High-energy cosmic-ray particles from space may create black holes when they collide with molecules in the Earth’s atmosphere, say physicists.

These black holes would be invisibly small (only 10 micrograms or so) and would be so unstable that they would explode in a burst of particles within around a billion-billion-billionth of a second.

If such tiny black holes exist, it would unveil hidden dimensions in our universe and would also show that the CERN particle physics laboratory near Geneva will be able to create thousands of black holes every day by 2007.