A particle that is too small to be seen directly but can be detected by its effects on other particles.
Virtual particle Term Timeline in A Brief History of Time
The timeline below shows where the term Virtual particle appears in A Brief History of Time. The colored dots and icons indicate which themes are associated with that appearance.
...space is not actually empty—there are certain minimum fluctuations and uncertainty. Pairs of particles and virtual particles will appear and collide, annihilating each other. One will have positive energy, the other negative.... (full context)
...in certain areas as long as the universe’s overall balance is positive. Scientists have detected virtual particles from observing the different pressures applied to metal plates created by discrepancies of the density... (full context)
...not been proven. The idea goes, when space-time is warped enough to allow time travel, virtual particles moving in closed loops become real particles moving forward in time, adding to the overall... (full context)