In cosmology, the end of the universe is as inevitable and inescapable as the laws of nature that predicted its birth. The observation that the expansion of the universe is accelerating came as a surprise even to the researchers who discovered it. Now, that discovery has earned the Nobel Prize in physics for 2011.
The cosmologists' vision of the ultimate end of the universe is by fire or ice, very much like the scenario portrayed in Robert Frost's poem "Fire and Ice":
Some say the world will end in fire;
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.
Of the numerous depictions about the fate of the universe, the most commonly accepted one is the Big Freeze, in which the universe will continue to expand forever, making it a cold and isolated place until the temperature reaches absolute zero. Beyond that point, molecular motion ceases and hence the existence of everything we know.
In the 1990s, two research teams, one headed by Saul Perlmutter (Lawrence Berkeley National Laboratory and the University of California, Berkeley), the other by Brian Schmidt (Australian National University at Weston Creek) and Adam Riess (Johns Hopkins University and Space Telescope Science Institute) independently confirmed the accelerating nature of the universe by studying Type Ia supernovae. They have been awarded the 2011 Nobel Prize in physics for their remarkable observation.
However, many questions still remain about the consequences of this discovery. For example, the accelerated expansion of the universe is considered to be driven by dark energy, which is an unsolved puzzle in cosmology.
Researchers predict that trillions of years into the future, the information that currently allows us to model how the universe expands will vanish from the visible horizon as galaxies drift away from each other, making it impossible for light to reach beyond their horizons. What remains will be "an island universe," comprising the Milky Way and its local neighbors in an overwhelmingly dark void.
Yet, the final destiny of the universe is written in stars -- no one disagrees.