If this new theory requires ~800kg of mass (Voyager 1's launch mass) be converted to energy, that means the space craft would need to be able to harness the equivalent power generated by ~344 Tsar bombs.
While it's not unimaginable for us to be able to generate such huge amounts of energy, the material sciences necessary to harness such huge energy levels are completely unimaginable.
I'm aware of that. I said 'more feasible than first thought,' as did the article. I took great pains to imply that nobody expects this sort of advancement to happen overnight. Also, 'exotic matter' just means we don't know what it'll have to be made of yet.
With just a small change to the shape of the theoretical warp drive, they reduced the energy required by many orders of magnitude, less than a decade after the theory was first proposed. Further refinement to the geometry and other things mentioned in the article could potentially lead to even lower power requirements. Combine that with advances to energy production and material sciences, and it's entirely possible that this sort of warp drive could become a reality within half a century (keyword: possible).
It's important not to look just at the current requirements of the design, but to look beyond that. The design isn't feasible in its current state, and nobody's arguing that it is. What's important is how massive of an improvement it is over the previous theoretical design with such a small change. There's at least one example of a theory progressing relatively rapidly to practical application (the nuke), so it would be crazy to completely dismiss the possibility.
This is all assuming this sort of thing gets properly funded. I think it will, since a device that can warp space-time has practical military applications (like the nuke) in addition to its use as an engine.
Warping space-time could be a very potent defensive tool, especially for anything with wheels/treads. Warp the area in front of an incoming bullet or artillery shell and you can change its trajectory slightly, basically using refraction. All you need to do is activate it for a few milliseconds at a time to change the trajectory by a couple degrees. It's much easier (requires less energy) and safer to deflect incoming fire slightly than to outright stop it with armor. If there's an explosion next to you, warp space for a few milliseconds so that the blast wave has to travel a little longer and dissipate more before it hits your armor (a shockwave's energy dissipates proportional to 1/r^2, so a very effective use).
No way of knowing how much energy that sort of thing will ultimately require, but you can bet DARPA would be interested in it.
