Another amazing fact, it is believed that the sum total of all energy in the universe is a big fat zero. It is theorized that as the universe expands the existing energy will dissipate to the point that it is on the level of the quantum fluctuations at which point it will be practically "nothing". Us, the Earth , the Carbon, Iron, Oxygen and Nitrogen that make up planets and nebula of the galaxy, the entire universe is nothing more than the remnants of an energy echo sent 13.5 billion years ago in the initial bang. The evolution of the universe is an expression of that energy as it evolves over time, if it is true that the Universe will continue to expand and in fact accelerate with age it will accelerate to a state of "nothing". Over the arch of observation that attended its creation, expansion and evolution and eventual death in a cold whimper it will be conserving energy as over that arc the sum of what was and what was not will still be zero. Incredibly cool isn't it? Recent evidence suggests that our Universe may have been created in a process called Inflation (theorized by Andre Linde in the early 80's) the idea is that our universe is a bubble in an ever roiling multiverse infinitely extended, a white noise of universes being created, evolving and dying forever...not unlike what we see in the zero point energy, an endless roiling of empty space. The beauty of this symmetry of the immensely large and the immensely small is hardly an accident in my view.
So something (virtual particles) can indeed come from "nothing" (empty space) and elicit real effects (Casimir Effect , dissolving black holes) on the Universe. In this, the physics definition of "nothing" is statistically the white noise of the zero point energy, which is as "nothing" as anything can get in space time. When I first learned of this correlation between reality and the equations of quantum mechanics I had one of the most incredible feelings in my life, that the probabilistic equations could give rise to such a prediction (vacuum fluctuations) of the very base nature of space itself was astonishing to me.