The Matrix, 4

However, the longer a virtual particle exists, the more closely it adheres to the mass-shell relation. A “virtual” particle that exists for an arbitrarily long time is simply an ordinary particle.

However, all particles have a finite lifetime, as they are created and eventually destroyed by some processes. As such, there is no absolute distinction between “real” and “virtual” particles. In practice, the lifetime of “ordinary” particles is far longer than the lifetime of the virtual particles that contribute to processes in particle physics, and as such the distinction is useful to make.

— Wikipedia on Virtual particle

The difference between the real world and a virtual world is that reality lasts longer. 

— Me@2013.06.20

2013.06.21 Friday (c) All rights reserved by ACHK