But if the producers have any say, grown-up versions of kid characters onYoung Sheldonmay someday appear onTBBT.

We are all in love with young Billy Sparks [played by Wyatt McClure].

To see him walk into Pasadena would be a thrill if we get that right.

Emerald City - Season 1

Credit: Michael Yarish/Warner Bros. Entertainment Inc.; CBS

[Matthew] McConaughey!

But Lorre dismissed any notion of a full-scale crossover night between the two CBS comedies.

I dont think we are that organized.

You have no idea of the chaos behind the scenes.

That kind of coordination is not possible.

Its also unlikelyYoung Sheldonwill feature lots of guest stars who are often featured onTBBT.

You have to remember this show takes place 30 years ago, says executive producer Steve Molaro.

Its a smaller world that we live in, Houston, added Lorre.

Its not likely a Nobel prize-winning scientist will come through.

Young Sheldonairs at 8:30 p.m. Thursdays ET on CBS.