Archive for the Biographical Category

Referendum Day

Posted in Biographical, Politics on June 23, 2016 by telescoper

Today has been a very eventful day. First I was up at 6am to get to my local polling station in order to cast my vote in the EU Referendum  as soon as the doors opened. I then had to get up to campus and spent all day from 9am until now interviewing for a Lectureship in Probability and Statistics. In between there have been thunderstorms, torrential rain, and flooding. Also, after checking the bookies’ odds on the Referendum result, I decided to place an insurance bet on Leave of £100 at 10/1 against. Given the closeness of the opinion polls I think those odds are far too long.

I’m far too tired to stay up and follow the results coming in, but tomorrow morning I’ll wake up to find that the UK will remain in the European Union or that I’m £1000 richer.

Anyway, for those of you out there who still haven’t voted – perhaps because of the inclement weather – there’s still three hours to get to it!

keep-calm-and-vote-remain-2

Why I think the United Kingdom should remain in the European Union

Posted in Biographical, History, Politics on June 19, 2016 by telescoper

These last few weeks have been absurdly busy, and even without Thursday’s referendum, next week promises to be even busier. I will, however, definitely make time to vote and I urge you to do the same, whichever way you feel inclined to cast your ballot.

A number of my friends and colleagues have been posting on social media about why they plan to vote for one side or the other, or in some cases already have voted ( by postal ballot), so I thought I’d do the same today. I don’t suppose my ramblings will change anyone’s mind, and that’s not the reason for posting this anyway. It’s just a personal opinion, that’s all. It’s fine if yours is different. I have friends who disagree strongly with what I’m going to say, but we’re still friends. There’s no reason to think that will change whichever way the vote goes, although I am deeply worried about what damage the campaign has done to British political culture (which was deeply flawed before it started).

Let me start with a bit of biography that might explain why I see things the way I do. I was born in Wallsend on Tyneside in 1963. My parents were both born just before World War 2 started also in the area where I was born. Of my four grandparents, one was born in England, one in Northern Ireland, one in Scotland, and one in Wales. I always smile when I get to right my nationality on a form, because I put “United Kingdom”. Of course being born in England makes me English too, but I find that less defining than “UK” or even “Geordie”. To be honest, my ancestry means that  I generally find the whole concept of nationality fundamentally silly. I find nationalism silly too, except for those occasions – regrettably frequent – when nationalism takes on the guise of xenophobia.  Then it is much more sinister. That is happening now in the United Kingdom, a point I will return to later.

I don’t come from a wealthy background. Holidays abroad were an unaffordable luxury when I was a kid. In fact, the only members of my immediately family ever to venture abroad before I did for the first time (in 1986) were my grandfather’s brother (who died at Arnhem in 1944), his cousin (who died at the Salerno landings in 1943), and my uncle Richard who crossed the Rhine with the British Army in 1945 and was stationed in the devastated city of Hamburg for the duration of his National Service; he at least survived the War.

I had the good fortune to be born during a time of peace and relative prosperity, and have experienced immense good fortune in my life. I got a scholarship to go to a very good school and thence won a place at Cambridge University, where I did well enough to go onto a PhD here at the University of Sussex. Thirty years ago last summer, when I was 23, I went abroad for the very first time – to a cosmology conference in Cargèse, in Corsica. Since then I’ve had the opportunity to travel widely in Europe and beyond, meeting and working with some wonderful people. What little sense of nationality I started with has diminished steadily with time, and I now have no difficulty at all in adding another label to my identity: European. I’m British and I’m European. And proud to be  both. That statement alone has led to me being called a “traitor”, such are the depths to which this wretched referendum campaign has sunk. Fortunately I an nowhere near sufficiently important or prominent for anyone to assassinate.

The United Kingdom joined the European Economic Community (as it was then called) in 1973, when I was ten years old. The EEC morphed into the EU in 1993, but in some form or another it has been a fact for all of my adult life. There is no question in my mind that Britain’s membership has been has been very good for Britain and for the other member states. We pay a subscription to the modern EU that amounts to around 0.5% of our public spending and for that we get preferential access to a free market that gives us around ten times as much back in trade and inward investment.

My career in science gives a perspective on this too. The UK is a member of the European Southern Observatory (ESO), the European Organization for Nuclear Research (CERN) and the European Space Agency (ESA), all of which have been stunningly successful. None of these are actually European Union organizations. ESO and CERN were founded in the 1950s and ESA in the 1970s, all before the EU formally came into existence. But they do serve as models for why the EU is such a good thing in a wider sense than the science that they do. Members of ESO, CERN and ESA pay a subscription which amounts to a pooling of resources into a pot far bigger than any individual country could manage. Each organization is run by a council that makes collective decisions on where and what to invest. The UK has a strong influence on those decisions. By being a member it has a seat at the table and a voice in the discussions. The net result is that each of these organizations is much more than the sum of its parts.

fat cut

That model that works so well for ESO, CERN and ESA is basically the model for the European Union. Even when they’re not lying about the cost of membership as the official Vote Leave campaign consistently does, people tend to talk in a very short-sighted way about the amount we pay and how much we get back. That’s the wrong way to look at it. The point is that, just as with scientific organizations,  the EU is more than the sum of its parts. Pooling some resources and doing things collectively does, for certain things, give a value way beyond the relatively small amount we invest. But remember that we only pool 0.5% of our public funds in this way. It’s an astonishingly good deal. And, what’s more, it’s mutually beneficial. The UK benefits and the other EU member states benefit too. It’s not “us” versus “them”, it’s “we”.

Now I know that BrExit advocates will say. “You profit from EU grants! You’ve been bought off by the EU! You’ve a vested interest!” I’ve been attacked on social media repeatedly for having the temerity to argue that EU membership is as good for science as it is for everything else. But the fact of the matter is that the accusation is completely false. My own research is wholly funded from UK sources. I don’t have any EU funding at all. Even if I had I’d still have a right to express my opinion, but I don’t. I haven’t been “bought off” by anyone. I’ve thought about the issues and come to my own conclusion. You can do that in a free country.

The EU is by no means perfect. I think it could be made more accountable, more democratic. I understand those concerns, but I do feel that they’re hard to justify coming from one of the least democratic countries in Europe. We have an entirely unelected House of Lords, and a House of Commons that has delivered an overall majority to a party with a minority share of the popular vote. Pot calling the kettle black?

I think the economic, educational, cultural and societal benefits of EU membership have been discussed widely in the referendum campaign so I won’t repeat them here. I’ll just say that I think the benefits are immense, and the risk to this country if they are lost is huge.

But there is one reason over and above all this why I shall be voting to Remain in the EU. For this I will quote note other than Boris Johnson, who wrote just two years ago in his biography of Winston Churchill:

It was his (Churchill’s) idea to bring those countries together, to bind them together so indissolubly that they could never go to war again – and who can deny, today, that this idea has been a spectacular success? Together with Nato the European Community, now Union, has helped to deliver a period of peace and prosperity for its people as long as any since the days of the Antonine emperors.

I won’t comment on why Boris Johnson has changed his mind, but I agree with that statement. It brings me back to the bit of personal family history with which I started this post. I have been lucky enough to live in the period of “peace and prosperity” described in that quote. I am sorry my grandfathers’ generation was not so lucky. I don’t have any children of my own, but  I categorically refuse to take any step that would risk any future generation having to endure the same horrors.

And then there’s this.

Nazi_UKIP

The top left image shows  a poster produced by the UK Independence Party. The other three are taken from a Nazi propaganda film of the 1930s. The historical parallels are obvious and not accidental. This is indeed “Breaking Point” indeed. It’s the point the BrExit campaign descended into the gutter.

Of course I’m not saying that all those who want the UK to Leave the EU are fascists. Far from it. Many – indeed the majority – are reasonable, civilised people. But like it or not, if you vote Leave you’re voting the way the far right want you to vote. I for one will not take a single step in that direction. Fascism only needs a foot in the door. I fear that the domestic political consequences of BrExit will give it far more than that. Once they get hold of it, we’ll never get our country back.

One final point. On Thursday I will definitely vote for the United Kingdom to remain in the EU. However, Article 50 of the Lisbon Treaty allows any member state to leave the European Union, and sets a protocol for how this can be achieved. This demonstrates that the UK has sovereignty over its own affairs, thus defeating one of the central arguments of the Leave campaign.

 

To Cambridge Again

Posted in Biographical, Education with tags , , , on June 13, 2016 by telescoper

The annual cycle of academic life brings me once again to my duties as External Examiner for Physics at the famous Midlands University called Cambridge, so I’m getting ready to take the train there. Here’s a picture of the Cavendish laboratory where I’ll be working for the next three days:

bragg_building_110309

It hasn’t changed much since I was an undergraduate there (I graduated 31 years ago), but the area around it has certainly been heavily developed in the intervening years.

Anyway, I’d better be going. Toodle-pip!

Flaming June Again

Posted in Art, Biographical, Bute Park, History with tags , , , , on June 10, 2016 by telescoper

Since we’re in the middle of a modest heatwave I thought “Flaming June” would be a good title for a blog post. Until a few years ago I always thought that “Flaming June” was some sort of folk expression or quotation from a poem, but it is instead the title of this Pre-Raphaelite painting by Frederic Leighton of a lady wearing what looks like a dress made out of old curtains. Apparently the oleander branch seen in the upper right symbolizes the fragile link between sleep and death. It looks to me like she must be attending a lecture…

But I’m rambling. This has been an exhausting week, probably because I a few days off last week and have come back to one of the busiest periods of the academic year. The examination period is over so there are scripts to mark,  examiners’ meetings, class lists and the like, all parts of the arcane business of academic life. In fact I’ll be spending the first three days of next week in Cambridge where I’m External Examiner for Physics, and I have a lot to do here before I go.

In between all the meetings I had to attend yesterday I noticed that it was the 9th of June, a date of enormous cultural significance for those of us born on Tyneside, as Geordie Ridley’s famous music hall song The Blaydon Races begins “I went to Blaydon Races, ’twas on the 9th of June… The original Blaydon Races were horse races and site of the course is long since gone, but the name has recently been resurrected as a road race involving people on foot rather than on horseback. Incidentally, the usual “Whit Week” holiday in late May or early June is still referred to on Tyneside as “Race Week”.

All this reminded me of the occasion – over twenty years ago – when I entered the Great North Run for the first time. Nowadays this race – the biggest mass participation half-marathon race in the world, with 50,000 competitors – is run in September, but in those days it was held in June. As it happened, there was also a heatwave the first time I did it. I remember lining up at 9.30 on a Sunday morning on the start grid (I was number eleven thousand and something) while the stewards went round pleading with all the participants to take plenty of water as they went around as it was going to be very hot indeed and they didn’t want people suffering from dehydration.

In those days I was quite a keen long-distance runner and was fairly fit. I wasn’t that concerned about the heat but took the advice to heart and determined to stop at all the water stations on the way from Newcastle to South Shields. When we started I also took care not to go off too fast over the first mile or so, which is basically all downhill from the Town Moor to the Tyne Bridge. Not that you could go fast anyway, as the track was so crowded with runners.

I remember the wonderful feeling as we emerged onto the Tyne Bridge and took in the splendid view of the bridges along the river. When we got to Gateshead the crowds were out in large numbers cheering everyone on and I felt completely elated. The first water station was near Gateshead athletics stadium, and I took a drink there as I did at the next, and the next. After Gateshead the route heads towards the Felling bypass at about 4-5 miles and then the runners can see a long climb in front of them. A large thermometer showed the temperature on the road to be about 45 Celsius. Fortunately the people living in houses either side of the road were out in their front gardens offering encouragement and sometimes had their hoses out to shower people as they went past. At one point there was a fire engine that had made an impromptu fountain by the side of the road too.

Unfortunately, as I near the ten mile mark I started to feel a bit strange. I had never actually taken on water while I was running before this race; I never felt the need for it when on training runs. My stomach wasn’t used to the water sloshing around while I was running. I felt quite sick by the time we got to the top of the climb but when I saw the sea and felt its breath on my face I cheered up and descended the steep downward slope towards the seafront near Marsden Rock.

There’s a good mile and a half along the seafront to the finish, however, and I was definitely struggling really badly by then. I could see the finish line but it felt like it wasn’t getting any closer. I slowed to a crawl but kept going, finally reaching the grandstand where a large crowd shouted encouragement. I must have looked dreadful because I heard several people shouting out my number along with “keep going, son”  and “you’re nearly there”.

Eventually I got to the finish line but the feeder lanes were quite busy then – I was finishing at about the peak  time of about 1hr 50 – so I was forced to slow right down because of the people in front of me.

As I crossed the line, I stopped running and was immediately overcome with nausea. I bent over, hands on my knees and emptied the contents of my stomach – mainly water – all over the grass. I felt absolutely dreadful but, after a quick check from the St John Ambulance crew who were on hand, I recovered and found my folks who were nearby. After we got home and I had a shower I felt fine.

About a week later, when I had returned to my flat in London a letter arrived for me. I opened it up and found a small passport-sized photograph, with the caption “YOUR MOMENT OF TRIUMPH”. It turns out there was an automatic camera near the finishing line that snapped everyone crossing it along with a shot of the digital clock showing their finishing time. The idea is that you could order a blow-up of the picture for £25 to put on your wall.

In my case, though, the picture showed not a moment of splendid athletic achievement, but a bedraggled creature puking uncontrollably while those around him looked on in disgust. I didn’t order the blow-up of my throw-up.

Over the years I did the Great North Run a number of times – six or seven, I don’t remember exactly – and a few marathons too, but the strain of running on the roads around London gradually told on my knees and I had to stop because of recurrent pain and swelling. Eventually, a few years ago I surrendered to the inevitable and had arthroscopic surgery to sort out the damage to my knee joints. That seems to have fixed the problem, but my running days are over.

 

R.I.P. John David Jackson (1925-2016)

Posted in Biographical, The Universe and Stuff with tags , on May 23, 2016 by telescoper

Yet again I have to pass on some very sad news. Physicist John David Jackson, best known for his classic textbook Classical Electrodynamics, has passed away at the age of 91. I’m sure I speak for many physicists when I say that Classical Electrodynamics was not only an essential part of my physics education but also a constant companion throughout the rest of my career. I have consulted my copy regularly over the last thirty years. I was often frustrated that when I found the topic I was looking for in the index, it referred to a problem (usually a difficult one) rather than a solution, but there’s no question it made me a better physicist.

Jackson

Rest in peace, John David Jackson (1925-2016).

The McGurk Effect – Do you always hear what you think you hear?

Posted in Biographical, The Universe and Stuff with tags , , , , on May 19, 2016 by telescoper

I saw this clip for the first time yesterday during a training session about unconscious bias. The context then was a discussion of how we make quick decisions about things (and people) relying on contextual associations of which we are often entirely unaware. The clip illustrates how difficult it is to overrule some things your brain does automatically even when you know they are wrong.

Related to this is something I’ve noticed in a slightly different setting. Not having a TV set I do sometimes watch DVDs on my laptop, but the screen is quite small and, for a person of my advanced years, rather difficult to view comfortably for a long period. A while ago I started plugging my laptop into a monitor instead. When I do that I usually put the laptop well out of the way, which means moving the relatively small loudspeaker out of the line of sight between myself and the screen. It is however immediately noticeable that the sound immediately seems to be coming from the screen rather than the speaker. I guess this is yet another example of the visual overruling the auditory which it does in the McGurk effect.

Oh, and I just remembered this, which I heard a while ago at a public talk given by Simon Singh. I guess many of you will have come across it before, but there’s no harm in repeating it. I don’t know why it popped into my head at this particular moment, but perhaps it’s because I’ve been reading some stuff about how my colleagues in gravitational wave research use templates to try to detect specific patterns in noisy data. The method involves cross-correlating a simulated signal against the data until a match is obtained; the problem is often how to assess the probability of a “chance” coincidence correctly and thus avoid spurious detections. The following might perhaps be a useful warning that unless you do this carefully, you only get out what you put in!

This is an excerpt from the classic track Stairway to Heaven, by the popular beat combo Led Zeppelin, played backwards. I suggest that you listen to it once without looking at the words on the video, and then again with the words in front of you. If you haven’t heard/seen it before, I think you’ll find it surprising…

 

The Thermal Syndicate

Posted in Biographical, History with tags , , , on May 16, 2016 by telescoper

image

I found the above map of the Tyne via the Tyne & Wear Archives on Twitter. It dates from the 1960s, and it caught my attention because it shows the area where I was born, between Walker and Wallsend.

I remember  the Shipyards very well, especially the famous Neptune Yard of Swan Hunter. In the early 70s the huge ESSO Northumberland loomed above the terraced streets like a monster but now shipbuilding has all but vanished. So have most of the other industries lining the river, for that matter.

The other thing this map jogged my memory about was the Thermal Syndicate building. This was the site of a glassworks and the source of large quantities of silver sand, which my Dad used to buy and sell on to schools and playgroups as part of his educational supplies business, before it went under in the 1980s. The name always intrigued me as it made me imagine it was run by gangsters pushing winter underwear.

Listening and Seeing (and Mahler)

Posted in Biographical, Music with tags , , , , on May 14, 2016 by telescoper

Three things led me to post this recording. One is that this piece (though not this performance) was one of the late Harry Kroto’s selections for Desert Island Discs. Another is that I had occasion to sort out my CD collection recently and I realised in doing so that I had more recordings of this Symphony than any other. And the third is that I heard a discussion on Radio 3 recently in which a record company executive noted that while sales of opera performances on DVD were very healthy, it was very difficult to sell DVDs of symphonic concerts. I am not particularly surprised by that but I have to say that I love the visual as well as the auditory experience of a classical concert. A large group of talented people coming together to make music is a great thing to watch, and it also helps understand the music a bit too. I’d much rather go to a live concert (even a mediocre one) than listen to a CD (even a very good one), but failing that I’d definitely go for a DVD.

All of this provides an excuse to show this film of the Vienna Philharmonic under the baton of Leonard Bernstein playing the gorgeous third moment (marked Ruhevoll) of Symphony No. 4 in G Major by Gustav Mahler. My favourite recording of this symphony is actually by Von Karajan with the Berlin Philharmonic on Deutsche Grammophon, but this is well worth watching to see the communication between Lenny and the band. And if you think Mahler is always gloomy and angst-ridden, hopefully this will make you change your mind.

 

 

Examination Time Yet Again

Posted in Biographical, Education with tags , , , , , on May 12, 2016 by telescoper

Once again the return of glorious weather heralds the return of the  examination season at the University of Sussex, so here’s a lazy rehash of my previous offerings on the subject that I’ve posted around this time each year since I started blogging.

My feelings about examinations agree pretty much with those of  William Wordsworth, who studied at the same University as me, as expressed in this quotation from The Prelude:

Of College labours, of the Lecturer’s room
All studded round, as thick as chairs could stand,
With loyal students, faithful to their books,
Half-and-half idlers, hardy recusants,
And honest dunces–of important days,
Examinations, when the man was weighed
As in a balance! of excessive hopes,
Tremblings withal and commendable fears,
Small jealousies, and triumphs good or bad–
Let others that know more speak as they know.
Such glory was but little sought by me,
And little won.

It seems to me a great a pity that our system of education – both at School and University – places such a great emphasis on examination and assessment to the detriment of real learning. On previous occasions, before I moved to the University of Sussex, I’ve bemoaned the role that modularisation has played in this process, especially in my own discipline of physics.

Don’t get me wrong. I’m not opposed to modularisation in principle. I just think the way modules are used in many British universities fails to develop any understanding of the interconnection between different aspects of the subject. That’s an educational disaster because what is most exciting and compelling about physics is its essential unity. Splitting it into little boxes, taught on their own with no relationship to the other boxes, provides us with no scope to nurture the kind of lateral thinking that is key to the way physicists attempt to solve problems. The small size of many module makes the syllabus very “bitty” and fragmented. No sooner have you started to explore something at a proper level than the module is over. More advanced modules, following perhaps the following year, have to recap a large fraction of the earlier modules so there isn’t time to go as deep as one would like even over the whole curriculum.

In most UK universities (including Sussex), tudents take 120 “credits” in a year, split into two semesters. In many institutions, these are split into 10-credit modules with an examination at the end of each semester; there are two semesters per year. Laboratories, projects, and other continuously-assessed work do not involve a written examination, so the system means that a typical  student will have 5 written examination papers in January and another 5 in May. Each paper is usually of two hours’ duration.

Such an arrangement means a heavy ratio of assessment to education, one that has risen sharply over the last decades,  with the undeniable result that academic standards in physics have fallen across the sector. The system encourages students to think of modules as little bit-sized bits of education to be consumed and then forgotten. Instead of learning to rely on their brains to solve problems, students tend to approach learning by memorising chunks of their notes and regurgitating them in the exam. I find it very sad when students ask me what derivations they should memorize to prepare for examinations. A brain is so much more than a memory device. What we should be doing is giving students the confidence to think for themselves and use their intellect to its full potential rather than encouraging rote learning.

You can contrast this diet of examinations with the regime when I was an undergraduate. My entire degree result was based on six three-hour written examinations taken at the end of my final year, rather than something like 30 examinations taken over 3 years. Moreover, my finals were all in a three-day period. Morning and afternoon exams for three consecutive days is an ordeal I wouldn’t wish on anyone so I’m not saying the old days were better, but I do think we’ve gone far too far to the opposite extreme. The one good thing about the system I went through was that there was no possibility of passing examinations on memory alone. Since they were so close together there was no way of mugging up anything in between them. I only got through  by figuring things out in the exam room.

I think the system we have here at the University of Sussex is much better than I’ve experienced elsewhere. For a start the basic module size is 15 credits. This means that students are usually only doing four things in parallel, and they consequently have fewer examinations, especially since they also take laboratory classes and other modules which don’t have a set examination at the end. There’s also a sizeable continuously assessed component (30%) for most modules so it doesn’t all rest on one paper. Although in my view there’s still too much emphasis on assessment and too little on the joy of finding things out, it’s much less pronounced than elsewhere. Maybe that’s one of the reasons why the Department of Physics & Astronomy does so consistently well in the National Student Survey?

We also have modules called Skills in Physics which focus on developing the problem-solving skills I mentioned above; these are taught through a mixture of lectures and small-group tutorials. I don’t know what the students think of these sessions, but I always enjoy them because the problems set for each session are generally a bit wacky, some of them being very testing. In fact I’d say that I’m very impressed at the technical level of the modules in the Department of Physics & Astronomy generally. I’ve been teaching Green’s Functions, Conformal Transformations and the Calculus of Variations to second-year students this semester. Those topics weren’t on the syllabus at all in my previous institution!

Anyway, my Theoretical Physics paper is next week (on 19th May) so I’ll find out if the students managed to learn anything despite having such a lousy lecturer. Which reminds me, I must remember to post some worked examples online to help them with their revision.

Lognormality Revisited (Again)

Posted in Biographical, Science Politics, The Universe and Stuff with tags , , , , , , , on May 10, 2016 by telescoper

Today provided me with a (sadly rare) opportunity to join in our weekly Cosmology Journal Club at the University of Sussex. I don’t often get to go because of meetings and other commitments. Anyway, one of the papers we looked at (by Clerkin et al.) was entitled Testing the Lognormality of the Galaxy Distribution and weak lensing convergence distributions from Dark Energy Survey maps. This provides yet more examples of the unreasonable effectiveness of the lognormal distribution in cosmology. Here’s one of the diagrams, just to illustrate the point:

Log_galaxy_countsThe points here are from MICE simulations. Not simulations of mice, of course, but simulations of MICE (Marenostrum Institut de Ciencies de l’Espai). Note how well the curves from a simple lognormal model fit the calculations that need a supercomputer to perform them!

The lognormal model used in the paper is basically the same as the one I developed in 1990 with  Bernard Jones in what has turned out to be  my most-cited paper. In fact the whole project was conceived, work done, written up and submitted in the space of a couple of months during a lovely visit to the fine city of Copenhagen. I’ve never been very good at grabbing citations – I’m more likely to fall off bandwagons rather than jump onto them – but this little paper seems to keep getting citations. It hasn’t got that many by the standards of some papers, but it’s carried on being referred to for almost twenty years, which I’m quite proud of; you can see the citations-per-year statistics even seen to be have increased recently. The model we proposed turned out to be extremely useful in a range of situations, which I suppose accounts for the citation longevity:

nph-ref_historyCitations die away for most papers, but this one is actually attracting more interest as time goes on! I don’t think this is my best paper, but it’s definitely the one I had most fun working on. I remember we had the idea of doing something with lognormal distributions over coffee one day,  and just a few weeks later the paper was finished. In some ways it’s the most simple-minded paper I’ve ever written – and that’s up against some pretty stiff competition – but there you go.

Lognormal_abstract

The lognormal seemed an interesting idea to explore because it applies to non-linear processes in much the same way as the normal distribution does to linear ones. What I mean is that if you have a quantity Y which is the sum of n independent effects, Y=X1+X2+…+Xn, then the distribution of Y tends to be normal by virtue of the Central Limit Theorem regardless of what the distribution of the Xi is  If, however, the process is multiplicative so  Y=X1×X2×…×Xn then since log Y = log X1 + log X2 + …+log Xn then the Central Limit Theorem tends to make log Y normal, which is what the lognormal distribution means.

The lognormal is a good distribution for things produced by multiplicative processes, such as hierarchical fragmentation or coagulation processes: the distribution of sizes of the pebbles on Brighton beach  is quite a good example. It also crops up quite often in the theory of turbulence.

I’ll mention one other thing  about this distribution, just because it’s fun. The lognormal distribution is an example of a distribution that’s not completely determined by knowledge of its moments. Most people assume that if you know all the moments of a distribution then that has to specify the distribution uniquely, but it ain’t necessarily so.

If you’re wondering why I mentioned citations, it’s because they’re playing an increasing role in attempts to measure the quality of research done in UK universities. Citations definitely contain some information, but interpreting them isn’t at all straightforward. Different disciplines have hugely different citation rates, for one thing. Should one count self-citations?. Also how do you apportion citations to multi-author papers? Suppose a paper with a thousand citations has 25 authors. Does each of them get the thousand citations, or should each get 1000/25? Or, put it another way, how does a single-author paper with 100 citations compare to a 50 author paper with 101?

Or perhaps a better metric would be the logarithm of the number of citations?