Worlds collided last season, when a love affair with Penny (Kaley Cuoco) opened a big, wide, wonderful world of romance for Leonard (Johnny Galecki). Sheldon (Jim Parsons), of course, likes the world just the way it is, thank you. And now, that Leonard and Penny have broken up again, all three can test all the variables of being neighbors once more. The result makes for a zany comic triangle with brainy, clueless Sheldon and practical, grounded Penny hilariously vying for the role of hypotenuse to level-headed Leonard. Add to this combustible chemistry, the terminally under-spoken Raj, the over-spoken Howard and guest stars like Apple’s Steve Wozniak and more and you’ve got all the fun of a series that only gets better. Entertainment Weekly raves that the show “has transformed from a cute comedy about eggheads and their hottie neighbor into an addictive ensemble piece that could be this decade’s answer to Friends."