Category: Science

Science, usually research I have done or topics on which I have lectured

Apr 03 2011

Obsession

This is a short story about obsession: with a map, four books and some numbers.

My last blog post was on Ken Alder’s book “The Measure of All Things” on the surveying of the meridian across France, through Paris, in order to provide a definition for a new unit of measure, the metre, during the period of the French Revolution. Reading this book I noticed lots of place names being mentioned, and indeed the core of the whole process of surveying is turning up at places and measuring the angles to other places in a process of triangulation.

To me places imply maps, and whilst I was reading I popped a few of the places into Google Maps but this was unsatisfactory to me. Delambre and Mechain, the surveyors of the meridian, had been to many places. I wanted to see where they all were. Ken Alder has gone a little way towards this in providing a map: you can see it on his website but it’s an unsatisfying thing: very few of the places are named and you can’t zoom into it.

In my investigations for the last blog post, I discovered the full text of the report of the surveying mission, “Base du système métrique décimal”, was available online and flicking through it I found a table of all 115 triangles used in determining the meridian. So a plan is formed: enter the names of the stations forming the 115 triangles into a three column spreadsheet; determine the latitude and longitude of each of these stations using the Google Maps API; write these locations out into a KML file which can be viewed in Google Maps or Google Earth.

The problem is that place names are not unique and things have changed in the last 200 years. I have spent hours transcribing the tables and hunting down names of obscure places in rural France, hacking away with Python and loved every minute of it. Cassini’s earlier map of France is available online but the navigation is rather clumsy so I didn’t use it. Although now I come to writing this I see someone else has made a better job of it.

Beside three entries in the tables of triangles are the words: “Ce triangle est inutile” – “This triangle is useless”. Instantly I have a direct bond with Delambre, who wrote those words 200 years ago –  I know that feeling: in my loft is a sequence of about 20 lab books I used through my academic career and I know that besides an (unfortunately large) number of results the word “Bollocks!” is scrawled for very similar reasons.

The scheme with the the Google Maps API is that your program provides a place name “Chester, UK”, for example, and the API provides you with the latitude and longitude of the point requested. Sometimes this doesn’t work, either because there are several places with the same name or the placename is not in the database.

I did have a genuine Eureka moment: after several hours trying to find missing places on the map I had a bath and whilst there I had an idea: Google Earth supports overlay images on its maps. At the back of the “Base du système métrique décimal” there is a set of images showing where the stations are as a set of simple line diagrams. Surely I could overlay the images from Base onto Google Earth and find the missing stations? I didn’t leap straight from the bath, but I did stay up overlaying images onto maps deep into the night. It turns out the diagrams are not at all bad for finding missing stations. This manual fiddling to sort out errant stations is intellectually unsatisfying but some things it’s just quicker to do by hand!

You can see the results of my fiddling by loading this KML file into Google Earth, if you’re really keen this is a zip file containing the image overlays from “Base du système métrique décimal” – they match up pretty well given they are photocopies of diagrams subject to limitations in the original drawing and distortion by scanning.

What have I learned in this process?

  • I’ve learnt that although it’s possible to make dictionaries of dictionaries in Python it is not straightforward to pickle them.
  • I’ve enjoyed exploring the quiet corners of France on Google Maps
  • I’ve had a bit more practice using OneNote, Paint .Net, Python and Google Earth so when the next interesting thing comes along I’ll have a head start.
  • Handling French accents in Python is a bit beyond my wrangling skills.

You’ve hopefully learnt something of the immutable mind of a scientist!
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Mar 31 2011

Book review: The Measure of All Things by Ken Alder

TheMeasureOfAllThings“The Measure of All Things“ by Ken Alder tells the story of Pierre Méchain and Jean Baptiste Joseph Delambre’s efforts to survey the line of constant longitude (or meridian) between Dunkerque and Barcelona through Paris, starting amidst the French Revolution in 1792.

The survey of the meridian was part of a scheme to introduce a new, unified system of measures. The idea was to fix the length of the new unit, the metre, as 1/10,000,000th of the distance between the North Pole and the equator on a meridian passing through Paris.

At the time France used an estimated 250,000 different measures across the country with each parish having it’s own (uncalibrated) weights and measures with different measures for different types of material i.e. a “yard” of cotton was different from a “yard” of silk, and different if you were buying wholesale or selling to end users. These measures had evolved over time to suit local needs, but acted to supress trade between communities. Most nations found themselves in a similar situation.

Although the process of measuring the meridian started under the ancien regime, it continued in revolutionary France as a scheme that united the country. The names associated with the scheme: Laplace, Legrendre, Lavoisier, Cassini, Condorcet, leading lights of the Academie des Sciences, are still well known to scientists today.

Such surveying measurements are made by triangulation, a strip of triangles is surveyed along the line of interest. This involves precisely measuring the angles between each each vertex of the triangles in succession: given the three angles of a triangle and the length of one side of the triangle the lengths of the other two sides can be calculated. It’s actually only necessary to measure the length of one side on one triangle on the ground. Once you’ve done that you can use the previously determined lengths for successive triangles. All of France had been surveyed under the direction of César-François Cassini in 1740-80, the meridian survey used a subset of these sites measured at higher precision thanks to the newly invented Borda repeating circle. As well as this triangulation survey a measure of latitude was made at points along the meridian by examining the stars.
The book captures well the feeling of experimental measurement: the obsession with getting things to match up via different routes; the sick feeling when you realise you’ve made a mistake perhaps never to be reversed; the frustration at staring at pages of scribbles trying to find the mistake; the pleasure in things adding up.

Méchain and Delambre split up to measure the meridian in two sections: Delambre taking the northern section from Dunkerque to Rodez and Méchain the section from Rodez to Barcelona. Méchain delayed endlessly throughout the project, trusting little measurement to his accompanying team. Early on in the process, at Barcelona, he believed he had made a terrible error in measurement, but was unable to check whilst Spain and France were at war. He was wracked by doubt for the following years, only handing over doctored notes with great reluctance at the very end of the project. He was to die not long after the initial measurements were completed, leaving his original notes for Delambre to sift through.

At the time the measurements were originally made the understanding of experimental uncertainty, precision and accuracy were poorly developed. Driven in part by the meridian project and similar survey work by Gauss in Germany, statistical methods for handling experimental error more rigorously were developed not long afterwards. I wrote a little about this back here. Satellite surveying methods show that the error in the measurement by Méchain and Delambre is equivalent to 0.2 millimetres in a metre or 0.02%.

In the end the Earth turns out not to be a great object on which to base a measurement system: although it’s pretty uniform it isn’t really uniform and this limits the accuracy of your units. The alternative proposed at the time was to base the metre on a pendulum: it was to have the length necessary to produce a pendulum of period 2 seconds. This is also ultimately based on properties of the Earth since the second was defined as a certain fraction of the day (the time the Earth takes to rotate on its axis) and the local gravity which varies slightly from place to place, as Maskelyne demonstrated.

Following the Revolution, France adopted, for a short time, a decimal system of time as well as metric units but these soon lapsed. However, the new metric units were taken up across the world over the following years – often this was during unification following war and upheaval.

The definition of the basic units used in science is still an active area. The definition of the metre has not relied on a unique physical object since 1960, rather it is defined by a process: the distance light travels in a small moment of time. However, the kilogram is still defined by a physical object but this may end soon with some exquisitely crafted silicon spheres.

I must admit to being a bit wary of this book in the first instance, how interesting can it be to measure the length of a line? However, it turns out I like to read history through the medium of science and the book provides an insight into France at the Revolution. Furthermore measuring the length of a line is interesting, or it is to a physicist like me.

Thanks to @beckyfh for recommending it!

Footnotes
1. The full-text of the three volume “Base du système métrique décimal” written by Delambre is available online. The back of the second volume contains summary tables of all the triangles and a diagram showing their locations.
2. The author’s website.
3. Some locations in Google Maps.

Mar 08 2011

Book review: Doomsday Men by P.D. Smith

DoomsdayMenMy next book review is on Doomsday Men: The Real Dr Strangelove and the Dream of the Superweapon by P.D. Smith. I arrived at this book via the comments on my earlier post about the Manhattan Project, the Allied project to develop the atomic bombs dropped on Hiroshima and Nagasaki at the end of the Second World War. I also wrote about science fiction, which is relevant to this book too.

Doomsday Men brings context to the Manhattan Project, it shows the early imagining of what radioactivity could bring in terms of weapons of war, it shows science fiction writers foreseeing the applications, politicians considering the practical use of weapons of mass destruction and scientists working towards them. Alongside atomic weapons the potential for war from the air had been well considered before it was implemented.

The book starts with the conception of a genuine doomsday superweapon, that’s to say one that would wipe out all life on earth. This had been a theme of science fiction in the past, but in the early 1950’s it became plausible. Essentially the trick is to set off a fusion explosion in the presence of a large quantity of a particular element, cobalt, which would pick up neutrons becoming intensely radioactive whilst being vapourised and cast up into the atmosphere to settle the world over providing a lethal dose of radiation. The amount of cobalt required is about 10,000 tonnes which is only a cube with sides 10 metres long. There’s an open question as to whether the dust would be distributed uniformly enough to wipe out all life.

Leo Szilard is a central character through the book, along with fellow Hungarians John Von Neumann, Eugene Wigner and Edward Teller, known collectively as the Hungarian Quartet. They arrived in the US, fleeing anti-Semitism in Europe and were to play an important part in the development of nuclear weapons. It’s very striking the number of European Jews who migrated to the US in the period after the First World War, including Albert Einstein and Enrico Fermi. In the first instance many of them were keen to help in the development of nuclear weapons as a response to Hitler’s rise in Germany: a state they believed had both the technical ability to make such weapons and, with Hitler, the will to use them in war. Towards the end of the Second World War many of them felt less enthusiastic about their use against the Japanese, despite Japan’s hideous development and use of biological weapons against the Chinese in the 1930’s. Following the war, Von Neumann and particularly Teller continued to be involved in further developments now driven by anti-Communism sentiments.

The route to the doomsday weapon started with the discovery of radioactivity towards the end of the 19th century, and in particular the discovery of radium by Pierre and Marie Curie at the turn of the century. Around 1902 Frederick Soddy and Sir William Crookes both highlighted the huge amounts of energy was bound up in matter. Crookes saying: “one gram could raise the entire fleet of the British Navy several thousand fleet in the sky”. By 1913 H.G. Wells had very explicitly written about a nuclear weapon in “A World Set Free”. The use of chemical weapons, tanks and aeroplanes in war had all been imagined well before they were used too. Clearly there are big technical issues to address in going from a science fiction idea to a real system in battle, but the point here is that these ideas had serious public currency well before they were realised: there could be no “we’ll keep this quiet and no-one will think of it”. In a sense the key theme of the book is the interweaving of fiction with fact through the first half of the 20th century.

It was during the First World War that “scientific” superweapons started to be used, and the importance of science in waging war started to be recognised explicitly. Fritz Haber, a chemist, Nobel prize-winner for his commercial synthesis of ammonia, contemporary of Einstein, was instrumental in bringing chemical weapons to war, he was a German nationalist and felt the development of such weapons a duty to his country. He seemed quite enthusiastic about his work, writing:

“Chlorine: easy to liquefy, disastrous to the human organism, very cheap, mind you! Phosgene: ten times as strong as chlorine. Mustard gas: the best fighting gas of all”.

Once the Germans had used chemical weapons the British and French quickly developed their own. Research and manufacture of chemical weapons was to involve up to 75,000 people by the end of the war – this is about half the number involved in the Manhattan Project. A minority of scientists considered chemical warfare as a blessing compared to the conventional equivalent, for many others it was utterly abhorrent. The military had mixed feelings. Chemical weapons were banned by a variety of treaties, practically they seemed something of a double-edged sword with the first British use of chlorine at Loos causing 2000 casualties on their own side which perhaps explains why they’ve been so rarely used since. With the rise of Nazism Haber, a Jew, was to flee Germany and die shortly thereafter.

The First World War also saw the foundation of the British Board of Invention and Research in 1916, tasked with finding science to fight wars – it sought ideas from the public, one of the which was to train cormorants to peck out the mortar between bricks!

Biological weapons were to be developed by the Japanese whilst at war in China during the 1930’s and the Second World War, in an effort led by Shiro Ishii. During this period thousands were to die through his work, many in a range of human experiments to match those carried out by the Nazi doctors. Following the Second World War Ishii was given immunity from prosecution in order that the US could obtain information on biological weapons from him.

So chemistry and biology produced rather unpleasant weapons but they could not be described as decisive: for that you need physicists.

Szilard was first to realise (in 1933) that an atomic bomb might be made via a chain reaction: the fission of an atomic nucleus producing two or more neutrons which would drive further fission. He made some effort to keep the idea secret, at least from the Germans, via a patent held by the British Admirality. This was a very unusual move for a scientist in an area of pure science. In 1939 he was to visit Roosevelt with Einstein to warn him of the potential for an atomic bomb and the possibility that the Germans would make one. Ultimately this contact led to the Manhattan Project and the bombs dropped on Hiroshima and Nagasaki: killing at least 200,000 people.

One of the recurring themes in fiction was the idea of a scientist discovering the doomsday weapon and then holding the world to ransom for peace with the new “system of the world”: a world government led by scientists and technocrats. This sort of idea is better described as left-wing rather than right-wing. And I can say, as a scientist, that it has a certain appeal! Perhaps this explains something of why scientists are more often perceived as left-wing rather than right-wing.

Doomsday Men ends with the story of Stanley Kubrick’s 1964 film “Dr Strangelove: or How I stopped worrying and learned to love the Bomb”. The title character appears to have been based on a combination of Teller, von Neumann and perhaps Werner von Braun – the German rocket scientist captured by the Americans who went on to found the US space programme.

Overall a rather good read: providing good context to the Manhattan Project and the Cold War, and the importance of science fiction in seeing into the future.

Footnote: one of the drawbacks of reading on a Kindle: I reached the end rather unexpectedly since the footnotes, bibliography, and index take up a third of the book!

Feb 14 2011

Book Review: For all the tea in China by Sarah Rose

ForAllTeaChinaBookI’ve been on a bit of a reading spree: next up is “For all the tea in China” by Sarah Rose. This is the story of Robert Fortune and his trips to China in the mid-nineteenth century to obtain tea plants and the secret of tea manufacture for the East India Company to use in India.

Robert Fortune (1812-1880) was a botanist with a modest background. Starting his working life at the Royal Botanic Garden Edinburgh, he later became Curator of the Chelsea Physic Garden. These were relatively poorly paid posts, however there were few such positions to support a professional botanist without their own means of support. He made several substantial visits to the Far East, funded by the Horticultural Society of London and the British East India Company. He died a wealthy man in large part through the wide range of plant introductions he had made, as well as through sales of artefacts he had acquired in the Far East. The list of introductions is well worth a skim through for the modern gardener:

The East India Company had been given a monopoly of trade to the Far East in 1600, through this monopoly they had built a lucrative trade in silk and tea from China, as well as effectively running India. The trades from China were matched with trades into China of opium from India, by the middle of the 19th century addiction to opium was a significant problem in China. The volume of trade it brought made the East India Company a very significant contributor to British government income (of order 10%). Although there are now many global corporations, the East India Company was one of the first and in many ways most powerful. The company was ultimately to lose its dominance following the Indian Mutiny in 1858, and was finally wound up in 1874. The mutiny was likely the cumulation of a long process since the monopoly that the East India Company enjoyed was not popular with free-marketeers who were starting to come to the fore.

At the time of Fortune’s first trip to China in 1845 the English had long been drinking tea imported from China, in exchange for opium grown in India. The English drank both green and black teas, although unlike the Chinese they added milk and sugar (obtained from another British colonial outpost). The Chinese were keen to keep the secret of both the tea plant, and its manufacture into tea leaves for making tea. Whilst the British, in particular the East India Company were keen to get these secrets believing (correctly) that tea would grow well in Himalayan India and would make a good profit. Some tea was already being grown in the Assam district of India but is was derived from inferior Chinese plants. The tea plant is Camellia sinensis a close relative of the decorative camellias of which Fortune also introduced some species.

Before Fortune’s first visit to China it had not even been established that black tea and green tea came from the same plant, but were processed differently. His trips required considerable subterfuge: Westerners had only recently been allowed into anywhere other than a limited number of ports in China, as a result of the first Opium War and Fortune’s activities went considerably beyond what was allowed even under these revised regulations. One of Fortune’s discoveries was that green tea had been coloured by the Chinese for the export market using Prussian Blue (which is toxic) and gypsum. Following a couple of false starts he was eventually able to transport a large number of highest quality tea plant seedlings to Darjeeling in India, as well as providing skilled tea makers and extensive notes on the tea making process.

The key to Fortune’s success in shipping out tea plants from China were Wardian cases, these are essentially sealed glass environments containing soil and some water. Plants, or more importantly, troublesome seeds could be sealed into these containers and as long as they remained sealed, and given some light there would be a good chance of their biological cargo surviving a lengthy sea journey through a range of climates. Prior to this discovery long distance transplantations were tricky. Nowadays we see Kew Gardens as largely a place of leisure, but in the 19th century it was very much at the heart of the Empire in terms of facilitating the movement of plants around the world for commercial reasons. This type of activity was also an early interest of the Royal Society.

It’s difficult not to draw parallels between the state sanctioned opium trade which the United Kingdom used to support, and its current attitude to drug smuggling. Nor between the industrial espionage of the East India Company in the 19th century, and the current issues with the Chinese approach to intellectual property.

I found the sections of the book reporting Fortune’s travels a bit unfulfilling: they seemed to be a sequence of travel anecdotes involving the mischief caused by his Chinese servants – this style does affect other parts of the books. However, more generally the book made me curious to know more about the East India Company, the Opium Wars and so forth and I felt I’d learnt something about the introduction of tea to India.

I’m tempted by Fortune’s book: Three years’ wanderings in the Northern Provinces of China 

Dec 30 2010

Book review: Mutants by Armand Marie Leroi

Mutants Armand Marie LeroiChristmas is a time for reading, so in addition to Rolt’s Brunel biography I have also read “Mutants: On the form, varieties & errors of the human body” by Armand Marie Leroi.

This is a story of developmental biology told through the medium of mutants, people for whom development doesn’t go quite to standard plan.

The book runs through a sequence of distinct mutations: Siamese twinning, deformities to arms and legs, skeletal defects, dwarfs and giants, various sexual variations, albinism and hairiness, and finally ageing. His approach does not revel in the freak show aspects of human mutants rather makes a brief reference to the historical recognition of such mutations and uses this as a jumping off point for discussion of modern biological understanding.

Mutations have long been an area for scientific study because it was realised that studying malfunction would provide clues to the mechanisms of normal development.

The marvel of developmental biology is that it is a method of construction completely at odds to the human way of making complex devices. Rather than a complex entity assembling pieces to a plan, biology starts with an instruction set which builds order out of chaos with no external help. It is self-organisation, creation from (nearly) nothing with no supporting infrastructure. There are non-biological self-organising systems and we make use of some of them industrially, but there is nothing that matches the complexity, the heterogeneity that biology can achieve.

The fundamentals of development biology are genes coding for proteins that tell you where you are in the developing embryo and trigger growth or differentiation on that basis i.e. “I find myself in the presence of proteins A, B, and C at these particular concentrations, therefore I must make a leg”. As an example, the proteins noggin and bone morphogenetic protein 4 (BMP4) define the top and bottom of the growing embryo – in simple terms noggin stimulates the growth of the brain. Whimsical naming of a protein may seem like a good idea in the lab but I imagine it makes discussions with parents about the problems of their perhaps-dead child difficult.

An intriguing point is the frequent robustness of developmental mechanisms, often as not molecular biologists have identified a “critical” protein, created a “knock-out” mouse lacking that protein and discovered that the mouse developed relatively well – other developmental systems having compensated for the loss.

The diverse effects of mutations can be surprising, for example there is a condition called Kartagener’s Syndrome whereby the internal organs of the body are flipped left-right – the heart, rather than lying slightly on the left of the body lies on the right and so forth. People with this syndrome have respiratory problems, a diminished sense of smell and sterility. The cause of these apparently disparate problems is a faulty cilia motor, cilia are small hairs on the surface of a cell that move. In the lungs and nose they whip about to move mucus around, in men the cilia motor drives the tail of sperm, and in the developing embryo the whipping of cilia break the left-right symmetry. Hence failure of the cilia motor proteins leads to a diverse set of impacts.

In addition to proteins which induce specific behaviours, there are proteins which have a more overarching impacts, such as those produced in the pituitary gland, malfunctions of which can lead to dwarfism or gigantism.

As usual my butterfly mind has fixed on some less relevant portions of the book. Plato giving voice to Aristophanes in The Symposium posited that sexual desire can be explained because man and woman were once combined: in fact three pairings existed man-man, man-woman and woman-woman. These creatures were physically joined, having four arms and legs, two heads and two “privy members”. However, they were troublesome (cartwheeling on their eight limbs is explicitly mentioned) – so Zeus separated them into the men and women. And now everyone seeks to find their original partner thus explaining homo- and hetero-sexuality. There’s some suggestion that Plato was making a little fun of Greek myth here!

Thanks to this book I have learned that the male scrotum is the homologous structure to the female labia, the two halves have fused to form a handy sack. The development of sexual organs finds the male really as something that has failed to become female.

Leroi finishes with signposts to a couple of open areas in developmental biology, one is race: people have a moderate ability to identify racial groups and tie them to countries but current genetics cannot match this ability often finding much bigger variations within populations. As Leroi highlights, this is a fraught area in social terms but it is interesting that differences obvious to people are not obvious to genetics. Secondly he mentions beauty: does beauty tell us something about genetic fitness?

This book highlights the huge gap between knowing the base pair sequence of DNA and understanding how the organisms arise from that sequence. At times the language gets technical a little too quickly and it could really have done with some explanatory diagrams.