** Albert****Einstein **born March14,1879,Ulm,Württemberg,Germany. German-born physicist who developed the special and general theories of relativity and won the Nobel Prize for Physics in 1921 for his explanation of the photoelectric effect.Einstein is generally considered the most influential physicist of the 20th century.After graduation in 1900, Einstein faced one of the greatest crises in his life. Because he studied advanced subjects on his own, he often cut classes; this earned him the animosity of some professors, especially Heinrich Weber.Unfortunately, Einstein asked Weber for a letter of recommendation. Einstein was subsequently turned down for every academic position that he applied to. He later wrote,(**I would have found a job long ago if Weber had not played a dishonest game with me**) .

The turning point came later that year, when the father of his lifelong friend Marcel Grossmann was able to recommend him for a position as a clerk in the Swiss patent office in Bern. About then, Einstein’s father became seriously ill and, just before he died, gave his blessing for his son. For years, Einstein would experience enormous sadness remembering that his father had died thinking him a failure.

In hindsight, Einstein’s job at the patent office was a blessing. He would quickly finish analyzing patent applications, leaving him time to daydream about the vision that had obsessed him since he was 16: What would happen if you raced alongside a light beam? While at the polytechnic school he had studied Maxwell’s equation,which describe the nature of light, and discovered a fact unknown to James Clerk Maxwell himself—namely, that the speed of light remains the same no matter how fast one moves. This violates Newton’s laws of motion, however, because there is no absolute velocity in Isaac Newton’s theory. This insight led Einstein to formulate the principle of relativity:“the speed of light is a constant in any inertial frame (constantly moving frame).”

During 1905, often called Einstein’s “miracle year,” he published four papers in the *Annalen der Physik*, each of which would alter the course of modern physics: Einstein also submitted a paper in 1905 for his doctorate.Other scientists, especially Henri Poincare and Hendrik Lorentz, had pieces of the theory of special relativity, but Einstein was the first to assemble the whole theory together and to realize that it was a universal law of nature, not a curious figment of motion in the ether.

In the 19th century there were two pillars of physics: Newton’s laws of motion and Maxwell’s theory of light. Einstein was alone in realizing that they were in contradiction and that one of them must fall.

At first Einstein’s 1905 papers were ignored by the physics community. This began to change after he received the attention of just one physicist, perhaps the most influential physicist of his generation, Max Planck, the founder of the quantum theory. Soon, owing to Planck’s laudatory comments and to experiments that gradually confirmed his theories, Einstein was invited to lecture at international meetings, such as the Solvay Conferences, and he rose rapidly in the academic world. He was offered a series of positions at increasingly prestigious institutions, including the University of Zürich, the University of Prague, the Swiss Federal Institute of Technology, and finally the University of Berlin, where he served as director of the Kaiser Wilhelm Institute for Physics from 1913 to 1933.

Even as his fame spread, Einstein’s marriage was falling apart. He was constantly on the road, speaking at international conferences, and lost in contemplation of relativity. The couple argued frequently about their children and their meagre finances. Convinced that his marriage was doomed, Einstein began an affair with a cousin, Elsa Löwenthal, whom he later married. Elsa was a first cousin on his mother’s side and a second cousin on his father’s side.When he finally divorced Mileva in 1919, he agreed to give her the money he might receive if he ever won a Nobel Prize.

One of the deep thoughts that consumed Einstein from 1905 to 1915 was a crucial flaw in his own theory: it made no mention of gravitation or acceleration. His friend Paul Ehrenfest had noticed a curious fact. If a disk is spinning, its rim travels faster than its centre, and hence (by special relativity) metre sticks placed on its circumference should shrink. This meant that Euclidean plane geometry must fail for the disk. For the next 10 years, Einstein would be absorbed with formulating a theory of gravity in terms of the curvature of space-time. To Einstein, Newton’s gravitational force was actually a by-product of a deeper reality: the bending of the fabric of space and time.

In November 1915 Einstein finally completed the general theory of relativity, which he considered to be his masterpiece. In the summer of 1915, Einstein had given six two-hour lectures at the University of Gottingen that thoroughly explained an incomplete version of general relativity that lacked a few necessary mathematical details. Much to Einstein’s consternation, the mathematician David Hilbert, who had organized the lectures at his university and had been corresponding with Einstein, then completed these details and submitted a paper in November on general relativity just five days before Einstein, as if the theory were his own. Later they patched up their differences and remained friends. Einstein would write to Hilbert, One of the deep thoughts that consumed Einstein from 1905 to 1915 was a crucial flaw in his own theory: it made no mention of gravitation or acceleration. His friend Paul Ehrenfest had noticed a curious fact. If a disk is spinning, its rim travels faster than its centre, and hence (by special relativity) metre sticks placed on its circumference should shrink. This meant that Euclidean plane geometry must fail for the disk. For the next 10 years, Einstein would be absorbed with formulating a theory of gravity in terms of the curvature of space-time. To Einstein, Newton’s gravitational force was actually a by-product of a deeper reality: the bending of the fabric of space and time.

In November 1915 Einstein finally completed the general theory of relativity, which he considered to be his masterpiece. In the summer of 1915, Einstein had given six two-hour lectures at the University of Gottingen that thoroughly explained an incomplete version of general relativity that lacked a few necessary mathematical details. Much to Einstein’s consternation, the mathematician David Hilbert, who had organized the lectures at his university and had been corresponding with Einstein, then completed these details and submitted a paper in November on general relativity just five days before Einstein, as if the theory were his own. Later they patched up their differences and remained friends. Einstein would write to Hilbert,(*I struggled against a resulting sense of bitterness, and I did so with complete success. I once more think of you in unclouded friendship, and would ask you to try to do likewise toward me).*Today physicists refer to the action from which the equations are derived as the Einstein-Hilbert action, but the theory itself is attributed solely to Einstein.

Einstein was convinced that general relativity was correct because of its mathematical beauty and because it accurately predicted the precession of the perihelion of Mercury’s orbit around the Sun. His theory also predicted a measurable deflection of light around the Sun. As a consequence, he even offered to help fund an expedition to measure the deflection of starlight during an eclipse of the Sun.

Einstein’s work was interrupted by World War I. After the war, two expeditions were sent to test Einstein’s prediction of deflected starlight near the Sun. One set sail for the island of Principe, off the coast of West Africa, and the other to Sobral in northern Brazil in order to observe the solar eclipse of May 29, 1919. On November 6 the results were announced in London at a joint meeting of the Royal Society and the Royal Astronomical Society.

Nobel laureate J.J.Thomson, president of the Royal Society, stated:

*This result is not an isolated one, it is a whole continent of scientific ideas.…This is the most important result obtained in connection with the theory of gravitation since Newton’s day, and it is fitting that it should be announced at a meeting of the Society so closely connected with him.*

The headline of The Times of London read, “Revolution in Science—New Theory of the Universe—Newton’s Ideas Overthrown—Momentous Pronouncement—Space ‘Warped.’” Almost immediately, Einstein became a world-renowned physicist, the successor to Isaac Newton.

Invitations came pouring in for him to speak around the world. In 1921 Einstein began the first of several world tours, visiting the United States,England,Japan and France. Everywhere he went, the crowds numbered in the thousands. En route from Japan, he received word that he had received the Nobel Prize for Physics, but for the photoelectric effect rather than for his relativity theories. During his acceptance speech, Einstein startled the audience by speaking about relativity instead of the photoelectric effect.