I was surprised to discover, a couple of days ago, that the classic textbook Gravitation by Misner, Thorne and Wheeler is 50 years old this year. MTW as it is usually known was first published in 1973, and has has now been reprinted 24 times. I bought my copy (shown above) about 30 years ago. I’ve often joked that this tome is so hefty that it not only allows one to read about Gravitation but also to experience its practical effects!

This anniversary reminds me that there was a competition running at ITP2022 last year that involved holding out a copy of the book  in one hand at arm’s length for as long as possible following the instructions below:

The winner of the competition was John Brennan of Maynooth University, with a time of 3 minutes and 29 seconds. If you can lay your hands on a copy of MTW you can try to do better!

New Publication at the Open Journal of Astrophysics

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , on January 5, 2023 by telescoper

I’ve been catching up on publishing matters over the past day or so, including dealing with a bit of a backlog generated by the Christmas break. The Open Journal is run entirely by volunteers and we all need some time off at some point.

To start with I’m delighted to be able to announce the last paper of 2022 at the Open Journal of Astrophysics.  The latest paper is the 17th paper in Volume 5 (2022) as well as the 65th in all. It’s yet another in the Cosmology and Non-Galactic Astrophysics folder.

The latest publication is entitled “The Cosmic Graph: Optimal Information Extraction from Large-Scale Structure using Catalogues“. It is written by a distinguished collection of cosmologists from around the world (and Alan Heavens).

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 officially accepted version of the paper on the arXiv here.

Here is a bigger version of the image from the paper used on the overlay:

 

 

Code and a tutorial for the analysis and relevant software can be found here .

Perihelion Again

Posted in The Universe and Stuff with tags on January 4, 2023 by telescoper

Earth’s elliptical orbit viewed at an angle (which makes it look more eccentric than it is – in reality is very nearly circular).

According to my new RAS Diary,  today (Wednesday 4th January 2023) at approximately 16.17 GMT the Earth reaches at the point on its orbit which which it is at its closest to the Sun, i.e. its perihelion. At this time the distance from the Sun’s centre to Earth’s centre will be  147,098,925 km. This year, aphelion (the furthest distance from the Sun) is at 21.06 GMT on July 6th 2023 at which point the centre of the Earth will be 152,093,251 km from the centre of the Sun. You can find a list of times and dates of perihelion and aphelion for future years here.

At perihelion the speed of the Earth in its orbit around the Sun is greater than at aphelion (about 30.287 km/s versus 29.291 km/s). This difference, caused by the Earth’s orbital eccentricity, contributes to the difference between mean time and solar time I blogged about when discussing the Winter Solstice a couple of weeks ago.

It surprises me how many people think that the existence of the seasons has something to do with the variation of the Earth’s distance from the Sun as it moves in its orbit in that the closer to the Sun we get the warmer the weather will be. The fact that perihelion occurs in the depth of winter should convince anyone living in the Northern hemisphere that this just can’t be the case, as should the fact that it’s summer in the Southern hemisphere while it is winter in the North.

The real reason for the existence of seasons is the tilt of the Earth’s axis of rotation. I used to do a little demonstration with a torch (flashlight to American readers) to illustrate this when I taught first-year astrophysics. If you shine a torch horizontally at a piece of card it will illuminate a patch of the card. Keep the torch at the same distance but tilt the card and you will see the illuminated patch increase in size. The torch is radiating the same amount of energy but in the second case that energy is spread over a larger area than in the first. This means that the energy per unit area incident on the card is decreases when the card is tilted. It is that which is responsible for winter being colder than summer. In the summer the sun is higher in the sky (on average) than in winter. From this argument you can infer that the winter solstice not the perihelion, is the relevant astronomical indicator of winter.

That is not to say that the shape of the Earth’s orbit has no effect on temperatures. It may, for example, contribute to the summer in the Southern hemisphere being hotter than in the North, although it is not the only effect. The Earth’s surface possesses a significant North-South asymmetry: there is a much larger fraction of ocean in the Southern hemisphere, for example, which could be responsible for moderating any differences in temperature due to insolation. The climate is a non-linear system that involves circulating air and ocean currents that respond in complicated ways and on different timescales not just to insolation but to many other parameters, including atmospheric composition (especially the amount of water vapour).

The dates when Earth reaches the extreme points on its orbit (apsides) are not fixed because of the variations in its orbital eccentricity so, in the short-term, the dates can vary up to 2 days from one year to another. The perihelion distance varies slightly from year to year too; it’s slightly smaller this year than last year, for example.

There is however a long-term trend for perihelion to occur later in the year. For example, in 1246, the December Solstice (Winter Solstice for the Northern Hemisphere) was on the same day as the Earth’s perihelion. Since then, the perihelion and aphelion dates have drifted by an average of one day every 58 years and this trend will continue. This means that by the year 6430 the timing of the perihelion and the March Equinox will coincide, although I will probably have retired by then…

 

First Day Back

Posted in Biographical, Education, Maynooth with tags , on January 3, 2023 by telescoper

So here we are, then, 3rd January 2023 and my first day back after the Christmas break. Maynooth University Campus has been largely deserted, though a few of my colleagues have been in today.

Quite a few people seem to have been down with various bugs over the holiday, including a few that have tested positive for Covid-19. We haven’t had information about actual case numbers since before Christmas but I expect a big increase when the figures are announced later this week. Hospitals are already under pressure here in Ireland so things could be quite difficult during the next few weeks.

My plans to do an in-person revision lecture were foiled by the fact that the teaching room I planned to use was locked so I adopted plan B which was to put up some lecture recordings to help the students with their revision ahead of the examination period which starts on Friday. That’s a bit early, really, as 6th January (being Epiphany) is still very much a part of the Christmas season for many people. I remember trying to arrange a meeting on January 6th years ago with a European collaboration only to be met with complete disbelief. At least the first examination for which I am responsible isn’t until Saturday.

For many of the students taking examinations in subjects I have been teaching, these will be the first University examinations and I’m sure many of them are a bit apprehensive, so I thought I’d pass on some advice.

  1. Try to get a good night’s sleep before the examination and arrive in plenty of time before the start. Spending all night cramming is unlikely to help you do well. Prepare well in advance so you’re relaxed when the time comes.
  2. Read the entire paper before starting to answer any questions. In particular, make sure you are aware of any supplementary information, formulae, etc, given in the rubric or at the end.
  3. Start off by tackling the question you are most confident about answering, even if it’s not Question 1. This will help settle any nerves. You’re under no obligation to answer the questions in the order they are asked.
  4. Don’t rush! Students often lose marks by making careless errors. Check all your numerical results on your calculator at least twice and – PLEASE – remember to put the units!
  5. Don’t panic! You’re not expected to answer everything perfectly. A first-class mark is anything over 70%, so don’t worry if there are bits you can’t do. If you get stuck on a part of a question, don’t waste too much time on it (especially if it’s just a few marks). Just leave it and move on. You can always come back to it later.

Nolan, Moran and Schwa…

Posted in Biographical, Irish Language with tags , , on January 2, 2023 by telescoper

This Bank Holiday afternoon I’ve been pottering about at home and listening to The Full Score on RTÉ Lyric FM, which is presented by Liz Nolan. I like this programme because it consists of performances of full works rather than bits and pieces extracted from longer compositions (“bleeding chunks” as my music teacher at school used to call them). Unfortunately this programme is broadcast on weekday afternoons so I can’t listen to it often except when I’m off work.

The presenter’s surname Nolan made me reflect on how many Irish surnames end with –an. Other examples aside from Nolan include Regan, Keegan, Dolan, Coogan, Behan, Whelan and Moran. In Ireland these are all pronounced with a stress on the first syllable, as they are in English pronunciation, but curiously English people usually pronounce the last with a stress on the second syllable, i.e. Mor-AN. I’ve been pulled up for doing this on more than one occasion. Here in Ireland it’s not Mor-AN but MOR-an. A little googling suggests that the English version is influenced by the French name Morant rather than the original Gaelic Ó Móráin.

Anyway this line of thought took me to the realization that the vowel in an unstressed final syllable such as in Nolan is a very indistinct sound. You could almost put any vowel in there and get the same sound: “Nolan” could easily be transcribed as “Nolon” or “Nolun” etc if the second syllable is not stressed.

Then I realized that linguists, specifically those who study phonetics and phonology, have been there long before me. There is a name for the indistinct vowel sound in such cases: it is called schwa and is denoted by the character ə. Schwa sits right in the middle of the vowel chart. Produced when the lips and tongue are completely relaxed, it’s neither an open nor a closed vowel but something in between. It’s actually quite a common sound in English, though it’s taken me almost 60 years to discover its name! – and exists in many other languages too.