I still think it is possible. Mr. Gluesenkamp probably doesn’t think warp speed is doable either. Silly believer in Newtonian physics you are  :)  – Jack
Via DVICE

Okay, folks, make sure you have some tissues handy because GE engineer Matt Gluesenkamp is about to break a lot of hearts. The laser just turned 50, and that got Gluesenkamp thinking about one of the most iconic representations of the technology: the lightsaber. He analyzes the tech it’d take to make them real. Is it possible? In a word, no.

So, let’s break the lightsaber down first, according to Gluesenkamp: “Each has a power source, a lightsaber crystal, one or more focusing crystals, and a stabilizing emitter system. The power source is typically a diatium power cell, often with a capacity of several megawatt-hours.”
The first snag you run into is that battery. “Although real-life battery technology is coming along great,” Gluesenkamp writes, “we are a long way off from creating handheld batteries with capacities like that the ones found in the lightsaber’s diatium power cell.” In Star Wars, Jedi didn’t have to worry about that because “diatium” is a convenient bit of fiction and are attuned to the Force, so, really, they could do anything.
Still, let’s say we did have such a battery. There’s another problem in getting a focused, powerful blade of plasma with an exact length and shape, which is where the concept of a lightsaber gets “really convoluted,” according to Gluesenkamp.
“There are also no crystals that can ‘direct’ a plasma,” Gluesenkamp writes, noting that today we use magnetic fields are used, but are limited as the machinery involved has to enclose the plasma. “In fact, a plasma ‘being directed’ by a crystal lens doesn’t make any physical sense anyway. A plasma is really just an ionized gas — a gas in which the electrons have been stripped from their atomic nuclei.”
Once again, let’s say we could direct a powerful plasma beam. That would require a huge difference in voltage, which means we’d need something along the lines of a powerful laser — or plain ol’ lightning. Given the amount of energy that would be required, it’d be “extremely difficult to control the plasma’s shape” using either approach, according to Gluesenkamp.
“An electrical arc can have wild shifts in direction, and it can hardly be controlled without being surrounded by magnets,” he writes. “A laser will go in a straight line, but of course it doesn’t stop. A laser-based lightsaber would require a block or a couple of mirrors floating in midair, moving in sync with the hilt — which is of course largely impossible.”
Well… damn.
Then again, they didn’t use modern tech in Star Wars. Lightsabers were created a long time ago in a galaxy far, far away, so maybe in that galaxy they have their own set of rules. Rules safe from smarty-pants engineers like Matt Gluesenkamp.