Why always so wrong
Ah, Scientific American (is that an oxymoron btw)?
a cloud of virtual particles around them that continually sweep in and out of existence
If they are virtual particles, they don't "sweep in and out of existence" (what does that even mean? is there a revolving door?). They never sweep "into existence" but you have to consider them in your integrations as if they were actually there, but weighted by their complex-valued probability (inversely proportional to their mass for a given dt and all cases subject to quantum number conservation) That's the trick.
Somewhat like the intermediary results in a classical computation reusing the same memory while working towards a result.
Doing it in one cycle.
And that is because Nature loves to do idle integration exercises to while away the time.