Mission creep continues on the cable TV front, with the Science Channel now trying mightily to justify its programming of "An Idiot Abroad," in which comedian Ricky Gervais and Stephen Merchant, Gervais' partner in crime on "The Office" and "Extras," send their friend Karl Pilkington to visit the Seven Wonders of the World. Never mind that Karl -- whom Gervais features in the podcast that morphed into HBO's "The Ricky Gervais Show" -- isn't exactly a brain surgeon, much less a scientist. The Science Channel seems to think he's investigating something. If the show , which premieres Jan. 22, is half as funny as the press conference, which took place via satellite, it might not seem to matter. But if you think about how far many basic cable channels have strayed from their original missions, you have to wonder how much longer any of them will even bother to pretend to be topic-driven.