The finding potentially rules out the standard theory of "Cold Dark Matter" where dark matter interacts only with gravity.The team found that one dark matter clump appeared to be lagging behind the galaxy it surrounds.The clump was currently offset from its galaxy by 5,000 light years (50,000 million million km) a distance that would take NASA's Voyager spacecraft 90 million years to travel.Such an offset is predicted during collisions if dark matter interacts, even very slightly, with forces other than gravity.

Computer simulations show that the extra friction from the collision would make the dark matter slow down, and eventually lag behind.Scientists believe that all galaxies exist inside clumps of dark matter called "dark" because it is thought to interact only with gravity, therefore making it invisible."We used to think that dark matter sits around, minding its own business.

The team made the discovery using the Hubble Space Telescope and the European Southern Observatory's Very Large Telescope to view the simultaneous collision of four distant galaxies at the centre of a galaxy cluster 1.3 billion light years away from the Earth.

Latest News from Lifestyle News Desk