Today a heavy Post, you will see…
String theory suggests that the big bang was not the origin of the universe but simply the outcome of a preexisting state
By Gabriele Veneziano
Image: ALFRED T. KAMAJIAN
The ancient Greeks debated the origin of time fiercely. Aristotle, taking the no-beginning side, invoked the principle that out of nothing, nothing comes. If the universe could never have gone from nothingness to somethingness, it must always have existed. For this and other reasons, time must stretch eternally into the past and future. Christian theologians tended to take the opposite point of view. Augustine contended that God exists outside of space and time, able to bring these constructs into existence as surely as he could forge other aspects of our world. When asked, “What was God doing before he created the world?” Augustine answered, “Time itself being part of God’s creation, there was simply no before!”
Image: SAMUEL VELASCO
Strings abhor infinity. They cannot collapse to an infinitesimal point, so they avoid the paradoxes that collapse would entail.
Einstein’s general theory of relativity led modern cosmologists to much the same conclusion. The theory holds that space and time are soft, malleable entities. On the largest scales, space is naturally dynamic, expanding or contracting over time, carrying matter like driftwood on the tide. Astronomers confirmed in the 1920s that our universe is currently expanding: distant galaxies move apart from one another. One consequence, as physicists Stephen Hawking and Roger Penrose proved in the 1960s, is that time cannot extend back indefinitely. As you play cosmic history backward in time, the galaxies all come together to a single infinitesimal point, known as a singularity–almost as if they were descending into a black hole. Each galaxy or its precursor is squeezed down to zero size. Quantities such as density, temperature and spacetime curvature become infinite. The singularity is the ultimate cataclysm, beyond which our cosmic ancestry cannot extend.
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To be specific, consider what has happened over the 13.7 billion years since the release of the cosmic microwave background radiation. The distance between galaxies has grown by a factor of about 1,000 (because of the expansion), while the radius of the observable universe has grown by the much larger factor of about 100,000 (because light outpaces the expansion). We see parts of the universe today that we could not have seen 13.7 billion years ago. Indeed, this is the first time in cosmic history that light from the most distant galaxies has reached the Milky Way.
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Evolution of a Revolution
Today two approaches stand out. One, going by the name of loop quantum gravity, retains Einstein’s theory essentially intact but changes the procedure for implementing it in quantum mechanics [see “Atoms of Space and Time,” by Lee Smolin; Scientific American, January]. Practitioners of loop quantum gravity have taken great strides and achieved deep insights over the past several years. Still, their approach may not be revolutionary enough to resolve the fundamental problems of quantizing gravity. A similar problem faced particle theorists after Enrico Fermi introduced his effective theory of the weak nuclear force in 1934. All efforts to construct a quantum version of Fermi’s theory failed miserably. What was needed was not a new technique but the deep modifications brought by the electroweak theory of Sheldon L. Glashow, Steven Wein-berg and Abdus Salam in the late 1960s.
The second approach, which I consider more promising, is string theory–a truly revolutionary modification of Einstein’s theory. This article will focus on it, although proponents of loop quantum gravity claim to reach many of the same conclusions.
Ekpyrotic Scenario
Vestiges of the pre-bangian epoch might show up in galactic and intergalactic magnetic fields.
what did i say, read the Full Story at Scientific American.com
very good Story…, and read all 5 Pages.
Sir Ulli