Archive for July, 2009

The Thermodynamics of Beards

Posted in Beards, The Universe and Stuff with tags , , , , , , , on July 14, 2009 by telescoper

When I was an undergraduate studying physics, my physics supervisor (who happens to be a regular contributor to the comments on this blog) introduced me to thermodynamics by explaining that Ludwig Boltzmann committed suicide in 1906, as did Paul Ehrenfest in 1933. Now it was my turn to study what had driven them both to take their own lives.

I didn’t think this was the kind of introduction likely to inspire a joyful curiosity in the subject, but it probably wasn’t the reason why I found the subject as difficult as I did. I thought it was a hard subject because it seemed to me to possess arbitrary rules that didn’t emerge from a simpler underlying principle, but simply had to be memorized. Lurking somewhere under it was obviously something statistical, but what it was or how it worked was never made clear. I was frequently told that the best thing to do was just memorize all the different examples given and not try to understand where it all came from. I tried doing this but, partly because I have a very poor memory, I didn’t so very well in the final examination on this topic. I was prejudiced against it for years afterwards.

Actually, now I have grown to like thermodynamics as a subject and have read quite a bit about its historical development. The field of thermodynamics is usually presented to students as a neat and tidy system of axioms and definitions. The resulting laws are written in the language of idealised gases, perfect mechanical devices and reversible equilibrium paths but, despite this, have many applications in realistic practical situations. What is particularly interesting about these laws is that it took a very long time indeed to establish them even at this macroscopic level. The deeper understanding of their origin in the microphysics of atoms and molecules took even longer and was an even more difficult journey.   I thought it might be  fun to celebrate  the tangled history of this fascinating subject, at least for a little while.  Unlike quantum physics and relativity, thermodynamics is not regarded as a very “glamorous” part of science by the general public, but it did occupy the minds of the greatest physicists of the nineteenth century, and I think the story deserves to be better appreciated. I don’t have space to give a complete account, so I apologize in advance for the omissions.

I thought it would also be fun to show pictures of the principal characters. As you’ll see, after  a very clean-shaven start, the history of thermodynamics is dominated by a succession of rather splendid beards…

I’ll start the story with Nicolas Léonard Sadi Carnot (left), who  was born in 1796. His family background was, to say the least, unusual. His father Lasare was known as the “Organizer of Victory” for the Revolutionary Army in 1794 and subsequently became Napoleon’s minister of war. Against all expectations he quit politics in 1807 and became a mathematician. Sadi had a brother, by the splendid name of Hippolyte, who was also a politician and whose son became president of France. Sadi himself was educated partly by his father and partly at the Ecole Polytecnhique. He served in the army as an engineer and was eventually promoted to Captain. He left the army in 1828, only to die of cholera in 1832 during an epidemic in Paris.

Carnot’s work on the theory of “heat engines” was astonishingly original and eventually had enormous impact, essentially creating the new science of thermodynamics, but he only published one paper before his untimely death and it attracted little attention during his lifetime. Reflections on the Motive Power of Fire appeared in 1824, but its importance was not really recognized until 1849, when it was read by William Thomson (later Lord Kelvin) who, together Rudolf Clausius, made it more widely known.

In the late 18th century, Britain was in the grip of an industrial revolution largely generated by the use of steam power. These engines had been invented by the pragmatic British, but the theory by which they worked was pretty much non-existent. Carnot realised that steam-driven devices in use at the time were horrendously inefficient. As a nationalist, he hoped that by thinking about the underlying principles of heat and energy he might be able to give his native France a competitive edge over perfidious Albion. He thought about the problem of heat engines in the most general terms possible, even questioning whether there might be an alternative to steam as the best possible “working substance”. Despite the fact that he employed many outdated concepts, including the so-called caloric theory of heat, Carnot’s paper was full of brilliant insights. In particular he considered the behaviour of an idealized friction-free engine in which the working substance moves from a heat source to a heat sink in a series of small equilibrium steps so that the entire process is reversible. The changes of pressure and volume involved in such a process are now known as a Carnot cycle.

By remarkably clear reasoning, Carnot was able to prove a famous theorem that the efficiency of such a cycle depends only on the temperature Tin of the heat source and the temperature Tout. He showed that the maximum fraction of the heat available to be used to do mechanical work is independent of the working substance and is equal to (Tin-Tout)/Tout; this is called Carnot’s theorem. Carnot’s results were probably considered too abstract to be of any use to engineers, but they contain ideas that are linked with the First Law of Thermodynamics, and they eventually led Clausius and Thomson independently to the statement of the Second Law discussed below.

James Prescott Joule (right) was growing up in a wealthy brewing family. He was born in 1818 and was educated at home by none other than John Dalton. He became interested in science and soon started doing experiments in a laboratory near the family brewery. He was a skilful practical physicist and was able to measure the heat and temperature changes involved in various situations. Between 1837 and 1847 he established the basic principle that heat and other forms of energy (such as mechanical work) were equivalent and that, when all forms are included, energy is conserved. Joule measured the amount of mechanical work required to produce a given amount of heat in 1843, by studying the heat released in water by the rotation of paddles powered by falling weights. The SI unit of energy is named in his honour.

William Thomson, 1st Baron Kelvin of Largs, was born in 1824 and came to dominate British physics throughout the second half of the 19th  century. He was extremely prolific, writing over 600 research papers and several books. No-one since has managed to range so widely and so successfully across the realm of natural sciences. He was also unusually generous with his ideas (perhaps because he had so many), and in giving credit to other scientists, such as Carnot.  He wasn’t entirely enlightened, however: he was a vigorous opponent of the admission of women to the  University.

Kelvin worked on many theoretical aspects of physics, but was also extremely practical. He directed the first successful transatlantic cable telegraph project, and his house in Glasgow was one of the first to be lit by electricity. Unusually among physicists he became wealthy through his scientific work. One can dream.

One of the keys to Kelvin’s impact on science in Britain was that immediately after graduating from Cambridge in 1845 he went to work in Paris for a year. This opened his eyes to the much more sophisticated mathematical approaches being used by physicists on the continent. British physics, especially at Cambridge, had been held back by an excessive reverence for the work of Newton and the rather cumbersome form of calculus (called “fluxions”) it had inherited from him. Much of Kelvin’s work on theoretical topics used the modern calculus which had been developed in mainland Europe. More specifically, it was during this trip to Paris that he heard of the paper by Carnot, although it took him another three years to get his hands on a copy. When he returned from Paris in 1846, the young William Thomson became Professor of Natural Philosophy at Glasgow University, a post he held for an astonishing 53 years.

Initially inspired by Carnot’s work, Kelvin became one of the most important figures in the development of the theory of heat. In 1848 he proposed an absolute scale of temperature now known as the Kelvin or thermodynamic scale, which practically corresponds with the Celsius scale except with an offset such that the triple point of water, at zero degrees Celsius, is at 273.16 Kelvin.  He also worked with Joule on experiments concerning heat flow.

At around the same time as Kelvin, another prominent character in the story of thermodynamics was playing his part. Rudolf Clausius (right) was born in 1822. His father was a Prussian pastor and owner of a small school that the young Rudolf attended. He later went to university in Berlin to study history, but switched to science. He was constantly short of money, which meant that it took him quite a long time to graduate but he eventually ended up as a professor of physics, first in Zürich and then later in Wurzburg and Bonn. During the Franco-Prussian war, he and his students set up a volunteer ambulance service and during the course of its operations, Rudolf Clausius was badly wounded.

By the 1850s, thanks largely to the efforts of Kelvin, Carnot’s work was widely recognized throughout Europe. Carnot had correctly realised that in a steam engine, heat “moves” as the steam descends from a higher temperature to a lower one. He, however, envisaged that this heat moved through the engine intact.  On the other hand, the work of Joule had established The First law of Thermodynamics, which states that heat is actually lost in this process, or more precisely heat is converted into mechanical work. Clausius was troubled by the apparent conflict between the views of Carnot and Joule, but eventually realised that they could be reconciled if one could assume that heat does not pass spontaneously from a colder to a hotter body. This was the original statement of what has become known as the Second Law of Thermodynamics.  The following year, Kelvin came up with a different expression of essentially the same law.  Clausius further developed the idea that heat must tend to dissipate and in 1865 he introduced the term “entropy”  as a measure of the amount of heat gained or lost by a body divided by its absolute temperature. An equivalent statement of the Second Law is that the entropy of an isolated system can never decrease: it can only either increase or remain constant. This principle was intensely controversial at the time, but Kelvin and Maxwell fought vigorously in its defence, and it was eventually accepted into the canon of Natural Law.

So far in this brief historical diversion, I have focussed on thermodynamics at a macroscopic level, in the form that eventually emerged as the laws of thermodynamics presented in the previous section. During roughly the same period, however, a parallel story was unfolding that revolved around explaining the macroscopic behaviour of matter in terms of the behaviour of its microscopic components. The goal of this programme was to understand quantitative measures such as temperature and pressure in terms of related quantities describing individual atoms or molecules. I’ll end this bit of history with a brief description of three of the most important contributors to this strand.

 James Clerk Maxwell (left) was probably the greatest physicist of the nineteenth century, and although he is most celebrated for his phenomenal work on the unified theory of electricity and magnetism, he was also a great pioneer in the kinetic theory of gases, He was born in 1831 and went to school at the Edinburgh academy, which was a difficult experience for him because he had a country accent and invariably wore home-made clothes that made him stand out among the privileged town-dwellers who formed the bulk of the school population. Aged 15, he invented a method of drawing curves using string and drawing pins as a kind of generalization of the well-known technique of drawing an ellipse. This work was published in the Proceedings of the Royal Society of Edinburgh in 1846, a year before Maxwell went to University. After a spell at Edinburgh he went to Cambridge in 1850; while there he won the prestigious Smith’s prize in 1854. He subsequently obtained a post in Aberdeen at Marischal College where he married the principal’s daughter, but was then made redundant. In 1860 he moved to London but when his father died in 1865 he resigned his post at King’s college and became a gentleman farmer doing scientific research in his spare time. In 1874 he was persuaded to move to Cambridge as the first Cavendish Professor of Experimental Physics, charged with the responsibility of setting up the now-famous Cavendish laboratory. He contracted cancer five years later and died, aged 48, in 1879.

Maxwell’s contributions to the kinetic theory of gases began by building on the idea, originally due to Daniel Bernoulli, that a gas consists of molecules in constant motion colliding with each other and with the walls of whatever container is holding it. Rudolf Clausius had already realised that although the gas molecules travel very fast, gases diffuse into each other only very slowly. He deduced, correctly, that molecules must only travel a very short distance between collisions. From about 1860, Maxwell started to work on the application of statistical methods to this general picture. He worked out the probability distribution of molecular velocities in a gas in equilibrium at a given temperature; Boltzmann (see below) independently derived the same result. Maxwell showed how the distribution depends on temperature and also proved that heat must be stored in a gas in the form of kinetic energy of the molecules, thus establishing a microscopic version of the first law of thermodynamics. He went on to explain a host of experimental properties such as viscosity, diffusion and thermal conductivity using this theory.

Maxwell was lucky that he was able to make profound intellectual discoveries without apparently suffering from significant mental strain. Unfortunately, the same could not be said of Ludwig Eduard Boltzmann, who was born in 1844 and grew up in the Austrian towns of Linz and Wels, where his father was employed as a tax officer. He received his doctorate from the University of Vienna in 1866 and subsequently held a series of professorial appointments at Graz, Vienna, Munich and Leipzig. Throughout his life he suffered from bouts of depression which worsened when he was subjected to sustained attack from the Vienna school of positivist philosophers, who derided the idea that physical phenomena could be explained in terms of atoms. Despite this antagonism, he taught many students who went on to become very distinguished and he also had a very wide circle of friends. In the end, though, the lack of acceptance of his work got him so depressed that he committed suicide in 1906. Max Planck arranged for his gravestone to be marked with “S=klogW”, which is now known as Boltzmann’s law; the constant k is called Boltzmann’s constant.

The final member of the cast of characters in this story is Josiah Willard Gibbs (left). He born in 1839 and received his doctorate from Yale University in 1863, gaining only the second PhD ever to be awarded in the USA.  After touring Europe for a while he returned to Yale in 1871 to become a professor, but he received no salary for the first nine years of this appointment. The university rules at that time only allowed salaries to be paid to staff in need of money; having independent means, Gibbs was apparently not entitled to a salary. Gibbs was a famously terrible teacher and few students could make any sense of his lectures (not a rare occurence amongst those trying to learn thermodynamics). His research papers are written in a very obscure style which makes it easy to believe he found it difficult to express himself in the lecture theatre. Gibbs actually founded the field of chemical thermodynamics, but few chemists understood his work while he was still alive. His great contribution to statistical mechanics was likewise poorly understood. It was only in the 1890s when his works were translated into German that his achievements became more widely recognised. Both Planck and Einstein held him in very high regard, but even they found his work difficult to understand. He died in 1903.

So there you are. The only one who didn’t have a beard was French and called Sadi. ’nuff said.

Vintage Bird

Posted in Jazz with tags , , , on July 14, 2009 by telescoper

I’ve gone  far too long without posting something by the great alto saxophonist Charlie Parker (“Bird”), undoubtedly one of the most influential musicians of the twentieth century. Together with trumpeter Dizzy Gillespie, Bird effectively created a  revolution in Jazz after the end of World War II in the form of a new style called bebop.

Like many Jazz legends, Charlie Parker died young as a result of chronic alcoholism and, especially in his case, drug addiction. He became hooked on heroin when he was a teenager and when he couldn’t get heroin he used anything else he could. The result was a body ravaged by abuse and a career frequently interrupted by illness. When he died, at the age of 35, the doctor who signed his death certificate estimated his age as “about 60″.

I remember, as a teenager,  finding a Charlie Parker LP  in a second-hand record shop and buying it for 50p. When I got home I put it straight on the record player and couldn’t believe my ears when I heard the staggering virtuosity of his playing. I just didn’t realise the alto sax could be played the way he played it. I’ve been a devout Charlie Parker fan ever since, although most of recorded output is quite difficult to get your hands on. In fact, the first record I bought as an LP has never been released on CD, which I think is a scandal.

Many people I know can’t really stand any Jazz that’s stylistically dated after about 1940. I have never really understood this attitude.  To my mind the two tracks I’ve picked here, recorded in 1948, sound as fresh and exciting to me now as they did when I first heard them 30 years ago. They also seem to me firmly rooted in a wonderful tradition of music-making that reaches back to Louis Armstrong and King Oliver and forward to the likes of John Coltrane, Eric Dolphy and Ornette Coleman. Anyway, I’m not going to preach. I love this music and it’s up to you whether you agree or not.

Parker’s ideas didn’t just remain within jazz, and bebop had a huge cultural influence on post-war America. It never became as popular as pre-war Jazz,  but had a devoted following on both sides of the Atlantic and breathed new creative life into a form that was in danger of becoming stale and commercialized.

The first piece  is called Ah Leu Cha and – as far as I’m aware – it is the only tune Bird ever wrote that involves any kind of counterpoint (provided by a very young Miles Davis on trumpet). The second track is a majestic solo blues called Parker’s Mood which demonstrates his deep understanding of and appreciation of the traditional 12-bar blues format.

The Great Escape

Posted in Cricket, Uncategorized with tags , , on July 12, 2009 by telescoper

Just a little postscript to my blog post about the cricket at Cardiff. After Australia ran away to 674-6 and had England at 20-2 last night before the rain came down after the tea interval, it looked odds-on for an Australian victory. That impression was strengthened by the feeble batting of  England’s leading batsmen this morning. The rain that had been forecast also failed to materialize, so  England were staring at defeat with the score at 70-5 at one stage.

This afternoon one England batsman, Paul Collingwood, did show some mettle and the tailenders who had played brightly on Day 2 demonstrated much greater resilience than their teammates had this morning. Nevertheless, when Collingwood was out later on, it still looked like Australia would win. Eventually it came down to the last pair, the bowlers Monty Panesar and James Anderson, to cling on, bat out time and attempt to salvage an unlikely draw from almost certain defeat. Monty in particular defended like his soul depended on it and together the two tail-enders saw England to safety. Great stuff.

I absolutely love it when things like this happen. There’s something very “Dad’s Army” about bowlers having to save the day with the bat. Backs to the wall and all that. I have to admit I was completely gripped by the drama of the last hour or so of play and so nervous I was shaking as I watched. One mistake and the match would be lost. Runs didn’t matter, just survival. Fielders all around the bat. The crowd applauding every delivery that was kept out. Only cricket can produce that stomach-churning intensity. At the end of the time allocated for play, England were 252-9, just 13 runs ahead. Australia just hadn’t managed to get that last one out. The defiant rearguard action had held off everything that was thrown at them. England may have needed two innings to reach the score that Australia obtained in one, but that doesn’t matter. Match drawn.

If you want to know how a game can go on for five days and still end in a draw, this is how. And bloody marvellous it is too!

England have their work cut out to improve enough to compete over the rest of the five-match series for the Ashes, but at least this escape has denied the Australians the massive psychological boost the expected  big victory would have given them. I know it’s a draw, but there’s no doubting which team will be happier tonight.

And I’m really happy that the First Ashes Test at Cardiff turned out to be such a memorable one!

Advanced Fellowships

Posted in Science Politics with tags , , , on July 11, 2009 by telescoper

This is just a quick Newsflash that UK Astronomers will be  interested in (and depressed by). My attention was drawn to it yesterday by Frazer Pearce of Nottingham.

The Science and Technology Facilities Council (STFC) has decided in its finite wisdom to cut in half the number of Advanced Fellowships (AFs) it awards each year, that is from 12 to 6, that number to cover all of Astronomy and Particle Physics.

These fellowships are awarded to researchers who do not have a permanent position but wish to pursue research, and are designed to further the careers of individuals with outstanding potential. They last 5 years – longer than the usual 2-3 year postdoctoral positions and have been for many a scientist an important stepping-stone to an academic career. A very large fraction of my colleagues who have permanent positions were awarded one of these fellowships when they were run by PPARC (including Frazer), as was I myself but, being an Oldie, mine was even pre-PPARC so was in fact given by SERC. Of course the fact that they gave me one doesn’t itself serve as much of a recommendation for continuing them, but it is worth drawing attention to the huge amount of  high quality research done in the UK by holders of these Fellowships.

A number of people have expressed to me their shock at this decision but it doesn’t surprise me at all. For one thing, it’s an open secret that STFC considers the academic community in these areas to be too large so the last thing it wants is more people getting permanent jobs through the AF route.  In any case, STFC’s prime concern is with facilities, not with scientific research.

Who needs half a dozen top class scientists when you can have Moonlite instead?

Ashes Ground

Posted in Cricket, Uncategorized with tags , , on July 11, 2009 by telescoper

Any of you who follow cricket will know that this is a very special time for the game and for the city of Cardiff. The First Test in the summer’s Ashes series against Australia is being played here. It’s the first time a test match has ever been played in Cardiff’s splendid ground at Sophia Gardens and to have an Ashes test as the inaugural fixture is a tremendous boost for the city. It’s actually a very good venue for Test cricket, being so close to the city centre and I hope this will be the first of many matches to be played here in Cardiff.

Owing to my general state of disorganization I didn’t manage to get a ticket when they first went on sale. Thinking I’d missed out I agreed to go and give a talk in Cambridge on the first day of the Test (Wednesday 8th July 2009). However,  a second load of tickets went on sale  a few weeks ago and I manage to get a couple for Thursday’s play (9th July). I was joined for the day by my regular contributor and old friend Anton.

The SWALEC stadium at Sophia Gardens, Cardiff (left) is actually just a short walk from my house in Pontcanna. The daily crowd of around 15,000 has caused a bit of congestion in the area but we got to our seats without any bother at all.

 

It’s actually quite a small ground, and our seats were right at the front of the Really Welsh Pavilion (which is the far side of the ground as seen in the picture), so we were close to where the players emerged onto the field. The outfield was extremely green with fairly lush grass on it and weather quite nice, with a mixture of broken cloud and sunshine.

England had won the toss and batted first on Wednesday, picking two spinners (Swann and Panesar), presumably in the belief that this was a slow wicket that would be increasingly helpful to the spinners as time wore on and the pitch began to break up a little. After some alarms and rash shots, and the unfortunate loss of two wickets right at the end of the day, England had batted their way to 336 for the loss of 7 wickets.

There having been no track record of Test cricket at Cardiff it was difficult to know whether this was a reasonable score or not. I had been away all day on Wednesday so hadn’t seen any of the play. By all accounts the pitch had played rather slow but was otherwise fairly good for batting. All England’s specialist batsmen were out so it wasn’t clear what kind of total they would reach with their remaining three wickets, but the tail wagged quite enjoyably and they added another 99 runs in the morning session until Swann ran out of partners and was left unbeaten on 47 with a little time to go before lunch.

So far, so good from an England point of view. However, from the point of view of their chances of winning the game it all started to go wrong as soon as the Ozzies went in to bat. The openers scored quite freely off the first few overs from England’s bowlers and went into lunch at 39-0.

For the rest  rest of the day, the England bowlers struggled to make any impression at all on the skilful and determined Australian batsmen. Flintoff accounted for the opener Hughes during a hostile spell of bowling in which he regularly exceed 90 mph and also dropped a very difficult caught-and-bowled chance. However, that only brought the Australian captain, Ricky Ponting, into bat which he did quite beautifully. He made no mistakes at all in his innings and played no rash shots, but by the end of play both he and Katich had reached centuries and Australia were 249-1.

Apart from Hughes’ wicket and Flintoff’s dropped return chance the only other time England were close to nabbing a wicket was a shout for LBW from Swann which was close but, I thought,  a bit high. Swann bowled very economically but without any real danger. Panesar was unimpressive, as where the other England seamers Broad and Anderson. It wasn’t that they bowled badly or were wayward, it just seemed that there was nothing in the pitch to help them and, of course, they were up against extremely good batting.

I wouldn’t say that this was the best day’s cricket I’ve ever seen – not by a long way – and I know that it’s a game that’s too slow for the taste of a lot of people anyway. There were, however, times – especially when Flintoff was bowling – where the atmosphere turned into something that you only get in cricket. As he pounded in over afer over with very few runs being scored and the batsmen defending stoutly, the action on the field became just the surface manifestation of a deep inner struggle between batsmen and bowler.  Who would win this battle of wills? The  stress could be felt all round the ground and one sensed that whoever came through that passage of play would have scored an important psychological victory. Undoubtedly the Australians came out of it stronger for having weathered everything England could throw at them. I find this kind of attritional cricket absolutely absorbing to watch, but I know many people who don’t get it.

Later on, after the match,  the England pace bowlers expressed their mystification that the ball simply wouldn’t swing. I was surprised too. I have no idea of the physics behind what makes a cricket ball swing but, empirically, it seems to correlate with the presence of cloud and humidity in the air. Both of these were present on Thursday but at no point did the ball curve, even for Anderson who is an accomplished swing bowler. This probably accounted for the ease with which the England tail had batted earlier in the morning.

Anyway, although I would definitely have preferred to see England skittle out the Australians, I did at least have the chance to watch a master batsman at work. I have to say I found it fascinating. Although there wasn’t a great deal of strokeplay – they didn’t really dominate the bowling – they ground their way to centuries in a very resolute fashion. There were very few boundaries scored, partly because of the very slow outfield.

Another reason I enjoyed the day was that our block of seats had its own resident comedian, a character called Chris who was found of shouting comments not only about the cricket but to anyone having the nerve to come into the stand during play.

Early on in the day this chap sitting behind us decided to amuse the crowd by shouting out clues from the Times crossword to see if anyone could get them. I got the first one straight away (the answer was METHODIST: IST was German for “is” and “Method” was clued by a reference to Stanislawski but I don’t remember the clue exactly).  Like a fool, shouted the answer back to him. I  became a target for him for the rest of the day’s play.

After several hours of his banter, I have to admit being a bit fed up with him but at least the crossword clues were fun.I don’t remember many of  them, but did get “Car held at murder location” (CATHEDRAL, i.e. anagram of car held at and reference to Murder in the Cathedral by TS Eliot) and “Rehabilitation of ailing animal” (NILGAI, anagram of ailing, is an Indian antelope). Eventually he came down, gave me the newspaper, and challenged me to finish the whole thing. I did so, and sent it back through the crowd, even getting a round of applause from them as I did so. I had become a minor celebrity providing a bit of distraction from Australia’s success. We may not have been doing well in the cricket, but at least I wasn’t letting the side down when it came to crosswords. Chris argued for a bit with some of my answers – he didn’t think TSETSE was a word, for example – but I think I convinced him I was right.

When play finished shortly after 6pm we left the ground to walk into town for something to eat. The path to the little bridge over the Taff was very crowded. Australian and England supporters mingled and, at one point, someone behind me shouted “Hey look, it’s Peter the crossword guy!”. Fame at last.

I didn’t have tickets for Friday but set out for work rather late. As I walked down Cathedral Road, crowds were turning up for Day 3. I nearly died when someone across the road shouted “Peter! Done the crossword yet?” I was quite impressed to be remembered, but hope my new found celebrity status disappears as quickly as it arose.

POSTSCRIPT: Australia batted throughout Day 3 to pass England’s total of 435 all out and had reached 479-5 despite losing some time to rain. The forecast for today (Saturday) was for rain, but it has so far refused to materialize and the Ozzies have powered on to 577-5 at lunch. It’s now a game that England can’t win. It is very overcast and still looks like some time will be lost to rain, so a draw is the likeliest result as long as England don’t fold pathetically in their second innings. Not that they haven’t done that before…

Sensational SPIRE

Posted in The Universe and Stuff with tags , on July 10, 2009 by telescoper

As I promised a few days ago, the “first light” images from the Herschel instrumment SPIRE have now been released (along with news of the other instruments on Herschel)  and I have to say they’re pretty spectacular! I’m told that these pictures are much better than anyone expected at this stage because Herschel as a whole still hasn’t finished its calibration and other preparations it needs to do before commencing as an observatory proper.

Here, for example, is an image of the spiral galaxy M74 (also known as NGC 628) as shown by SPIRE and by the American Spitzer satellite, which was launched a few years ago. This image is taken at 250 microns, which is further into the infrared than the Spitzer image (160 microns), but has higher resolution owing to Herschel’s bigger mirror (3.5m). The SPIRE instrument is also much more sensitive than Spitzer so by a combination of these effects the detail this image reveals is really stunning.

What you’re actually seeing in this image is long-wavelength radiation emitted by dust which has been heated up by stars in the galaxy. The dust obscures the optical light from the stars but they leave clues to their existence in the infrared light the dust gives off. You can see dark lanes in the optical image here where the dust is absorbing the starlight.

Here is M74 again, but shown with two additional infrared “colours” (at 350 and 500 microns). By making observations like this at different wavelengths SPIRE can reveal information about the spectrum and hence temperature of the dust emission.

Congratulations to the Cardiff SPIRE team for a stunning success. If these images are any guide to the quality of data Herschel is going to be producing over the next few years then we’re all in for a treat!

Why the Big Bang is Wrong…

Posted in Biographical, The Universe and Stuff with tags , , on July 7, 2009 by telescoper

I suspect that I’m not the only physicist who has a filing cabinet filled with unsolicited correspondence from people with wacky views on everything from UFOs to Dark Matter. Being a cosmologist, I probably get more of this stuff than those working in less speculative branches of physics. Because I’ve written a few things that appeared in the public domain (and even appeared on TV and radio a few times), I probably even get more than most cosmologists (except the really  famous ones of course). 

I would estimate that I get two or three items of correspondence of this kind per week. Many “alternative” cosmologists have now discovered email, but there are still a lot who send their ideas through regular post. In fact, whenever I get a envelope with an address on it that has been typed by an old-fashioned typewriter it’s usually a dead giveaway that it’s going to be one of  those. Sometimes they are just letters (typed or handwritten), but sometimes they are complete manuscripts often with wonderfully batty illustrations. I have one in front of me now called Dark Matter, The Great Pyramid and the Theory of Crystal Healing. I might even go so far as to call that one bogus. I have an entire filing cabinet in my office at work filled with things like it. I could make a fortune if I set up a journal for these people. Alarmingly, electrical engineers figure prominently in my files. They seem particularly keen to explain why Einstein was wrong…

I never reply, of course. I don’t have time, for one thing.  I’m also doubtful whether there’s anything useful to be gained by trying to engage in a scientific argument with people whose grip on the basic concepts is so tenuous (as perhaps it is on reality). Even if they have some scientific training, their knowledge and understanding of physics is usually pretty poor.

I should explain that, whenever I can, if someone writes or emails with a genuine question about physics or astronomy – which often happens – I always reply. I think that’s a responsibility for anyone who gets taxpayers’ money. However, I don’t reply to letters that are confrontational or aggressive or which imply that modern science is some sort of conspiracy to conceal the real truth.

One particular correspondent started writing to me after the publication of my little book, Cosmology: A Very Short Introduction. I won’t gave his name, but he was an individual who had some scientific training (not an electrical engineer, I hasten to add). This chap sent a terse letter to me pointing out that the Big Bang theory was obviously completely wrong.  The reason was  obvious to anyone who understood thermodynamics. He had spent a lifetime designing high-quality refrigeration equipment  and therefore knew what he was talking about (or so he said).

His point was that, according to  the Big Bang theory, the Universe cools as it expands. Its current temperature is about 3 Kelvin (-270 Celsius or therabouts) but it is now expanding. Turning the clock back gives a Universe that was hotter when it was younger. He thought this was all wrong.

The argument is false, my correspondent asserted, because the Universe – by definition –  hasn’t got any surroundings and therefore isn’t expanding into anything. Since it isn’t pushing against anything it can’t do any work. The internal energy of the gas must therefore remain constant and since the internal energy of an ideal gas is only a function of its temperature, the expansion of the Universe must therefore be at a constant temperature (i.e. isothermal, rather than adiabatic, as inthe Big Bang theory). He backed up his argument with bona fide experimental results on the free expansion of gases.

I didn’t reply and filed the letter away. Another came, and I did likewise. Increasingly overcome by some form of apoplexy his letters got ruder and ruder, eventually blaming me for the decline of the British education system and demanding that I be fired from my job. Finally, he wrote to the President of the Royal Society demanding that I be “struck off” – not that I’ve ever been “struck on” – and forbidden (on grounds of incompetence) ever to teach thermodynamics in a University.

Actually, I’ve never taught thermodynamics in any University anyway, but I’ve kept the letter (which was cc-ed to me) in case I am ever asked. It’s much better than a sick note….

This is a good example of a little knowledge being a dangerous thing. My correspondent clearly knew something about thermodynamics. But, obviously, I don’t agree with him that the Big Bang is wrong.

Although I never actually replied to this question myself, I thought it might be fun to turn this into a little competition, so here’s a challenge for you: provide the clearest and most succint explanation of why the temperature of the expanding Universe does fall with time, despite what my correspondent thought.

Answers via the comment box please, in language suitable for a nutter non-physicist.

News from L2

Posted in The Universe and Stuff with tags , on July 6, 2009 by telescoper

Just a quick update with a couple of bits of news about Planck.

First, the satellite has completed its final  manoeuvre and is now in its orbit around the second lagrange point. The  orbit is, in fact, slightly smaller than was originally planned owing to the fact that the extreme accuracy of the post-launch trajectory left a bit of extra fuel. Anyway, it’s now about 1.5 million kilometres from home, circling L2 which is what it will be doing for about a year.

The second bit of news has been the cause of particular celebration here at Cardiff. The High Frequency Instrument (HFI) has been cooling down since launch and has now reached its operating temperature of 0.1K (100 milliKelvin). The environment it is sitting in is about 60-70K so it’s no easy job to get it down to such a low level. Anyway, it’s now definitely the coolest thing in space…

The Cardiff HFI team celebrated on Friday, with beer that was no doubt suitably chilled.

Planck spins at about 1 revolution per minute and has been sending back scans of the sky for test purposes.  The HFI scans show that it is working well, detecting dust emission from the Galactic Plane well before it got down to sufficiently low temperatures to see the cosmic microwave background.

What happens next is the Calibration and Performance Verification phase during which the instruments will be checked out in great detail before the real science gets started in August.

Space Camp

Posted in Uncategorized with tags , , , , , on July 4, 2009 by telescoper

The other day I was looking through my copy of the Men’s Disciplinary Rubberwear Gazette (which I buy for the Spot-the-Ball competition). Turning to the advertisements, I discovered that the Science & Technology Facilities Council is conducting a review of its space facilities and operations. Always eager to push back the frontiers of science, I hurried down to their address in Swindon to find out what was going on.

ME: Hello. Is there anyone there?

JULIAN: Oh hello. My name’s Julian, and this is my friend Sandy.

SANDY: Oooh hello! What can we do for you?

ME: Hello to you both. Is this Polaris House?

JULIAN: Not quite. Since we took over we changed the name…

ME: To?

SANDY: It’s now called Polari House…

JULIAN: On account of that’s the only language spoken around here.

ME: So you’re in charge of the British Space Programme then?

JULIAN:  Yes, owing to the budget, the national handbag isn’t as full as it used to be so now it’s just me and her.

SANDY: But never fear we’re both dab hands with thrusters.

JULIAN: Our motto is “You can vada about in any band, with a satellite run  by Jules and…

SANDY: …Sand.

ME: I heard that you’re looking for some input.

SANDY: Ooooh. He’s bold, in’e?

ME: I mean for your consultation exercise…

JULIAN: Oh yes. I forgot about that. Well I’m sure we’d welcome your contribution any time, ducky.

ME: Well I was wondering what you could tell me about Moonlite?

SANDY: You’ve come to the right place. She had an experience by Moonlight, didn’t you Jules?

JULIAN: Yes. Up the Acropolis…

ME: I mean the Space Mission “Moonlite”

SANDY: Oh, of course. Well, it’s only small but it’s very stimulating.

JULIAN: Hmmm.

SANDY: Yes. It gets blasted off into space and whooshes off to the Moon…

JULIAN: …the backside thereof…

SANDY: ..and when it gets there it shoves these probes in to see what happens.

ME: Why?

SANDY: Why not?

ME: Seems a bit pointless to me.

JULIAN: There’s no pleasing some people is there?

ME: Haven’t you got anything more impressive?

SANDY: Like what?

ME:  Maybe something that goes a bit further out? Mars, perhaps?

JULIAN: Well the French have this plan to send some great butch omi to troll around on Mars but we haven’t got the metzas so we have to satisfy ourselves with something a bit more bijou…

SANDY: Hmm…You can say that again.

JULIAN: You don’t have to be big to be bona.

SANDY: Anyway, we had our shot at Mars and it went willets up.

ME: Oh yes, I remember that thing named after a dog.

JULIAN: That’s right. Poodle.

ME: Do you think a man will ever get as far as Uranus?

JULIAN&SANDY: Oooh! Bold!

SANDY: Well I’ll tell you what. I’ll show you something that can vada out to the very edge of the Universe!

ME: That sounds exciting.

JULIAN: I’ll try to get it up right now.

ME: Well…er…

JULIAN: I mean on the computer

ME: I say, that’s an impressive piece of equipment

JULIAN: Thank you

SANDY: Oh don’t encourage her…

ME: I meant the computer.

JULIAN: Yes, it’s a 14″ console.

SANDY:  And, believe me, 14 inches will console anyone!

JULIAN; There you are. Look at that.

ME: It looks very impressive. What is it?

SANDY: This is an experiment designed to charper for the heat of the Big Bang.

JULIAN. Ooer.

SANDY: The Americans launched WMAP and the Europeans had PLANCK. We’ve merged the two ideas and have called it ….PLMAP.

ME: Wouldn’t it have been better if you’d made the name the other way around? On second thoughts maybe not..

JULIAN: It’s a little down-market but we have high hopes.

SANDY: Yes, Planck had two instruments called HFI and LFI. We couldn’t afford two so we made do with one.

JULIAN: It’s called MFI. That’s why it’s a bit naff.

ME: I see. What are these two round things either side?

SANDY: They’re the bolometers…

ME: What is this this long thing in between pointing up? And why is it leaning to one side?

SANDY: Well that’s not unusual in my experience …

JULIAN:  Shush. It’s an off-axis Gregorian telescope if you must know.

ME: And what about this round the back?

SANDY: That’s your actual dish. It’s very receptive, if you know what I mean.

ME: So what does it all do?

JULIAN: It’s designed to make a map of what George Smoot called “The Eek of God”. It’s fabulosa…

SANDY: Or it would be if someone hadn’t neglected to read the small print.

ME: Why? Is there are problem?

JULIAN: Well, frankly, yes. We ran out of money.

SANDY: It was only when we got it out the box we realised.

ME: What?

JULIAN & SANDY: Batteries Not Included!

(With thanks to cosmic variance for the inspiration, and apologies to Barry Took and Marty Feldman, who wrote the original Julian and Sandy sketches for the radio show Round the Horne.)

Slippage and Slideage

Posted in Science Politics with tags , on July 3, 2009 by telescoper

Back from the week’s exertions I’ve just realised that I missed the announcement from the Science and Technology Facilities Council (STFC) of the changes to their programme as a result of the 2009 budget settlement.

You can find the full statement here, but of immediate concern to astronomers is the plan to cut funding for the Cambridge Astronomical Survey Unit (CASU) and the Wide-Field Astronomy Unit (WFAU) at Edinburgh. I’m not sure how much their support is to be reduced and what the long-term implications of the cuts will be.

Expenditure on the outrageously useless space gizmo Moonlite will be delayed until next year, thus saving another bit of money. In my opinion, it would have been better simply to have cancelled this one altogether and diverted the funding into research grants which are instead to be held at the levels they were cut to last year.

Other savings will be made by “rephasing” (i.e. delaying) other projects in particle and nuclear physics and some others have started late anyway for other reasons.

Any optimism there might have been about a better settlement at the next Comprehensive Spending Review has now totally evaporated, however, and I wouldn’t bet against STFC having to cope with further large cuts  (in cash terms) a few years down the line. There are several ongoing consultation exercises (see Andy’s discussion and my earlier post for details) which will no doubt be used to draw up hit lists that will be used to make further cuts if and when needed.

The immediate impact of this review exercise on the astronomy programme seems considerably less brutal than I feared, but what may be going on is simply a holding operation and that the really drastic decisions will happen later, after money has already been spent on projects that are really already doomed. Still, a stay of execution is better than immediate termination.

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