Is it true that virtual particules pop into existence uncaused?
Let's put it this way: they do not violate causality, because causality has a limited domain. Causation is a probabilistic affair, and the Heisenberg Uncertainty Principle makes sure that there is always room for fluctuations without violating the laws of physics. Even more so: much of what we deem causation is directly due to the appearance and disappearance of virtual particles, since a number of forces are carried by them. (In any case, virtual particles popping into existence will usually pop out of existence quickly enough, although there are instances in which a virtual particle can become real.)
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