It's been a decade since astronomers discovered most of the universe. It's known as dark energy -- a mysterious force that makes up about 70 percent of all the matter and energy in the universe, and that is causing the universe to expand faster as it ages. And then again, maybe it's not. University of Texas astronomer Karl Gebhardt explains:
GEBHARDT: We think we have an idea of how the universe is supposed to expand, and so when we try to measure how fast the universe is actually expanding, it's wrong -- it's actually expanding faster than we think it should be. And that's what we call dark energy. It may not be dark, and it may not be energy. All it is is our ignorance of how the universe is expanding, and we don't know what it is at this point.
Scientists do have some ideas, though. Dark energy could spring from the vacuum of space itself. As the universe expands, there's more space, so dark energy gets stronger. Or it might take the form of new particles or fields. And then again, it might just be that our understanding of gravity is off -- that gravity changes as the universe gets bigger.
Whatever the explanation, it will tell us about how the universe was born, how it's aged, and how it will end. As Texas astronomer Gary Hill explains:
HILL: No matter what happens, any solution to dark energy is going to end up meaning fundamental change in the way we look at physics. The laws of nature will change as a result of explaining this.
More about dark energy tomorrow.
Script by Damond Benningfield, Copyright 2008
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