Sheldon and Amy consummate their relationship on "The Big Bang Theory"

BURBANK, Calif. -- In the same week, "Star Wars" returns and scientists-in-love Sheldon and Amy finally consummate their relationship on "The Big Bang Theory." Could even the geekiest fan ask for more?

On Thursday's episode (8 p.m. ET, CBS), Jim Parsons' Sheldon and Mayim Bialik's Amy have sex for the first time, with each other or anyone else, more than six TV seasons after meeting through an online dating site.

But let the stars of the top-rated comedy tell you about it.

"Amy's been eager all along for a different kind of connection, but it's actually initiated by Sheldon," Bialik said.

"Sheldon's eager for her to know she's special to him, and this is one of the items on the list that he feels could show that," Parsons said.

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Sheldon (Jim Parsons) doesn't know how to act after Amy (Mayim Bialik) pushes pause on their relationship, on the ninth season premiere of "The Big Bang Theory." Sonja Flemming/CBS

So romantic! And how explicit is the scene?

Bialik: "More than we thought. We're in bed."

Parsons: "Well, of course we are. We aren't going into the back of a car."

Bialik: "I thought we would just talk about it when it finally happened."

Parsons (dismissively): "Oh, no!"

Bialik: "There's a before and there's an after. There's no during."

Emmy-winner Jim Parsons on his "Big Bang" success

"Star Wars: The Force Awakens," out Friday in the real world, is used as a comic device throughout the episode and even threatens to derail the couple's coupling.

After deciding to give Amy the gift of sex on her birthday, Sheldon realizes there's a conflict with his opening-day movie ticket. He gets sage advice from the late Professor Proton, his childhood hero resurrected in ghostly form as a figment of Sheldon's subconscious.

The great Bob Newhart returns as the professor, grandly decked out in Obi-Wan Kenobi robes.

"It's hard for him (Sheldon) to understand that Amy won't accept the fact that this is the premiere of 'Star Wars,' so I have to present that side," Newhart said.

His delivery is as droll and his timing as impeccable as ever, Newhart milks the scene for all it's worth.

"Can I get out of this muumuu now?" Proton asks after counseling Sheldon.

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"Those are the robes of the Jedi, the guardians of peace and justice in the galaxy," Sheldon replies.

"And they don't wear underwear," the professor complains.

Parsons and Bialik also make the most of the smartly -- and sweetly -- written episode, stumbling toward intimacy with tender regard for each other.

Series executive producer and co-creator Chuck Lorre, a master of network TV comedy whose credits include "Two and a Half Men," ''Mike & Molly" and "Mom," had a look of eager anticipation when he arrived for the episode's taping last month at a Warner Bros. soundstage.

"It's exciting to see how far these characters have grown," Lorre said afterward. "We would never have anticipated that they would have progressed to the point where they're having real, in-depth relationships."

"It happened rather naturally, slowly, incrementally, but it's really delightful to get to see it play out," he said.

This fall Bialik told CBS News that she's enjoyed watching her character grow through the years.

"She's evolved a lot," Bialik said. "She went from being very insecure, socially, to much more confident ... With Sheldon (played by Jim Parsons), she's gotten a lot more clear in her communication, which has led to some conflict, but we see her more comfortable socially in a way that Sheldon doesn't -- he's comfortable where he is, but Amy really wanted to evolve."

While newer cable and streaming comedies such as "Veep" and "Transparent" are reaping more Emmy and Golden Globe attention these days, "The Big Bang Theory" audience is steadfast.

Each episode is getting nearly 21 million views within seven days after it airs, up 10 percent compared to last year.

It's set to return for another season, No. 10. And after that?

"As long as we're telling good stories and the audience still wants to watch, why not?" Lorre said. "We're having a great time making the show, and hopefully a little of that gets on television."