எனக்கு ரிலேட்டிவிட்டி தியரி பிரகாசமாய்த் தெரியும் என்றெல்லாம் ஒன்றும் கிடையாது. ஆனால் அது எதைப் பற்றியதாயிருக்கும் என்பதைப் பற்றித் தெரியும், ஒரு முறை என் சித்தப்பா(என்று நினைக்கிறேன்), ரிலேட்டிவிட்டி தியரியை ஒரு 'ஈ'யைக் கொண்டு விளக்கினார். எப்படியென்றால்,

நாம் ஒரு காரில் பயணம் செய்கிறோம், 60km வேகத்தில், ஆனால் நாம் பயணம் செய்யத் தொடங்கிய அதே சமயத்தில் அந்தக் காரினுள் புகுந்த 'ஈ' ஒன்று நம்முடைன் பயணம் செய்கிறது, எப்படியென்றால் காரின் எந்த ஒரு பகுதியையும் தொடாமல் - காருக்குள் பறந்துகொண்டேயிருக்கிறது. 'ஈ' காருக்குள் பயணம்(பறந்து) செய்து கொண்டுதானே இருக்கிறது.

இதன் காரணமாகயெல்லாம் 'ஈ'யும் 60km வேகத்தில் பயணம் செய்ததாகக் கொள்ள முடியுமா? இப்படித்தான் வேகம் என்பது வேறுபடுவதாய் இருக்கிறது. இந்த சூழ்நிலையில் காரில் பயணம் செய்த நம்முடைய வேகத்தையும், நம்முடை பயணம் செய்த 'ஈ'யினுடைய வேகத்தையும் ஒரு சமன்பாட்டிற்குள் கொண்டுவருவது தான் ரிலேட்டிவிட்டி என்றார் அவர். இது உண்மையா எனக்குத் தெரியாது.

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The Valiant Swabian - A new biography of Albert Einstein.



When youthful and frisky, Albert Einstein would refer to himself as “the valiant Swabian,” quoting the poem by Ludwig Uhland: “But the valiant Swabian is not afraid.” Albert—the name Abraham had been considered by his unreligious parents but was rejected as “too Jewish”—was born in Ulm, in March of 1879, not long after Swabia joined the new German Reich; he was the first child and only son of a mathematics-minded but financially inept father and a strong-willed, musically gifted woman of some inherited means. A daughter, Maria, was born to the couple two and a half years later; when shown his infant sister, Albert took a look and said, “Yes, but where are the wheels?” Though this showed an investigative turn of mind, the boy was slow to talk, and the family maid dubbed him der Depperte—“the dopey one.”

As the boy progressed through the schools of Munich, where his father had found employment in his brother Jakob’s gas-and-electrical-supply company, Albert’s teachers, though giving him generally high marks, noted his resistance to authority and Germanic discipline, even in its milder Bavarian form. As early as the age of four or five, while sick in bed, he had had a revelatory encounter with the invisible forces of nature: his father brought him a compass, and, as he later remembered it, he was so excited as he examined it that he trembled and grew cold. The child drew the momentous conclusion that “something deeply hidden had to be behind things.” That intimation was to carry him to some of the greatest scientific discoveries of the twentieth century, and to a subsequent persistent but unsuccessful search for a theory that would unite all the known laws of nature, and to a global fame impossible to imagine befalling any mere intellectual now.

Walter Isaacson’s thorough, comprehensive, affectionate new biography, “Einstein: His Life and Universe” (Simon & Schuster; $32), relates how, in 1931, during the fifty-one-year-old scientist’s second visit to America, he and his second wife, Elsa, attended, in California, a séance at the home of Mr. and Mrs. Upton Sinclair. He must have allowed a little skepticism to creep into his polite conversation, for “Mrs. Sinclair challenged his views on science and spirituality.” His own wife overheard and indignantly intervened, telling their hostess, “You know, my husband has the greatest mind in the world.” Mrs. Sinclair didn’t dispute the assertion, replying, “Yes, I know, but surely he doesn’t know everything.” On the same excursion, Einstein, at his own request, met Charlie Chaplin, who, as they arrived at the première of “City Lights,” said, of the applauding public, “They cheer me because they all understand me, and they cheer you because no one understands you.”

In 1905, Einstein, a twenty-six-year-old patent clerk in Bern, Switzerland, had produced in rapid succession five scientific papers that (a) proposed that light came not just in waves but in indivisible, discrete packets of energy or particles called, after Max Planck’s discovery, quanta; (b) calculated how many water molecules existed in 22.4 litres (a number so vast that, Isaacson tells us, “that many unpopped popcorn kernels when spread across the United States would cover the country nine miles deep”); (c) explained Brownian motion as the jostling of motes of matter by invisible molecules; (d) expounded the special theory of relativity, holding that all measurable motion is relative to some other object and that no universal coördinates, and no hypothetical ubiquitous ether, exist; and (e) asserted that mass and energy were different manifestations of the same thing and that their relation could be tidily expressed in the equation E=mc², where c is the speed of light, a constant. Only a few friends and theoretical physicists took notice.

from the issuecartoon banke-mail thisIn 1903, Einstein had married a woman three years older than he, Mileva Marić, a lame, homely Serbian he had met when both were students at the Zurich Polytechnic. It emerged only in 1986 that before their marriage the couple became parents of a girl, Lieserl, whom Einstein probably never saw and whose fate is unknown. A legitimate son, Hans Albert, was born in 1904. Einstein had not been able to secure any teaching job; his cavalier and even defiant attitude toward academic authority worked against his early signs of promise. He had left Germany and renounced his citizenship at the age of sixteen, and for four years was too poor to buy Swiss citizenship, depending for sustenance on a monthly stipend from his mother’s family and some fees from private tutorials. In the pinch, Marcel Grossmann, a brilliant math student whose meticulous lecture notes helped Einstein get high grades at the Zurich Polytechnic, managed to secure him a job at the Swiss Patent Office, in Bern. His long stint there figures, in the conventional Einstein mythology, as the absurd ordeal of a neglected genius, but Isaacson thinks it might have been a good thing:

So it was that Albert Einstein would end up spending the most creative seven years of his life—even after he had written the papers that reoriented physics—arriving at work at 8 A.M., six days a week, and examining patent applications.…Yet it would be wrong to think that poring over applications for patents was drudgery.…Every day, he would do thought experiments based on theoretical premises, sniffing out the underlying realities. Focusing on real-life questions, he later said, “stimulated me to see the physical ramifications of theoretical concepts.”

“Had he been consigned instead to the job of an assistant to a professor,” Isaacson points out, “he might have felt compelled to churn out safe publications and be overly cautious in challenging accepted notions.” Special relativity has a flavor of the patent office; one of the theory’s charms for the fascinated public was the practical apparatus of its exposition, involving down-to-earth images like passing trains equipped with reflecting mirrors on their ceilings, and measuring rods that magically shrink with speed from the standpoint of a stationary observer, and clocks that slow as they accelerate—counterintuitive effects graspable with little more math than plane geometry.

The general theory of relativity took longer, from 1907 to 1915, and came harder. Generalizing from the special theory’s assumption of uniform velocity to cases of accelerated motion, and incorporating Newton’s laws of gravity into a field theory that corrected his assumption of instant gravitational effect across any distance, led Einstein into advanced areas of mathematics where he felt at sea. He turned to his invaluable friend Marcel Grossmann, now chairman of the math department at the Zurich Polytechnic; Isaacson quotes him as saying, “Grossmann, you’ve got to help me or I will go crazy.” After consulting the literature, Grossmann “recommended the non-Euclidean geometry that had been devised by Bernhard Riemann.” Einstein, beginning with the insight that acceleration and gravity exert an equivalent force, worked for years to find the equations that would describe

1. How a gravitational field acts on matter, telling it how to move.

2. And in turn, how matter generates gravitational fields in spacetime, telling it how to curve.

“I have gained enormous respect for mathematics,” he wrote a friend, “whose more subtle parts I considered until now, in my ignorance, as pure luxury!” For a time, he discarded Riemannian tensors, but eventually returned to them, and, to quote Isaacson, “in the throes of one of the most concentrated frenzies of scientific creativity in history,” he felt close enough to the solution to schedule four Thursday lectures at the Prussian Academy, in Berlin, which would unveil his “triumphant revision of Newton’s universe.” Then, heightening the suspense, another player entered the game. Einstein, still a little short of the full solution and beset with nervous stomach pains, showed one of his lectures to David Hilbert, “who was not only a better pure mathematician than Einstein, he also had the advantage of not being as good a physicist.” Hilbert told Einstein that he was ready to lay out his own “axiomatic solution to your great problem,” and the physicist battled to establish the priority of his theory even as he was putting the last, perfecting touches into his fourth and final lecture. It all came down to:

Rµν—½gµνR = 8πTµν

The other giants of physics in the first half of the twentieth century applauded. Paul Dirac called general relativity “probably the greatest scientific discovery ever made,” and Max Born termed it “the greatest feat of human thinking about nature, the most amazing combination of philosophical penetration, physical intuition and mathematical skill.” In 1919, the discovery was given empirical proof when Arthur Eddington, the director of the Cambridge Observatory, led an expedition to equatorial realms to observe a solar eclipse and see if, as Einstein’s field equations predicted, stars near the sun’s rim would be apparently displaced 1.7 arc seconds. With a little massaging from Eddington, they were. Einstein, asked what his reaction would have been if the experiment had showed his theory to be wrong, serenely replied, “Then I would have been sorry for the dear Lord; the theory is correct.”

from the issuecartoon banke-mail thisThough Einstein was to reap many honors (including the 1921 Nobel, belatedly, for his early work on the photoelectrical effect) and was to serve humanity as a genial icon and fount of humanist wisdom for three more decades, he never again made a significant contribution to the ongoing life of the physical sciences. Beginning around 1918, he devoted himself to a quest even more solitary and visionary than his relativity triumphs. “We seek,” he said in his Nobel Prize lecture, “a mathematically unified field theory in which the gravitational field and the electromagnetic field are interpreted only as different components or manifestations of the same uniform field.” Quantum theory, with its built-in uncertainties and paradoxes, struck him as a spooky violation of physical realism. “The more successes the quantum theory enjoys,” he lamented to a friend in 1912, “the sillier it looks.” In an autobiographical sketch published in 1949, he described his frustrated attempts “to adapt the theoretical foundation of physics” to quantum science: “It was as if the ground had been pulled out from under one, with no firm foundation to be seen anywhere upon which one could have built,” leaving “an intermediate state of physics without a uniform basis for the whole, a state that—although unsatisfactory—is far from having been overcome.”

His faith that a unified theory of all the fields exists went back to his childhood sense that “something deeply hidden had to be behind things,” a something that would evince itself in an encompassing theory of elegant simplicity. Isaacson tells us: “On one of the many occasions when Einstein declared that God would not play dice, it was Bohr”—the physicist Niels Bohr—“who countered with the famous rejoinder: Einstein, stop telling God what to do!” God, sometimes identified as “the Almighty” or “the Old One” (der Alte) frequently cropped up in Einstein’s utterances, although, after a brief period of “deep religiousness” at the age of twelve, he firmly distanced himself from organized religion. In a collection of statements published in English as “The World As I See It,” there is this on “The Religiousness of Science”:

The scientist is possessed by the sense of universal causation.…His religious feeling takes the form of a rapturous amazement at the harmony of natural law, which reveals an intelligence of such superiority that, compared with it, all the systematic thinking and acting of human beings is an utterly insignificant reflection. This feeling is the guiding principle

The apparition of a superior intelligence behind the impassive arrangements of nature was more than a playful metaphor for Einstein, and the escape from selfishness through scientific thought was a principle he lived. In composing, at the request of an editor, his “Autobiographical Notes,” he concentrated almost exclusively on his thought processes, complete with equations.

Yet things happened to him; he had a life. In 1909, the University of Zurich upped an initial offer, and Einstein, “four years after he had revolutionized physics,” resigned from the patent office and accepted his first professorship. “So, now I too am an official member of the guild of whores,” he told a colleague. In 1910, Mileva gave birth to a second son, Eduard, who as he grew older developed mental illness and was to end up in a Swiss asylum. In 1911, the Einsteins moved to Prague, where Einstein accepted a full professorship at the German part of the University of Prague. Offers kept coming; in 1912 he returned to the Zurich Polytechnic, which had become a full university, the Eidgenössische Technische Hochschule. Mileva should have been happy back in Zurich, among old friends, but her health was uncertain, carrying with it depression, and continued to decline. In 1913, an invitation was personally delivered by two pillars of Berlin’s academic establishment, Max Planck and Walther Hermann Nernst, to come to Berlin as a university professor and the director of a new physics institute, and to become, at the age of thirty-four, the youngest member of the Prussian Academy. Einstein stayed in Berlin until 1932, when the combination of rising Nazism and tempting offers from America impelled him to leave Germany, never to return.

In America, Robert A. Millikan, a physicist whose experiments had verified Einstein’s photoelectrical equation, was now the president of Caltech, and he aggressively courted Einstein to come to Pasadena. However, the educator Abraham Flexner, a former officer of the Rockefeller Foundation, was in the process of establishing, with funds from the Bamberger department-store fortune, a haven for scholars named the Institute for Advanced Study, to be situated in New Jersey, next to but not affiliated with Princeton University. Einstein, intending to split his time between Europe and America, accepted the Princeton proposal. He and Elsa moved there, and in 1935, after renting for a few years, they bought a modest frame house at 112 Mercer Street, where Einstein lived until his death, in 1955.

He and Mileva had divorced, after many difficulties, in March, 1919. One of the attractions of Berlin in 1913 had been the presence of his divorced cousin Elsa Einstein. During the First World War, while Mileva stayed in Zurich with the two boys, Elsa and Einstein shared a life in Berlin—in his divorce deposition he gave the period of “intimate relations” as “about four and a half years.” After some friction (Einstein wasn’t sure that he wanted to be married at all, after the mental exertions of general relativity, but Elsa’s respectable family wanted her reputation salvaged), he and Elsa married, in June, 1919. In their “spacious and somberly furnished apartment near the center of Berlin,” with her two daughters, he seemed, a colleague remarked, “a Bohemian as a guest in a bourgeois home.” Elsa was shrewd but, unlike Mileva Marić, not scientific, which at his stage of life and eminence may have been a blessing. Einstein and women are a complicated story, and Isaacson doesn’t attempt to tell it all. There were a number of extramarital relationships; how many of them tipped from companionship into sex is, like the electron, difficult to measure. (One startling fact, according to Isaacson: beginning in 1941, Einstein was sleeping with an alleged Soviet spy, the multilingual Margarita Konenkova, though the F.B.I., which was keeping close tabs on him, never twigged.) Isaacson, a former managing editor of Time, whose previous biographies dealt with Benjamin Franklin and Henry Kissinger, writes in short paragraphs; taking up in rotation science and politics and personal developments, he has much material to compress. He notes that at Elsa’s untimely death, in 1936, “Einstein was hit harder than he might have expected,” and pronounces on their marriage:

Beneath the surface of many romances that evolve into partnerships, there is a depth not visible to outside observers. Elsa and Albert Einstein liked each other, understood each other, and perhaps most important (for she, too, was actually quite clever in her own way) were amused by each other. So even if it was not the stuff of poetry, the bond between them was a solid one.

Yet when Michele Besso, an old friend from his youth in Zurich, died, not long before Einstein’s own death, he wrote to Besso’s family that the deceased’s most admirable trait had been to live harmoniously with a woman, “an undertaking in which I twice failed rather miserably.” He was married to the universe, and gave back to people less love than he attracted. Max Born said, “For all his kindness, sociability and love of humanity, he was nevertheless totally detached from his environment and the human beings in it.”

But he loved America, and America reciprocated. Its informality, optimism, and emphasis on free speech delighted him: “From what I have seen of Americans, I think that life would not be worth living to them without this freedom of self expression.” Except for a brief trip to Bermuda as part of his application for citizenship, he never left; he never returned to Europe, let alone to Germany, whose crimes, he wrote the chemist Otto Hahn, “are really the most abominable ever to be recorded in the history of the so-called civilized nations.” To America, Isaacson says, he projected a “rumpled-genius image as famous as Chaplin[’s] little tramp.” As famous as Chaplin, he appeared, to Americans of my age, as saintly as Gandhi. Einstein’s public political life—his initially reluctant but eventually committed Zionism, his initially militant but eventually modified pacifism, his wartime patriotism (including a sponsoring role in the creation of the atomic bomb), his scorn of McCarthyism, and his good humor and amiable wit in shouldering all the causes and interviews he was asked to shoulder—contributed to American morale in the challenging years between 1933 and 1955. Having the greatest mind in the world on the premises lifted American spirits. In his own freedom of thought, the valiant Swabian demonstrated how to be free.