 Frank Wilczek (1980), Stephen Hawking and Leonard Mlodinow (2010, 180) as well as Lawrence Krauss (2012) explicitly claim that this answers the question of why there is something rather than nothing. The basic idea goes back to an issue raised by the symmetry of matter and anti-matter. Given that the symmetry implies equality, matter and anti-matter should have annihiliated each other. Creation should have been aborted. Why is there NOW something (particles) rather than nothing (mere energy in a quantum field)? This question was answered by calculations suggesting that there was about a billionth more matter than anti-matter. Although it is still possible for the universe to be without particles, the slight numeric imbalance biases the universe toward states in which there are many particles. A small random change can trigger a phase transition analogous to the transformation of very cold liquid beer into solid beer when the cap of the bottle is popped (suddenly reducing the pressure in the bottle).