Getting Real About Light Sabers

Scientists from Harvard, MIT and CIT have demonstrated that light can behave in a way previously observed only in science fiction -- that is, photons can bond and create a molecule. The fundamental properties of light derive from the fact that photons, which are the quanta of light, do not interact with one another. The scientists created a medium in which photons interact with each other so strongly that they seem to have mass. That's most easily seen by shining two beams of light at each other cross-wise -- the beams pass through one other.