I can't remember where I've read it (I think it was in a popular book by Brian Greene) but it was written that there is a chance that a cola bottle can appear from nothing due to quantum fluctuations. The chance is very small though, to say the least. Now I'm not sure if the bottle lasted for a long time. I think that this was not supposed, as the book was written by a renowned theoretical physicist. And he should know that even a real, lasting electron can't appear from the vacuum if no energy is added. But is it possible that a virtual cola bottle configuration of elementary particles is there for a very short while? I can't imagine this, though I can imagine that a proton or an atomic nucleus can appear as a "coherent" quantum fluctuation.
The existence of a Planck time probably prohibits this, but if we don't take that into account, is it possible?
In other words, can we see short-lived appearances of whatever macroscopic object inside the quantum vacuum? By shortlived, I mean the minimum time required for an elementary particle-antiparticle to appear. Can't you always "see" (you caný actually see virtual particles but by adding energy they can be made real) macroscopic structures in the vacuum?