Sheldon Cooper would probably approve of the logic (and be able to explain the physics) that caused his character to become the central force of CBS’ “The Big Bang Theory.” Jim Parsons gives us expert delivery and timing as Sheldon, and it made sense that such a dynamic presence would become the series’ key figure. Johnny Galecki is underrated as Leonard, but he is more of a straight man.

But Sheldon’s character, almost fundamentally, lacks the ability to grow in significant ways. He’s both content with who he is and mostly unable to appreciate what he isn’t. And that’s a potential problem for the series.

If Sheldon doesn’t grow or change, “Bang” runs the risk of getting stuck in a rut or forcing itself into increasingly ridiculous situations to generate new laughs: “What zaniness can we put Sheldon in this week?” Don’t get me wrong — you could put Sheldon anywhere from outer space to an avocado farm and it’s going to be funny — but the chuckles will become more and more shallow. Arguably, that’s already happening.

Danica Added to this concern is how casually “Bang” treats the character development it does have among the rest of its cast. Howard (Simon Helberg) got an interesting girlfriend, but weeks go by without us seeing her. Even worse, Raj (Kunal Nayyar) hooked up with a woman, played by Danica McKellar (the former “Wonder Years” star and UCLA math scholar who was a natural fit for a long arc on the show), but after that single appearance, McKellar disappeared, and Nayyar returned to lamenting his sex life as if she were never there.

It doesn’t require a spoiler alert to expect that “Bang” will have new story opportunities arising from what figure to be inevitable romantic struggles between Leonard and Penny (Kaley Cuoco). I’ve earlier speculated that over the long haul, Penny and Sheldon are destined to end up together, though “Big Bang” exec producer Chuck Lorre has said that won’t happen. Either way, it doesn’t really solve the more immediate problem that the show’s breakout star has broken out into something of a confined space.

Lorre, fellow exec producer Bill Prady and the rest of the “Big Bang” crew have earned a considerable amount of faith from viewers like me, but I still think something about Sheldon’s situation is going to have to change to keep the “Bang” at its best. I’m curious to see what happens.