It sounds flesh-crawlingly awful, but "The Big Bang Theory" is turning out to be funny and touching. And don't miss Laurie Metcalf in tonight's repeat

It shouldn't work, but amazingly it does--left to right, Howard Wolowitz (Simon Helberg), Leonard (Johnny Galecki), Penny (Kaley Cuoco), Sheldon (Jim Parsons), and Rajesh Koothrappali (Kunal Nayyar).

I've been meaning to say something more about the CBS Monday night sitcom The Big Bang Theory, which I approached with utter dubiousness (now there's a brilliant comedic premise: making fun of really smart people) but which I've gradually warmed to, to my considerable surprise. I have to warn you, though, that there isn't any way, at least none I can think of, to talk about the show without making it sound as hideous as I assumed it would be.

The premise, in case you haven't heard, is that two 20-something scientific geniuses and social retards are roommates in a dilapidated apartment building (the elevator is apparently permanently out of order), into which moves--conveniently across the hall--wholesome blonde bombshell Penny. Sheldon and Leonard's social circle is completed by two off-premises geeks, doubling the number of hijinks that ensue.

There are, for one thing, degrees of social retardation. Leonard, as I suggested here previously, would really like to be a real boy--interacting wtih real girls, even to the point of having sex with them. Naturally Penny lands with a thud on his latent libido. Sheldon by contrast doesn't seem to notice that there's anything missing in his life, while poor Koothrappali is mostly unable to talk to women at all. In this company, it's not wildly unreasonable that Wolowitz fancies himself the Hugh Hefner of his peer group.

So why does it work? I think because the characters are treated with a certain empathic gentleness; their foibles, for all the absurdity, have real human resonance; and the actors never play for cheap laughs. As it happens, the episode that sold me is being repeated tonight--the one where supergenius Sheldon blows up at his boss and is fired from his research position, and undergoes a complete meltdown--to the point where it becomes necessary to call in the real shock troops in the form of his mom, played by the remarkable Laurie Metcalf--not the only Roseanne alum on-set, with series regular Johnny Galecki (Leonard) familiar as Darlene Conner's long-suffering boyfriend David, and Sara Gilbert herself having made recurring appearances as a scientist-geekette and unlikely potential romantic interest for Leonard.

It's fun just imagining Sheldon's mother, but creator-producers Chuck Lorre and Bill Prady outdid anything I could have imagined, thanks in good part to the inspired casting of Metcalf, playing a sort of country-hick mama who's no sort of genius but manages Sheldon with basically the same techniques she uses her on her other children, who apparently are distinctly on the dim side. (On the mother theme, in last week's show we were introduced to at least the voice of Wolowitz's bellowing off-screen mater. It was striking how much more sympathetic he suddenly became.)

I realize I've made the thing sound even more flesh-crawlingly horrible than you already fantasized. If only to prove me wrong, I encourage you to catch tonight's episode. You don't want to miss Sheldon's mom.

Note that the show has been flipflopped with How I Met Your Mother, which has been pushed back into the 8:30 ET/PT time slot where The Big Bang Theory had its early run. This is, unfortunately, a sensible move. After two season that approached incandescence, How I Met Your Mother has had a stinkeroo of a season. Those remarkably appealing five central characters are still there, but the writers seems to have run out of ideas for them.

Can it be simply because Lily (Alyson Hannigan) and Marshall (Jason Segel) finally got married? You wouldn't think so, but this season's scripts have been about as involving as if the five of them just sat around reading newspapers. A real shame, and a surprise. I would have thought the characters were so endearingly and quirkily created that there would be at least a few more years' worth of healthy life in them. I'm still hoping for a bounceback, but now it's more like praying.