Jazz – Man Ray

by Man Ray (1919, oil on canvas, 71.12 x 55.88 cm).

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`An Astronomer’ – Ferdinand Bol

by Ferdinand Bol (1619-1680), painted in 1652, 127 x 135 cm, Oil on Canvas.

I saw the above painting the other day and thought I’d share it here, as part of an occasional series of works of art. It can be found in the National Gallery in London.

It’s a fairly conventional composition and the style is clearly heavily influenced by Rembrandt, but this painting is beautifully done and has some interesting features all of its own. On the table is a celestial globe, and behind it a terrestrial one. The darkness surrounding the astronomer and his desk suggests isolation and introspection which, together with the pose of the figure and his abstracted manner, indicates that the painting may belong to the visual tradition of Melancholia, made famous by the work of Albrecht Dürer, in which it was suggested that a scholar’s research would inevitably lead him to an awareness of the futility of his endeavours in the face of death.

It’s being so cheerful that helps keep me going…

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Tonight is Culture Night!

Just time for a quick post to mention that tonight is Culture Night in Ireland, which means that over 1600 venues around the country are open this evening for free cultural events. Museums, art galleries and other public buildings and spaces will open later this evening to welcome the general public and there are scores of free concerts going on all over the place. There’s a useful guide here.There are some events in Maynooth tonight, including one at Maynooth Castle.

I would have gone to tonight’s free concert at the National Concert Hall. Although it’s free you have to book a ticket because the capacity is limited and unfortunately I was too late getting around to doing that so couldn’t get in. I’ll probably listen to it on the radio tonight instead.

I think Culture Night is a great idea, as it encourages people to sample cultural fare they might otherwise not get around to trying, and may boost the audiences for the rest of the year as a result. I wonder if anyone has ever thought of running a Culture Night in, say, Cardiff?

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Brú na Bóinne

Today is Lá Saoire i mí Lúnasa (August Bank Holiday) in Ireland, but I thought I’d pop into the Department at Maynooth University to say farewell to the guests at the Quark Confinement Conference, the last of whom depart today. As I mentioned on Saturday I helped guide a party of around 40 conference participants around the prehistoric sites at Brú na Bóinne.

There’s a huge amount of information on the official website for this site and there’s no point trying to repeat it here, but I will say a few things. First of all, the site is about 5 miles inland (west) along the River Boyne from Drogheda. There is a huge amount of archaeology in the Boyne Valley and it’s impossible to see all of it in the half-day trip we had on Saturday, so we went to just one of the three major megalithic sites in the area, at Knowth. The two other sites are Newgrange and Dowth (where another passage tomb has just been discovered), neither of them far from where we were but we didn’t have time to visit them. In order to restrict numbers, access to all three of these monuments is by guided tour only. You have to take a shuttle bus from the main visitor’s centre, which is near to the oldest site at Newgrange. You could see all three in a day but you need at least an hour at each one to appreciate it fully, plus time to get to and fro by shuttle bus.

Anyway, people do say that the main Knowth monument is the most impressive not least because the main passage tomb has never collapsed. You can see from the above picture that the main structure is surrounded by many smaller structures. The `passage’ is about 40 metres long:

Guests at the site are not allowed into the depths of the site, but there is an antechamber with a display explaining what the interior looks like. The passage is quite constricted and oppressive: anyone over 5 foot tall would have to crouch. It’s also not inconsiderably creepy!

I took the above picture with my mobile phone. Here is one with a better camera and a flash which gives you a better idea of the construction:

Incidentally, this and the other structures nearby are all called `passage tombs’ because evidence of cremation has been found inside them, and (in the case of Knowth) a basin stone on which remains had been placed, but it is generally accepted that they were much more than just graves. They were probably temples of some sort. Each of three major monuments at Knowth, Newgrange and Dowth, has a convincing astronomical alignment but each is different: there are alignments with sunrise at the winter solstice (Newgrange) and summer solstice (Dowth); there are two alignments at Knowth for the two equinoxes.

The people who built these extraordinary buildings are thought to have been the first farmers in Ireland (as opposed to the hunter-gatherers who preceded them). It seems likely that the astronomical alignments were to do with some kind of rituals that marked the seasons of the year; the spring equinox would be associated with planting crops and the autumn equinox with harvesting.

The generally good state of preservation of Knowth is partly accidental: at some point in the Iron Age, a Celtic chief decided to build a fort on top of the main tumulus and dig a ditch around its perimeter. The soil removed from the ditch was used to build an embankment on the inside and that provided protection for the right of about 130 kerbstones that surrounds the tomb. Only three of these are missing. They are weathered and worn, which is hardly surprising given that they are 5000 years old, but can be seen in place:

The stones are all carved in different ways – a complete gallery can be found here – but their meaning is lost. As well as the kerbstones there are pieces of quartz and smooth granite stones like large round pebbles, which may have been used for some sort of ritual magic. There are also carved stones inside the monument, including one thought to depict the moon.

For me, it’s the fact that sites like this are so mysterious that makes them so fascinating. Five thousand years is just the blink of an eye on a geological or astronomical timescale, and no doubt the people who lived at Knowth were not all that different from you or I, but what they have left behind is unknowable. If there is life on Earth in 5000 years’ time, what will they think of our civilization?

The stones used at Knowth came from as far away as County Wicklow. It was once believed that these were lugged overland to their current location (which is in County Meath) but the land would probably have been heavily wooded at that time and it is now thought much more likely they were transported by river and sea, probably using log rafts.

As an added bonus you can climb on top of the monument. The view is grand. This is the view to the South, with the hills North of Dublin visible in the distance.

This is to the West; you can see the River Boyne.

The countryside, as you can see, is lovely. Irish agriculture is much less intensive than in England, with the result that woodland and hedgerows are much more abundant. It’s a pity that in so many minds the name `Boyne’ is just an excuse to use a battle that happened over 300 years ago to stir up sectarian conflict.

Anyway, that will have to do. I will definitely return to Brú na Bóinne in the not-too-distant future as I still have to see Newgrange and Dowth. I thoroughly recommend a trip there to anyone visiting Ireland. The professional guides were really good and the visitor’s centre contains excellent reconstructions of everyday life in the neolithic era.

No doubt for a group of particle physicists the site had a particular resonance:

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The Art of Knowth

Just back to Maynooth after a fascinating afternoon at the megalithic sites at Brú na Bóinne. I’ll post a few more pictures in due course, but how’s this for an amazing piece of abstract art?

These carvings are on one of the kerb stones that surround the large passage tomb at Knowth. There are about 130 of these stones ringing the main structure and many more inside, all carved differently. Some of the patterns seem to have astronomical significance, but nobody knows exactly what they mean.

These works of art are about 5000 years old and were made by a stone age civilisation that comprised farmers rather than hunter-gatherers.

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Hair pursued by two planets

Joan Miró (1893-1993), painted in 1968. Oil and acrylic on canvas, 195 X 130 cm (Fundació Joan Miró, Barcelona). Original title: Cabell perseguit per dos planetes.

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Day and Night and CP Violation

I’ve had these pictures for quite a while and can’t remember where I got them from, but I used them in my lectures on Theoretical Particle Physics when I was in Nottingham to illustrate CP-violation.

The following picture by M.C. Escher is called Day and Night:

If you look at it you can see two kinds of symmetry emerging. One is a kind of reflection symmetry about a vertical axis drawn through the centre of the picture that applies to shapes but not to colour. The other is between black and white. But it is obvious that the picture doesn’t display these symmetries separately: to get a picture unchanged from the original you would have to do the mirror reflection and change black to white (and vice-versa).

The mirror reflection in the image can be taken to represent parity (P). Strictly speaking parity refers to a reflection through the origin in 3D rather than a mirror reflection, but it’s just for illustration. We know that a parity symmetry is violated in weak interactions just as it is in the picture.

The other possible symmetry, between black and white can be taken to represent charge-conjugation (C), the operation that converts particles into anti-particles and vice-versa.

While P is not an exact symmetry of weak interactions, it was long thought that the combination of C and P (CP) would be. Actually it isn’t. The story of the discovery of CP-violation is fascinating but I don’t have time to go into it here. It suffices to say that the Escher print also displays CP violation.

First lets do `C’, i.e. convert black to white and vice-versa. The result is:

Now reflect about the vertical mid-line to illustrate `P’:

If `CP’ were an exact symmetry then that image would be identical to the original, which I reproduce here:

You can see, however, that while some elements of the picture do look the same after this combined operation (e.g. the birds), others (e.g. the buildings at the bottom) do not.

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