I take it this means you don't know what the Casimir effect is then? It has been raised three times now in this thread and even your direct reply to a post mentioning the Casimir effect totally fails to address whether it shows the existence of virtual particles as a real phenomenon rather than a theoretical construct.
The existence of virtual particles doesn't neccessarily mean there is no such thing as cause and effect, but what underlying causes there are to virtual pair formation may reside within the very structure of the universe itself and well below our current ability to resolve.
TTFN,
WK