Physicists Mikhail Lukin (Harvard) and Vladan Vuletic (MIT) claim to have invented a new form of matter: photons that act as though they have mass. I have no idea if it's true. But I am certain that Prof. Lukin knows exactly how to get media attention:
"Photonic molecules," however, behave less like traditional lasers and more like something you might find in science fiction – the light saber.
"Most of the properties of light we know about originate from the fact that photons are massless, and that they do not interact with each other," Lukin said. "What we have done is create a special type of medium in which photons interact with each other so strongly that they begin to act as though they have mass, and they bind together to form molecules. This type of photonic bound state has been discussed theoretically for quite a while, but until now it hadn't been observed.
"It's not an in-apt analogy to compare this to light sabers," Lukin added. "When these photons interact with each other, they're pushing against and deflect each other. The physics of what's happening in these molecules is similar to what we see in the movies."