With this assumption in hand, the team recalculated what the centre of a black hole might look like. To simplify their equations, they used only two dimensions instead of the three dimensions of space and one of time that exist in our Universe. In a two-dimensional system, they found that the singularity vanished and was replaced by a bizarre region where quantum fluctuations ran wild.

Space-time in that part of the hole would become so unpredictable that all conventional ideas of cause and effect would break down. "Classical intuition fails in that region, but quantum mechanics is definitely happy," says Ashtekar, who will report the results in the 20 May issue of Physical Review Letters 1.

If black holes behave in the way Ashtekar predicts, information will never be lost and quantum mechanics will continue to function, even in the extreme environment beyond the event horizon.