Astronomers find evidence of mysterious 'dark forces'

Astronomers have discovered a mysterious phenomenon that is making the Universe expand at an ever-faster rate.

Astronomers have discovered a mysterious phenomenon that is making the Universe expand at an ever-faster rate.

In a series of experiments using the Jodrell Bank observatory in Cheshire, a team of British and American scientists has confirmed the existence of "dark energy" by measuring the amount of light from distant star-like objects that is bent by this hidden force during its long journey through space.

"Unfortunately, we don't have the faintest idea what this dark energy is," said Ian Browne, a senior member of the research team at the University of Manchester.

Cosmologists have known for some time that about 90 per cent of the mass of the Universe is missing because it cannot be seen by telescopes. They call it "dark matter" but its existence cannot explain the anti-gravity forces causing the universe to expand at an accelerating rate.

To try to account for the expanding universe, scientists came up with the idea of dark energy forcing stars and galaxies apart. Now the team at Jodrell Bank has found hard evidence of this dark energy by looking at distant quasars, quasi-stellar objects emitting intense amounts of radiation.

The additional dark energy is causing about twice as much light from quasars in space to be bent as would occur if the gravity from visible and dark matter was the only force at work. "It is now looking as if we need this extra ingredient of dark energy. It's quite embarrassing that we are not able to come up with any idea about what it is," Dr Browne said.

Dark energy only affects the properties of the Universe over very large distances, which has made it hard for astronomers to study it using more conventional techniques of optical telescopes. But by using "gravitational lensing", in which light and radiation from distant objects are distorted by the gravitational pull of an intermediate object, the astronomers were able to discriminate between the forces of gravity.