Archive for Cambridge

A Question of the Past

Posted in Biographical, Cute Problems, Education, Maynooth, The Universe and Stuff with tags , , , , , on April 20, 2022 by telescoper

I was tidying up some old files earlier today and came across some old examination papers, including those I took for my final examinations in Part II of the Natural Sciences Tripos in 1985. There were six of these, in the space of three consecutive days…

I picked one of the questions to share here because it covers similar ground to my current (!) Advanced Electromagnetism module for final-year students in Maynooth. Sorry it’s a bit grubby!

It’s been a long time since I took my finals and I’d largely forgotten what the format was. The question above was taken from Paper II which consisted of nine questions altogether in three Sections, A (Solid State Physics), B (Statistical Physics) and C (Electromagnetism, from which Q9 above was taken; I think the course was actually called Electrodynamics & Relativity). The examination was 3 hours in duration and students were asked to answer four questions, including one from each Section. That means each question would be expected to take about 45 minutes.

Looking at the paper in general and the above question in particular, a number of things sprang to mind about differences between then in Cambridge and now in Maynooth:

  1. Our theoretical physics papers in Maynooth are 2 hours in duration in which time students are to answer four questions, so that the questions are a bit shorter – 30 minutes each rather than 45.
  2. Our papers are also on a single subject rather than a composite of several; we typically don’t offer the students choice; my Advanced Electromagnetism paper has four questions and students have to answer all four for full marks.
  3. The questions on the old Tripos papers are less structured. There is no indication of the marks allocated to each part of the question in the question above.
  4. As far as I can recall there was no formula booklet back in 1985, though there was a sheet of physical constants. My Advanced Electromagnetism examination this year comes with a couple of pages of useful formulae from vector calculus and key equations in EM theory. One might argue that the old Cambridge papers relied rather more on memory (especially when you take into account that everything was in the space of three days).
  5. Back to Question 9, it is true that this along with the other Electromagnetism questions is at a similar level to what I have been teaching this Semester. If I recall correctly the relevant course in Cambridge was of 24 lectures, the same length as the course I’m teaching this year.
  6. Students taking my course should know how to do both parts of Question 9 without too much difficulty.

On the final point, the easiest way to tackle this sort of problem is to do what the question says: determine the electric and magnetic potentials, derive the electric and magnetic fields from them, then work out the Poynting vector quantifying the energy flux. The part of this that survives in the far-field limit gives you the radiated power then – Bob’s your Uncle – the answer is basically the Larmor Formula which is ubiquitous in problems of this type. The case of an oscillating dipole is a standard derivation but this method works for any time-varying source, as long as you remember to include the retarded potentials if it’s not periodic.

Had I been writing this question for a modern exam I think I would at very least have ended the first part with “Show that the radiated power is…” and then given the formula, so that it could be used for the second part even if a student could not derive it.

R.I.P. Bamber Gascoigne

Posted in Biographical, Television with tags , , , on February 8, 2022 by telescoper

I was saddened this morning to hear of the death at the age of 87 of Bamber Gascoigne who was best known as the original presenter of University Challenge. He was an excellent quizmaster, not least because he actually seemed to know the answers to the questions (rather than just reading them from the cards like his successor Jeremy Paxman did) and often supplied extra pieces of information off his own bat.

Though he cut a stern figure whenever anybody transgressed e.g. the “no conferring” rule, he always seem to be generous in his praise and people who took part in the show say he was very gentle with the contestants who were often very nervous.

I never met Bamber Gascoigne in the flesh, although I attended the same college (Magdalene College, Cambridge) as he did when he was an undergraduate (though not at the same time) and I’m sure he was around at some dinners and other events while I was there.

I used to watch University Challenge a lot when I was at school. It’s sad to have to say goodbye to yet another figure from the era.

Rest in Peace Bamber Gascoigne (1935-2022)

Clusters and Superclusters of Galaxies 1991

Posted in Biographical, The Universe and Stuff with tags , , on November 23, 2021 by telescoper

As part of an occasional series of blasts from the past down memory lane of days gone by I present this, which was taken in Cambridge in July 1991 – 30 years ago!!! – at the NATO ASI Clusters and Superclusters of Galaxies:

Picture Credit: Alberto Fernandez Soto

There are no prices for putting names to faces because the names are all along the bottom but it’s still fun to try doing it without looking at the answers!

It’s a Sin

Posted in Biographical, History, LGBT, Television with tags , , , , , on January 23, 2021 by telescoper

My Twitter feed was on fire last night with reactions to the first episode of the new Channel 4 drama series It’s a Sin. The title is taken from the 1987 hit of the same name by the Pet Shop Boys.

I didn’t watch it. I told a friend that I would find it impossible to watch. He asked “Why, would the memories be uncomfortable?”. I said “No. I can’t get Channel 4 on my television”.

I only have the minimum Saorview you see.

Now I’ve been informed that it is possible to stream Channel 4 for free in Ireland I will definitely watch it, so consider this a prelude to the inevitable commentary when I’ve actually seen it.

The reason why my friend thought I’d find it uncomfortable is that the story of the first episode is set in 1981 and revolves around five characters who were eighteen years old at that time. As it happens I was also 18 in 1981. On the other hand the story involves the protagonists all moving to London in 1981, which I didn’t. I was living in Newcastle in 1981, doing my A-levels and then taking the entrance exam for Cambridge where I went the following year (1982).

Before going on I’ll just mention that 1981 was – yikes – 40 years ago and – double yikes – is closer in time to the end of World War 2 than to today.

Anyway, a major theme running through the 5-part series is the AIDS epidemic that was only just starting to appear on the horizon in 1981. I recall reading an article in a magazine about GRIDS (Gay Related Immune Deficiency Syndrome), which it was what AIDS was called in the very early days. I remember it only vaguely though and didn’t think much about AIDS during the time I was an undergraduate student, although became terrifyingly relevant when I moved to Sussex in 1985 to start my graduate studies.

Although I had been (secretly) sexually active at school and definitely knew I was gay when I was an undergraduate at Cambridge, I wasn’t very open about it except to my closest friends. I also didn’t do much about it either, apart from developing a number of crushes that were doomed to be unrequited.

In my final year at Cambridge I decided that I would try to get a place to do a PhD (or, as it turned out, a DPhil). I applied to a few places around the country, and was very happy to get an offer from Sussex and started my postgraduate studies there in 1985. The reputation of Brighton as being a very `gay’ place to live was definitely part of the decision to go there.

Having been very repressed at Cambridge and mostly unhappy as a consequence I decided that I couldn’t continue to live that way. One of the first things I did during `Freshers Week’ at Sussex was join the GaySoc (as it was called) and I gradually became more involved in it as time went on. To begin with I found it helped to pluck up the nerve to go into gay bars and clubs, which I was a bit scared to do on my own having never really experienced anything like them in Newcastle or Cambridge.

It didn’t take me long to acquire an exciting sex life, picking up guys here and there and having (mostly unprotected) sex with strangers several times a week (or more). I then met an undergraduate student through the GaySoc. Although younger than me he was more experienced and more confident about sex. The relationship I had with him was a real awakening for me. We had a lot of sex. I would often sneak off form my office to his room on campus during the day for a quickie. We never even talked about wearing condoms or avoiding ‘risky’ behaviour. This was in 1986. The infamous government advertising campaign began in 1987.

Then one evening we went together to a GaySoc meeting about AIDS during which a health expert explained what was dangerous and what wasn’t, and exactly how serious AIDS really was. Most of us students were disinclined to follow instructions from the Thatcher government but gradually came round to the idea that it wasn’t the attempt at social control that we suspected but a genuine health crisis. That day my partner and I exchanged sheepish glances all the way through the talk. Afterwards we discussed it and decided that it was probably a good idea for us both to get tested for HIV, though obviously if one of us had it then both of us would.

Having been told what the riskiest sexual practices were, and knowing that I had been engaging very frequently precisely in those behaviours, I just assumed that I would be found HIV+. When I did eventually have a test I was quite shocked to find I was negative, so much so that I had another test to make sure. It was negative again. We were both negative, in fact, so we carried on as before.

It was in the next few years that people I knew started to get HIV, and then AIDS, from which many died. I imagine, therefore, that It’s a Sin will have a considerable personal resonance for me. Even without watching it (yet) a question that often troubles me returned once again to my mind: why am I still alive, when so many people I knew back then are not?

Charles Kingsley on the Irish

Posted in Biographical, History, Politics with tags , , , , on September 4, 2018 by telescoper

I’ve been aware since my schooldays that there has been (and still is) a significant tendency among the English (especially their governing classes) to regard the Irish as lawless barbarians, but this quote which I found in a book I’ve been reading really took my breath away. It’s from a letter written by Charles Kingsley to his wife in 1861, while he was travelling through an Ireland still reeling from the devastation of the Great Famine:

But I am haunted by the human chimpanzees I saw along that hundred miles of horrible country. I don’t believe they are our fault, I believe that there are not only more of them than of old, but that they are happier, better, more comfortably fed and lodged under our rule than they ever were. But to see white chimpanzees is dreadful; if they were black, one would not feel it so much, but their skins, except where tanned by exposure, are as white as ours.

This passage is revolting in so many ways that I don’t think it needs any further comment, but it is worth mentioning that Charles Kingsley was, by the standards of his time, regarded as something of a progressive. As well as being a Church of England priest, Professor of History and a novelist (I read The Water-Babies when I was a child), he was also a social reformer involved in such initiatives as the working men’s college and labour cooperatives. Clearly his concern for the poor and oppressed didn’t extend much beyond his own people.

P.S. In the interest of full disclosure, I should also mention that Charles Kingsley did his undergraduate studies at Magdalene College, Cambridge, as did I (thought not at the same time).

Project Work

Posted in Biographical, Education, mathematics with tags , , , , , on April 23, 2018 by telescoper

I’m progressively clearing out stuff from my office prior to the big move to Ireland. This lunchtime I opened one old box file and found my undergraduate project. This was quite an unusual thing at the time as I did Theoretical Physics in Part II (my final year) of Natural Sciences at Cambridge, which normally meant no project but an extra examination paper called Paper 5. As a member of a small minority of Theoretical Physics students who wanted to do theory projects, I was allowed to submit this in place of half of Paper 5…

The problem was to write a computer program that could solve the equations describing the action of a laser, starting with the case of a single-mode laser as shown in the diagram below that I constructed using a sophisticated computer graphics package:

The above system is described by a set of six simultaneous first-order ordinary differential equations, which are of relatively simple form to look at but not so easy to solve numerically because the equations are stiff (i.e. they involve exponential decays or growths with very different time constants). I got around this by using a technique called Gear’s method. There wasn’t an internet in those days so I had to find out about the numerical approach by trawling through books in the library.

The code I wrote – in Fortran 77 – was run on a mainframe, and the terminal had no graphics capability so I had to check the results as a list of numbers before sending the results to a printer and wait for the output to be delivered some time later. Anyway, I got the code to work and ended up with a good mark that helped me get a place to do a PhD.

The sobering thought, though, is that I reckon a decent undergraduate physics student nowadays could probably do all the work I did for my project in a few hours using Python….

The Parnell Connection

Posted in Beards, Biographical, History with tags , , , , on April 19, 2018 by telescoper

Charles Stewart Parnell (1846-1891)

Taking a short breather and a cup of coffee in between this morning’s lecture and a forthcoming computer lab session I thought I’d do a quick post following on from a comment on yesterday’s post about an O-level History paper.

I was an undergraduate student at Magdalene College, Cambridge, which just happens to be where 19th century Irish nationalist politician Charles Stewart Parnell (above) studied, although I hasten to add that we weren’t contemporaries. There is an annual Parnell Lecture at Magdalene in his honour; an annual Coles lecture is yet to be established. Parnell is widely remembered here in Ireland too, not least in place names: there is , for example, a handsome Georgian square in Dublin named after him.

Parnell was one of the most charismatic, capable and influential Parliamentarians of his era, and led the Irish Parliamentary Party at the forefront of moves for Home Rule for Ireland. He also had a splendid beard. His career was cut short by scandal in the form of an adulterous relationship with Kitty (Katherine) O’Shea, whom her husband divorced in 1889 naming Parnell in the case, and whom he married after the divorce. (Kitty, that is, not her husband.) They were not to enjoy life together for long, however, as Parnell died in 1891 of pneumonia in the arms of his wife in 1891 at their home in Brighton (Hove, actually).

 

Cardiff, City of Cycling?

Posted in Bute Park, Cardiff with tags , , , , , , , on February 22, 2017 by telescoper

Two recent news items about Cardiff caught my attention so I thought I’d do a quick post. The first piece was about the terrible state of traffic congestion in the city. This doesn’t affect me directly as I normally work to work and back, but it has definitely got much worse in the last few years. The roads are regularly gridlocked, a situation made worse by the interminable and apparently pointless roadworks going on everywhere as well as absurdly slow and dysfunctional traffic lights. There’s a common view around these parts that this is being allowed to happen – or even engineered – so that Cardiff City Council can justify the introduction of congestion charging. This would be an unpopular move among motorists, but I think a congestion charge would not be a bad idea at all, as what the city really needs is to reduce the number of motor vehicles on its streets, to deal with the growing problem of pollution and long journey times.

One day, about six years ago,  I was almost run over three different times by three different vehicles. The first was near the car park in Sophia Gardens, where there are signs and road marking clearly indicating that there is a speed limit of 5 mph but where the normal speed of cars is probably more like 35; the guy who nearly killed me was doing about 60.

Next, in Bute Park, a heavy lorry belonging to the Council, engaged in some sort of “tree-management” business, thundered along the footpath past me. These paths used to be marked 5mph too, but the Council removed all the signs when it decided to build a huge road into the Park and encourage more vehicles to drive around inside. The lorry wasn’t going as fast as the Boy Racer of Sophia Gardens, but the size of the truck made it just as scary.

Finally, using a green light at the pedestrian crossing at Park Place I was narrowly missed by another car who had clearly jumped a red light to get onto the dual carriageway (Dumfries Place) leading to Newport Road.

I have to say things like this aren’t at all unusual, but that is the only time I’ve had three close encounters in one day! Although most car drivers behave responsibly, there seems to be a strong concentration of idiots in Cardiff whose antics are exacerbated by the hare-brained Highways Department of the local council. There are many things to enjoy about living in Cardiff, and the quality of life here is very good for a wide range of reasons, but of all the cities I’ve lived in it is by a long way the least friendly to pedestrians and cyclists.

Which brings me to the second news item, which is about Cardiff City Council’s ambitious new Cycling Strategy, which aims to double the number of trips made using cyclists over the next ten years. That still wouldn’t reach the level of Cambridge, where 30% of all journeys in the city are done by bicycle.

Cardiff has a long way to go to match Cambridge and further still to be like Copenhagen, one of the loveliest and most livable cities I’ve ever experienced, partly because of its traffic policies.

In the interest of balance I should also point out that I was once actually hit on a pedestrian crossing in Cardiff by a bicycle steered by a maniac who went through a red light. In this case, however, I did manage to push him off his bike as he tried to get away, so he ended up more seriously hurt than I was. I was hoping that a friendly car would run over his bike, which was lying in the road, but sadly that didn’t happen.

I hope in their desire to increase the number of cyclists, the town planners don’t forget those of us who travel on foot!

One Fine Conformal Transformation

Posted in Brighton, Cute Problems with tags , , , , , on March 25, 2015 by telescoper

It’s been a while since I posted a cute physics problem, so try this one for size. It is taken from a book of examples I was given in 1984 to illustrate a course on Physical Applications of Complex Variables I took during the a 4-week course I took in Long Vacation immediately prior to my third year as an undergraduate at Cambridge.  Students intending to specialise in Theoretical Physics in Part II of the Natural Sciences Tripos (as I was) had to do this course, which lasted about 10 days and was followed by a pretty tough test. Those who failed the test had to switch to Experimental Physics, and spend the rest of the summer programme doing laboratory work, while those who passed it carried on with further theoretical courses for the rest of the Long Vacation programme. I managed to get through, to find that what followed wasn’t anywhere near as tough as the first bit. I inferred that Physical Applications of Complex Variables was primarily there in order to separate the wheat from the chaff. It’s always been an issue with Theoretical Physics courses that they attract two sorts of student: one that likes mathematical work and really wants to do theory, and another that hates experimental physics slightly more than he/she hates everything else. This course, and especially the test after it, was intended to minimize the number of the second type getting into Part II Theoretical Physics.

Another piece of information that readers might find interesting is that the lecturer for Physical Applications of Complex Variables was a young Mark Birkinshaw, now William P. Coldrick Professor of Cosmology and Astrophysics at the University of Bristol.

As it happens, this term I have been teaching a module on Theoretical Physics to second-year undergraduates at the University of Sussex. This covers many of the topics I studied at Cambridge in the second year, including the calculus of variations, relativistic electrodynamics, Green’s functions and, of course, complex functions. In fact I’ve used some of the notes I took as an undergraduate, and have kept all these years, to prepare material for my own lectures. I am pretty adamant therefore that the academic level at which we’re teaching this material now is no lower than it was thirty years ago.

Anyway, here’s a typically eccentric problem from the workbook, from a set of problems chosen to illustrate applications of conformal transformations (which I’ve just finished teaching this term). See how you get on with it. The first correct answer submitted through the comments box gets a round of applaud.

conformal transformation

 

Freshers’ Week Reminiscences

Posted in Biographical, Education with tags , , , , on September 13, 2014 by telescoper

So here I am again, on campus, on a Saturday, this time to attend some receptions for new students (“Freshers”) who have just arrived at the University of Sussex to start their courses. I always enjoy meeting the new intake at this time of year; we sometimes call them “The Autumn Collection”, although it’s only mid-September and definitely not autumn yet. In fact it’s very warm and sunny and summery on Falmer campus today. The  downside of these annual events is that the students look much younger every year, so every one makes me feel a lot older than the one before!

Looking through my back catalogue of blog posts I realize that this blog is six years old next week. One of my first blog posts was about  memories of my own first day at University and it seems appropriate to repeat some of it here. I notice actually that virtually all Freshers’ weeks I’ve written about over the past six years have been accompanied by fine weather. I find this kind of weather a bit spooky because it always takes me back to the time when I left home to go to University, as thousands of fledgling students are about to do this year in their turn. I did it 32 years ago, getting on a train at Newcastle Central station with my bags of books and clothes. I said goodbye to my parents there. There was never any question of them taking me in the car all the way to Cambridge. It wasn’t practical and I wouldn’t have wanted them to do it anyway. After changing from the Inter City at Peterborough onto a local train, we trundled through the flatness of East Anglia until it reached Cambridge. The weather, at least in my memory, was exactly like today.

I don’t remember much about the actual journey, but I must have felt a mixture of fear and excitement. Nobody in my family had ever been to University before, let alone to Cambridge. Come to think of it, nobody from my family has done so since either. I was a bit worried about whether the course I would take in Natural Sciences would turn out to be difficult, but I think my main concern was how I would fit in generally.

I had been working between leaving school and starting my undergraduate course, so I had some money in the bank and I was also to receive a full grant. I wasn’t really worried about cash. But I hadn’t come from a posh family and didn’t really know the form. I didn’t have much experience of life outside the North East either. I’d been to London only once before going to Cambridge, and had never been abroad.

I didn’t have any posh clothes, a deficiency I thought would mark me as an outsider. I had always been grateful for having to wear a school uniform (which was bought with vouchers from the Council) because it meant that I dressed the same as the other kids at School, most of whom came from much wealthier families. But this turned out not to matter at all. Regardless of their family background, students were generally a mixture of shabby and fashionable, like they are today. Physics students in particular didn’t even bother with the fashionable bit. Although I didn’t have a proper dinner jacket for the Matriculation Dinner, held for all the new undergraduates, nobody said anything about my dark suit which I was told would be acceptable as long as it was a “lounge suit” (whatever that is).

Taking a taxi from the station, I finally arrived at Magdalene College. I waited outside, a bundle of nerves, for some time before entering the Porter’s Lodge and starting my life as a student. My name was found and ticked off and a key issued for my room in the Lutyens building. It turned out to be a large room, with a kind of screen that could be pulled across to divide the room into two, although I never actually used this contraption. There was a single bed and a kind of cupboard containing a sink and a mirror in the bit that could be hidden by the screen. The rest of the room contained a sofa, a table, a desk, and various chairs, all of them quite old but solidly made. Outside my  room, on the landing, was the gyp room, a kind of small kitchen, where I was to make countless cups of tea over the following months, although I never actually cooked anything there.

I struggled in with my bags and sat on the bed. It wasn’t at all like I had imagined. I realized that no amount of imagining would ever really have prepared me for what was going to happen at University.

I  stared at my luggage. I suddenly felt like I had landed on a strange island where I didn’t know anyone, and couldn’t remember why I had gone there or what I was supposed to be doing. I’ve had that feeling ever since, but after 32 years I think I’m used to it.