Archive for Copenhagen

Return to Cardiff

Posted in Biographical with tags , , , on August 15, 2017 by telescoper

Well, I made it back to Cardiff on schedule last night, although that did involve getting home at 2am. I was pretty much exhausted by then so had a bit of a lie-in this morning. I think I’m getting too old for all this gallivanting about. I crashed out soon after getting home and had to spend an hour or so this morning sorting through the stack of mail that arrived while I was away (including some book tokens courtesy of another crossword prize).

I usually try to get to the airport plenty of time in advance when I’m flying somewhere, so got to Copenhagen airport yesterday a good three hours before my scheduled departure. I had checked in online before setting out so I could have left it later, but I’m obviously a creature of habit. As it happened I was able to leave my luggage at the bag drop immediately and it took no longer than 5 minutes to clear the security checks, which meant that I was left with time to kill but I had my iPod and plenty to read so it was all fine.

I was a little disturbed when I got to the departure gate to hear the announcement that `Tonight’s British Airways flight to London Heathrow is operated by Qatar Airways’, but at least it explained why it wasn’t a BA plane standing outside on the tarmac. As it happened the flight went smoothly and Qatar Airways do free food and drink for economy class passengers (unlike BA who nowadays sell expensive snacks and beverages supplied by Marks and Spencer). The only downside when we arrived at Heathrow was that we parked at a remote stand and had to wait 20 minutes or so for a bus to take us to Terminal 5.  I could hear the ground crew unloading luggage while we waited, however, so that meant less time waiting at the carousels…

On previous occasions I’ve been greeted at Heathrow by a packed passport control area, but this time it was virtually deserted. In fact I’ve never seen it so empty. My bag was waiting for me when I got to the reclaim area so I got to the Heathrow Express terminal and thence to Paddington in time for the 10.45pm train to Cardiff.

When I got back to the Data Innovation Research Institute office around lunchtime I discovered that our big screen TV has been installed.

 

This will of course be used exclusively for skype calls and video conferences and in no way for watching cricket or football or any other inappropriate activity.

Well, I’d better get on. Marking resit exams is the order of the day.

 

 

 

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Grave Thoughts Again

Posted in Biographical, History, Literature with tags , , , , on August 13, 2017 by telescoper

This is my last full day in Copenhagen before flying back tomorrow evening, so I decided to take care of some unfinished business by visiting the famous Assistens Kirkegård  in the Nørrebro district of the city. I went there five years ago (almost to the day) but on that occasion I didn’t find the memorial I was looking for, that of the great Heldentenor Lauritz Melchior.

I was surprised to find at the time that his name was absent from the main index, and still doesn’t appear on the maps displayed at the cemetery. Its location is however now on a guide you can find online so I had little difficulty locating it this time round. In case anyone is interested it is in section F, near the western end of the park. Lauritz Melchior was cremated, and his remains interred in a small family plot:

The small slab to the left marks the burial of Lauritz Melchior:

In fact this memorial is not far from that of another famous Dane I missed last time, pioneering physicist Hans Christian Ørsted:

The Hans Christian Ørsted Institute, part of the University of Copenhagen, is a short walk from the main buildings of the Niels Bpohr Institute. It houses Chemistry and Mathematical Sciences and some physicists of the Niels Bohr Institute.

You might think that a cemetery was a rather morbid choice of place to go for a stroll in the sunshine, but actually it’s not that way at all. It’s actually a rather beautiful place, a very large green space criss-crossed by pleasant tree-lined paths. These are poplars:

We British have a much more reserved attitude to cemeteries than the Danes seem to have, at least judging by  their behaviour in this place; joggers and cyclists pass through Assistens Cemetery at regular intervals, and many people were having picnics or just sitting and reading between the gravestones.  I find this matter-of-fact attitude to the dead rather refreshing, actually.

Part of the attraction of Assistens Kirkegård – the name derives from the fact that it was originally an auxiliary burial place, outside the main city, designed to take some of the pressure off the smaller cemeteries in the inner areas – is the large number of famous people buried there, many of whose graves I found last time. I didn’t however notice the large area devoted to common graves nor did I realise that there was a memorial to French and Belgian soldiers of World War 1. Most of these died in 1919, which puzzled me. It turns out that they had been prisoners of war and many of them were ill or injured and had been sent to Copenhagen to recuperate only to be struck down by the Spanish ‘flu epidemic of 1919.

It’s noticeable that some of the smaller graves are extremely well-tended whereas many of the more opulent memorials are in a state of considerable disrepair. I think there’s a moral in there somewhere. My ambition is to be forgotten as quickly as possible after my death so the idea of anyone erecting some grandiose marble monument on my behalf fills me with horror, but I have to say I do find graveyards are strangely comforting places. Rich and poor, clever and stupid, ugly and beautiful; death comes to us all in the end. At least it’s very democratic.

Things Falling

Posted in Finance, Politics with tags , , , , , , on August 3, 2017 by telescoper

A very busy but also very interesting day at the office in the Niels Bohr Institute ended this evening with a thunderstorm, complete with spectacular lightning and torrential rain. I got wet on the walk back to my small home, but I managed to get inside before the worst of it started. I seem to remember a similar thing happened last time I was in Copenhagen. Maybe it’s the time of year.

Anyway, torrential rain isn’t the only thing that’s been falling today. The Pound dropped sharply against the Euro, so it is currently around €1.1069, not far from its lowest point in the last year. That’s not directly relevant to my visit to Denmark, which isn’t in the Eurozone, but the Pound has tumbled against the Danish Kroner too. In fact it’s been falling steadily over the past three months:

At 8.234 Kroner to the Pound, this the worst exchange rate I can remember in all the approximately 30 years I’ve been travelling to Copennhagen. The rate has usually been about 10:1 or even higher. Copenhagen has always seemed a rather expensive place, but converting prices into Pounds at the current exchange rate makes your eyes water. Fortunately I’m getting my local expenses paid by the NBI so the increased cost won’t really affect me, but it’s definitely noticeable. Such is the shambolic state of our government that I wouldn’t bet against the pound reaching parity with the Euro before too long.

Of course one is not allowed to suggest that the falling pound and sluggish economic growth might be something to do with BrExit because that would be `talking the country down’. The worrying thing, though, is that we haven’t left the European Union yet. Just wait until March 2019 when we leave the European Union, together with the Single Market and Customs Union without any trade agreement. Where will the pound be then, I wonder?

Copenhagen Again

Posted in Biographical, The Universe and Stuff with tags , , on August 1, 2017 by telescoper

As you might have inferred from my earlier post, I’m back again in the wonderful city of Copenhagen, as a guest of the Niels Bohr Institute. I’ve been here almost every year since my first visit here way back in the 1980s. I didn’t come here last summer, as I was too busy finishing off my duties at Sussex and relocating back to Cardiff so it’s nice to be back again now. I’m staying in one of the `9 small homes‘ that comprise a hotel near the NBI. I’ve stayed here before though not in my current small home, which is actually a self-contained apartment on the ground floor with its own front door. It’s also got a small kitchen so I can cook for myself when I don’t feel like eating out (like tonight). Incidentally, `hjem’ (the Danish word for `home’) is pronounced exactly as `home’ is pronounced in Geordie (i.e. as `hyem’). I did some shopping earlier this evening and attempted to speak Danish when I paid for my groceries. As always, however, I got a reply in English.

I realised only this morning that it’s a year since I left my previous job. I haven’t done half the things I had hoped to do in the year after stepping down as Head of School, but that’s partly because it took quite a while to get over certain health problems and also because quite a few things have come up that I didn’t anticipate. From what I’m told the old place is doing just fine without me!

Coincidently (?), I have arrived here at the Niels Bohr Institute at precisely the time that there is a delegation here from LIGO and there’s been a lot of serious – but good-natured – discussion of `The Danish Paper‘ that came out some time ago and which questioned some aspects of the data analysis of the first detection of gravitational waves. I think there are still quite a few issues to be resolved between the two groups. Although they do seem to be converging on what’s going on, I don’t think this controversy will be fully concluded until more data are made public, as the currently available time series are not exactly those used in the actual LIGO analysis.

I think this discussion can only be of benefit to the science community in the long run, especially if it encourages LIGO to get more fully into the spirit of open science, by releasing more data for use of researchers outside the consortium.

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!

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?

Lognormality Revisited

Posted in Biographical, Science Politics, The Universe and Stuff with tags , , , , , on January 14, 2015 by telescoper

I was looking up the reference for an old paper of mine on ADS yesterday and was surprised to find that it is continuing to attract citations. Thinking about the paper reminds me off the fun time I had in Copenhagen while it was written.   I was invited there in 1990 by Bernard Jones, who used to work at the Niels Bohr Institute.  I stayed there several weeks over the May/June period which is the best time of year  for Denmark; it’s sufficiently far North (about the same latitude as Aberdeen) that the summer days are very long, and when it’s light until almost midnight it’s very tempting to spend a lot of time out late at night..

As well as being great fun, that little visit also produced 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. 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:

lognormal

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.

Picture1

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 it looks like they’re going to play a big part in the Research Excellence Framework, yet another new bureaucratical exercise to attempt to measure the quality of research done in UK universities. Unfortunately, using citations isn’t straightforward. Different disciplines have hugely different citation rates, for one thing. Should one count self-citations?. Also how do you aportion 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 the REF panels should use the logarithm of the number of citations instead?