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Re: Universe
Forum List  Follow Ups  Post Message  Back to Thread Topics  In Response To Posted by Richard/">Richard on June 8, 1999 15:34:35 UTC 
: : I was watching the Discovery Chanel the other day and they had a show on gravity and they had some scientist that found out that the universe was going to keep expanding at a faster and faster rate forever. Is this information true? : YES. Astronomers have found that the universe was expanding at a slower rate billions of years ago. From this they assume that there is a nonzero cosmological constant in the universe. This constant comes from the energy of the vacuum which is an expansive force. Knowing the constant which is a constant in the solution of Einstein's equations of General Relativity, they can determine the past and the future of the universe. Present predictions is that it will expand forever at a faster and faster rate. However, there are a number of assumptions in this prediction like that the cosmological constant remains constant for all times. So, althought the prediction is fairly likely to be true, like almost everything in science, it ain't necessarily so. Solutions to some of the equations of string theory indicate that the cosmological constant is actually a constant for all time. This is not surprising since gravitational effects are a natural product of string theory. We never can be absolutely sure, but it seems that some things are necessarily so. 

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