*
New Scientist *reports on an intriguing suggestion by South Korean physicist Jae-Weon Lee: Maybe the mysterious dark energy that seems to be forcing the universe to accelerate its expansion stems from the universe's own resemblance to a black hole.
Quantum physics predicts that empty space is in fact full of a froth of so-called virtual particle pairs, winking into existence for a moment before being annihilated by their virtual antiparticle. But say these particles were to appear one on either side of a black hole's event horizon – the radius at which gravity is so strong that not even light can escape. Then they would essentially be stuck in the real universe, unable to meet and destroy each other, with the outer twin radiating away from the black hole in a phenomenon known as Hawking radiation.
Lee and his team note that that the observable universe has something analogous to this event horizon, called the "cosmological horizon," the
New Scientist article explains. This is essentially the distance, constantly expanding, at which light sources are too far away for the light to have reached us in the time since the universe's beginning.
The Korean group has calculated the amount of energy that would be generated by particles winking into existence split by this cosmological horizon, and believe it matches the amount of energy needed to explain the acceleration of the universe's expansion.
It's a tricky concept to get the mind around, like dark energy (energy with observable effect on the universe's expansion rate, but so far undetectable by humans) itself. But according to the magazine, it is prompting interest among other physicists, and might even be testable once Europe's Planck satellite launches next year to test the background radiation left over from the
Big Bang.
'Black-hole universe' might explain dark energy [New Scientist (subscription required)]
(Image: Illustration of a black hole's immediate vicinity. Credit: NASA)
