Science Story

02 December 2008 22:30 BST

Flowing water used to help explain black holes

Scientists have used flowing water to simulate black holes in the hope of better understanding their composition.

Researchers from the universities of St Andrews and Nice used a water channel to create analogues of black holes to simulate event horizons.

An event horizon within the water channel was declared as the place in the channel where the water began to flow faster than the waves.

Over a period of time scientists sent waves of varied speed and wavelength against the water current and filmed the results, the report in the New Journal of Physics explains.

The footage was then examined to prove or disprove Stephen Hawking's famous prediction that event horizons create particles and anti-particles.

Professor Ulf Leonhardt, from the School of Physics and Astronomy, said: "It is probably impossible to observe the Hawking radiation of black holes in space, but something like the radiation of black holes can be seen on Earth, even in something as simple as flowing water."

Scientists claim that with a black hole, space flows faster the closer you get to it and with an event horizon, space reaches the speed of light, so nothing - not even light - can escape from it.

"Flowing water does not create anti-particles, but it may create anti-waves. Normal waves heave up and down in the direction they move, whereas anti-waves do the opposite," Professor Leonhardt said.

"We definitely have observed these negative-frequency waves.

"These waves were tiny, but they were still significantly stronger than expected. However, our experiment does not completely agree with theory and so much work remains to be done to understand exactly what happens at the event horizon for water waves."