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Future Skies

August 30, 2011

The year one trillion is a long way off. But an astronomer at Harvard says that if there are any scientists around then, they'll still be able to deduce the basic properties of the universe -- thanks to the black hole at the center of the Milky Way.

We know that the universe is expanding, because we see that most other galaxies are moving away from ours -- a result of the Big Bang. And the expansion is getting faster. Within a hundred billion years, all galaxies except the few that are close to the Milky Way will be speeding away so fast that astronomers won't be able to see them. Because of that, no one in that far distant time should be able to tell that the universe is expanding.

But Abraham Loeb thinks otherwise. Every now and then, a binary system -- two stars that are orbiting each other -- skirts past the supermassive black hole at the galaxy's heart. One star falls toward the black hole, while the other shoots away from the black hole at high speed.

Even a trillion years from now, the black hole will still be hurling stars out of the galaxy. Once those stars are a few million light-years out, Loeb calculates, the universe's expansion will speed them up. From that, astronomers who monitor the stars should be able to deduce that the universe is expanding and that the expansion is getting faster. If so, then future astronomers will be able to "see" that there's a big, wide universe out there -- even if they can't see it at all.


Script by Ken Croswell, Copyright 2011


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