科学与翻译

利用Google地图照片确定船只速度

September 7th, 2009

Did a Chinese calligrapher use “fractal expression”?

October 21st, 2008

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Is the end in sight for theoretical physics

May 7th, 2008

Stephen Hawking has said that there is a 50-50 chance that we will find a complete unified theory in the next 20 years. Do you agree that the end of theoretical physics is in sight?

The most common criticism was equating the discovery of a theory that unified the four fundamental forces of nature - a so-called theory of everything - with the end of theoretical physics. Some theoretical particle physicists agreed with Hawking’s prediction about the chances of discovering a theory of everything, although several reckoned that it would take 50 to 100 years. Steven Weinberg, for example, said: “20 years is possible, but unlikely. I would guess 100 years for a ‘complete unified theory’. But a ‘complete unified theory’ would not be the end of theoretical physics.”

Kaku agreed that 20 years will be enough “to prove whether superstring theory is the theory of everything or the theory of nothing - there is no middle path. But even then, knowing the rules of chess does not mean we have become grand masters of chess. Similarly, knowing the rules of the unified field theory does not mean we have become grand masters of that theory. It may take us centuries before we exhaust the full implications and applications of a theory of everything”.

Gerard ‘t Hooft, however, was less optimistic about even the more limited interpretation of Hawking’s statement: “Absolutely not. He has been saying the same thing for more than 20 years. Physicists like him will say this again and again, always projecting the ultimate solution 20 years to the future. Although I do believe an ultimate theory is conceivable, we are many generations away from it.”

“Physics is not like getting to the top of Everest,” said Luciano Maiani, director general of CERN. “It is more like trying to get to absolute-zero temperature. As you get closer, new scales of phenomena appear and these call for a new effort and new understanding.”

Eugene Parker at Chicago was not convinced either. “The idea that when the last field equation is written down on paper, physics will come to an end is naive in the extreme,” he said. “In 1865, for example, Maxwell completed the electromagnetic field equations by adding the displacement current to Ampère’s law. That was the beginning of electromagnetism, not the end. When Schrödinger and then Dirac wrote down the quantum-mechanical wave equation, that was the beginning of quantum mechanics, not the end. When Einstein wrote down the equations of general relativity, that was the beginning of modern gravitational theory and cosmology, not the end.”

Many respondents pointed out that the discovery of a theory of everything will have little impact on the rest of physics “A unified theory would be a tremendous breakthrough,” said astronomer Alex Filipenko at the University of California at Berkeley, “but it would not, for example, lead to solutions of many important problems in condensed-matter physics, biophysics, astrophysics, and so on. It certainly won’t give us a much clearer picture of the origin of life or of intelligence. Much will remain to be done!”
摘自：http://physicsworld.com/cws/article/print/851

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William Thomson’s School Life

May 5th, 2008

In October 1841 the 17-year-old Thomson entered St Peter’s College (Peterhouse), Cambridge, as a “pensioner” in other words as a student who paid his own way. The formal tutoring in mathematics in his first year was of a very low level compared with what Thomson already knew. Indeed, by the time he reached Cambridge, Thomson had already published a paper in the Cambridge Mathematical Journal, in which he defended the mathematical rigour of Fourier series against the erroneous criticisms of Philip Kelland, a mathematician at Edinburgh University. During his time as an undergraduate he wrote a further 10 papers and was quickly tipped to be the “senior wrangler” (the student who would come first in the final mathematics examinations).

While Thomson was at Cambridge every member of his family regularly wrote to him. His father, who was footing all the bills, often advised him on the wise use of money and time. Yearly college maintenance fees alone came to £230, which would probably have accounted for as much as one-third of his father’s annual income. Thomson’s letters to his father often contained detailed lists of all expenditure. If writing to ask for extra money, he would sometimes include a mathematical theorem for possible use in exams to soften his father up.

In one early letter to his father, Thomson outlined how he planned to spend his days at Cambridge. His intention was to rise at 5 a.m. and light his fire; read until 8:15 a.m.; attend his daily lecture; read until 1 p.m.; exercise until 4 p.m.; attend chapel until 7 p.m.; read until 8:30 p.m.; and finally go to bed at 9 p.m. As Thomson’s modern biographers point out, it is doubtful whether he actually adhered strictly to this timetable, but it does illustrate his lifelong desire to minimize wasted time.

Thomson took part in many other activities at Cambridge besides studying. He rowed, becoming an excellent oarsman. He played the cornet and helped to establish the university’s music society. He also walked, skated and swam. Of all these activities it was Thomson’s rowing that his father disapproved of the most, fearing that it would bring his son into loose company, which would “ruin [Thomson] forever” with wine parties and time wasting.

Thomson’s final exams - the Senate House examinations - began on New Year’s Day 1845 and went on until 7 January. There were 12 papers, with morning papers lasting two and a half hours and afternoon papers three hours. The final result depended on both the quantity and quality of the answers to the questions. The exams were the toughest mathematical racecourse in the land, with the competitors trained like thoroughbreds to answer questions at top speed, and to use all possible short cuts to reach the answers.

To universal surprise Thomson came not first but second, behind one Stephen Parkinson of St John’s College. The family was disappointed, but justice was eventually done when Thomson came first in the Smith’s prize examination at the end of January. The papers for this exam were more suited to Thomson’s abilities, containing as they did more problem-solving questions and less of the bookwork that characterized the Senate House papers. Even though Thomson had come second in the Senate House examinations, the comments around Cambridge showed that he was by far the greater mind. As one examiner commented to a colleague: “You and I are just about fit to mend [Thomson’s] pens.” These successes meant that Thomson was elected a fellow of St Peter’s in June 1845 at the age of 21.

摘自：http://physicsworld.com/cws/article/print/16484

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Faraday’s heritage

April 29th, 2008

The year 1821 was in many ways one of the most important in Faraday’s life. On 21 May 1821 he was promoted in the Royal Institution to be Superintendent of the House. On 2 June he married Sarah Barnard who was a member of one of the leading Sandemanian families in London and on 15 July Faraday made his Confession of Faith in the Sandemanian Church. The year was also the one when he made his first major contribution to natural knowledge.

In 1820 the Danish natural philosopher Hans Christian Oersted had discovered electro-magnetism. This he announced in a paper written in Latin, but was quickly translated into the major scientific languages of Europe. It was immediately evident that Oersted had made a major discovery, but because he belonged to the German school of naturphilosophie his paper contained views which many of its readers found strange. Indeed writing later Faraday commented that “I have very little to say on M. Oersted’s theory, for I must confess I do not quite understand it”. What was clear was that Oersted had opened up a major field of scientific enquiry which was exploited by savants all over Europe. Faraday was part of this effort and on 3 and 4 September 1821 in his basement laboratory at the Royal Institution, he undertook a set of experiments which culminated in his discovery of electro-magnetic rotation - the principle behind the electric motor. Apart from the practical significance of this discovery, it was important as Faraday’s interpretation of the phenomenon indicated that he was not a Newtonian in supposing that forces had to act rectilinearly.

In the ensuing decade following this discovery, Faraday’s opportunity for doing original research was severely circumscribed, although he was able to liquefy chlorine in 1823 and discover bicarbuet of hydrogen (later renamed benzene by Eilhard Mitscherlich) in 1825. At Davy’s instigation he was the first secretary of the newly founded Athenaeum Club in 1824 and in the late 1820s undertook an extensive project on making optical glass for a joint committee of the Royal Society and Board of Longitude. In addition in 1826 he founded the Friday Evening Discourses and in the same year the Christmas Lectures for juveniles. In total Faraday gave 123 Friday Evening Discourses between 1826 and 1862 and 19 series of Christmas lectures between 1827 and 1861. These and other lectures that he gave served to establish his reputation as the outstanding scientific lecturer of the time. Both the Friday Evening Discourses and the Christmas lectures continue to this day. The latter series is televised each year.

It was not until nearly ten years to the day after his discovery of electro-magnetic rotations that Faraday was able to resume his work on electro-magnetism, when he discovered on 29 August 1831, electro-magnetic induction. This is the principle behind the electric transformer and generator. It was this discovery, more than any other, that allowed electricity to be turned, during the nineteenth century, from a scientific curiosity into a powerful technology. During the remainder of the 1830s Faraday worked on developing his ideas on electricity. He enunciated a new theory of electro-chemical action between 1832 and 1834 one of the results of which was that he coined, with William Whewell, many of the words now so familiar - electrode, electrolyte, anode, cathode and ion to name but five. In the later half of the 1830s Faraday worked on a new theory of static electricity and electrical induction. This work led him to reject the traditional theory that electricity was an imponderable fluid or fluids. Instead he proposed that electricity was a form of force that passed from particle to particle of matter.

摘自： http://www.rigb.org/heritage/faradaypage.jsp

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The life of Antoine-Laurent Lavoisier (1743-1794)

April 23rd, 2008

“Lavoisier was a Parisian through and through and a child of the enlightenment,” wrote biographer Henry Guerlac. The son of Jean-Antoine and Émilie Punctis Lavoisier, he entered Mazarin College when he was 11. There, he received a sound training in the arts and classics and an exposure to science that was the best in Paris. Forgoing his baccalaureate of arts degree, Lavoisier yielded to the influence of his father and studied law, receiving a law degree in 1763. But his interest in science prevailed, kindled by the geologist Jean-Étienne Guettard, whom he met at Mazarin. After graduation, he began a long collaboration with Guettard on a geological survey of France.

Lavoisier showed an early inclination for quantitative measurements and soon began applying his interest in chemistry to the analysis of geological samples, especially gypsum. Because of his flair for careful analyses and his prodigious output, he was elected to the Academy of Sciences at the age of 25. At the same time, Lavoisier used part of the fortune he had inherited from his mother to buy a share in the Ferme Générale, a private group that collected various taxes for the government. This fateful decision would later cost him his life at the height of his intellectual powers.

He married Marie Anne Pierrette Paulze on Dec. 16, 1771; he was 28, she was 14. “The marriage was a happy one,” according to McKie. “Mme Lavoisier was possessed of a high intelligence; she took a great interest in her husband’s scientific work and rapidly equipped herself to share in his labors. Later, she helped him in the laboratory and drew sketches of his experiments. She made many of the entries in his laboratory notebooks. She learned English and translated a number of scientific memoirs into French.”

Lavoisier became further involved in public life in 1775, when he was appointed one of four commissioners of the Gunpowder Commission, charged with reforming and improving the production of gunpowder. Lavoisier moved his residence and laboratory to the arsenal in Paris, where for almost 20 years it drew many distinguished visitors. He devoted several hours every day and one full day a week to experiments in his laboratory. According to his wife: “It was for him a day of happiness; some friends who shared his views and some young men proud to be admitted to the honor of collaborating in his experiments assembled in the morning in the laboratory. There they lunched; there they debated. . . . It was there that you could have heard this man with his precise mind, his clear intelligence, his high genius, the loftiness of his philosophical principles illuminating his conversation.”

Ironically, Lavoisier, the ardent and zealous chemical revolutionary, eventually was caught in the web of intrigue of a political revolution. The Traité was published in 1789, the same year as the storming of the Bastille. A year later, Lavoisier complained that “the state of public affairs in France . . . has temporarily retarded the progress of science and distracted scientists from the work that is most precious to them.”

Lavoisier, however, could not escape the wrath of Jean-Paul Marat, the adamant revolutionary, who began publicly denouncing him in January 1791. During the Reign of Terror, arrest orders were issued for all of the Ferme Générale, including Lavoisier. On the morning of May 8, 1794, he was tried and convicted by the Revolutionary Tribunal as a principal in the “conspiracy against the people of France.” He was sent to the guillotine that afternoon. The next day, his friend, the French mathematician Joseph-Louis Lagrange, remarked that “it took them only an instant to cut off that head, and a hundred years may not produce another like it.”

原文： http://acswebcontent.acs.org/landmarks/chemrevolution/lavoisier.html

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Replaying the tape

April 13th, 2008

The evolutionary biologist Stephen Jay Gould once proposed a thought experiment that he called “replaying life’s tape”. Suppose we press the rewind button and return to some point in the past, erasing all interim evolutionary developments. If we let the tape run again, will evolution occur in exactly the same way as before? Gould answered “no”, and used the thought experiment to challenge the assumption that biological evolution is a “ladder of progress” that drives life inevitably to the same advanced forms.

It is interesting to think what might happen if we carried out the same thought experiment, not for living things, but for equations. Would the equations develop in an unpredictable way, like the evolution of species? Or would it be inevitable? If we started all over again, would we still have F = ma? Indeed, would we have equations at all?

In the 19th century, the French philosopher Auguste Comte thought he could answer such questions. Comte advanced what he called “a great fundamental law” according to which each branch of human knowledge - as well as each person, state and civilization - passes through three different developmental stages: theological, metaphysical and scientific. In each stage, human beings try different approaches to securing stable and progressive relations with nature to make their surroundings peaceful and predictable. But inadequacies in each approach force human beings to make revisions, leading to the next stage.

The development of the concept of force nicely illustrates Comte’s law. In primitive times, Comte thought, humans saw the world as ruled by deities. This was natural and inevitable, for all humans acquire a notion of force from individual experiences of pushes and pulls in daily life. Projected into nature, this creates a theological picture in which everything from thunder and rain to the stars is the result of spirits behaving and misbehaving. The theological stage is indispensable because, in it, we learn how to explain, strive for consistency and overcome contradictions with new explanations.

But trying to control nature by pleasing the spirits through ritual and prayer (the earliest forms of technology) did not succeed in bringing about the desired predictability. A far more effective way of influencing nature turned out to be studying the changes that the spirits produced - the patterns in the seasons, tides and stars, in the behaviour of fire, and so on. This shift of attention moved humanity into the second, metaphysical stage. Here humans continued to attempt to explain the “why” of things through some ultimate cause or essence. But the supernatural agents were now replaced by what Comte called “abstract forces, real entities or personified abstractions”.

Force, for instance, was explained as operating through the medieval notion of “impetus”, which is passed from one body to another and causes motion. But these metaphysical agents, too, gradually became emptied of meaning, and reason itself did not provide a sufficient ground for understanding nature.

This led to the final - scientific - stage, which saw the maturation of the human intellect. Physics and astronomy, Comte thought, reached this stage in the 17th century. Human beings ceased to ask why phenomena happened and instead sought to answer how they happened by finding the appropriate laws. The number of such laws tends to decrease as science progresses. Gravitation, for example, was found to unify what had seemed to be myriads of forces into one.

Comte never considered the question of whether individual equations such as F = ma would reappear if the process recurred. But had this thought experiment been proposed to him, he would surely have held that the conceptual trajectory that led to F = ma would be more or less repeated, with theological concepts of force giving way to metaphysical concepts and then to mathematical laws governing abstract quantities.

摘自：http://physicsworld.com/cws/article/print/24291

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Galileo’s telescope

April 2nd, 2008

In 1609, Galileo had set a telescope in the garden behind his house and turned it skyward. Never-before-seen stars leaped out of the darkness to enhance familiar constellations; the nebulous Milky Way resolved into a swath of densely packed stars; mountains and valleys pockmarked the storied perfection of the Moon; and a retinue of four attendant bodies traveled regularly around Jupiter like a planetary system in miniature.

“I render infinite thanks to God,” Galileo intoned after those nights of wonder, “for being so kind as to make me alone the first observer of marvels kept hidden in obscurity for all previous centuries.”

Galileo found himself lionized as another Columbus for his conquests. Even as he attained the height of his glory, however, he attracted enmity and suspicion. For instead of opening a distant land dominated by heathens, Galileo trespassed on holy ground. Hardly had his first spate of findings stunned the populace of Europe before a new wave followed: He saw dark spots creeping continuously across the face of the Sun, and “the mother of loves,” as he called the planet Venus, cycling through phases from full to crescent, just as the Moon did.

All his observations lent credence to the unpopular Sun-centered universe of Nicolaus Copernicus, which had been introduced over half a century previously, but foundered on lack of evidence. Galileo’s efforts provided the beginning of a proof. And his flamboyant style of promulgating his ideas–sometimes in bawdy humorous writings, sometimes loudly at dinner parties and staged debates–transported the new astronomy from the Latin Quarters of the universities into the public arena. In 1616, a pope and a cardinal inquisitor reprimanded Galileo, warning him to curtail his forays into the supernal realms. The motions of the heavenly bodies, they said, having been touched upon in the Psalms, the Book of Joshua, and elsewhere in the Bible, were matters best left to the Holy Fathers of the Church.

Galileo obeyed their orders, silencing himself on the subject. For seven cautious years he turned his efforts to less perilous pursuits, such as harnessing his Jovian satellites in the service of navigation, to help sailors discover their longitude at sea. He studied poetry and wrote literary criticism. Modifying his telescope, he developed a compound microscope. “I have observed many tiny animals with great admiration,” he reported, “among which the flea is quite horrible, the gnat and the moth very beautiful; and with great satisfaction I have seen how flies and other little animals can walk attached to mirrors, upside down.”

摘自：http://www.galileosdaughter.com/firstchapter.shtml

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Seeing the hidden fresco

March 26th, 2008

Spread over a 16 m-wide wall in the Palazzo Vecchio town hall in Florence, Leonardo da Vinci’s The Battle of Anghiari is a magnificent fresco depicting two horse riders in combat. Also impressive are la America Tropical by the Mexican muralist David Alfaro Siqueiros in the Italian Hall in Los Angeles, and the numerous frescos adorning the ancient Hagia Sophia church in Bulgaria. Unfortunately no one can see these paintings: they are all hidden beneath a layer of plaster.

If studies by a team of scientists from the US and France continue to prove successful, however, then it could be only a matter of time before such frescoes, which have often been covered for religious or political motives, are exposed. Although plaster is opaque to visible light, in the much lower frequency terahertz (10¹² Hz) it all becomes clear. “Most non-polar, dielectric materials are transparent in the terahertz spectral range,” says Bianca Jackson, a physicist at Michigan University in the US. “Therefore, with enough power, terahertz can penetrate ‘infinitely’ thick, optically opaque materials suchas concrete or wood.”

Jackson and her colleagues are collaborating with researchers from Picometrix — a photonics company based in Ann Arbor, Michigan —as well as the National Higher School of Advanced Techniques (ENSTA) and the Centre for Research and Restoration in the Louvre Museum, both in Paris. Their system involves scanning a pulse of terahertz light over a surface and then measuring how the amplitude of the reflected signal changes with time. Because materials have different dielectric properties, which determine how much light is reflected, these measurements can tell how dissimilar materials are layered on top of one another. This makes it ideal for imaging frescos — a technique that won favour during the Renaissance in which pigments are painted into wet plaster.

Although art historians regularly employ ultraviolet, infrared and Raman spectroscopy to examine the surfaces of murals, these techniques cannot probe deeper than a millimetre into plaster. On the other hand, X-rays and microwaves can penetrate many layers, but X-rays cannot distinguish between the layers and microwaves have a poor spatial resolution. Terahertz radiation has none of these drawbacks and, because it is non-ionizing, should not damage a painting either.

The Michigan team has already tested Picometrix’s “T-ray 4000” system on a graphite sketch of a butterfly imbedded in a 4 mm layer of plaster-of-Paris. After focusing the T-ray transceiver onto the back of the plaster, they found that they could make out the 2 mm wide graphite lines of the butterfly. The team is now planning to take the system next month to the St John the Baptist church in Vif, France, where there are believed to be many hidden frescoes.

Irl Duling, director of terahertz business development at Picometrix, says that the company is already shipping the T-ray system to customers. “T-ray 4000 is the only full-featured, portable time-domain terahertz system.”

原文：http://physicsworld.com/cws/article/news/32833

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Muslim scientists and Scientific method

March 23rd, 2008

Muslim scientists placed far greater emphasis on empiricism and experimentation than any previous ancient civilization, and they introduced quantification, precise observation, controlled experiment, and careful records. Their new approach to scientific inquiry led to the development of the scientific method in the Islamic world. In particular, the empirical observations and quantitative experiments of Ibn al-Haytham (Alhacen) in his Book of Optics (1021) is seen as the beginning of the modern scientific method.

Ibn al-Haytham, who is now known as the father of optics, used the scientific method to obtain the results in his Book of Optics. In particular, he combined observations, experiments and rational arguments to show that his modern intromission theory of vision, where rays of light are emitted from objects rather than from the eyes, is scientifically correct, and that the ancient emission theory of vision supported by Ptolemy and Euclid (where the eyes emit rays of light), and the ancient intromission theory supported by Aristotle (where objects emit physical particles to the eyes), were both wrong. It is known that Roger Bacon (who was sometimes erroneously given credit for the scientific method) was familiar with Ibn al-Haytham’s work.

Ibn al-Haytham developed rigorous experimental methods of controlled scientific testing in order to verify theoretical hypotheses and substantiate inductive conjectures. Ibn al-Haytham’s scientific method was very similar to the modern scientific method and consisted of the following procedures:

1. Observation
2. Statement of problem
3. Formulation of hypothesis
4. Testing of hypothesis using experimentation
5. Analysis of experimental results
6. Interpretation of data and formulation of conclusion
7. Publication of findings

The development of the scientific method is considered to be so fundamental to modern science that some — especially philosophers of science and practicing scientists — consider earlier inquiries into nature to be pre-scientific. Some have described Ibn al-Haytham as the “first scientist” for this reason.

In The Model of the Motions, Ibn al-Haytham also describes an early version of Occam’s razor, where he employs only minimal hypotheses regarding the properties that characterize astronomical motions, as he attempts to eliminate from his planetary model the cosmological hypotheses that cannot be observed from Earth.

George Sarton, the father of the history of science, wrote: “The main, as well as the least obvious, achievement of the Middle Ages was the creation of the experimental spirit and this was primarily due to the Muslims down to the 12th century.”

摘自：http://www.answers.com/topic/islamic-science?cat=technology

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