My grasp of physics is limited, however, I am an engineer, thus I am asking for other's assistance in understanding how to delay the annihilation of a virtual particle pair. Most literature I've read, indicates a virtual particle pair is "real" if only briefly. QUESTION: How long is briefly? QUESTION: Can this time frame be slightly extended? A scenario I've proposed to University professors via email and gotten nothing back follows: The intent is to provide a method of propulsion for a spacecraft. I understand this is not free energy. What I am proposing, is to utilize magnetic fields and an electric field to stimulate the creation of virtual particles, and then separate a virtual particle pair as it is created to then reunite the two "temporarily real" particles at one location. Then repeat this process to cause more annihilations to occur on one side of the device than on the opposing side. If this scenario were to be possible, would a push or thrust be experienced on the side of the device where more annihilations are occurring? Just today, I read in physics dot org an article titled 'Could the Big Bang have been a quick conversion of antimatter to matter'. This seems to dovetail into what I've propsed as a potential for using particle pair annihilation as a method of thrust. "To explain how these virtual particle-antiparticle pairs can become real ones, Hajdukovic turns to the Schwinger mechanism, which says that an electric field stronger than a critical value can create real electron-positron pairs from the quantum vacuum." QUESTION: Would it be difficult to test this type of idea? QUESTION: How large an electric field is needed?