Virtual Particles and the Speed of Light
Do virtual particles travel faster than light?
I think the simple answer is that it depends on whether or not the
virtual particle has mass. If it is massless, then it would have a
velocity of the speed of light. If it has mass, then it would travel
as some speed less than that of light. If they could travel faster
than light (or if massive ones could travel at the speed of light),
then I would expect some really bizarre breaking of causality and energy
Virtual particles are invoked in modern field theory as a way of
describing how real particles interact. The simplest intuitive idea
is that if these particles were traveling at faster than light speeds,
then there would be severe cause and effect problems.
Michael S. Pierce
Click here to return to the Physics Archives
Update: June 2012