Video | Something From Nothing
The only "nothing" we're capable of observing is the empty space inside of our universe. We know that in empty space, virtual particles arise spontaneously. We also know that the virtual particles in empty space have more mass than all of the ordinary matter in space. Virtual particles are real physical things.
We are not able to examine "nothing" where there is no space-time. However the same physics that apply to empty space which allow virtual particles to spontaneously appear, also apply to "nothing" where there is no space-time. Quantum physics allows for space-time to appear spontaneously.
If a universe were to arise from "nothing", we would expect the total energy of such a universe to be zero to satisfy the constraints of quantum physics. It appears that the total energy of our universe is zero.