Others have chewed over this calc in more detail, different subthreads. To increase perceived G you can always spin the ship. Also, the relativistic round trip doesn't require high peak acceleration to be doable in 6.2 years moving-frame, but it does require *massive* speed: as others have said, once you have got up to 0.6c (relative to the galactic frame) the vague fluff of stray protons etc that are floating around in deep space starts to look like concrete. The main problem for the moment is reaction mass: the Apollo rockets were mass ratio > 19:1 [(fuel+reactionmass):(everything else)]. To burn for twice as long you need to square the fuel, because you are also carrying your reaction mass. There is a lot of loose talk about ramscoops, but they seem like a pretty insane engineering challenge: the practical solution that seems more likely is to develop a super-dense energy storage technology like antimatter, so that reaction mass can be pushed out harder and we don't have to carry as much of it. Once that happens, ramscoops might be the next step but interstellar probes at least would start to make sense without them. AFAIK a human-survivable round trip to gliese (20-40 years, moving frame) would be doable quite soon using nuclear engines such as UF6-water design.... but those babies are not certified for terrestrial launch. Frankly I wouldn't even want one in orbit around my home planet thankyou very much.

Relativistic journeys calculator here: http://www.cthreepo.com/lab/math1/ Gives 6.2 years (moving frame) or 24 years (earth frame) to get there, assuming constant 1G accel, deccel. I've spent longer (subjective) than that waiting for a British train.

TFA draws a flawed conclusion as the final paragraph. Suggesting that superfunky microprocessors enable radio spectrum to be shared like finite but abundant beer is daft. For reliable QOS, modern information theory (should instead be/ IS) used to ensure that what expensive spectrum has been aquired is used efficiently. Eg DAB radio. For CB or the ISM band, then fine, share it - by definition.