Word: worlds
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Dates: during 1990-1999
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...have his own personal time. The clocks of two people would agree if they were at rest with respect to each other but not if they were moving. This has been confirmed by a number of experiments, including one in which an extremely accurate timepiece was flown around the world and then compared with one that had stayed in place. If you wanted to live longer, you could keep flying to the east so the speed of the plane added to the earth's rotation. However, the tiny fraction of a second you gained would be more than offset...
Among the consequences of this law is that if the nucleus of a uranium atom fissions (splits) into two nuclei with slightly less total mass, a tremendous amount of energy is released. In 1939, with World War II looming, a group of scientists who realized the implications of this persuaded Einstein to overcome his pacifist scruples and write a letter to President Roosevelt urging the U.S. to start a program of nuclear research. This led to the Manhattan Project and the atom bomb that exploded over Hiroshima in 1945. Some people blame the atom bomb on Einstein because he discovered...
...Newton's head because of gravity or that Newton's head hit the apple because he and the surface of the earth were accelerating upward. This equivalence between acceleration and gravity didn't seem to work for a round earth, however; people on the other side of the world would have to be accelerating in the opposite direction but staying at a constant distance from...
With the help of his friend Marcel Grossmann, Einstein studied the theory of curved spaces and surfaces that had been developed by Bernhard Riemann as a piece of abstract mathematics, without any thought that it would be relevant to the real world. In 1913, Einstein and Grossmann wrote a paper in which they put forward the idea that what we think of as gravitational forces are just an expression of the fact that space-time is curved. However, because of a mistake by Einstein (who was quite human and fallible), they weren't able to find the equations that related...
...quantum laws because they showed excellent agreement with observations and because they seemed to explain a whole range of previously unaccounted-for phenomena. They are the basis of modern developments in chemistry, molecular biology and electronics and the foundation of the technology that has transformed the world in the past half-century...