Arabic Science Tidbits

February 10, 2011

Another episode in the “Andy’s favourite books” series. I just finished reading “Pathfinders : The Golden Age of Arabic Science” by Jim Al-Khalili. Jim is a physicist from Surrey, but also a TV presenter – you may remember “Atom” and “The Secret Life of Chaos”. This book grew out of a three part TV series called “Science and Islam”, but goes well beyond it. I love books that are popular in intent, but also serious works of scholarship. I won’t attempt to review the whole book. Here are just a few things that struck me as interesting.

  • I had thought that mediaeval Arabic science was important mainly for passing the flame from Greece to Europe, and that this happened through Andalusia. In fact they clearly made deeply original contributions and greatly improved on Greek science; and the Andalusian thing was a late stage. The golden age was ninth century Bagdhad.
  • As ever, patronage was crucial. The early Abbasid caliphs encouraged and funded open-ended work, which was incredibly successful. This coincided with growth and confidence of the Abbasid empire itself. As the good times ebbed, science continued, but the authorities were more insistent on it being useful – economically, militarily, or religiously. Sound familiar ? Thinking of the Medicis of course…
  • The broader intellectual outlook was important for encouraging science. Just as Renaissance science flourished in the context of the humanist movement, so too did Arabic science in the context of Mutazilism , which argued against over-literal reading of the Qu’ran,  and stressed the importance of human reason within Islam.
  • Why then ? Why there ? Al-Khalili suggests there is a technological answer –  papermaking (as opposed to papyrus or parchment) which came to Samarkand in 751 when a Chinese army was defeated, and prisoners taken who knew the technology. Flax and hemp were abundant around Samarkand. Around the same time, there were great advances in the making of dyes, glues, leather, and book-binding techniques, all of which resulted in cheap and robust books.
  • Hundreds of years later, Al-Khalili argues that part of the reason for the decline of Arabic science just while European science was starting up, was that Arabic script was much harder to print than Latin script, because letters take different shapes depending on their position in a word.
  • Here is a favourite wee snippet, which is the origin of the term “sine”, as in opposite-over-hypotenuse. Hindu mathematicians used the Sanskrit word jya-ardha, meaning “half the bowstring”. (Draw the chord of a circle and stare at it…) This was abbreviated to jiva, which Arabic scientists transliterated as jiba, and customarily abbreviated as jb. Robert of Chester first translated the Arabic work, and misread jb as jayb, which means “pocket”. So he used the Latin word for pocket – sinus.

Well you do learn stuff if ya read books.


Beat Pilgrimage

March 3, 2009

I love the way history soaks into the streets of a town. Most of the time it leaves nothing more than a slightly coloured stain and you walk past, unknowing. Sometimes there is a hidden plaque.  Sometimes you know there were shattering events, but the traces are lost. I used to walk round the streets of East London trying to imagine the Cable Street riots.

We came back from a Sunday stroll to find two men on the kerb, clutching a battered red paperback, staring at our anonymous rented house. Oh, they said, do you live here ? Do you know who lived here in the sixties ? Lew Welch.

It turns out they were on a kind of Beat Poet pilgrimage. Lew Welch was part of the 1960s “San Francisco Renaissance”, was friends with Gary Snyder and Lawrence Ferlinghetti, and was apparently “Dave Swain” in Kerouac’s “On the Road”. He finished high school in Palo Alto and lived for many years in our house. He had success for a few years, and then one day he walked out of Gary Snyders’ house and never came back.

So we showed them round the house and we all tried to catch the vibrations for ten or fifteen minutes. Then they left to find the next station of the cross.

You can read about Welch here, here and here, and about the San Francisco Renaissance here. A collection of Welch’s poems, Ring of Bone, is on Amazon. Here is the title poem.

I Saw Myself

I saw myself
a ring of bone
in the clear stream
of all of it

and vowed
always to be open to it
that all of it
might flow through

and then heard
“ring of bone” where
ring is what a

bell does


Geek Tour

September 13, 2008

My daughter’s friend Lewis is here to visit. He’s a computer whizz-kid – eighteen and already has his own business building web sites – so he was pretty excited coming to Silicon Valley. I bought some McIntosh apples specially for his arrival. Apparently they were the favourite apple of Macintosh inventor Jef Raskin . (I was disappointed. In the McIntosh. Not the Macintosh.)

Yesterday we did the geek tour. Lewis had already found the garage at 367 Addison Ave where BillDave HewlettPackard started in the fifties, and the Facebook Offices in University Ave. (The HP garage is officially California historic landmark number 976). I had told him that Steve Jobs lives a few blocks away in a modest house, but we don’t know where. Today we drove past the Googleplex on Amphitheatre Parkway, and most important of all, went to the Apple Campus at 1 Infinite Loop Cupertino. It is HUGE. I was ready for a giant corporate building of some kind, maybe some surrounding greenery, but there is street after street after street of Apple buildings. Seems to be half of Cupertino. I was going to call this post “a visit to the Mothership” but when we dropped in to the company store I found there were T-shirts for sale that said “I visited the Mothership” so suddenly that all seemed obvious. Lewis loaded his bag with goodies.

Americans tend to tell you they don’t have any history, and that they are jealous of Europeans and their ancient buildings. The truth is that Americans are obssessed with history, and the place is crammed full of the stuff. Its not a quaint museum thing. Its real and resonating. Years back when I lived in Massachusetts you could walk round the Freedom Trail or drive out to Concord and practically feel the Minutemen breathing down your neck; people were debating whether their precious freedom was being eroded. History happens fast. The modern world started here in the nineteen fifties, accelerated in the 1970s, and again in the 1990s dotcom boom. As soon as I got here, people told me about the Homebrew Computer Club that used to meet in the Panofsky Auditorium.

Of course, if the HP Garage is the birthplace of Silicon Valley, and the Apple Campus is the Mothership, the Stanford Campus, where all that useless academic research goes on, is the Queen Bee. Sorry about the gharssly mixed metaphors, but there’s got to be a lesson there somewhere.


Dragons, Nuns, and the ATC

February 19, 2008

History can vanish in an instant. Does it matter ?

Walking to the Royal Observatory from my house I start along Lover’s Loan. Where it ends, there is a strange pillar topped by a winged dragon. At the weekend I read that this is not a dragon, or a gryphon, but a wyvern. The pillar is a tiny saved piece of the grand house that stood here for centuries before the ground was washed over by a sea of Victorian villas. I also read that its matching twin is further along Grange Loan, so on the walk home I diverted and found it. The house was scrubbed from the surface of the earth in 1936, apart from the wyvern pillars. The once powerful families that owned the house – the Dicks and the Lauders – still have a ghostly presence in the names of streets. Nothing beside remains.

So thats the Grange. Further north, where I live, is Sciennes, pronounced “Sheens”. I had long heard that this is a corruption of “St Catherine of Siena”, the name of a convent founded after the Battle of Flodden. Like Grange House, it is now utterly vanished apart from the muffled resonance of place names. My weekend reading however told me that the convent was commemorated at 16 St Catherine’s Place, so I took another arc to look for this. There was nothing on the street, nothing on the side of the house. Then, as I peered along the driveway, I saw it – an eighteen inch plaque on a rock in the middle of the garden. I didn’t feel bold enough to walk into somebody else’s garden, so I don’t know what it says.

After a brief stay at home, I walked in to Old College, where the Principal was hosting a reception for all the boys and girls who worked so hard on our submission to the Research Assessment Exercise. From there I kinda drifted to the Royal Oak, and finally, late at night and somewhat stoatered, found myself buying a bag of chips at Luciano’s, opposite the Dick Vet School. Until a few years ago, Luciano’s, in an astonishing five hundred year chain of unbroken memory from the Battle of Flodden to Blair’s Britain, was called the Siena Fish Bar. Then some random guy buys it up, thinks huh, dumb name, and crunch – history snapped.

Some days, working at the Royal Observatory on Blackford Hill I can feel the history oozing out of the stones. The nightmare scenario is that if the ATC reduces in half, it becomes unviable and closes anyway; then the University can’t afford to keep a medium sized astronomy research group on a large ancient site, and finally we all get shifted down to Kings Buildings. History snapped again.

By the way, it ain’t happening.


Drinking the Rubicon

July 25, 2007

Caesar crossing the Rubicon (Ridpath)On the way down south recently, my girlfriend handed me a fruit drink called Rubicon. How strange. I felt at the edge of history. I opened the can and held it open before me, pausing. If I drink this now, I thought, there is no going back…

So I did. It was yummy. Will get it again. Rubicon crossed.


The sixty three year lifetime of nebulium

June 24, 2007

This evening I rediscovered the story of Nebulium. Nebulium doesn’t exist. But its “discovery” was a key step in both astronomy and quantum physics. It took sixty three years to realise what was really going on. What have we “discovered” recently that doesn’t mean what we think it means ? Dark energy maybe ?

I was looking for a book, but ran across an old favourite, and plucked it out instead, the way you do. The old favourite was an Edwardian book about the life of William Huggins, one of the founders of modern astrophysics – the man who turned the spectroscope to the stars. Huggins is a scientific hero, but its also a lovely wee book. Huggins smallIts one of “The People’s Books” – cheap pocket sized summaries of everything a person should know – from Inorganic Chemistry to The Life of Caesar through Kant’s Philosophy and Women’s Suffrage to The Stock Exchange and The Crusades. When the biography of Huggins was published in 1913, there were eighty four titles; by 1920 (the lastest volume I have) there were a hundred and thirty three. Whenever I drift by a second hand bookshop a magnet pulls me in and I check for People’s Books… I have twenty eight of them. Here is a picture of the frontispiece of the Huggins book.

Any other fans out there ? There seems to be little information on the Web …

Anyhoo … Huggins, working from his home in Tulse Hill in the suburbs of London, turned a spectroscope to the stars, and found them to contain Hydrogen, Sodium, Magnesium, Calcium, and Iron. Astronomy turned into Astrophysics in 1864. (You can read the real thing in Huggins and Miller 1864a). This was the start of the long confused path that led through Rutherfurd, Secchi, Pickering, Fleming and Cannon to the modern classification of stars. In 1866 Huggins took the first spectrum of a Nova, finding Hydrogen in emission, and in 1868, he took the first spectrum of a comet, finding, amongst other things, ethylene. These things alone would put him amongst the giants of astronomy; but his fame rests on the observations of nebulae.

On August 29th 1864, Huggins turned his spectroscope to the Cats ECats Eye Nebula (HST)ye Nebula in Draco. He was amazed to find, not a continuous spectrum with dark lines, but a single bright emission line. (A few other lines were found later). He correctly deduced that nebulae were not aggregations of stars, but glowing gas. These observations and more were formally published in a series of papers starting with Huggins and Miller (1864b). However, my wee People’s Book contains a beautiful and moving informal account, written later by Huggins for the “Nineteenth Century Review” of 1897. Here is a link to a photo of the relevant pages.… I hope you can read it ok.

Now here is the problem. The “Chief Nebular Line” at 5007 Angstroms wavelength, had never been seen in a laboratory spectrum. It must be from a new substance, not found on Earth, which became known as “Nebulium”. (I am not sure when the word was first used.. ) This was a popular game in the 1860s. In 1868, Norman Lockyer found mystery lines in the Sun, which he decided were likewise due to a new element, christened Helium. Over the coming years, Helium lines were also found in nebulae, and nebulium lines found in novae, and all this spectroscopy was a major industry. By 1895, Helium had been found on Earth – William Ramsay managed to isolate it from the mineral Cleveite – but Nebulium was still confined to the Heavens, and was the subject of much speculation. By 1911, J.W.Nicholson had developed a full theory of the Nebulium atom, and calculated its size.

Finally in 1928 Ira Bowen solved the puzzle, in a classic paper. By this time, we knew about quantum mechanics, and how emission lines arise when atoms are excited, and then spontaneously decay to lower energy states. Some energy states are “metastable”; you have to wait a really long time before the spontaneous decay happens. In practice it never happens, as a collision with another atom always kicks it out of the excited state first. At least thats true on Earth … but in nebular gases the densities are so low these collisions happen very rarely .. and so the “forbidden” lines do occur after all. The Chief Nebular Line is not from Nebulium .. but from plain old Oxygen.

So all that time the wondrous nebulium did not exist. But the nebulium lines were a clue to the fundamental nature of the material world .. if only we had known.

So in modern times we measure the brightness and redshifts of distant supernovae, and find the universe, to our considerable surprise, to be accelerating. In the context of modern cosmology this requires a vacuum energy. Vacuum energy is proposed in some particle physics theories, but of a size many orders of magnitude different. This is something stranger, something new. The concordance cosmology has the universe made of ordinary (baryonic) matter, dark matter (non-bayonic particles), and “dark energy” .. a completely new substance … hmm..

Come back in sixty three years and maybe we will know what the hell this means.


The man who measured the size of the Universe

April 14, 2007

Last night I was faced with a mixture of achievement and failure, wonder and decay, drinking tea in the room where Thomas Henderson calculated the distance to the stars.

I was giving a talk to the Astronomical Society of Edinburgh, a long established amateur society. My talk was about mapping the Universe, first stepping through the history, and ending up with modern results from SDSS, 2dFGRS, and UKIDSS. I mentioned Thomas Henderson, my predecessor as Regius Professor; a great hero, as in 1833 he was the first man to measure parallax and so determine the distance to a star (Alpha Centauri). He made the measurements in South Africa and finished the calculations in Edinburgh. Alpha Centauri is the very nearest star system; but it is almost seven thousand times further away than Pluto… The universe of stars is unimaginably vast.

I showed a picture of a memorial to Henderson Thomas Henderson Memorial on Calton Hill Edinburghwhich I had found on the web, and mentioned that I wasn’t sure where it was – maybe in the same cemetery as David Hume ? Oh no, they piped up – its on the side of this building ! (And the image came from their website… oops.) The ASE are lucky enough to use as their HQ the old City Observatory on Calton Hill, where the Astronomers Royal worked until 1894 when the new Royal Observatory was built on Blackford Hill on the outskirts of Edinburgh. (This is where I work now of course..). Well…I say lucky, but the state of the buildings is a scandal. They are owned by the City, but gradually decaying. The toilets don’t work, and the ASE guys warned me to go before I turned up.

After the talk they fed me tea and biscuits in a room where they reckon Henderson did his calculations after returning from the Cape. But its also where he lost his nerve. In the 1830s measuring parallax was the big prize, and some people had had egg on their faces -Henderson was nervous about whether he had got it right, and didn’t publish. Finally in 1838 Friedrich Bessel beat him to it and published the parallax of 61 Cygni. Henderson finally published the next year. His distance was right within about 30%.

So on the way out I walked around the side of the beautiful Playfair building. Fog was swirling around the walls (no observing last night !). ASE scretary Graham Rule shone his torch for me, and there it was – a modest monument to the man who showed just how big the Universe really is.


The Internet and the Persian Wars

April 7, 2007

Information is power they say. I have just been watching the return of the British sailors from Iran on TV, and their stories of blindfolding and isolation. Iran of course denies all this. How does someone in Palestine know who is telling the truth ? It seems scary that the West and Iran are inching towards a crisis just as “300” is hitting our cinema screens … a garish cartoon version of the founding myth of Western Civilisation – the defeat of Persia. But we are the masters of the world .. are we not ?

So here we are at the peak of Western Power. What is our secret ? Capitalism ? Energy ? Technology ? Or Information – knowledge, infrastructure, organisation ? All these things are connected, but you could argue that information is the key. A surplus of energy allows you to organise life – to build roads and hospitals, and to pay people to do things other than fight and farm – e.g. to play with technology, design systems of law, set exams, and so on. Free market Capitalism is just a form of organisation, as is the ideal Socialist State. In one method, a highly structured system is designed and implemented top down; in the other, a network of interacting agents is left to organically evolve under a simple set of rules. In both cases a highly non-random information-rich structure appears.

The easier it is for information to flow, the more quickly a system can restructure. Hence libraries, education, and TV have also been crucial to the dominance of Western societies. Through most of history, the ruling classes have had more access to, and more control of, information than the majority of the population. During the nineteenth century, the mass production of cheap books was starting to change this, and information became very diffuse and democratic – every shopkeeper could read Dickens. The arrival of cinema, radio and TV stopped all this, along with national newspapers. Information flowed outwards from a few central points. It is probably not a coincidence that the golden age of popular revolt was from the mid-nineteenth century to the early twentieth, whereas the rest of the twentieth century was characterised by happy but docile populations. (Lets count the second world war as a horrific gap between these eras ..)

The Internet is all about information transparency. Basic protocols (TCP/IP) allow messages to pass between computers; FTP allows whole files to flow from place to place; the Web (HTML, HTTP) makes documents visible transparently from any location. Web services and associated standards like XML, SOAP and REST are about achieving transparency for data (as opposed to human readable documents). Grid middleware (Condor, GLOBUS, WSRF) is about making processing power transparent, so programmes can run anywhere.

For most people the World Wide Web is the visible surface of the new infrastructure. Sitting here on the sofa, surfing the Web, it feels like all the documents in the world are right here inside my computer. Fifteen years ago this was for a handful of geeks. Now every day my kids show me stuff I didn’t know and my sister shops on the web. The world is transparent and information is flooding to and fro at a fantastic rate. The effects are very hard to predict. Of course .. the thing about the Web is that (a) there is just too much stuff, and (b) nearly all of it is dross. How does that vast turbulence settle into an organised structure ? Web-1 answers : bookmarks; search engines; portals … mostly deliverer centred, like TV. Web-2 answers are famously more diffuse, democratic, and user centred – social networking; tags and social bookmarking; self publication; popular voting (Digg etc). These things produce accelerated spontaneous structuring at the same time as producing more and more utter drivel. Its excitingly powerful and unstable. Who knows where we are going ?

The Internet is a symbol of Western success. The Chinese are frightened of it. If war is coming, we will win for sure, won’t we ? Information is power. So was this true in the ancient Persian wars ?

My Christmas reading left me confused. I got a wonderful book called “Persian Fire” by Tom Holland. Its a popular history, the story of the war between Persia and Greece in the fifth century B.C.E. – Marathon, Thermopylae, Salamis, and all that. Its is a riveting read. Tom Holland is a magician. When most people try to write popular history with a narrative flow, it comes out as patronising and sub-novelistic. Holland does it and its grown-up and gripping. If I can figure out the trick I will bottle and sell it.

One thing that took me by surprise was how bureaucratic the Persian Empire was. Everything was recorded. The Imperial staff knew the whereabouts of every chicken in the empire. This was not the sign of a decadent society past its best; rather, it was precisely the secret of an unstoppable war machine. Cyrus, Darius, and then Xerxes, all knew that information was power. When that vast army set off, they knew who would feed it where and when. They knew the size and strength of every city on the way, the factions it contained, and who to pay off. They captured spies and sent them back with carefully planted disinformation. They knew what was going on and the other guys didn’t.. So there we go .. information produces organisation produces power.

And yet … the Greeks won. They won against much bigger numbers and against a much better machine. So maybe it was the superior moral strength of democracy versus despotism ? Err .. don’t think so. The Athenians were in the middle of their democratic experiment, but none of the other city states were, and the Spartans were completely bizarre weirdos. Greek cunning ? Well, partly. Salamis was the real victory, a beautifully planned strategy. Technology ? Certainly important. The Hoplite Phalanx was the secret weapon – a wall of metal bristling with spears.

Or maybe there is no systemic answer. Everything cracks in the end. There are fault lines in History. As Bush lines up the battle ships in the Gulf, take nothing for granted.