Archive for the History Category

The Zel’dovich Universe – Day 1 Summary

Posted in Biographical, History, The Universe and Stuff with tags , on June 24, 2014 by telescoper

I’m up possibly bright but definitely early to get ready for day two of IAU Symposium No. 308 The Zel’dovich Universe. The weather was a bit iffy yesterday, with showers throughout the day, but that didn’t matter much in practice as I was indoors most of the day attending the talks. I have to deliver the conference summary on Saturday afternoon so I feel I should make an effort to attend as much as I can in order to help me pretend that I didn’t write my concluding talk in advance of the conference.

Day One began with some reflections on the work and personality of the great Zel’dovich by two of his former students, Sergei Shandarin and Varun Sahni, both of whom I’ve worked with in the past.
zeldovichZel’dovich (left) was born on March 8th 1914. To us cosmologists Zel’dovich is best known for his work on the large-scale structure of the Universe, but he only started to work on that subject relatively late in his career during the 1960s. He in fact began his life in research as a physical chemist and arguably his greatest contribution to science was that he developed the first completely physically based theory of flame propagation (together with Frank-Kamenetskii). No doubt he also used insights gained from this work, together with his studies of detonation and shock waves, in the Soviet nuclear bomb programme in which he was a central figure, and which no doubt led to the chestful of medals he’s wearing in the photograph. In fact he was awarded the title of  Hero of Socialist Labour no less than three times.

My own connection with Zel’dovich is primarily through his scientific descendants, principally his former student Sergei Shandarin, who has a faculty position at the University of Kansas, but his work has had a very strong influence on my scientific career. For example, I visited Kansas back in 1992 and worked on a project with Sergei and Adrian Melott which led to a paper published in 1993, the abstract of which makes it clear the debt it owed to the work of Ze’dovich.

The accuracy of various analytic approximations for following the evolution of cosmological density fluctuations into the nonlinear regime is investigated. The Zel’dovich approximation is found to be consistently the best approximation scheme. It is extremely accurate for power spectra characterized by n = -1 or less; when the approximation is ‘enhanced’ by truncating highly nonlinear Fourier modes the approximation is excellent even for n = +1. The performance of linear theory is less spectrum-dependent, but this approximation is less accurate than the Zel’dovich one for all cases because of the failure to treat dynamics. The lognormal approximation generally provides a very poor fit to the spatial pattern.

The Zel’dovich Approximation referred to in this abstract is based on an extremely simple idea but which, as we showed in the above paper, turns out to be extremely accurate at reproducing the morphology of the “cosmic web” of large-scale structure.

Zel’dovich passed away in 1987. I was a graduate student at that time and had never had the opportunity to meet him. If I had done so I’m sure I would have found him fascinating and intimidating in equal measure, as I admired his work enormously as did everyone I knew in the field of cosmology. Anyway, a couple of years after his death a review paper written by himself and Sergei Shandarin was published, along with the note:

The Russian version of this review was finished in the summer of 1987. By the tragic death of Ya. B.Zeldovich on December 2, 1987, about four-fifths of the paper had been translated into English. Professor Zeldovich would have been 75 years old on March 8, 1989 and was vivid and creative until his last day. The theory of the structure of the universe was one of his favorite subjects, to which he made many note-worthy contributions over the last 20 years.

As one does if one is vain I looked down the reference list to see if any of my papers were cited. I’d only published one paper before Zel’dovich died so my hopes weren’t high. As it happens, though, my very first paper (Coles 1986) was there in the list. That’s still the proudest moment of my life!

reference

We then went into a Dick Bond Special, with a talk entitled: From Superweb Simplicity to Complex Intermittency in the Cosmic Web. The following pic will give you a flavour:

IMG-20140623-00347

It’s all very straightforward, really. Um…

The rest of the day consisted of a number of talks about the Cosmic Web of large-scale structure using techniques inspired by the work of Zel’dovich, particularly the Zel’dovich approximation which I’ve mentioned already. There were many fascinating talks but I had to single out Johan Hidding of Groningen for the best use of graphics. Here’s a video of his from Youtube as an example:

Well, I must get going for the start of Day Two. The first session starts at 9am (7am UK time) and the day ends at 19.30. Conferences like this are hard work!

PS. If anyone reading this either at the conference or elsewhere has any questions or issues they would like me to raise during the summary talk on Saturday please don’t hesitate to leave a comment below or via Twitter using the hashtag #IAU308.

 

The Fallen Project

Posted in Art, History with tags , , , on June 6, 2014 by telescoper

It’s not known exactly how many people died on D-Day 6th June 1944 when the Normandy landings took place, but a  fairly conservative estimate is about 9000 (including about 3000 French civilians).

In September last year, the beach at Arromanches (code-named Gold ) was the site of a remarkable art installation called The Fallen 9000 during which hundreds of volunteers stencilled images of 9000 fallen soldiers into the sand.

 

o-FALLEN-900

It’s a moving image, not least because the figures were soon to be washed away by the incoming tide. Let’s hope the courage and self-sacrifice of the soldiers who gave their lives that day are not forgotten too. Seventy years on, fascism is apparently once again on the rise in Europe. We should not forget where that road has led in the past.

Lest we forget.

Jim Europe’s Society Orchestra

Posted in History, Jazz with tags , , , , on April 30, 2014 by telescoper

More than a few people have commented on the fact that my musical tastes are a little old-fashioned, but here’s a piece that’s a bit old even by my standards. It’s by a band from the immediately pre-Jazz era called Jim Europe’s Society Orchestra. Led by James Reese Europe this band pre-dated the much more famous Paul Whiteman band in popularity, playing at the Carnegie Hall for example long before Whiteman’s ever did which, for a group of black musicians, was quite remarkable at a time of racial segregation in the United States.

When World War 1 started, Jim Europe enlisted in the 369th Infantry Regiment, which fought with immense distinction on the Western Front. The regiment, comprised of African-American and Puerto Rican soldiers, was dubbed the “Men of Bronze” by the French army and as the “Hellfighters” by the German army, on account of their legendary toughness. In the latter stages of the war, Jim Europe formed a military band to which he gave the name “The Harlem Hellfighters”. He died in 1919, after being stabbed in the neck by one of his own musicians.

This particular record was made over a century ago, on December 29 1913. As you might expect, the recording quality is not particularly good (to put it mildly) but it always strikes me as absolutely amazing that we can hear anything at all that was recorded so long ago. The line-up is very unusual by modern standards: two pianos, five banjo mandolins, three violins, clarinet, cornet, and a drummer. That’s on this particular tune. No personnel information is available except that it is certainly Jim Europe himself who delivers the encouraging shouts.

It’s pretty basic stuff from a musical point of view, in that everyone plays in unison and there’s no improvisation or any other development of the tune, but it’s certainly a performance full of energy and fun as well as a valuable piece of Jazz prehistory. The tune is Downhome Rag, which was written sometime in 1913 by Wilbur C Sweatman, is still performed by traditional jazz bands today. But not like this!

Who was the Bringer of the Lines from Pauli?

Posted in History, The Universe and Stuff with tags , , , , on April 13, 2014 by telescoper

Part of the entertainment at last night’s Physics & Astronomy Ball was a marvellously entertaining and informative after-dinner speech by particle physicist David Wark. David had to leave before the evening ended in order to get a taxi to Heathrow and thence a flight to Japan, so he missed out on the dancing and general merriment. I may get time tomorrow to write a bit more about the Ball itself, including the fact that I received an award from the students! For the time being, though, I’ll just pass on a fascinating snippet that David Wark, an expert on neutrinos, mentioned in his speech.

It is well known that the neutrino was first postulated by Wolfgang Pauli in 1930 to account measurements that suggested that energy and momentum were not conserved in beta decay. What is perhaps less well known – it was certainly new to me until I heard about it last night – is that Pauli’s proposal is described in famous letter, addressed rather charmingly to “Radioactive Ladies and Gentlemen” of Tübingen from his base the ETH in Zürich. Part of the letter is reproduced here:

pauli_1930_neutrino_letter_head_smaller

The opening phrases of the letter “Wie der überbringer dieser Zeilen den ich huldvollst anzuhören bitte…” is a polite request that the recipient(s) listen to the “bearer of these lines”. Presumably, Pauli being unable to visit Tübingen himself, he sent someone else along with the letter and that person gave some sort of seminar or informal presentation of the idea.

The mystery is that despite the obvious importance of this episode for the history of physics, nobody seems to know who the “bearer of the lines” from Pauli actually was. In his speech David Wark said he had been trying for 15 years to identify the individual, without success.

Anyone out there in Internetshire got any ideas?

A Bit of Green Trivia..

Posted in Film, History, The Universe and Stuff, Uncategorized with tags , , , on March 8, 2014 by telescoper

Following on from yesterday’s post about George Green, I thought I’d add this little bit of Green trivia.

George Green’s sponsor and patron  was the mathematician Edward Bromhead, a Baronet and member of the landed gentry of the county of Lincolnshire. Two generations later in the Bromhead family you will find a certain Gonville Bromhead (presumably named after Gonville & Caius College, the Cambridge college that both Edward Bromhead and George Green attended). As a young man, in January 1879, Lt. Gonville Bromhead fought in the Battle of Rorke’s Drift. Almost a century later he was played by Michael Caine in the film Zulu.

Not a lot of people know that.

From Darkness to Green

Posted in History, The Universe and Stuff with tags , , , , , , , , , , on March 7, 2014 by telescoper

On Wednesday this week I spent a very enjoyable few hours in London attending the Inaugural Lecture of Professor Alan Heavens at South Kensington Technical College Imperial College, London. It was a very good lecture indeed, not only for its scientific content but also for  the plentiful touches of droll humour in which Alan specialises. It was also followed by a nice drinks reception and buffet. The talk was entitled Cosmology in the Dark, so naturally I had to mention it on this blog!

At the end of the lecture, the vote of thanks was delivered in typically effervescent style by the ebullient Prof. Malcolm Longair who actually supervised Alan’s undergraduate project at the Cavendish laboratory way back in 1980, if I recall the date correctly. In his speech, Malcolm referred to the following quote from History of the Theories of the Aether and Electricity (Whittaker, 1951) which he was kind enough to send me when I asked by email:

The century which elapsed between the death of Newton and the scientific activity of Green was the darkest in the history of (Cambridge) University. It is true that (Henry) Cavendish and (Thomas) Young were educated at Cambridge; but they, after taking their undergraduate courses, removed to London. In the entire period the only natural philosopher of distinction was (John) Michell; and for some reason which at this distance of time it is difficult to understand fully, Michell’s researches seem to have attracted little or no attention among his collegiate contemporaries and successors, who silently acquiesced when his discoveries were attributed to others, and allowed his name to perish entirely from the Cambridge tradition.

I wasn’t aware of this analysis previously, but it re-iterates something I have posted about before. It stresses the enormous historical importance of British mathematician and physicist George Green, who lived from 1793 until 1841, and who left a substantial legacy for modern theoretical physicists, in Green’s theorems and Green’s functions; he is also credited as being the first person to use the word “potential” in electrostatics.

Green was the son of a Nottingham miller who, amazingly, taught himself mathematics and did most of his best work, especially his remarkable Essay on the Application of mathematical Analysis to the theories of Electricity and Magnetism (1828) before starting his studies as an undergraduate at the University of Cambridge which he did at the age of 30. Lacking independent finance, Green could not go to University until his father died, whereupon he leased out the mill he inherited to pay for his studies.

Extremely unusually for English mathematicians of his time, Green taught himself from books that were published in France. This gave him a huge advantage over his national contemporaries in that he learned the form of differential calculus that originated with Leibniz, which was far more elegant than that devised by Isaac Newton (which was called the method of fluxions). Whittaker remarks upon this:

Green undoubtedly received his own early inspiration from . . . (the great French analysts), chiefly from Poisson; but in clearness of physical insight and conciseness of exposition he far excelled his masters; and the slight volume of his collected papers has to this day a charm which is wanting in their voluminous writings.

Great scientist though he was, Newton’s influence on the development of physics in Britain was not entirely positive, as the above quote makes clear. Newton was held in such awe, especially in Cambridge, that his inferior mathematical approach was deemed to be the “right” way to do calculus and generations of scholars were forced to use it. This held back British science until the use of fluxions was phased out. Green himself was forced to learn fluxions when he went as an undergraduate to Cambridge despite having already learned the better method.

Unfortunately, Green’s great pre-Cambridge work on mathematical physics didn’t reach wide circulation in the United Kingdom until after his death. William Thomson, later Lord Kelvin, found a copy of Green’s Essay in 1845 and promoted it widely as a work of fundamental importance. This contributed to the eventual emergence of British theoretical physics from the shadow cast by Isaac Newton which reached one of its heights just a few years later with the publication a fully unified theory of electricity and magnetism by James Clerk Maxwell.

But as to the possible reason for the lack of recognition for John Michell who was clearly an important figure in his own right (he was the person who first developed the concept of a black hole, for example) you’ll have to read Malcolm Longair’s forthcoming book on the History of the Cavendish Laboratory!

The Royal Observatory Bomb and the Rise of Unreason

Posted in History, Literature, Politics, Science Politics with tags , , , , , , , , , , on February 16, 2014 by telescoper

I missed the anniversary by a day but I thought I’d pass on a fascinating but very sad little bit of history. One hundred and twenty years ago yesterday, on February 15th 1894, a 26-year old Frenchman by the name of Martial Bourdin blew himself up near the Royal Observatory in Greenwich. His death seems to have been an accident caused by the bomb he was carrying going off prematurely. It is not really known either whether the bomb was meant for the Royal Observatory or somewhere else. Anarchist attacks involving bombs were not uncommon in the 1890s and the range of targets was very wide.

Greenwich_Observatory_Bomb

Bourdin was found alive, though very seriously injured, by people who heard the blast. Though able to speak he did not offer any explanation for what had happened. He died about half an hour later.

This sad and perplexing story inspired Joseph Conrad‘s famous novel The Secret Agent. Conrad added an “Author’s Note” to the manuscript of his book:

The attempt to blow up the Greenwich Observatory: a blood-stained inanity of so fatuous a kind that is is impossible to fathom its origin by any reasonable or even unreasonable process of thought. For perverse unreason has its own logical processes. But that outrage could not be laid hold of mentally in any sort of way, so that one remained faced by the fact of a man blown to pieces for nothing even most remotely resembling an idea, anarchistic or other. As to the outer wall of the Observatory, it did not show as much as the faintest crack.

We’ll never know what Bourdin’s motivations were; perhaps he didn’t really know himself. He is usually described as an “anarchist” although that term describes such a wide spectrum of political beliefs that it doesn’t really explain Bourdin’s actions; not all anarchists embrace violence and aggression, for example, although some – such as the members of Class War – clearly do. At one end of the anarchist spectrum there are the violent thugs who are nothing more than the mirror image of fascism and at the other there are reasonable intelligent people who simply don’t believe in hierarchical structures.

Brighton has its share of anarchists and the thing that’s most noticeable about them to an outsider like me is their conformity; the dress code is apparently very strictly enforced. The obvious irony aside, this suggests to me that much of the attraction of being an anarchist is not really the existence of a compelling political philosophy, but simply to fulfill the need to belong to something.

The main thing that occurred to me yesterday while I was reading about the Greenwich Observatory bomb plot concerns the implications of the location. If the Royal Observatory was the intended target then why was it so? The simple answer is that a core belief for most varieties of anarchist is their opposition to “the State”. A powerful symbol of the British state in 1894 was the Royal Navy; it was Britain’s maritime traditions that led to the founding of the Royal Observatory in the first place and most of the work carried out there involved accurate positional measurements designed to help with navigation. Or maybe it was to do with the role of the Observatory in defining the time? Insofar as acts like this make any sense at all, these seem reasonable interpretations. 

I’m tempted to suggest that the adoption of Greenwich as the Prime Meridian in 1884 may have given a young Frenchman additional grounds for resentment..

A different answer from the suggestion that it was an anti-establishment gesture stems from  the conflict between anarchism and the nature of scientific knowledge. Anarchists usually express their beliefs in terms of the desire to make society more “equal” and “democratic”, so that decisions should be made collectively for the common good. I’m happy with that line of argument, and agree that we should all enjoy equal rights versus the government and other institutions, and in relation to one another. However, having equal rights does not mean having equal knowledge and it doesn’t mean that any person’s opinion about anything is as good as anyone else’s. What I mean is that there are scientific experts, and the knowledge they possess has demonstrable value.

The approach of some to this challenge is simply to deny the value of scientific knowledge, and assert instead that it’s just a social construct like anything else. I am aware of a number of so-called social scientists at the University of Sussex and elsewhere who hold this view; my usual response is to ask them whether they regard witchcraft or crystal healing as equal to orthodox medicine.

CLARIFICATION: Please note I do not mean to imply that all social scientists hold the opinions described above. I’m fully aware that they are fringe views. The phrase “so-called social scientists” does not refer to all social scientists, just the fringe in much the same way I’d use “so-called geographers” to describe the Flat Earth Society.

I’m not trying to suggest that members of the Department of Sociology are plotting to blow up the Astronomy Centre! What I do think that while we should always strive to be as democratic as possible there are always limits, not just because of what is practically possible but also what is socially desirable. Any organization in which everyone votes about every decision that has to be made would struggle to function at all. We have to find ways of working that make best use of the different skills and knowledge we all possess.

A constructive approach is to argue that if we are to build  a more democratic society it is first necessary to greatly increase the level of scientific literacy in the population, so that more people can make informed decisions about the big issues facing the future, such as how we fulfill our energy requirements for the next 30 years and how we cope with global warming. That will not be an easy thing to do given the dearth of scientists in Parliament and in the media, but that’s not an argument for not trying.

Symptomatic of the widespread rejection of science among the politically disaffected is the lamentable state of Green politics in the United Kingdom. In my opinion there is huge potential for a scientifically-informed political movement focussed on environmental issues. Unfortunately the current Green Party is anti-science to the core, which would doom it to perpetual marginalization even without the loss of credibility stemming from the childish antics of the only Green MP, Caroline Lucas. I know that many will argue with me about whether the Green Party should be included in “The Left”, but since both Labour and Conservative parties now belong to the Centre-Right it seems a sensible classification to me.

It hasn’t always been like this. As Alice Rose Bell pointed out in a Guardian piece some time ago, there have been examples of constructive engagement between science and left-wing politics. This seems to me to have largely evaporated. I don’t think that’s so much because scientists have rejected the left. It’s more that the left has rejected science.

The Queen’s Agent

Posted in History, Literature with tags , , , , , on February 9, 2014 by telescoper

francis-walsinghamI’ve just finished reading The Queen’s Agent: Francis Walsingham at the Court of Elizabeth I by John Cooper and thought I’d post a quick review before settling down to an afternoon of work in the office. Sir Francis Walsingham (left) has acquired an almost mythical status as chief “spymaster” for the Crown during a time when Queen Elizabeth I was beset on all sides by plots and intrigues; The Queen’s Agent tries to find the man behind the legend. Not surprisingly, as Walsingham was as secretive as his trade might suggest, it doesn’t always succeed, but it does at least explode a few myths and give some insights into the character of a very complex man who was capable of great compassion as well as terrible ruthlessness.

Apart from anything else this book allowed me to indulge a longstanding interest in codes and ciphers; specifically, there are many interesting parallels between the story of the Spanish Armada and the breaking of the Enigma code at Bletchley Park during World War II, of which more shortly.

My first encounter with Sir Francis Walsingham came during history lessons at School, especially concerning his role in the infamous Babington Plot of 1586, which resulted in the execution for treason of Mary Stuart (Mary Queen of Scots). Mary had been officially under arrest for 18 years, and had been moved around the country for much of that time with her retinue lest she become a focus for a Catholic plot to put her on the throne of England. In fact for much of her time in captivity, Mary had been communicating in secret with various individuals for precisely that purpose but, unknown to her, most of her letters were being read by Walsingham and his expert team of code-breakers, including  Thomas Phelippes. By 1586 Walsingham already had more than enough evidence to have Mary Stuart tried for treason, but he hit on a plan that if it worked would lead to the entrapment of a large number of her supporters as well as ensuring that he knew the full extent of the conspiracy surrounding Mary Stuart. And so the Babington plot was hatched.

In late 1585, Mary Stuart was moved to Chartley Hall in Staffordshire. A young man called Gilbert Gifford with impeccable Catholic credentials, and apparently sympathetic to the Stuart cause, starting working for the household.  Gifford was in fact a double agent, placed there by Walsingham. Mary was shown a new way to communicate with the outside world, by concealing letters in the beer barrels that were brought regularly in and out of the Hall. She was eventually persuaded to try this channel, but was reluctant to take too many risks; her caution led her to commit a terrible error.

The encryption system used by Mary Stuart was widespread in Europe at that time. It was a form of substitution cipher known as a nomenclator. This consisted of a large alphabet with symbols (some made up, some from other languages) standing sometimes for individual letters, and sometimes for the names of individuals or places. Interesting devices were also deployed to try to confound the frequency analysis that was already being used in code-breaking at this time: symbols were included in the alphabet to instruct the recipient to “repeat the next letter”, for example.

In fact the Babington cipher (or at least a copy of it) still exists:

443px-Mary-cipher-code

Incidentally, in the nomenclators in use by Spain during the time of the Spanish Armada the symbol for Sir Francis Drake was “22”. I’m tempted to suggest that this is the origin of the Bingo call “two little ducks, quack quack”!

As is the case with most ciphers of this type, both sender and receiver would have to have a copy of the agreed alphabet and it is in the possibility of intercepting the key that such methods are most vulnerable . Nomenclators are not impossible to break without the key but not easy either; some 16th century codes of this type remain unbroken to this day. Mary did not know that the communication channel that had opened up was compromised at the very outset, so it probably seemed a sensible move for her to use it first to send a new cipher alphabet to Babington. Of course that decision was an enormous stroke of luck for Elizabeth’s agents because it meant that Phelippes and Walsingham could immediately read every single word of her subsequent messages all of which were intercepted and transcribed, before being replaced in the beer barrels and delivered to their recipient. Her fate, and that of a dozen or so co-conspirators, was quickly sealed. A transcript of the crucial item of correspondence, in which Mary discussed openly the strategy for the planned coup, was forwarded to Walsingham after decryption with a macabre addition: a picture of a gallows drawn in Phelippes’ own hand.

Another dimension that emerges from this story relates to just how difficult it must have been to know who was really on what side. Double agents abounded, and Walsingham must have known that some of his own men were actually working for the enemy at least some of the time; he apparently kept them going despite knowing that they had been turned in order to feed them with false information for the purposes of deception. That’s a very dangerous game to play, but they were dangerous times.

A couple of years after the Babington Plot came the Spanish Armada. The English army was so tiny in comparison with the huge force that planned to invade in 1588 that there was no way it could defend the entire coastline of England. Walsingham relied on intelligence in order to come to the conclusion that the invasion (if it came) would be in Essex. The Spanish would have wanted to get to London as quickly as possible, so this was far more likely to be the landing place than Sussex or the Isle of Wight, both of which were touted as possibilities. An English army of 16,500 was therefore assembled at Tilbury. It’s by no means clear how they would have fared against the Spanish, who outnumbered them by more than two-to-one and who were vastly more experienced and better equipped, but at least they would have had a chance. Walsingham must have been vastly relieved when he received news that the Armada had passed Portsmouth without attempting a landing, because had they done so they would not have met with any meaningful opposition.

Of course we all know what actually happened: harried but not seriously disrupted by a much smaller English naval force, the Armada proceeded up the English channel to Gravelines where it was planned to link up with Spanish ground forces encamped in the Netherlands. There they were attacked by Drake’s Fire Ships and fled into the North Sea in panic. The bulk of the Armada foundered on the coasts of Scotland and Ireland trying to find its way back to Spain in terrible weather.

We’re all taught at school that this was a defining period in English history, when our island nation was saved from Spanish tyranny and emerged into an age of unparalleled peace and prosperity. That’s the narrative we like to hear over and over again, perhaps because it provides us with a sense of moral certainty. A truer picture perhaps emerges when you look at it through the eyes of a man like Walsingham. This is history in all its cloak-and-dagger brutality, fascinating but at the same time profoundly unsettling because it reveals that all that ever really happens is that one side is slightly cleverer and more ruthless than the other.

So what was Walsingham really like as  a man? Obviously we’ll never know. But I’m glad I’ll never have him as an enemy…

Happy Birthday, Harry Nyquist!

Posted in History, The Universe and Stuff with tags , on February 7, 2014 by telescoper

Harry_NyquistThis morning I learned via Twitter that today is the 125th anniversary of the birth of Harry Nyquist, a physicist and electrical engineer, who was a prolific inventor who made fundamental theoretical and practical contributions to the field of telecommunications. He also gave his name to the Nyquist frequency and the Nyquist sampling theorem, now usually known as the Nyquist-Shannon sampling theorem.

Harry Nyquist (left) was born on February  7, 1889, in Nilsby, Sweden but moved to the United States in 1907. In 1917, after earning a Ph.D. in physics from Yale University, he joined the American Telephone and Telegraph Company (AT&T). There he remained until his retirement in 1954, working in the research department and then (from 1934) at Bell Laboratories.  Apparently he didn’t have a beard, but he seems to have overcome this obstacle and had an illustrious career in research.

In my opinion, Harry Nyquist’s achievements are not sufficiently appreciated either by physicists or by the wider world, so here’s a quick summary of some of his greatest hits:

Some of Nyquist’s best-known work was done in the 1920s and was inspired by telegraph communication problems of the time. Because of the elegance and generality of his writings, much of it continues to be cited and used. For example, his 1928 paper Certain Topics in Telegraph Transmission Theory refined his earlier results and established the principles of sampling continuous signals to convert them to digital signals. The Nyquist sampling theorem showed that the sampling rate must be at least twice the highest frequency present in the sample in order to reconstruct the original signal. These two papers by Nyquist, along with one by R.V.L. Hartley, are cited in the first paragraph of Claude Shannon’s classic essay The Mathematical Theory of Communication (1948), where their seminal role in the development of information theory is acknowledged.

In 1927 Nyquist provided a mathematical explanation of the unexpectedly strong thermal noise studied by J.B. Johnson. The understanding of noise is of critical importance for communications systems. Thermal noise is sometimes called Johnson noise or Nyquist noise because of their pioneering work in this field.

In 1932 Nyquist discovered how to determine when negative feedback amplifiers are stable. His criterion, generally called the Nyquist stability theorem, is of great practical importance. During World War II it helped control artillery employing electromechanical feedback systems.

I think that demonstrates the tremendous debt the modern world of telecommunications owes to Harry Nyquist, and why we should remember him on his 125th birthday..

The Medical Case for Beards in the 19th Century

Posted in Beards, History on January 13, 2014 by telescoper

Fascinating article by historian of medicine, Dr Alun Withey, about the medical benefits of facial hair. ..

Dr Alun Withey's avatarDr Alun Withey

As Christopher Oldstone-Moore has argued in his excellent article about the Victorian ‘beard movement’, the middle years of the nineteenth century witnessed an abrupt volte-face in attitudes towards facial hair. The eighteenth century had been one where men were almost entirely clean-shaven. The face of the enlightened gentleman was smooth, his face youthful and his countenance clear, suggesting a mind that was also open. Growing a beard at this point would have been a deliberate act done purposefully to convey a message. John Wroe, for example, leader of the Christian Israelite group, let his beard grow wild to signify his withdrawal from society.

By the mid-Victorian period, however, the beard came back into fashion with remarkable swiftness. Part of the reason for this was changing ideals of masculinity. This was the age of exploration, of hunters, climbers and explorers. As rugged adventurers began to tackle the terra incognita of far-flung…

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