Word: spaced
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Dates: during 1990-1999
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Einstein's general theory of relativity transformed space and time from a passive background in which events take place to active participants in the dynamics of the cosmos. This led to a great problem that is still at the forefront of physics at the end of the 20th century. The universe is full of matter, and matter warps space-time so that bodies fall together. Einstein found that his equations didn't have a solution that described a universe that was unchanging in time. Rather than give up a static and everlasting universe, which he and most other people believed...
General relativity also predicts that time comes to a stop inside black holes, regions of space-time that are so warped that light cannot escape them. But both the beginning and the end of time are places where the equations of general relativity fall apart. Thus the theory cannot predict what should emerge from the Big Bang. Some see this as an indication of God's freedom to start the universe off any way God wanted. Others (myself included) feel that the beginning of the universe should be governed by the same laws that hold at all other times...
...doing, Einstein hoped also to resolve the conflict between two competing visions of the universe: the smooth continuum of space-time, where stars and planets reign, as described by his general theory of relativity, and the unseemly jitteriness of the submicroscopic quantum world, where particles hold sway...
...know now, however, that it is Einstein's theory that ultimately fails. On extremely fine scales, space-time, and thus reality itself, becomes grainy and discontinuous, like a badly overmagnified newspaper photograph. The equations of general relativity simply can't handle such a situation, where the laws of cause and effect break down and particles jump from point A to point B without going through the space in between. In such a world, you can only calculate what will probably happen next--which is just what quantum theory is designed...
Replacing particles with strings eliminated at least one problem that had bedeviled scientists trying to meld general relativity and quantum mechanics. This difficulty arose because space lacks smoothness below subatomic scales. When distances become unimaginably small, space bubbles and churns frenetically, an effect sometimes referred to as quantum foam. Pointlike particles, including the graviton, are likely to be tossed about by quantum foam, like Lilliputian boats to which ripples in the ocean loom as large waves. Strings, by contrast, are miniature ocean liners whose greater size lets them span many waves at once, making them impervious to such disturbances...