STAND by for a nightmare end to the Universe - a runaway expansion so violent that galaxies, planets and even atomic nuclei are literally ripped apart. The scenario could play out as soon as 22 billion years from now.
"Until now we thought the Universe would either re-collapse to a big crunch or expand forever to a state of infinite dilution," says Robert Caldwell of Dartmouth College, New Hampshire. "Now we've come up with a third possibility - the 'big rip'."
Whether the big rip happens or not depends on the nature of the mysterious dark energy that is pulling the Universe apart. We know that the expansion of the Universe is speeding up, but most physicists assume the acceleration is likely to stay constant or get weaker over time. But Caldwell takes a different view. He thinks the dark energy causing the expansion could be growing more powerful. "We ...
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