Archive for the History Category

Dark Matter Day

Posted in History, The Universe and Stuff with tags , , , , , on October 31, 2017 by telescoper

As a welcome alternative to the tedium of Hallowe’en (which I usually post about in this fashion), I notice that today (31st October 2017) has been officially designated Dark Matter Day. I would have sent some appropriate greetings cards but I couldn’t find any in the shops…

All of which gives me the excuse to post this nice video which shows (among other things) how dark matter plays a role in the formation of galaxies:

P.S. Lest we forget, today is also the 500th anniversary of the day that Martin Luther knocked on the door of All Saints’ Church in Wittenberg and said `Trick or Theses?’ (Is this right? Ed.)

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Homes from Home in Pune

Posted in Biographical, History, The Universe and Stuff with tags , , , on October 16, 2017 by telescoper

Since I’m coming back tomorrow I thought I’d wander around this morning and take a few pictures of where I’ve been staying most of the last 10 days or so. First, this is a snap of the housing complex which contains my guest apartment.

I’m actually in the first building on the right. Here is the front door.

The faculty at both IUCAA (Pune) and TFIR (Mumbai) live in housing areas provided by their respective institutions, so they form quite a close-knit community. Some of the senior staff in IUCAA are housed just round the corner from my place.

IUCAA is on the Pune University Campus (except that it has its own entrance from the main road that runs along the Northern edge of the campus, where there is a security post. There are a few of these around the IUCAA site itself, so it is very secure and quite private. The campus is large with many tree-lined roads. At its heart, on a small hill, you can find this building:

This is (or was) the Raj Bhavan (`Government House’) and it was essentially the Governor of Maharashtra’s residence during the Monsoon season. Built in 1866, it was a sort of home-from-home when Bombay (the state capital) became too unbearable.

When I was last here in 1994, this was the Main Building of the University and was quite busy. Now, however, it seems to be disused and is in a state of some disrepair, the gardens also need a bit of love and attention. There are many new buildings around the University of Pune campus (including a modern administration block nearby). Since this building is a relic of the old colonial days it may be that it will be demolished to make way for something that better suits modern India. By the way, there’s a stone slab just next to the site of this building that displays the preamble to the Constitution of India, as adopted in 1949.

Anyway, this afternoon and evening promise to be quite busy. There is a press conference at IUCAA at 6.30pm about the gravitational waves discovery I mentioned a few days ago. There will be presentations before a viewing of the live feed from Washington DC then there’ll be a panel answering questions from the press. They’ve asked me to be on the panel, so I might appear in the India media, but as I’m leaving first thing tomorrow morning I probably won’t see any of the coverage!

Before the Storm…

Posted in Biographical, History with tags , , , , on October 16, 2017 by telescoper

Nearly at the end of my short visit to India I find myself checking on the UK news. Home thoughts from abroad and all that. Anyway, it’s quite a coincidence that Hurricane Ophelia is arriving,  exactly on the thirtieth anniversary of the famous `Great Storm‘ that wrought destruction across the South-East of England in 1987. The path of Ophelia is rather different from that of the 1987 `Hurricane’, and it looks like Ireland will bear the brunt over the next day or two, as the storm will weaken as it encounters land, though there will be strong winds far outside the path denoted in this map:

 

I hope the damage from this storm  isn’t too bad and that people in its path stay safely out of harm’s way, especially in Ireland. It’s possible the winds may affect my current home in Wales too. I hope I don’t get back tomorrow evening to find the roof has blown off!

Thirty years ago today I was living in Brighton as a graduate student at the University of Sussex. On October 16th 1987 (a Friday) I woke up to find the electricity had been cut off. Without breakfast I struggled out to find the street lined with fallen trees, smashed cars and houses with broken windows. I got to the railway station to get the train to Falmer (where the University of Sussex is located) only to find that no trains were running. I walked home and went back to bed. It took several days for normal service to resume. When I did get up to campus the following week, I found that almost all the trees in Stanmer Park had come down and were combed flat on the top of the hill.

The Great Storm of 1987 , according to weather forecaster Michael Fish, was “not a hurricane” had nevertheless caused enormours destruction. And I had slept through the whole thing…

Here’s the infamous weather forecast broadcast on the Thursday evening:

and here is the BBC News from the following day:

 

Going Doolally

Posted in Biographical, History with tags , , on October 14, 2017 by telescoper

Yesterday evening, after my seminar and discussions I went with members of the cosmology group at the Tata Institute for Fundamental Research to a place called the Doolally Tap Room which is not far from TIFR. Thundery clouds had gathered and rain was in the air so we took a taxi there and back.

It’s a nice, modern-looking bar with a range of craft beers and food. The Belgian Witbier and Abbey Tripel went down well, but I wasn’t tempted to try Mango Cider. It was a very pleasant evening, but I was dog tired after it and crashed out as soon as I got back to the TIFR guesthouse.

The name Doolally Tap Room is a very clever name for a bar. The word Doolally (or sometimes Dolally), as it is used in English especially in `going Doolally’ etc, generally means `deranged’ or `crazy’ (often as a result of being confined somewhere involuntarily, rather like cabin fever), is thought to derive from Deolali a place in Maharashtra (the state which contains both Mumbai and Pune). Deolali was used as a transit camp for British Army soldiers waiting to be deployed, many of whom became extremely bored stuck there in the heat.

Interestingly though the original phrase describing the madness induced by such boredom was `Deolali Tap’ (the latter word from a Hindhi word meaning `fever’). Doolally Tap Room therefore works rather well as a play on words.

There are of course many words in contemporary English that have their origins in Indian languages: here are 50 of them, which may or may not surprise you: atoll, avatar, bandana, bangle, bazaar, Blighty, bungalow, cashmere, catamaran, char, cheroot, cheetah, chintz, chit, chokey, chutney, cot, cummerbund, curry, dinghy, doolally, dungarees, guru, gymkhana, hullabaloo, jodhpur, jungle, juggernaut, jute, khaki, kedgeree, loot, nirvana, pariah, pashmina, polo, pukka, pundit, purdah, pyjamas, sari, shampoo, shawl, swastika, teak, thug, toddy, typhoon, verandah, and yoga.

Reminded by the above old British Army connection with doolally I can’t resist mentioning the phrase `When I was in Poona…‘. One doesn’t hear it much these days but aficianados of older humorous novels and radio comedy will recognize it as a kind of catchphrase introducing a boring old ex-soldier. It appears thus in Eric Patridge’s Dictionary of Catch Phrases (2003):

The legacy of Pune’s past as a large British Army base is still apparent: a large area in the centre is still called `Camp’ and there is still a tendency among some to refer to non-vegetarian restaurants as `Military’ (though I’m told this is more the case in Southern India, where the traditional local food is entirely vegetarian). In Maharashtra the diet is very mixed, but I’ve eaten relatively little meat since I came here.

All of which rambling might suggest that I’ve gone Doolally, or indeed that I’m turning into an old bore, but I’m actually enjoying this trip very much indeed. It’s fascinating not only to see what has changed in India in the 23 years since I was last here, but also what has remained the same. Moreover, everyone I have met here has been so friendly and hospitable that it’s been an absolute pleasure all round.

Joseph Bertrand and the Monty Hall Problem

Posted in Bad Statistics, History, mathematics with tags , , , , on October 4, 2017 by telescoper

The death a few days ago of Monty Hall reminded me of something I was going to write about the Monty Hall Problem, as it did with another blogger I follow, namely that (unsrurprisingly) Stigler’s Law of Eponymy applies to this problem.

The earliest version of the problem now called the Monty Hall Problem dates from a book, first published in 1889, called Calcul des probabilités written by Joseph Bertrand. It’s a very interesting book, containing much of specific interest to astronomers as well as general things for other scientists. Ypu can read it all online here, if you can read French.

As it happens, I have a copy of the book and here is the relevant problem. If you click on the image it should be legible.

It’s actually Problem 2 of Chapter 1, suggesting that it’s one of the easier, introductory questions. Interesting that it has endured so long, even if it has evolved slightly!

I won’t attempt a full translation into English, but the problem is worth describing as it is actually more interesting than the Monty Hall Problem (with the three doors). In the Bertrand version there are three apparently identical boxes (coffrets) each of which has two drawers (tiroirs). In each drawer of each box there is a medal. In the first box there are two gold medals. The second box contains two silver medals. The third box contains one gold and one silver.

The boxes are shuffled, and you pick a box `at random’ and open one drawer `randomly chosen’ from the two. What is the probability that the other drawer of the same box contains a medal that differs from the first?

Now the probability that you select a box with two different medals in the first place is just 1/3, as it has to be the third box: the other two contain identical medals.

However, once you open one drawer and find (say) a silver medal then the probability of the other one being different (i.e. gold) changes because the knowledge gained by opening the drawer eliminates (in this case) the possibility that you selected the first box (which has only gold medals in it). The probability of the two medals being different is therefore 1/2.

That’s a very rough translation of the part of Bertrand’s discussion on the first page. I leave it as an exercise for the reader to translate the second part!

I just remembered that this is actually the same as the three-card problem I posted about here.

Death and Shingles

Posted in Biographical, History, Mental Health with tags , , , , , on August 31, 2017 by telescoper

So it is now twenty years to the day since news broke of the death of Diana Spencer, formerly the Princess of Wales, along with Dodi Fayed and driver Henri Paul, after a car accident in Paris. I’ve noticed many people posting their memories on social media of where they were when they heard that Diana had died so I thought I’d do the same as I remember it very well.

In the weeks leading up to 31st August 1997 I had been suffering from shingles, a very unpleasant condition that results from the reactivation of the virus responsible for chicken pox, which I’d suffered from as a kid. Shingles causes nasty skin rashes, but on this occasion I was also treated to a spell of almost total deafness. This is a fairly unusual side-effect of the disease but is well known to occur in some cases. Hearing loss caused in this way can be permanent, but thankfully mine wasn’t.  I responded rather well to the anti-viral drugs I was given and it took only a matter of weeks for my hearing to be fully restored.

Suddenly becoming deaf was an unsettling enough experience, but it was even stranger to have been unable to hear anything during the period just after Diana’s death, which turned out to be one of the weirdest times of my life.

On the morning of 31st August 1997, which was a Sunday, I got up rather late and went to the local newsagent to buy a Sunday paper. They were sold out of everything. I thought that was a bit strange but walked out unaware of the reason everyone was buying papers that morning. I went back to my flat – I was living in London at the time – made breakfast, and did some reading. I was looking forward to the football match that was going to be live on TV that afternoon – Liverpool versus Newcastle Utd – but didn’t switch on the TV until it was just about the start. All I saw was a shot of an empty Anfield and some football pundits talking. I assumed there had been a bomb score or something, but I couldn’t hear so had no idea. I decided to have a look at Ceefax (remember that?) and then found out the story.

I was shocked, of course. She was still young when she died and I was fully aware of the reputation she had earned through numerous acts of kindness, e.g. towards people living with AIDS. That said, I was completely unprepared for the events of the following week which seemed to me to amount to an outbreak of national hysteria. I don’t know if it was more extreme in London than elsewhere in the UK, but I felt the whole country had lost its grip. Together with the sense of isolation caused by my deafness, it was a most uncomfortable time. I was saddened by her death, but I just couldn’t feel the extreme grief that others seemed to be displaying about someone that I didn’t know personally. Worse, there was a palpable sense of pressure being exerted on people to fall into line with the deification of Diana. Anyone who expressed anything even slightly short of devout praise was treated as some kind of blasphemer. It is probably the only time in my life I’ve felt that I was the only one to have remained sane while everyone around me had gone mad.

As my hearing slowly recovered I decided to go out with some friends for a drink in a pub in Bethnal Green. I mentioned in a conversation that I never knew her personally and therefore found it hard to understand how the feelings of grief people professed to having could be genuine and that the whole atmosphere that had been created seemed to me to be profoundly unhealthy. A bloke from another table came across and threatened me with violence unless I stopped `insulting Diana’. Insulting Diana was not at all my intention, though I think what the bloke was angry about was the (probably correct) interpretation that I was criticising those who had bought into the Diana cult.

Anyway, over the week following her death my hearing had improved a little bit, so I decided to watch the memorial service on TV. I couldn’t hear the music or speeches very well, but I remember watching the soldiers carrying Diana’s coffin into Westminster Abbey. It must have been a very heavy coffin as it was a very wobbly process and I thought at one moment the pall-bearers might drop it. They slowly approached stone structure on which the coffin was to be laid. Then I heard the commentator on TV solemnly announce that it was “placed on the catapult”.

This is novel, I thought. She’s going to be launched into the hereafter on a ballistic trajectory through the stained glass windows.  However, that didn’t happen and the service continued without an aerial display.

I found out much later that the word used was not catapult, but catafalque….

 

 

 

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.

 

–0–

 

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….