Archive for August, 2017

The Story of the 1919 Eclipse Expeditions

Posted in Books, Talks and Reviews, History, The Universe and Stuff with tags , , , , , , on August 21, 2017 by telescoper

Unless you have been living on another planet, you will know that today there will be an eclipse of the Sun although from the UK it will be rather underwhelming, as only about 4% of the Sun’s disk will be covered by the moon; for totality you have to be in the United States.  For the record, however, the eclipse will begin 15:46 GMT on August 21 out over the Pacific. It will reach the coast of Oregon at Lincoln City, just west of Salem, at 16:04 GMT (09:04 local time) where it will reach its maximum  at 17:17 GMT (10:17 local time). The path of totality will then track right across the United States to South Carolina. For more details see here. Best wishes to all who are hoping to see this cosmic spectacle! I saw the total eclipse of August 11, 1999 from Alderney in the Channel Islands, and it was a very special experience.

Here’s a (not very good and slightly damaged) scan of a picture from that eclipse that I found last night in a box of old photographs:

Before starting I can’t resist adding this excerpt from the Times warning about the consequences of a mass influx of people to Cornwall for the 1999 eclipse. No doubt there are similar things going around about today’s eclipse:

I did write a letter to the Times complaining that, as a cosmologist, I felt this was very insulting to druids. They didn’t publish it.

This provides me with a good excuse to repost an old item about the famous expedition during which, on 29th May 1919, measurements were made that have gone down in history as vindicating Einstein’s (then) new general theory of relativity. I’ve written quite a lot about this in past years, including a little book and a slightly more technical paper. I decided, though, to post this little piece which is based on an article I wrote some years ago for Firstscience.




The Eclipse that Changed the Universe

A total eclipse of the Sun is a moment of magic: a scant few minutes when our perceptions of the whole Universe are turned on their heads. The Sun’s blinding disc is replaced by ghostly pale tentacles surrounding a black heart – an eerie experience witnessed by hundreds of millions of people throughout Europe and the Near East last August.

But one particular eclipse of the Sun, eighty years ago, challenged not only people’s emotional world. It was set to turn the science of the Universe on its head. For over two centuries, scientists had believed Sir Isaac Newton’s view of the Universe. Now his ideas had been challenged by a young German-Swiss scientist, called Albert Einstein. The showdown – Newton vs Einstein – would be the total eclipse of 29 May 1919.

Newton’s position was set out in his monumental Philosophiae Naturalis Principia Mathematica, published in 1687. The Principia – as it’s familiarly known – laid down a set of mathematical laws that described all forms of motion in the Universe. These rules applied as much to the motion of planets around the Sun as to more mundane objects like apples falling from trees.

At the heart of Newton’s concept of the Universe were his ideas about space and time. Space was inflexible, laid out in a way that had been described by the ancient Greek mathematician Euclid in his laws of geometry. To Newton, space was the immovable and unyielding stage on which bodies acted out their motions. Time was also absolute, ticking away inexorably at the same rate for everyone in the Universe.

Sir Isaac Newton, painted by Sir Godfrey Kneller. Picture Credit: National Portrait Gallery,

For over 200 years, scientists saw the Cosmos through Newton’s eyes. It was a vast clockwork machine, evolving by predetermined rules through regular space, against the beat of an absolute clock. This edifice totally dominated scientific thought, until it was challenged by Albert Einstein.

In 1905, Einstein dispensed with Newton’s absolute nature of space and time. Although born in Germany, during this period of his life he was working as a patent clerk in Berne, Switzerland. He encapsulated his new ideas on motion, space and time in his special theory of relativity. But it took another ten years for Einstein to work out the full consequences of his ideas, including gravity. The general theory of relativity, first aired in 1915, was as complete a description of motion as Newton had prescribed in his Principia. But Einstein’s description of gravity required space to be curved. Whereas for Newton space was an inflexible backdrop, for Einstein it had to bend and flex near massive bodies. This warping of space, in turn, would be responsible for guiding objects such as planets along their orbits.

Albert Einstein (left), pictured with Arthur Stanley Eddington (right). Picture Credit: Royal Greenwich Observatory.

By the time he developed his general theory, Einstein was back in Germany, working in Berlin. But a copy of his general theory of relativity was soon smuggled through war-torn Europe to Cambridge. There it was read by Arthur Stanley Eddington, Britain’s leading astrophysicist. Eddington realised that Einstein’s theory could be tested. If space really was distorted by gravity, then light passing through it would not travel in a straight line, but would follow a curved path. The stronger the force of gravity, the more the light would be bent. The bending would be largest for light passing very close to a very massive body, such as the Sun.

Unfortunately, the most massive objects known to astronomers at the time were also very bright. This was before black holes were seriously considered, and stars provided the strongest gravitational fields known. The Sun was particularly useful, being a star right on our doorstep. But it is impossible to see how the light from faint background stars might be bent by the Sun’s gravity, because the Sun’s light is so bright it completely swamps the light from objects beyond it.


A scientific sketch of the path of totality for the 1919 eclipse. Picture Credit: Royal Greenwich Observatory.

Eddington realised the solution. Observe during a total eclipse, when the Sun’s light is blotted out for a few minutes, and you can see distant stars that appear close to the Sun in the sky. If Einstein was right, the Sun’s gravity would shift these stars to slightly different positions, compared to where they are seen in the night sky at other times of the year when the Sun far away from them. The closer the star appears to the Sun during totality, the bigger the shift would be.

Eddington began to put pressure on the British scientific establishment to organise an experiment. The Astronomer Royal of the time, Sir Frank Watson Dyson, realised that the 1919 eclipse was ideal. Not only was totality unusually long (around six minutes, compared with the two minutes we experienced in 1999) but during totality the Sun would be right in front of the Hyades, a cluster of bright stars.

But at this point the story took a twist. Eddington was a Quaker and, as such, a pacifist. In 1917, after disastrous losses during the Somme offensive, the British government introduced conscription to the armed forces. Eddington refused the draft and was threatened with imprisonment. In the end, Dyson’s intervention was crucial persuading the government to spare Eddington. His conscription was postponed under the condition that, if the war had finished by 1919, Eddington himself would lead an expedition to measure the bending of light by the Sun. The rest, as they say, is history.

The path of totality of the 1919 eclipse passed from northern Brazil, across the Atlantic Ocean to West Africa. In case of bad weather (amongst other reasons) two expeditions were organised: one to Sobral, in Brazil, and the other to the island of Principe, in the Gulf of Guinea close to the West African coast. Eddington himself went to Principe; the expedition to Sobral was led by Andrew Crommelin from the Royal Observatory at Greenwich.

British scientists in the field at their observing site in Sobral in 1919. Picture Credit: Royal Greenwich Observatory

The expeditions did not go entirely according to plan. When the day of the eclipse (29 May) dawned on Principe, Eddington was greeted with a thunderstorm and torrential rain. By mid-afternoon the skies had partly cleared and he took some pictures through cloud.

Meanwhile, at Sobral, Crommelin had much better weather – but he had made serious errors in setting up his equipment. He focused his main telescope the night before the eclipse, but did not allow for the distortions that would take place as the temperature climbed during the day. Luckily, he had taken a backup telescope along, and this in the end provided the best results of all.

After the eclipse, Eddington himself carefully measured the positions of the stars that appeared near the Sun’s eclipsed image, on the photographic plates exposed at both Sobral and Principe. He then compared them with reference positions taken previously when the Hyades were visible in the night sky. The measurements had to be incredibly accurate, not only because the expected deflections were small. The images of the stars were also quite blurred, because of problems with the telescopes and because they were seen through the light of the Sun’s glowing atmosphere, the solar corona.

Before long the results were ready. Britain’s premier scientific body, the Royal Society, called a special meeting in London on 6 November. Dyson, as Astronomer Royal took the floor, and announced that the measurements did not support Newton’s long-accepted theory of gravity. Instead, they agreed with the predictions of Einstein’s new theory.

The final proof: the small red line shows how far the position of the star has been shifted by the Sun’s gravity. Each star experiences a tiny deflection, but averaged over many exposures the results definitely support Einstein’s theory. Picture Credit: Royal Greenwich Observatory.

The press reaction was extraordinary. Einstein was immediately propelled onto the front pages of the world’s media and, almost overnight, became a household name. There was more to this than purely the scientific content of his theory. After years of war, the public embraced a moment that moved mankind from the horrors of destruction to the sublimity of the human mind laying bare the secrets of the Cosmos. The two pacifists in the limelight – the British Eddington and the German-born Einstein – were particularly pleased at the reconciliation between their nations brought about by the results.

But the popular perception of the eclipse results differed quite significantly from the way they were viewed in the scientific establishment. Physicists of the day were justifiably cautious. Eddington had needed to make significant corrections to some of the measurements, for various technical reasons, and in the end decided to leave some of the Sobral data out of the calculation entirely. Many scientists were suspicious that he had cooked the books. Although the suspicion lingered for years in some quarters, in the end the results were confirmed at eclipse after eclipse with higher and higher precision.

In this cosmic ‘gravitational lens,’ a huge cluster of galaxies distorts the light from more distant galaxies into a pattern of giant arcs.  Picture Credit: NASA

Nowadays astronomers are so confident of Einstein’s theory that they rely on the bending of light by gravity to make telescopes almost as big as the Universe. When the conditions are right, gravity can shift an object’s position by far more than a microscopic amount. The ideal situation is when we look far out into space, and centre our view not on an individual star like the Sun, but on a cluster of hundreds of galaxies – with a total mass of perhaps 100 million million suns. The space-curvature of this immense ‘gravitational lens’ can gather the light from more remote objects, and focus them into brilliant curved arcs in the sky. From the size of the arcs, astronomers can ‘weigh’ the cluster of galaxies.

Einstein didn’t live long enough to see through a gravitational lens, but if he had he would definitely have approved….

The Vale of Clwyd

Posted in Music with tags , , , on August 19, 2017 by telescoper

Why did nobody tell me that Beethoven wrote a collection of 26 Welsh Folk Songs? I had to rely on BBC Radio 3 to educate me about them!

Here’s one example, Number 19 in the published collection, arranged for soprano voice with piano, violin and cello accompaniment and  called The Vale of Clwyd .

Here is a picture taken across the Vale of Clwyd, taken by Jeff Buck.


Photo © Jeff Buck (cc-by-sa/2.0)


Natwest T20 Blast: Glamorgan v Middlesex

Posted in Cricket with tags , , , on August 18, 2017 by telescoper

This evening sees the last set of group matches in this summer’s Natwest T20 Blast. Weather permitting, I’ll be at the SSE Swalec Stadium at 7pm to Glamorgan play Middlesex. Glamorgan are currently top of the South Group, with only two teams (Hampshire and Surrey) able to catch them:

This means that Glamorgan have already qualified for the Quarter Finals to take place next week. If they finish in one of the top two places they will have a home tie against the third or fourth club from the North (or, more properly, Midlands) group. If they finish third they will play away against whichever Midlands team finishes second in that group.

Hampshire are also guaranteed a Quarter Final place but there are many possibilities for the other two slots: only Gloucestershire, who played their final game last night, are definitely eliminated.

Normally, a home Quarter Final tie would regarded as a `reward’ for doing well in the group, but this season Glamorgan haven’t won any of their home games (either losing them or having them rained off). They might do better to lose tonight and play their next match somewhere else! However, if they beat Middlesex (or if tonight’s game is rained off) I’ll have another match in this competition to watch at Sophia Gardens. After that, proper cricket resumes in the form of championship matches against Sussex (at Colwyn Bay) and in Cardiff against Northamptonshire and Gloucestershire.

I have to say that I find the format of the Natwest T20 Blast group matches a bit strange. It would make sense for each of the 9 teams in each division to play each of the others home and away. That would mean 16 matches per side altogether. In fact each team plays only 14 matches: each plays six teams home and away and two teams only once. Presumably that is to avoid fixture congestion, but the group games are spread over a six week period, so I would have thought it wouldn’t be too difficult to fit another couple of games in.

This morning the Cardiff weather pulled out all the stops. I woke up to bright sunshine, then a few minutes later the rain was lashing down. Then we had thunder and lightning, with rain and hail, followed by more sunshine. It’s also been rather windy. It’s anyone’s guess what will happen this evening, but I’ve paid for my season ticket so I’ll try to make the best of it!

I’ll update this post with pictures of the action. If there is any!

UPDATE. Play was scheduled to start at 7pm. This was the scene at 7.02. 

Still raining. Toss delayed until further notice.

UPDATE to the UPDATE: After a pitch inspection at 8pm we finally got going at 8.20, with 14 overs a side. There were a couple of short interruptions when the rain started again, but the game was completed.

Glamorgan won the toss and decided to field. Middlesex got off to a terrible start and were at one point 7 for 3, and then 24 for 5. They recovered somewhat but could only reach 99 for 8 off their 14 overs. 

Despite a wobble in the middle when they lost 3 quick wickets, including the talismanic Ingram, Glamorgan reached the required round hundred comfortably to win by 7 wickets. 

Their reward is a home tie against Leicestershire next Wednesday evening. I hope the weather is a bit better then!


Posted in Music with tags , , on August 18, 2017 by telescoper

After yesterday’s terrible news, it seems apt to remember happier times.



Clearing Advice for Physics and Astronomy Applicants!

Posted in Education with tags , , , , on August 17, 2017 by telescoper

Today’s the day! This year’s A-level results are out today, Thursday 17th August, with the consequent scramble as students across the country to confirm places at university. Good luck to all students everywhere waiting for your results. I hope they are what you expected!

For those of you who didn’t get the grades they needed, I have one piece of very clear advice:


The clearing system is very efficient and effective, as well as being quite straightforward to use, and there’s still every chance that you will find a place somewhere good. So keep a cool head and follow the instructions. You won’t have to make a decision straight away, and there’s plenty of time to explore all the options.

As a matter of fact there are a few places still left for various courses in the School of Physics & Astronomy at Cardiff University. Why should you choose Cardiff? Well, obviously I have a vested interest since I work here, but here’s a video of some students talking about the School.

For further information check here!

The Anomaly of Research England

Posted in Politics, Science Politics with tags , , , , on August 16, 2017 by telescoper

The other day I was surprised to see this tweet announcing the impending formation of a new council under the umbrella of the new organisation UK Research & Innovation (UKRI):

These changes are consequences of the Higher Education and Research Act (2017) which was passed at the end of the last Parliament before the Prime Minister decided to reduce the Government’s majority by calling a General Election.

It seems to me that it’s very strange indeed to have a new council called Research England sitting inside an organisation that purports to be a UK-wide outfit without having a corresponding Research Wales, Research Scotland and Research Northern Ireland. The seven existing research councils which will henceforth sit alongside Research England within UKRI are all UK-wide.

This anomaly stems from the fact that Higher Education policy is ostensibly a devolved matter, meaning that England, Wales, Scotland and Northern Ireland each have separate bodies to oversee their universities. Included in the functions of these bodies is the so-called QR funding which is allocated on the basis of the Research Excellence Framework. This used to be administered by the Higher Education Funding Council for England (HEFCE), but each devolved council distributed its own funds in its own way. The new Higher Education and Research Act however abolishes HEFCE and replaces some of its functions into an organisation called the Office for Students, but not those connected with research. Hence the creation of the new `Research England’. This will not only distribute QR funding among English universities but also administer a number of interdisciplinary research programmes.

The dual support system of government funding consists of block grants of QR funding allocated as above alongside targeted at specific projects by the Research Councils (such as the Science and Technology Facilities Council, which is responsible for astronomy, particle physics and nuclear physics research). There is nervousness in England that the new structure will put both elements of the dual support system inside the same organisation, but my greatest concern is that by exlcuding Wales, Scotland and Northern Ireland, English universities will be given an unfair advantage when it comes to interdisciplinary research. Surely there should be representation within UKRI for Wales, Scotland and Northern Ireland too?

Incidentally, the Science and Technology Facilities Council (STFC) has started the process of recruiting a new Executive Chair. If you’re interested in this position you can find the advertisement here. Ominously, the only thing mentioned under `Skills Required’ is `Change Management’.

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.




Farvel til NBI

Posted in Biographical with tags on August 14, 2017 by telescoper

I just had my last lunch in the canteen in the Niels Bohr Institute and will shortly be heading off to the airport to begin the journey back to Blighty. It’s been a pretty intense couple of weeks but I’ve enjoyed it enormously and have learnt a lot, even though I’ve done hardly any of the things I originally planned to do!

I haven’t been staying in the building shown in the picture, but in one of the adjacent buildings not shown. In fact my office is directly above the canteen. I took this picture on the way home on Sunday, as I noticed that the main entrance has the date `1920′ written on it. I do hope they’re planning a 100th anniversary!

Anyway, farewell to everyone at the Niels Bohr Institute and elsewhere. I hope to return before too long.

A Picture of Peter Cvitanovic

Posted in Politics with tags , on August 14, 2017 by telescoper

The angry chap on the right (appropriately enough) on this image taken at the violent demonstration at Charlottesville Va at the weekend is a white nationalist  member of the alt-right white supremacist Nazi by the name of Peter Cvjetanovic.

Apparently Peter is unhappy that his picture is being shared so widely on the internet. Life is tough sometimes.

And, yes, I mean Nazi.

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.