According to the laws of physics, the speed of light is a good boundary, as going beyond it opens you up to all sorts of paradoxes and space-time phenomena that are usually the stuff of sci-fi. But two Austrian researchers claim that there’s no reason that they can’t build a computer that processes information at superluminal speeds.
The idea is not quite as crazy as it might sound. It’s based on the same principle as that of quantum entanglement – the notion that two particles on opposite sides of the universe can be linked through their quantum states such that one cannot be adequately described without the other. That is, an action on one particle instantaneously influences its counterpart, even if they are separated by light years.
This quantum non-local phenomenon cannot transmit information faster than the speed of light, but according to Volkmar Putz and Karl Svozil at the Vienna University of Technology there’s no reason we can’t process information at superluminal speeds as long as doing so doesn’t create any time travel paradoxes.
All we need to do is create a medium conducive to the kind of pair formation and recombination described by entanglement. The material in which this kind of pair formation and recombination was promoted would have a refractive index less than one. Then we simply build an optical computer around all of this controlled quantum mayhem, and we will get the computer that processes faster than the speed of light.
But what could we do with a superluminal computer? That’s a good question that scientists do not address directly. They say such a device would fall into a class of processing machine known as hypercomputers. In theory, hypercomputers can compute certain kinds of otherwise noncomputable functions. That sounds handy but even though there are uncountably many non-computable functions, it’s actually quite hard to come up with an example of one that might seem useful. If you have any ideas, post them in the comments. [TechnologyReview via Popsci]