There's been an exciting shift in scientific thinking about life beyond Earth recently. Extraterrestrial-seeking group SETI has started to recognize the importance of detecting alien artifacts along with radio signals. The most viable target for these searches is the Dyson sphere, a massive shell that envelops an entire star. But as Discovery's Ray Villard rightly points out, the difficulty of finding these near-invisible objects could be offset by searching for them in nearby galaxies where their presence would be much more obvious.
Finding a Dyson sphere is not easy — and it's not because we don't know how to do it. As we've discussed before, the trick is to distinguish the infrared signature of a Dyson sphere candidate from natural phenomenon. According to Villard, Dyson hunters have catalogued 17 "quasi-plausible" signatures — but they can't prove one way or another that they're not just, say, stars enshrouded in dust.