The Alteration of Time

It’s that time of year again. The clocks went forward at 1am on 26th March, when I was in bed.  I  scheduled this post for exactly that time to see what would happen. By the time I get up tomorrow morning I’ll be on Irish Summer Time and it will probably take me most of the day to work out how to change the clock on my oven again. Still, at least there will be a slight reduction in the amount of confusion over the timing of next week’s batch of telecons.

Among the many sensible decisions made recently by the European Parliament was to approve a directive that will abolish `Daylight Saving Time’. I’ve long felt that the annual ritual of putting the clocks forward in the Spring and back again in the Autumn was a waste of time effort, so I’ll be glad when this silly practice is terminated. It would be better in my view to stick with a single Mean Time throughout the year. This was supposed to happen in 2021 but has been delayed and I gather there are no plans to make it happen in the foreseeable future.

The  splendid poster above is from 1916, when British Summer Time was introduced. You might be surprised to learn that the practice of changing clocks backwards and forwards is only about a hundred years old, in the United Kingdom. To be honest I’m also surprised that the practice persists to this day, as I can’t see any real advantage in it. Any institution or organization that really wants to change its working hours in summer can easily do so, but the world of work is far more flexible nowadays than it was a hundred years ago and I think few would feel the need.

Anyway, while I am on about Mean Time, here is a another poster from 1916.

Until October 1916, clocks in Ireland were set to Dublin Mean Time, as defined at Dunsink Observatory, rather than Mean Time as defined at Greenwich. The adoption of GMT in Ireland was driven largely by the fact that the British authorities found that the time difference between Dublin and London had confused telegraphic communications during the Easter Rising earlier in 1916. Its imposition was therefore, at least in part, intended to bring Ireland under closer control of Britain. Needless to say, this did not go down well with Irish nationalists.

Ireland had not moved to Summer Time with Britain in May 1916 because of the Easter Rising. Dublin Mean Time was 25 minutes 21 seconds behind GMT but the change was introduced at the same time as BST ended in the UK, hence the alteration by one hour minus 25 minutes 21 seconds, i.e. 34 minutes and 39 seconds as in the poster.

Lá Fhéile Pádraig sona daoibh go léir!

So it’s St Patrick’s Day, a bank holiday here in Ireland. I shall probably observe the festivities in Maynooth later on, though it is pouring down at the moment and very likely to rain on the parade, which starts at 11am. That would be disappointing, as it hardly ever rains in Ireland.

I came second in the Beard of Ireland poll, by the way. Thanks to everyone who voted for me and congratulations to the winner, Aodhan Connolly. A few people have asked for an up-to-date picture of me and my beard, so here goes:

Not many facts are known about the life of St Patrick, but it seems he was born in Britain, probably in the late 4th Century AD, probably somewhere around the Severn Estuary and probably in Wales and according to virtually all artistic depictions of him he had a fine beard. It also appears that he didn’t know any Latin. When a young man, it seems he was captured by Celtic marauders coming up the River Severn and taken as a slave to Ireland. He eventually escaped back to Britain, but returned to Ireland as a missionary and succeeded somehow in converting the Irish people to Christianity.

Ireland was the first country to be converted to Christianity that had never been part of the Roman Empire. That made a big difference to the form of the early Irish Church. The local Celtic culture was very loose and decentralized. There were no cities, large buildings, roads or other infrastructure. Life revolved around small settlements and farms. When wars were fought they were generally over livestock or grazing land. The early Irish Church that grew in this environment was quite different from that of continental Europe. It was not centralized, revolved around small churches and monasteries, and lacked the hierarchical structure of the Roman Church. Despite these differences, Ireland was quite well connected with the rest of the Christian world.

Irish monks – and the wonderful illuminated manuscripts they created – spread across the continent, starting with Scotland and Britain. Thanks to the attentions of the Vikings few of these works survive but the wonderful Lindisfarne Gospels, dating from somewhere in the 8th Century were almost certainly created by Irish monks. The Book of Kells was probably created in Scotland by Irish Monks.

Saint Patrick’s Day is celebrated on March 17th, the reputed date of his death in 461 AD. Nobody really knows where St Patrick was born, though, so it would be surprising if the when were any better known.

In any case, it wasn’t until the 17th Century that Saint Patrick’s feast day was placed on the universal liturgical calendar in the Catholic Church. Indeed, St Patrick has never been formally canonized. In the thousand years that passed any memory of the actual date of his birth was probably lost, so the choice of date was probably influenced by other factors, specifically the proximity of the Spring Equinox (which is this year on Monday, March 20th).

The early Christian church in Ireland incorporated many pre-Christian traditions that survived until roughly the 12th century, including the ancient festival of Ēostre (or Ostara), the goddess of spring associated with the spring equinox after whom Easter is named. During this festival, eggs were used a symbol of rebirth and the beginning of new life and a hare or rabbit was the symbol of the goddess and fertility. In turn the Celtic people of Ireland probably adapted their own beliefs to absorb much older influences dating back to the stone age. St Patrick’s Day and Easter therefore probably both have their roots in prehistoric traditions around the Spring Equinox, although the direct connection has long been lost.

Lá Fhéile Pádraig sona daoibh go léir!

Update. I waited until it stopped raining before leaving the house, which meant that I missed the start of the Maynooth parade but there seemed to be a very good turnout. Here are some snaps of the bit I saw:

A bit wet

A refuse collection truck, somewhat incongruous…

Local GAA club

The view down Straffan Road

Ponies!

The End

Cavete Quod Idibus Martiis

Today is the Ides of March so I thought I’d keep post this priceless bit of British cultural history relevant to such a fateful day.
This is from the First Folio Edition of Carry On Cleo, and stars the sublime Kenneth Williams as Julius Caesar delivering one of the funniest lines in the whole Carry On series. The joke may be nearly as old as me, but it’s still a cracker…

And if one old joke isn’t enough for you, here is a Caesar Salad:

To-Wa-Bac-A-Wa

Today is Shrove Tuesday, Pancake Day, and Mardi Gras, which gives me three excuses to post an authentic New Orleans parade tune from way back in 1927.

Jazz began with the marching bands that performed in New Orleans but then largely moved into the bordellos of Storyville, the biggest (legal) red light district in the history of the United States. When Storyville was closed down in 1917 as a threat to the health of the US Navy most professional jazz musicians lost their only source of regular income. Fortunately the very lawmakers who condemned jazz for its association with vice and crime soon passed a law that unwittingly ensured the music’s survival, proposing the 18th Amendment to the Constitution of the United States, passed in 1919, which prohibited the manufacture, distribution and sale of alcohol for human consumption. This was soon followed by the Volstead Act, which gave federal government the powers to enforce the 18th amendment. This ushered in the era of Prohibition, which turned Chicago into a bootlegger’s paradise almost overnight and jazz musicians flocked there to perform in the numerous speakeasies. That’s why so many of the great New Orleans Jazz records of the 1920s were actually made in Chicago.

Although the exodus was substantial, not all Jazz musicians left New Orleans. Many stayed there and kept the roots of the music going while it branched out in Chicago and, later, New York. Most of the bands that stayed kept going through the depression but never really achieved great commercial success until the traditional Jazz revival of the 1940s and 1950s. This example is a record produced by the Victor Record Company who sent a recording unit to New Orleans in 1927 to record some of the musicians who had stayed behind, many of them still playing in the marching band tradition of Buddy Bolden.

The title is To-Wa-Bac-A-Wa. I don’t know what it means but it’s an old French creole version of a tune that has subsequently reappeared many times in different forms with different names, most notably Bucket’s Got A Hole In it. The band is Louis Dumaine’s Jazzola Eight. Besides the lead cornet of Louis Dumaine, who lived from 1889 to 1949, it’s worth mentioning the clarinet style of Willie Joseph, which is heavily influenced by that of the great Johnny Dodds.

Anyway, it’s the kind of jaunty march-like number that’s perfect as a Mardi Gras parade tune and it always puts a spring in my step every time I hear it! There are also some old photographs of Mardi Gras parades to get you in the mood.

Parnell Memorial

Yesterday’s march, which started near Parnell Square, passed by the Monument to 19th century Irish nationalist politician Charles Stewart Parnell on O’Connell Street in Dublin. I took the above picture on the way there, before the march.

I was an undergraduate student at Magdalene College, Cambridge, which just happens to be where  Charles Stewart Parnell studied, although I hasten to add that we weren’t contemporaries. There is an annual Parnell Lecture at Magdalene in his honour; an annual Coles lecture is yet to be established.

Parnell was reportedly one of the most charismatic, capable and influential Parliamentarians of his era. He led the Irish Parliamentary Party at the forefront of moves for Home Rule for Ireland. He also had a splendid beard:

His career was cut short by scandal in the form of an adulterous relationship with Kitty (Katherine) O’Shea, whom her husband divorced in 1889 naming Parnell in the case, and whom he married after the divorce. (Kitty, that is, not her husband.) They were not to enjoy life together for long, however, as Parnell died in 1891 of pneumonia in the arms of his wife at their home in Brighton (Hove, actually).

An Interview with Georges Lemaître

This fascinating video surfaced recently after having been lost for decades. It’s an interview with Georges Lemaître who, along with Alexander Friedmann, is regarded as one of the originators of the Big Bang theory. Lemaître first derived the “Hubble’s law”, now officially called the Hubble–Lemaître law after a vote by members of the International Astronomical Union in 2018, by the IAU and published the first estimation of the Hubble constant in 1927, two years before Hubble’s article on the subject.

Lemaître is such an important figure in the development of modern cosmology that he was given his own Google Doodle in 2018:

The interview was recorded in 1964, just a couple of years before Lemaître’s death in 1966. It was broadcast by Belgische Radio- en Televisieomroep (BRT), the then name of the national public-service broadcaster for the Flemish Community of Belgium (now VRT). Lemaître speaks in French, with Flemish subtitles (which I didn’t find helpful), but I found I could get most of what he is saying using my schoolboy French. Anyway, it’s a fascinating document as it is I think the only existing recording of a long interview with this undoubtedly important figure in the history of cosmology.

As you can see, if you want to watch the video you have to click through to YouTube:

UPDATE: A transcript of this interview in French along with a translation into English can be found here.

The Passage of Time

We have arrived at last at the final week of teaching for this term. The way the timetable has worked out, my last lecture before the break will be on Wednesday afternoon. Later that evening we have our staff Christmas party. I did one lecture this morning, by the end of which I had completed the syllabus for my Mechanics & Special Relativity Module. I have two more sessions with that class, tomorrow and Wednesday, which I will devote to some worked examples and revision for the examination which is on January 14th.

I’m sure the students are tired too, but at least they have the advantage of youth which probably endows them with more energy than I can summon at this point!

Two events over the weekend added to the general sense of exhaustion and made me feel even older. One was that a very dear friend whom I first met, when he was 19 and I was 29, just had his 50th birthday. I remember very well celebrating his 20th. For some reason I felt more comfortable when our ages began with the same digit, if only for a few months. Now he’s 50 and I’m 59…

The other thing that happened was that last night I watched the first episode of a three-part documentary series The Irish Civil War. I thought it was excellent and will definitely watch the other two programmes. The Irish Civil War, which was raging 100 years ago, was as brutal as it was tragic and the episode made uncomfortable viewing, not least because even a century later many of the scars are still painful.

The thought suddenly struck me watching the programme that I was born in 1963, just 40 years or so after the end of the Civil War and 20 years closer in time to that event than to today. Time passes.

Anyway, enough of that. I don’t have time to mope about feeling old. I’ve got some examples to work out for tomorrow’s lecture, including a problem on time dilation…

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Save the Holmdel Antenna!

I’ve used the above image hundreds of times in popular talks. It shows Robert W. Wilson (left) and Arno A. Penzias (right) standing in front of the famous horn antenna that (accidentally) discovered what we now know to be the cosmic microwave background radiation left over after the Big Bang. Penzias and Wilson made their historic measurements in 1964, published their results in 1965, and received the Nobel Prize for Physics in 1978.

At the time of their historic experiment, the scientists were working at Bell Telephone Laboratories at Holmdel, New Jersey, on Project Echo. The antenna was built to receive radio signals bounced off a passive satellite in a low Earth orbit to check the feasibility of satellite radio communication. They found excess noise in their receiver, which was eventually identified as a relic of a time when the Universe was extremely hot. Coincidentally, the theory of this yet undiscovered radiation was being worked on by Bob Dicke and his group in Princeton at about the same time (and also in New Jersey). Discussions ensued, and the discovery paper by Penzias & Wilson appeared in the Astrophysical Journal in 1965 beside a paper by Dicke et al. giving the theoretical interpretation.

Anyway, in case you were wondering whatever happened to the Holmdel Antenna, it is still there in Holmdel (at the top of Crawford Hill) and in 1988 was declared a National Historic Landmark:

Bell Labs (as it was usually known) was acquired by Nokia in 2016 and subsequently called Nokia Bell Labs. In 2019, however, Nokia put the entire Holmdel site up for sale and redevelopment of the entire site is currently being considered. This would not only bring to an end the connection between Holmdel and the telecommunications industry but also places a big question mark over the famous antenna. A petition has been raised to secure the future of this extremely important piece of scientific history. I encourage you to read more about the situation here and consider signing the petition.

Sine and Other Curves

Last week I learned something I never knew before about the origin of the word sine as in the well-known trigonometric function sin(x). I came to this profound knowledge via a circuitous route which I won’t go into now, involving the Italian word for sine which is seno. Another meaning of this word in Italian is “breast”. The same word is used in both senses in Spanish, and there’s a word in French, sein, which also means breast, although the French use the word sinus for sine. The Latin word sinus is used for both sine and breast (among other things); its primary meaning is a bend or a curve.

A friend suggested that it has this name because of the shape of the curve (above) but I didn’t think it would be so simple, and indeed it isn’t.

Since trigonometry was developed for largely for the purpose of compiling astronomical tables, I looked in the excellent History of Ancient Mathematical Astronomy by Otto Neugebauer. What follows is a quick summary.

Astronomical computations only became possible after the adoption of the Babylonian sexagesimal notation for numbers, which is why we still use seconds and minutes of arc. Trigonometry is indispensable in most such computations, such as passing from equatorial to ecliptic coordinates. This is needed for such things as calculating the time of sunrise and sunset. Spherical trigonometry was more important than plane trigonometry for this type of calculation, though both were developed alongside each other.

As an aside I’ll remark that I had to do spherical trigonometry at school, but I don’t think it’s taught anymore at that level. Because everything is done by computers nowadays it’s no longer such a big part of astronomy syllabuses even at university level either. I’m also of an age when we had to use the famous four-figure tables for sine and cosine. But I digress.

The first great work in the field of spherical trigonometry was Spherics by Menelaus of Alexandria which was written at the end of the First Century AD. If Menelaus compiled any trigonometric tables these have not survived. The earliest surviving work where trigonometry is fully developed is Ptolemy‘s Almagest which was written in the 2nd Century contains the first known trigonometric tables.

Almagest, however, does not use our modern trigonometric functions. Indeed, the only trigonometric function used and tabulated there was the chord, define in terms of modern sin(x) by 

chd(x)= 2 sin(x/2).

If you’re familiar with the double-angle formulae you will see that chd²(x)=2[1-cos(x)].

Sine was used by Persian astronomer and mathematician Abu al Wafa Buzjani in the 10th Century from which source it began t spread into Europe. The term had however been used elsewhere much earlier and many historians believe it was initially developed in India at least as early as the 6th century. Anyway, sine proved more convenient than chord, but its usage spread only very slowly in Europe. Nicolaus Copernicus used sine in the discussion of trigonometry in his De revolutionibus orbium coelestium but called it “half of the chord of the double angle”.

But what does all this have to do with breasts?

Well, the best explanation I’ve seen is that Indian mathematicians used the Sanskrit word jīva which means bow-string (as indeed does the Greek chordē). When Indian astronomical works were translated into Arabic, long before they reached Europe, the Indian term was translated as jīb. This word is written and pronounced in the same way as the word jayb which means the “hanging fold of a loose garment” or “breast pocket”, and this subsequently mistranslated into Latin as sinus “breast”.

I hope this clarifies the situation.

P.S. I’m told that if you Google seno iperbolico with your language set to Italian, you get some very interesting results…

The Special Beards of Relativity

I’ve recently moved on to the part about Special Relativity in my module on Mechanics and Special Relativity and this afternoon I’m going to talk about the Lorentz-Fitzgerald contraction or, as it’s properly called here in Ireland, the Fitzgerald-Lorentz contraction.

The first thing to point out is that the physicists George Francis Fitzgerald and Hendrik Lorentz, though of different nationality (the former Irish, the latter Dutch), both had fine beards:

George Francis Fitzgerald (1851-1901)

Hendrik Lorentz (1853-1928)

One of the interesting things you find if you read about the history of physics just before Albert Einstein introduced his theory of special relativity in 1905 was how many people seemed to be on the verge of getting the idea around about the same time. Fitzgerald and Lorentz were two who were almost there; Poincaré was another. It was as if special relativity was `in the air’ at the time. It did, however, take a special genius like Einstein to crystallize all that thinking into a definite theory.

Special relativity is fun to teach, not least because it throws up interesting yet informative paradoxes (i.e. apparent logical contradictions) arising from  that you can use to start a discussion. They’re not really logical contradictions, of course. They just challenge `common sense’ notions, which is a good thing to do to get people thinking.

Anyway, I thought I’d mention one of my favorite such paradoxes arising from a simple Gedankenerfahrung (thought experiment) here.

Imagine you are in a railway carriage moving along a track at constant speed relative to the track. The carriage is dark, but at the centre of the carriage is a flash bulb. At one end (say the front) of the carriage is a portrait of Lorentz and at the other (say the back) a portrait of Fitzgerald; the pictures are equidistant from the bulb and next to each portrait is a clock.The two clocks are synchronized in the rest frame of the carriage.

At a particular time the flash bulb goes off, illuminating both portraits and both clocks for an instant.

It is an essential postulate of special relativity that the speed of light is the same to observers in any inertial frame, so that an observer at rest in the centre of the carriage sees both portraits illuminated simultaneously as indicated by the adjacent clocks. This is because the symmetry of the situation means that light has to travel the same distance to each portrait and back.

Now suppose we view the action from the point of view of a different inertial observer, at rest by the trackside rather than on the train, who is positioned right next to the centre of the carriage as the flash goes off. The light flash travels with the same speed in the second observer’s frame, but this observer sees* the back of the carriage moving towards the light signal and the front moving away. The result is therefore that this observer sees the two portraits light up at different times. In this case the portrait of Fitzgerald is lit up before the portrait of Lorentz.

Had the train been going in the opposite direction, Lorentz would have appeared before Fitzgerald. That just shows that whether its Lorentz-Fitzgerald contraction or Fitzgerald-Lorentz contraction is just a matter of your frame of reference…

But that’s not the paradoxical thing. The paradox is although the two portraits appear at different times to the trackside observer, the clocks nevertheless display the same time….

*You have to use your imagination a bit here, as the train has to be travelling at a decent fraction of the speed of light. It’s certainly not an Irish train.