Interesting paragraphs.........................

     From the quantum point of view, a zero-energy universe presents an interesting possibility, which Tryon seized upon.  Suppose the total energy of the universe is exactly zero.  Then, owing to the trade-off in uncertainty between energy and time (as decreed by the Heisenberg principle) the indeterminacy in its time span becomes infinite.  In other words, such a universe, once it popped into existence out of the void, could run away with itself and last forever.  It would be like a loan of pure being that need never be repaid.  As for what "caused" such a universe to pop into existence, that is simply a matter of quantum chance.  "In answer to the question of why it happened,"  Tryon later commented, "I offer the modest proposal that our universe is simply one of those things which happen from time to time."
-Jim Holt,  Why Does The World Exist?:  An Existential Detective Story