I don't think we have covered that. Thanks for checking!
A sonic boom arises when an object travels through a medium (say air) faster than sound speed in the air. This causes sound waves emitted at different times to overlap, building up into the boom. To get something light that for light, you'd need a particle which interacts strongly with light to travel through a medium faster than the speed of light in the medium. Since the speed of light in a medium is lower than the universal speed limit, c, that's possible. An example would be a very energetic proton (charged) traveling through a piece of glass. The boom-like radiation that's emitted is called Cherenkov radiation. () It's used quite a bit in particle detectors.
As for the cosmic questions, no, it's not connected. The expansion of the universe doesn't consist of something moving through some medium. Near some part of the universe, that's all there is. So there's no boom-like effect. The "faster than light" part does describe the growth of the spatial coordinate of something in our conventional coordinate frame, but it doesn't describe the motion of something as seen by its neighbor.
As for Krauss' "something from nothing", that idea has stimulated a great deal of philosophical argument. So far as I can see, the argument is semantic, just concerning what people are willing to call "nothing".
Mike W.
(published on 07/30/2012)