Your lightsaber is nothing against the power of the dark side

Posted: January 20, 2014 in False or true?, X-treme physics
Tags: , , , , ,

This was the formal weapon of a Jedi Knight. Not as clumsy or random as a blaster. More skill than simple sight was required for its use. An elegant weapon. It was a symbol as well. Anyone can use a blaster or a fusioncutter—but to use a lightsaber well was a mark of someone a cut above the ordinary.” (Obi Wan Kenobi)

What’s the coolest thing about being a jedi? Guys, I don’t know about you, but I’d totally forego levitation and mind tricks if I could have a light saber.

In fact, there are dozens of flicks out there on the web of everyday people fighting with light sabers. Too bad it works just like in the movies: with post-production. The idea is simple: one gets a stick and fights the usual way. Afterwards, when everything is filmed and digitally stored, here comes a program to replace the stick in every frame with the laser beam. In fact, there are dozens of tutorials on the web about how to manipulate your video using, for example, After Effects.

Although post-processing results are nifty, the downside of it is that combatants can’t actually watch the laser blade until much time later, in a computer. In order to get real time feedback, Augmented Reality may come in handy. In this case, as long as sabers have a recognizable landmark attached, we have a camera equipped processing unit fast enough to process more than 16 frames per second and landmarks are within the field of view of the camera, we are in for a light fight. Optimally, we would need glasses to be able to see what the computer generates. Otherwise we are limited to watching ourselves in a big screen or projection. More frequently than not, though, the camera won’t be able to track your blade unless you are moving frustratingly slow. Kinect Star Wars, for example, works fine, but you will be fighting with a virtual avatar, so you won’t get freaky pics like this one:


Apparently, it looks like the best way to fight with a light saber would be indeed to build a real light saber. How Stuff Works already proposed some ideas to this respect, but nothing solid. Not as solid as what Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic, working with colleagues at the Harvard-MIT Center for Ultracold Atoms, have produced, at least.

These guys have created a medium in which photons behave like they have mass, bonding together into a molecule. And, if light gain mass …

Don’t get your hopes too high, though. These “light molecules” are not going to be sold in IKEA anytime soon. As researchers described in a Sept. 25 paper in Nature, in order to merge photons into a molecule, they began by pumping rubidium atoms into a vacuum chamber, then used lasers to cool the cloud of atoms to just a few degrees above absolute zero. Finally, using extremely weak laser pulses, they fired single photons into the cloud of atoms.

Apparently, the photon’s energy excites atoms along its path, and slows dramatically. Like when Jack B Quick speeding ticketed photons, too. As photons move through the cloud, that energy is handed off from atom to atom. Due to the Rydberg blockade, when an atom is excited, nearby atoms cannot be excited to the same degree. This basically means that two photons moving in the cloud at the same time push and pull each other in order to deliver their energy from one atom to the next (right! as if they had mass). All in all, they tend to exit the medium together, all molecule-like.

Although researchers themselves make references to light sabers, the real application domain of this effect would be quantum computing. Thus far, photons are optimal to carry quantum information, but since they don’t interact with each other, processing is kind of tricky.

In any case, if I had to choose between a quantum computer and a light saber, I’d be counting with my fingers for a long, long time.

Source: Harvard Gazette


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