Since nobody else jumped in...
To my knowledge - nobody has seen interference at slits for the electric field due to a static charge.
It does not even set off sensitive photodetectors.
The charge does not act like a source of light.
The theory is just math that gives good predictions. It does not have to match reality every step of the way... only at the endpoint. You've heard Feynman on this subject right? [1]
The weird thing here is that the virtual particles have corresponding real particles.
That just means that there is a step in the math for working out interactions that looks a lot like the math for exchanging particles. But not exactly like it.
For a decent picture you probably have to go into the field theory.
The best way to approach this concept, I believe, is to forget you ever saw the word “particle” in the term. A virtual particle is not a particle at all. It refers precisely to a disturbance in a field that is not a particle. A particle is a nice, regular ripple in a field, one that can travel smoothly and effortlessly through space, like a clear tone of a bell moving through the air. A “virtual particle”, generally, is a disturbance in a field that will never be found on its own, but instead is something that is caused by the presence of other particles, often of other fields.
##\qquad## --Strassler, M. (2011) [2]
... though there are also debates about whether the fields of Field Theory are real or the particles are real. Just search through PF for examples.
It can get philosophical very fast.
You'll find plenty of sources which
appear to take the position that virtual particles are a case of a real particle that violates conservation of energy for such a short time the Universe doesn't notice. For instance:
these high-energy force-carrier particles may exist if they are short lived. In a sense, they escape reality's notice.
##\qquad##-- Barnett et al. [3]
... which can be confusing.
A useful rule of thumb is that it is not real unless you can detect it (at least in principle) - the rest is maths.
That should provide enough for others to disagree with ... I would hope that people will provide their own citations to back up their comments ;)
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[1] Feynman R. (1979)
Nuts, Counting, and Physics - excerpt from the Douglass Robb Memorial Lectures given at the University of Auckland. The complete set [url=http://vega.org.uk/video/subseries/8]are compulsory viewing for anyone contemplating particle physics.
Just because, in QED, you have to compute a probability amplitude for every possible path does not mean that one particle actually travels every possible path. OTOH it is possible to exploit the idea to great effect.
[2] Strassler M. (2011)
Virtual Particles: What are they?
Matt Strassler is a visiting scholar at Harvard University, and until recently a full professor at Rutgers University.
[3] Barnett et al (no date) http://pdg.web.cern.ch/pdg/cpep/unc_vir.html
The "Particle Adventure" resources are sponsored by the Particle Data Group of the at Lawrence Berkeley National Laboratory under the aegis of Michael Barnett.
