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[There is more to this commentary on the publisher's website. Follow the DOI. The article is open access.] ...Jim Papadopoulos, who is 62, has spent much of his life fascinated by bikes, often to the exclusion of everything else. He competed in amateur races while a teenager and at university, but his obsession ran deeper. He could never ride a bike without pondering the mathematical mysteries that it contained. Chief among them: What unseen forces allow a rider to balance while pedalling? Why must one initially steer right in order to lean and turn left? And how does a bike stabilize itself when propelled without a rider? He studied these questions intensely as a young engineer at Cornell University in Ithaca, New York. But he failed to publish most of his ideas — and eventually drifted out of academia. By the late 1990s, he was working for a company that makes the machines that manufacture toilet paper. “In the end, if no one ever finds your work, then it was pointless,” he says. But then someone did find his work. In 2003, his old friend and collaborator from Cornell, engineer Andy Ruina, called him up. A scientist from the Netherlands, Arend Schwab, had come to his lab to resurrect the team's research on bicycle stability.... Together, the researchers went on to crack a century-old debate about what allows a bicycle without a rider to balance itself, publishing in Proceedings of the Royal Society1 and Science2. They have sought to inject a new level of science into the US$50-billion global cycling industry, one that has relied more on intuition and experience than on hard mathematics. Their findings could spur some much needed innovation — perhaps helping designers to create a new generation of pedal and electric bikes that are more stable and safer to ride. Insights from bicycles also have the potential to transfer to other fields, such as prosthetics and robotics. “Everybody knows how to ride a bike, but nobody knows how we ride bikes,” says Mont Hubbard, an engineer who studies sports mechanics at the University of California, Davis. “The study of bicycles is interesting from a purely intellectual point of view, but it also has practical implications because of their ability to get people around.” For a mechanician — that fusty breed of engineer whose subject is defined by Newton's three laws of motion — the conundrums of the bicycle hold a special allure. “We are all stuck in the nineteenth century, when there wasn't such a difference between math and physics and engineering,” says Ruina. Bicycles, he says, are “a math problem that happens to relate to something you can see”. The first patents for the velocipede, a two-wheeled precursor to the bike, date to 1818. Bikes evolved by trial and error, and by the early twentieth century they looked much as they do today. But very few people had thought about how — and why — they work. William Rankine, a Scottish engineer who had analysed the steam engine, was the first to remark, in 1869, on the phenomenon of 'countersteering', whereby the rider can steer to the left only by first briefly torquing the handlebars to the right, allowing the bike to fall into a leftward lean. The link between leaning and steering gives rise to the bicycle's most curious feature: the way that it can balance while coasting on its own. Give a riderless bike a shove and it may wend and wobble, but it will usually recover its forward trajectory. In 1899, English mathematician Francis Whipple derived one of the earliest and most enduring mathematical models of a bicycle, which could be used to explore this self-stability. Whipple modelled the bicycle as four rigid objects — two wheels, a frame with the rider and the front fork with handlebars — all connected by two axles and a hinge that are acted upon by gravity.... Plugging the measurements of a particular bicycle into the model revealed its path during motion, like a frame-by-frame animation. An engineer could then use a technique called eigenvalue analysis to investigate the stability of the bicycle as one might do with an aeroplane design. In 1910, relying on such an analysis, the mathematicians Felix Klein and Fritz Noether along with the theoretical physicist Arnold Sommerfeld focused on the contribution of the gyroscopic effect — the tendency of a spinning wheel to resist tilting. Push a bicycle over to the left and the rapidly spinning front wheel will turn left, potentially keeping the bicycle upright... In April 1970, chemist and popular-science writer David Jones demolished this theory in an article for Physics Today3 in which he described riding a series of theoretically unrideable bikes. One bike that Jones built had a counter-rotating wheel on its front end that would effectively cancel out the gyroscopic effect. But he had little problem riding it hands-free. This discovery sent him hunting for another force that could be at play. He compared a bike's front wheel to the casters on a shopping trolley, which turn to follow the direction of motion. A bicycle's front wheel can act as a caster because the point at which the wheel contacts the ground typically sits anywhere from 5 centimetres to 10 centimetres behind the steering axis (see 'What keeps a riderless bike upright?'). This distance is known as the trail. Jones discovered that a bike with too much trail was so stable that it was awkward to ride, whereas one with negative trail was a death trap and would send you tumbling the moment you released the handlebars. When a bicycle starts to topple, he concluded, the caster effect steers the front end back under the falling weight, keeping the bicycle upright. To Jones, the caster trail was the sole explanation for a bike's self-stability. In his memoir, published 40 years later, he counted the observation as one of his great accomplishments. “I am now hailed as the father of modern bicycle theory,” he declared... ...Papadopoulos's first goal was to finally understand what makes one bicycle more stable than another. He sat in his office and scrutinized 30 published attempts at writing the equations of motion for a bicycle. He was appalled by the “bad science”, he says. The equations were the first step towards connecting the geometry of a bicycle frame with how it handled, but each new model made little or no reference to earlier work, many were riddled with errors and they were difficult to compare. He needed to start from scratch.... [There is more to this commentary on the publisher's website. Follow the DOI. The article is open access.] Language: en

The “synthetic cell” created by Craig Venter and his colleagues (D. G. Gibson et al. Science doi:10.1126/science.1190719; 2010) is a normal bacterium with a prosthetic genome. As the genome is only about 1% of the dry weight of the cell, only a small part of the cell is synthetic. But the genome is pivotal because it contains the hereditary information that controls so much of a cell’s structure and function. The ability to make prosthetic genomes marks a significant advance over traditional genetic engineering of individual genes. The prosthetic genome contains all the information in the natural genome that it supplants, except for a few minor differences (for example, some ‘watermarks’ were added). There is no technical reason to stop there; any of the information in a prosthetic genome can be changed. Tomorrow’s synthetic cell could be radically unlike anything encountered in the history of life. Putting prosthetic genomes into bacteria raises important scientific and societal issues, beyond those raised by biotechnology in general and genetic engineering in particular. I will mention just four. First, we now have an unprecedented opportunity to learn about life. Having complete control over the information in a genome provides a fantastic opportunity to probe the remaining secrets of how it works. Second, even the simplest forms of life have unpredictable, emergent properties. These properties are often useful and we want to control them, but their unpredictability presents a conundrum for traditional engineering. We must develop and perfect methods for engineering emergence. Third, these new powers create new responsibilities. Nobody can be sure about the consequences of making new forms of life, and we must expect the unexpected and the unintended. This calls for fundamental innovations ‘Bottom-up’ will be more telling

When American and Chinese scientists agreed to measure pollution and dust over China, nobody foresaw how difficult it would be. Jane Qiu reports.

Australia's universities begin this month an academic year that will see them well on the way towards a unified system of higher education. Hopes that an election later in the year will bring a change of course, probably misplaced, are unlikely to be fulfilled. But nobody can guess what the consequences will be except that they will be profound.

Using silicon as a 'thermoelectric' material to convert heat into electricity would be a technological leap forward. But silicon conducts heat so well that nobody thought that could work — until now.

Funds are distributed through a system that runs on favours: nobody gets on without friends in high places.

The San Andreas Fault System, California. Edited by Robert E. Wallace. US Geological Survey Professional Paper 1515. US Government Printing Office, Washington: 1990. Pp.283. $20.

Nobody disputes that women have health problems that differ from those of men, but NIH may be wasting $625 million or more in pursuit of an ambition to be seen to be politically correct.

WHEN Sir Joseph Larmor edited the scientific papers of Lord Kelvin and Prof. Fitzgerald he did work which nobody else could have done so perfectly; his time, however valuable, was spent to advantage. The editing of these papers of Lord Kelvin's brother might have been undertaken by many others, but now that the excellent result is before us we cannot regret it, and we must confess that we did not expect to find in the editor such a perfect sympathy with James Thomson's methods of study. He shares with Prof. Thomson's son the honour and credit of this publication. The book begins with about a hundred pages of biography and comment upon Thomson's works—excellent reading. Then we have 153 pages of papers relating to fluid motion, dating from 1852 to the Bakerian lecture of 1892; nearly eighty pages on congelation and liquefaction from 1849 to 1888; forty pages on the continuity of states in matter from 1869 to 1873; seventy pages on dynamics and elasticity from 1848 to 1887; and about eighty pages on geological and miscellaneous subjects from 1848 to 1892. Collected Papers in Physics and Engineering. Prof. James Thomson, F.R.S. Selected and arranged with unpublished material and brief, annotations by Sir Joseph Larmor, Sec. R.S., and James Thomson. Pp. civ + 484. (Cambridge: University Press, 1912.) Price 15s. net.)

Now that the importance of rhythmicity in biological behavioural functions has been recognized, the traditional distinctions between psychology and physiology have had to be reappraised. For example, the regular alternation between mania and depression in manic-depressive psychosis suggests the possibility of underlying rhythmic phsyiological mechanisms1. Similarly, the temporal structure of social interaction has been investigated and regular patterns have been found2. Chapple3 and others4 have suggested a loose analogy between these patterns and biological rhythms. Nobody, however, has analysed the temporal structure of interaction with the perspective and statistical techniques of chronobiologists.

CONTROVERSY is commonly interesting, if only for the fact that it appeals to a man's pugnacious instincts; and most readers like to be invited to take sides. Eight of the eleven papers in this book were originally lectures, and in most of them Dr. Marett argues vigorously against what he regards as a lifeless manner of attacking the problems of folk-lore. He states his position in the first paper, and stands by it staunchly all through the volume. To him it is perfectly clear that every scrap of folk material is ultimately due to the more or less primitive reactions of the individual mind. Now nobody can understand either the productions or the modes of operation of the human spirit, he believes, by merely looking at them from the outside. The prime problem of all folk-lore is to enter into a man's thoughts, fancies, and emotions when he is confronted by certain definable situations. But simply to study objectively the changes which folk material has undergone in the course of its history is only to gather together a lot of dry bones. The psychologist is needed to put flesh on them, and to breathe into them the breath of life. Dr. W. H. R. Rivers is thereupon, in the most pleasant manner possible, held up as an awful example of the soulless sociologist. Psychology and Folk-lore. By Dr. R. R. Marett. Pp, ix + 275. (London: Methuen and Co., Ltd., 1920.) Price 7s. 6d. net.

I MUST confess that discussions upon mathematical metaphysics appear to me to be somewhat unpractical. They are suggestive of the case upon which Serjeant Snubbin was engaged, which related to a right of way “leading from some place which nobody ever came from, to some other place which nobody ever went to.” Nevertheless, I propose to offer some remarks upon this subject.

SLOWLY but surely the mist which for many a year has enveloped the subject of studio materials and methods is beginning to lift. Probably one reason why it has hung about for so long is that nobody with the requisite knowledge coupled with due detachment has been willing to tackle the task of dissipation. The authors of this book have set about it with a will. Their first attempt was to contribute an article to Technical Studies in 1936 on 'supports' (substances like wood, canvas, paper, and so forth, upon which paintings are executed). Since then, they have followed it up with further papers to the same periodical, dealing with adhesives, pigments, solvents, tools and equipment. The volume now before us is composed of all this valuable data—rounded off with a glossary of scientific terms—collated and arranged for easy reference. Painting Materials : a Short Encyclopedia By Rutherford J. Gettens George L. Stout. Pp. vii+333. (New York: D. Van Nostrand Co., 1942.) 3.75 dollars.

In a recent communication describing the synthesis of feldspathoids by feldspar-carbonate reactions, R. D. Schuiling discussed the limestone-syntexis hypothesis, which proposes that rock-types under-saturated in silica can form from silica-over-saturated magmas by assimilation of limestone, and he stated that, from a physico-chemcial point of view, there was no essential difference between this process and one involving the assimilation of sialic material by a carbonatite magma. He remarked that: "Nobody, however, seems to have tried to verify experimentally such proposed processes". The purposes of this communication are: (1) to direct attention to an extensive series of experiments by Stansfield which were aimed directly at testing assimilation hypotheses, and which included investigation of the extent and products of assimilation of limestone by various igneous melts; (2) to outline some of our own experiments which are concerned with the origin of carbonatites and associated alkalic rocks and, inevitably therefore, with the limestone assimilation hypothesis as well; (3) to comment on some points of Schuiling's communication.

Nobody quite understands why there is such excitement about the succession of superconducting materials with ever-higher transition temperature. But the phenomenon may be simpler than it seems.

THE British Council has done well to add this pamphlet to its “Science in Britain” series. Nobody else now alive could have written it with quite the same zest as Sir Lawrence Bragg: he has produced an essay in close accord with his title, the “History of X-Ray Analysis” ; and that is what is wanted. The Histroy of X-Ray Analysis By Sir Lawrence Bragg. (Science in Britain Series; Published for the British Council.) Pp. iv + 24 + 4 plates. (London, New York and Toronto: Longmans, Green and Co., Ltd., 1943.) 1s. net.

I AM truly sorry that the obituary notice published in NATURE two weeks ago should seem to Sir O. Lodge to minimise the work of Prof. Carey Foster and others. I feel sure that nobody can value Prof. Foster's work more than I do, but he had neither the money nor the other opportunities that Prof. Ayrton had in Japan. I admit a little overstrain in the statement that at the time when he created his Japanese laboratory “there were not half a dozen people in Great Britain who had experimented in electricity.” I ought to have said that there were only a few workers in electricity. I had in my mind that before starting for Japan early in June, 1875, I had the curiosity to count the number of electrical papers published before the Royal Society, and now printed in vols. xxii. and xxiii. of the Proceedings. I had no knowledge of meetings after May 13, 1875, as I lived in Glasgow. At the forty-one consecutive meetings from December 11, 1873, to May 13, 1875, there were in all only five papers read having a bearing on electricity. These were two by Dr. Gore, one by Prof. Adams, one by Messrs, de la Rue, Hugo Muller and Spottiswoode, and one by Prof. Balfour Stewart. I was on my way to Japan when my own first published electrical investigation was described at the Royal Society on June 10, 1875.

NOBODY, not even Prof. Kent or Mr. Heron-Allen, really wants Latin as a universal language. Latin is dead; its natural development has ceased and could not possibly meet the growing needs of international thought. Every one recognises that the classical tongue, if it is to satisfy modern needs, must have its grammar simplified and its vocabulary, especially of abstract terms, enlarged. But the features which are to be changed are those which give Latin its peculiar savour and the educational value that some would claim for it. “Modernised Latin” is not Latin at all; it is a hybrid jargon as artificial as Volapuk or Esperanto, as devoid of literary tradition, as incapable of artistic expression, as subject to national and individual vagaries. Of this last defect, of which he accuses Esperanto, Mr. Allen gives a crushing example. Few but English speakers would understand statio for railway-station; few but blundering schoolboys would use quae as a substantive for quis.

WAVE mechanics notwithstanding, the electronic conception of valence in chemistry is serving a useful purpose. It is true that we know little in regard to what we symbolise by a shared pair of electrons, but even less was ever known of the inner meaning of the single bond of organic chemistry, although nobody would deny that the conception of such a bond has been a useful one.

IT is rather surprising that Prof. Ayrton should indulge in covert sneers at Universities for devoting themselves to useless studies. It certainly ill becomes one whose life is bound up with electrical science, which is of such recent growth that nobody can pretend to forget how it owes its origin to those who studied it while useless. If Universities do not study useless subjects, who will? Once a subject becomes useful, it may very well be left to schools and technical colleges, to patent-mongers, and the trade. Mr. Bury is, on the other hand, mistaken in two respects. That a subject is useless is hardly worth considering as a recommendation for its being made compulsory on students. There are too many useless subjects for that. The great objection to compulsory Greek is that it is the principal stumbling-stone in the way of any literature being studied by ordinary University students. The Bible produced very little effect until it was read in translations; and the danger of a pagan revival, if ancient literature were studied without the obstruction of difficult languages, is the best reason for insisting on these languages in a Christian University. The second mistake of Mr. Bury is that it is any part of the business of a Universtiy to teach. Universities should certainly give facilities for students to learn. It is the business of the students to learn. If they are so ill prepared that they have not acquired the art of learning, they should go to a college or school or private teachers, and get taught; for teaching is the business of these institutions and persons. The business of Universities is to advance culture and knowledge, and to afford students an opportunity of learning how to do this. Prof. Ayrton, by omission rather than by commission, seems utterly unable to appreciate the value of literature for its own sake. How can all this fierce toil he extols so justly advance a lot of savages?

IT seems improbable that nobody should have ever tried replacing the telephone by a loud speaker in conductivity measurements, but I have never heard of it, nor read anything about its possibility and advantages; I will, therefore, describe it very briefly, as I feel convinced that it represents a real improvement over the customary procedure.

IN my younger days it was well recognised that such statements as “perfectly smooth” and the like were mere conventional phrases for designating an ideal state, of matter, which was assumed to exist for the purpose of simplifying the mathematical conditions as far as possible. Nobody can learn mathematics without working out a large number of problems and examples, and in order to make these sufficiently easy for the beginner, various fictitious hypotheses have to be introduced.

IT is impossible to make a detailed study of the status of nutrition in Colombia and determine the exact diet of the people because of the lack of information on the subject. No statistics are kept of the production and consumption of food articles, with the exception of meat and sugar. Therefore nobody knows what quantities of milk, bread, eggs, cheese, butter, fruits, vegetables and legumes are consumed annually. These figures could easily be obtained in the larger cities, but not in rural sections where there are no facilities for so doing.

THREE letters have lately appeared in these columns commenting on my book lately published under the title of “Organic Evolution Cross-examined.” Two of these are by Prof. Meldola, and one by Mr. Herbert Spencer. By the first I ought to feel much honoured, because the Professor lays down the law that nobody outside the class to which he himself belongs, namely professional experts, should be allowed to write or be listened to on such subjects as biology.

WITH reference to Sir Cyril Fox's interesting article under the above heading1, I wish to make certain comments. I think that nobody maintains that the Kohat-Potwar Saline Series is of post-Eocene age. As Prof. Sahni says2, his "fossil evidence is consistent with any geological age from the Lower Tertiary to the recent. But since on stratigraphical grounds the Saline Series cannot be younger than early Tertiary, the conclusion is that it is of Eocene age". I have shown3 that the latest marine beds of that region are of Upper Khirthar (Auversian) age; so there were apparently no marine waters to desiccate, in that region, after the Eocene.

ATTENTION has been directed on page 351 of NATURE of February 27, 1937, to a natural bridge ” so strong that it bears the elephant from one bank to another”, near Nimule, which is situated at the point where the Albert Nile, as it is commonly called to-day, becomes the Bahr el Jebel. It is clear that Dr. Hurst finds difficulty in believing in any such phenomenon, for in his review of May H. Lindsay's translation, the ” Life Story of a River”, from Emil Ludwig's work, he says: ” Nobody else has ever reported this bridge.” This is not so.

THE earthquake alleged to have taken place near Colchester on Sunday night, Jan. 18, and mentioned in the “Notes” of NATURE last week, on the authority of the Standard newspaper, turns out on inquiry to have been reported on very doubtful authority. The place referred to as “Leden” is evidently meant for Lexden, which is really a suburb of Colchester. Immediately after seeing the newspaper paragraph I communicated with some of the residents, asking them to obtain particulars for me, as the occurrence of another shock so near the district which was skaken in April of last year, would have been of considerable interest in connection with the report upon this last earthquake, which I am about to present to the Essex Field Club. It seems, however, according to the results of these inquiries, confirmed by a paragraph in the Colchester Gazette of January 21, that the shock was said to have been felt by one person only, the postman, and nobody else in the place heard or felt anything, nor was any crockery shaken or any vibration experienced in any other house. One gentleman, who was out of doors at the time mentioned (midnight), states that he heard a peal of thunder, but felt no shock, and he suggests that this might have awakened the postman, upon whose authority the newspaper paragraph appears to have been founded.

I HAVE no desire to resuscitate or discuss law court cases in the correspondence columns of NATURE ; but in the summing up of a recent case, which many readers of NATURE will have followed, the judge made the following statement: "Nobody suggested that [the plaintiff] was anything but a thoroughly, perhaps exceptionally competent person in his scientific work, but [the defendants] said that his incompetence lay in his failure to administer his department properly, that is, to keep an eye on finance and to see that the machinery of the department was running with reasonable smoothness" (The Times, July 22, 1938).

SURELY the time has come to abandon the practice of attaching to elements fancy names arbitrarily selected by individuals. When names concerned: nobody but a small clique in constant personal communication, and when they had nothing more important to record about an element than the personality of its discoverer, there may have been something to say for the system. Nowadays neither condition is fulfilled. Thousands are interested who have no means of expressing their opinion: and there is something definitely scientific to be said about elements. The new element was discovered as a consequence of a theory of the structure of the atom, and its discoverers should surely be glad to see a record left in the name that their discovery was no lucky fluke.

MAY I beg you will introduce to the notice of your readers a grievance urgently in need of a remedy? The grievance is considerable; the remedy simple; and if scientific men will not make it their concern, nobody else will.

THE letter from Mr. A. G. Lowndes, published in NATURE of Dec. 24, raises a question of great and increasing importance. We all know that the old controversy between materialism and vitalism has entered on a new phase, and a decision is once more in the balance. It is, therefore, premature to clear our biological language of all terms savouring of vitalism, more especially as materialism has definitely failed to account for certain well-defined phenomena of development. The modern tendency is distinctly against ignoring mental Phenomena, and making a sharp line of demarcation between humanity and the rest of the world of life. Biologists with a philosophic training prefer to explain unknown things in terms of the known, and nobody can deny that mental processes are much more amenable to cognition than any material processes whatever. We know what we mean by the term ‘self adaptation,’ and we have no reason to exclude the animal world, or even the vegetable kingdom, from the working of a process familiar to our own experience.

MOCHUS OF SIDON, the alleged precursor of Demokritus, is not so unknown to historians of science as Prof. See seems to think (February 13, p. 345), nor is Strabo the only ancient writer who alludes to him; see, for instance, Josphus, “Antiquities,” 1, 3, 9. But nobody takes him seriously. The book of Mochus is one of the numerous literary forgeries which appeared in Alexandrian times. So far as I can find, it is not mentioned by any of the doxographic writers, so it is probably not much older than the time of Posidonius.