virtual particles

[Marcin Hajduk]

Hello!

I've got (perhaps silly) a short question. Vacuum is fulfilled by virtual
particles (especially photons - I suppose). According to Heisenberg
uncertainty principle - dE*dt>h/4*Pi or something like that. So virtual
particle with energy dE exist dt seconds (in case there's no other particles 
nor magnetic field which could give for the virtual photon enough of energy
to make it real). But energy of virtual particles is real. So can it
influence on evolution of Universe? Can virtual particles appear in all
points of space simultaneously?

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