Quantum mechanics applies to atomic and subatomic particles, it is related to Heinburgs principal:

This big bang theory consists of the fact that quantum fluctuations are not caused by anything, they are spontaneous which is vital to nature and could explain how the universe could suddenly exist out of 'nothing'.

A quantum vacuum is a very active place where all sorts of particles are appearing and then disappearing. Heinberg's principle led physicists to predict that particles could spontaneously appear in a vacuum as long as the disappear before violating the principal.. Experiments have demonstrated that these quantum theories are correct in the interpretation of the vacuum.