Matter Should Dominate the Universe Forever
http://www.universetoday.com/

April 25th, 2007 by Fraser Cain

Thanks to Einstein, we know that matter and energy are just different
versions of one another. E=mc^2 tells you how much energy you'd get
if you converted mass into energy. Don't try, it's hard. Physicists
were concerned that all matter in the Universe would eventually decay
into radiation after trillions and trillions of years of time.

But the impact of dark energy, a mysterious force accelerating the
expansion of the Universe, might change those predictions for the
fate of matter. Physicists Lawrence Krauss and Robert Scherrer
recently published a paper in the journal Physical Review D that
predicts that the radio between matter and radiation should remain
roughly the same as dark energy continues to spread the Universe
apart.

Right now we can see most of the Universe, but as it continues to
expand, distant objects will appear to be moving away from us faster
than the speed of light, and will disappear from view. In 10 trillion
years from now, only our local cluster of galaxies will be visible.
Krauss and Scherrer have calculated that new radiation created from
decaying matter will be diluted as soon as it's created, thanks to
dark energy.

As particles decay into radiation, the dark energy will increase the
separation between photons, decreasing their energy and density in
the Universe. The clumps of matter that remain will still dominate.

See: http://www.universetoday.com/