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Repulsive Force Discovered In Light
Aurispector writes in with news that the Yale team that recently discovered an attractive force between two light beams in waveguides has now found a corresponding repulsive force. "'This completes the picture,' [team lead Hong] Tang said. 'We've shown that this is indeed a bipolar light force with both an attractive and repulsive component.' The attractive and repulsive light forces Tang's team discovered are separate from the force created by light's radiation pressure, which pushes against an object as light shines on it. Instead, they push out or pull in sideways from the direction the light travels. Previously, the engineers used the attractive force they discovered to move components on the silicon chip in one direction, such as pulling on a nanoscale switch to open it, but were unable to push it in the opposite direction. Using both forces means they can now have complete control and can manipulate components in both directions. 'We've demonstrated that these are tunable forces we can engineer,' Tang said."
I always thought lightsabers don't work so much on the notion of light as the convergence of energy and solid matter where energy becomes matter and matter becomes energy explaining why lightsabers cast a shadow and why training lightsabers don't cut. (And also why there are light bridges that are mentioned but never seen in star wars.) It just happens that light is given off in this mashup of state changes.
Actually, they cast a shadow because the actors are really holding flash gun handles with white sticks in them, and the blades are rotoscoped on later. Yup, they were just too lazy to get rid of the shadows/film at angles to avoid them.
Here is a very good paper that might give you some insight.
http://www.opticsinfobase.org/DirectPDFAccess/7CB1DC52-BDB9-137E-C347E05AD6F7E2D4_84895.pdf?da=1&id=84895&seq=0&CFID=48237375&CFTOKEN=15548595
"Angular momentum of circularly polarized light in dielectric media"