How can something come from nothing?

Since we don't have a time machine to experiment and prove a theory my response is based on our Universe as we know it's existence. Nothing is really in fact something. There has always been and will always be something in this universe, even if it appears to be nothing. Our Universe has always been "something". And in it, there are a lot of "nothing". And the nothing is derived from the help of (or some form of) something. The word Universe is usually defined as encomping everything. In a well-defined mathematical sense (quantum measurements, collapse of the wavefunction and many worlds hypotheses) even that which does not exist (all possible paths) can influence that which does finally exist. As a specific example, every electron in an atom is intrinsically identical to every other; therefore, probability amplitudes must be computed allowing for the possibility that they exchange positions, something known as exchange symmetry. This conception of the Universe embracing both the existent and the non-existent loosely parallels the Buddhist doctrines of shunyata and interdependent development of reality, and Gottfried Leibniz's more modern concepts of contingency and the identity of the indiscernible.