It is reported that US network CBS is in negotiations for a Big Bang Theory spin-off series which will focus on the childhood years of central character Sheldon Cooper.

US entertainment trade publication Deadline, which first reported the story, says that the prequel would be a single camera comedy focussing on Sheldon as a 12-year-old in Texas. Actor Jim Parsons, who plays Sheldon in The Big Bang Theory, is said to be among the producers along with the show's co-creator and executive producer Chuck Lorre.  

A script for Sheldon has yet to be written but a pilot episode has reportedly been ordered with sources telling Deadline the project is "considered a shoo-in" for a full season. 

The Big Bang Theory is now in its tenth season and has become both the biggest comedy and most-watched show on US television. The current season is the last under the present deal between CBS and Warner Bros TV, which makes the show. Deadline says it understands that the spin-off and original show are set up in a way that allows them both to air at the same time. 

Emmy and Golden Globe winner Parsons and co-stars Johnny Galecki (Leonard) and Kaley Cuoco (Penny) have yet to agree new deals to continue on as The Big Bang Theory's central trio. It is estimated they currently make around $1m per episode, in addition to owning part of the show. 

Looks like their universe is about to expand...