Einstein: His Life and Universe By Walter Isaacson Simon and Schuster 641 pages; $35 Albert Einstein, arguably the most famous scientist of all time, was, all in all, a very nice man, a liberal, a pacifist (except in the case of resistance to Nazi Germany) and no respecter of authority. He was a competent violinist who played for royalty and also a charmer of no small wit. But, above all, he was the largely self-taught thinker who gave physics its lasting foundation stone, the general theory of relativity. There are more than 600 books about Einstein and his theories about relativity, the nature of time and the relationship between mass and energy. The elegance and significance of his deceptively simple - and thus eminently quotable - equation, E=mc2 (energy equals mass times the speed of light squared, a huge number) was only fully understood when the first atom bombs released enormous amounts of energy from just a few kilos of enriched uranium. The first book I read about Einstein's science was Bertrand Russell's The ABC of Relativity, which I purchased more than half a century ago. Decades later, I read the first successful popular biography of Einstein, written by Ronald Clark, published in the 1970s. This new biography by Walter Isaacson is the first since all the Einstein papers have come into the public domain and throws much light on Einstein the man, husband, awkward father and late-life Lothario. But it is equally about his science, carefully vetted by young scientists like Columbia's Brian Greene, whose own books about the universe, relativity, particle physics and string theory are masterpieces of clarity. Einstein had little faith in quantum physics and was out of step with most leading physicists. He would, I think, have hated string theory, which, with its 16 dimensions, cannot be verified. It exists only in its equations. Einstein did not initially think in equations. His youthful math was good, but only up to a point. He achieved his amazing breakthroughs in his famous annus mirabilis of 1905 without instruments, without a lab and without much math. Instead, he conducted solitary thought experiments. But he lacked the math he needed to resolve his ideas of general relativity and eventually turned for help to mathematicians like Marcel Grossmann, the man who had found him a living as an examiner in a Swiss patent office. Einstein was to spend most of the rest of his life scribbling equations, even when drifting in his little sailboat (where he could be quite alone) in an unsuccessful search for a unified field theory. Einstein was fascinated by fields ever since he was a small boy, when he was given a magnetic compass. He was soon to show that the gravitational fields of our sun and planets distort the shape of space around them, so that they roll through their prescribed orbits along the distortions. But while we can observe the effects of gravity at work, gravity itself remains a mystery. A gravity particle is yet to be found. He predicted that light passing close to the sun would be "bent" by the gravity of its mass. The photo observations of the displacement of stars visible behind the sun's rim, made by Sir Arthur Eddington during Mercury's eclipse of the sun in 1919, revealed that the bending of the light accorded exactly to Einstein's predictions of 1.7 arc seconds. The press, led by The New York Times, was enthused. Almost overnight, Einstein, previously held in high regard by just a small coterie of scientists, was suddenly world famous, the Yoda of the universe. The kindly absent-minded professor, no threat to anyone, was widely perceived as the master of the cosmos. His name was a synonym for brilliance. EINSTEIN ENJOYED his fame without ever letting it go to his head. It was reported that he never wore socks, so playing up to his image as an absent-minded genius, he made sure that he never wore any. He also enjoyed the groupies who came to see him in his modest Princeton home and was happy to pleasure them. His most durable extramarital lover was a notably beautiful married woman; neither Einstein nor the Keystone Kops of the FBI were aware that she was, among other things, a Russian spy. Einstein's family life was a little more disordered than his universe. In 1903 he married a Serbian gentile, the budding physicist Mileva Maric, with whom he had previously had a daughter out of wedlock. The illegitimate infant, in those days a bar to their obtaining any academic post, was given away and evidently soon died. The Einsteins then produced two legitimate sons. Mileva, who was both lame and plain, was embittered by her looks and lack of creativity as a physicist. Einstein soon left her behind. When she finally agreed to a divorce, Einstein, in addition to providing support to her and the boys, also promised her the Nobel Prize money he was sure that he would win. He kept his promise. He did not keep his sons. The embittered Mileva saw to that. The sickly younger son, Eduard, died in a mental institution. The elder, Hans Albert Einstein, born in 1904, became a successful professor of civil engineering and was reunited with his father in his old age. Einstein had made a comfortable home by exchanging Mileva for his divorced cousin Elsa, who had two daughters. Elsa, proud to be married to "the cleverest man in the world," catered to all his demands and put up with his groupies. When she fell ill, Einstein nursed her with love and was distraught when she died. As a boy, Einstein was horrified by the lockstep parades of the kaiser's troops. As a youth, he went to Switzerland and divested himself of German citizenship. At the Zurich Polytechnic, his intellectual impudence annoyed his professors and he did not get a recommendation for a teaching post. But in a single year, 1905, while working as an examiner (third class) of patent applications, the 26-year-old published five papers in Annalen der Physik that were read and understood by only a few scientists but which were to shake the world. The paper on special relativity (it took Einstein nearly another decade to turn it into a general theory) did away with the notion of absolute time; Einstein demonstrated that it could change with the location and speed of the observer. Relativity soon did away with Newton's physics, which worked only locally; and with theories of an ether. The other papers asserted that mass and energy were manifestations of the same thing; that light, the speed of which was constant, came in both waves and discrete packets of particles; that the Brownian motions of motes in a fluid were caused by unseen molecules; and that it was possible to calculate exactly the number of water molecules (another vast number) in a given number of liters of water. Einstein finally became a professor in Zurich but was forced to reaccept German citizenship when he at last became a professor at a German university. But in 1933, at 54, Einstein and Elsa left Germany for good and settled in Princeton, where he was given a post at the Institute of Advanced Studies. His baggy clothes and wild hair became a symbol of his lack of pretense. Children stopped him on the street to ask for help with their homework. He never refused them. Einstein's innate distrust of quantum theories continued to needle good friends like the Danish physicist Niels Bohr and Germany's Werner Heisenberg. He got nowhere in his lifelong quest for a unified field theory. But in the early '30s he did, however, work (by mail) with the brilliant Indian physicist Satyendranath Bose, who had devised a set of statistics for quantum particles. Einstein realized that the method could be applied to atoms and was soon able to demonstrate how atoms crashed to their lowest energy levels at very low temperatures. He thus devised what is known as the Bose-Einstein Equations which indicate that all atoms are basically similar. Einstein's warning to president Franklin D. Roosevelt that the free world must not lose the race to build an atomic weapon resulted in the Manhattan Project. Einstein did not contribute to it; the FBI, though it had nothing on him apart from a vicious letter from an influential woman who did not know him, would not have given him a security clearance. Einstein did not believe in a personal God and I suspect his references to Der Alte (the Old One) were merely a shield against being branded an atheist. Yet he felt a great sense of kinship with Jews and, partly thanks to Hitler, became a Zionist. He loathed Judah Magnes and kept his distance from Jews who wanted to manipulate or exploit him. Wisely, he turned down David Ben-Gurion's offer to be the second president of Israel. B-G was relieved. Einstein loved America and America loved him. After gaining citizenship, he never left it. He was applauded for his stand on McCarthyism but was criticized for appealing against the death sentence of the Rosenbergs. At every turn, Einstein preached moderation. In 1948 he learned that he had an aneurysm in his abdominal aorta but declined further surgery. It burst in April 1955, just as Einstein decided, at 76, that he had lived enough: "I want to go elegantly." At his bedside were his son and a draft of an undelivered address marking Israel's Independence Day. It began, "I speak to you today not as an American citizen and not as a Jew, but as a human being..." Author Isaacson, a former managing editor of Time magazine and currently CEO of the Aspen Institute, has written a loving biography of a very special humanist. Isaacson even tells the story of the bizarre folderol of the theft of Einstein's brain.