Here is the gist of Krauss' lecture:
The universe is flat.
The universe has zero total energy.
The universe could’ve begun from nothing.
Why is there something rather than nothing? The answer is there had to be. If you have nothing in quantum mechanics you’ll always get something. It’s that simple, but it’s true.
Quantum fluctuations produced the flat universe out of nothing.
What are Quantum fluctuations? Please note that Krauss gives no explanation to the audience concerning what the quantum fluctuations are that produced the universe out of nothing.
That said I have the definition from one of my saved links:
In the strange strange non-intuitive world of quantum mechanics some very peculiar things are allowed. Within the limits of the Heisenberg uncertainty principle, changes in mass, energy, position, momentum and time are allowed that otherwise are impossible. Although the uncertainty principle is simply stated its consequences are complex and profound. Heisenberg showed that the product of momentum and position as well as the product of energy and time cannot be known in the usual sense to a precision less than of the order of magnitude of Planck's constant which is a very small number (about 10^-34 joule sec) but not zero. Below that limit the variables above are no longer conserved. What this "means" is energy can spontaneously appear from no where so long as it does not last too long. Particles can "pop up" out of a vacuum so long as they do not have too large a mass or do not last too long. One might be inclined to dismiss all this as the wild imagination of physicists, but some things have been observed that require that interpretation. One example is black holes from which nothing, not even light, is able to escape -- well not quite. Black holes are not quite black -- they leak -- due to quantum fluctuations. So called "virtual particles" appear out of a vacuum only to disappear very quickly -- in times less than the limits set by the uncertainty principle. Richard Feynman once said that anyone who claims to understand quantum mechanics does not understand the problem!!! So on the very small scale our intuition fails us completely. The Big Bang theory of the Universe is generally accepted as the best explanation of the evolution of the Universe, but even that theory does not begin at time = 0 (exactly) but only after a infinitesimally short time later. Such is the world of quantum fluctuations.
Krauss' lecture was presented at the National Atheist convention. If anyone needs full notes on his lecture I have them.
