Repulsive Force Discovered In Light 176
Posted
by
kdawson
from the push-me-pull-you dept.
from the push-me-pull-you dept.
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."
Re:Psssssssshhhhhhh!!!!!! (Score:5, Informative)
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.
Re:Psssssssshhhhhhh!!!!!! (Score:4, Informative)
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.
Re:Force source? (Score:5, Informative)
http://www.opticsinfobase.org/DirectPDFAccess/7CB1DC52-BDB9-137E-C347E05AD6F7E2D4_84895.pdf?da=1&id=84895&seq=0&CFID=48237375&CFTOKEN=15548595 [opticsinfobase.org]
"Angular momentum of circularly polarized light in dielectric media"
Re:Psssssssshhhhhhh!!!!!! (Score:1, Informative)
Lightsabers are supposed to be closed circuits of energy that are held in shape by a confinement field (possibly the force imbued within the lightsaber crystals upon construction). Presumably it is the force that gives the blade its solid surface. Because lightsaber blades are closed circuits, they recycle their power and expend almost nothing unless they are in contact with a solid surface or another lightsaber. They do not cast shadows and even if they did, you would not be able to see it because the "blade" is microscopic in width. The fat blade that you see is mostly coronal light bleed, not the blade itself. As far as I know, any visible shadow in the films is an editing slip-up cast by the lightsaber prop. As you can see here [blogspot.com] and here [starwars.com], there are no shadows cast by the blades in the ideally lit Yoda training scene of episode 2, yet you can see the shadows of the lightsaber hilts. None of the Star Wars games that I know of have lightsaber blades that cast shadows either.
Of course it's all fiction and there is no plausible explanation for how one could possibly work in the real world, so the discussion is pointless beyond a fun factor. This is only they way I've come to understand how they work through the films, books and games based in the Star Wars universe.
Re:Nice. But. (Score:3, Informative)
Probably not. Things are worded this way to explain them to laymen. Physicists are going to describe these phenomena with systems of equations and words and the equations will suggest deeper intuitive meaning to those used to working with them.
Re:Psssssssshhhhhhh!!!!!! (Score:3, Informative)
Might have been just the first movie, since the later ones had them using the things in darker settings as well.
Re:Psssssssshhhhhhh!!!!!! (Score:3, Informative)
You are correct. For the first film, they were octagonal blades with rotating motors and scotchlite paint, which reflected light back to the camera from a large light shooting from just behind it.
The effect was weak (see Vader's as he is walking towards the closing blast doors before they escape the deathstar) so they ended up animating over it in almost all the shots.
The rotation motor is the reason Obi-wan's saber has a white electric cord coming out of the hilt and going into his sleeve in the shot where he first energies it for his duel. Something I am at a loss to explain why they would not have digitally removed in one of the more recent editions. You can also see dust and chips from the impacts in the closeups during their duel.