"Furthermore, a real electron attracts virtual positrons and repulses virtual electrons, in accordance with the law we learned in school: electric charges of like kind repel each other, while charges of unlike kind attract each other. As a result the vacuum is polarized because the charges in it are separated in space. An electron surrounded by a layer of virtual positrons turns out to be behind a real screen of such particles. This reduces the so-called effective charge of the electron manifested in its interactions with other particles. The polarization of vacuum, as will be evident further on, is a process that should play an exceptionally important role in many physical events.
Each elementary particle, physicists believe today, travels in company with a whole retinue of virtual particles. Dmitri Ivanovich Blokhintsev, associate member of the USSR Academy of Sciences, wrote: "... As a result of the polarization of a vacuum, a charged 'atmosphere' is set up around a charged particle and is linked to this particle"." [Something Called Nothing]