A presidential address (7 p.m., ABC, CBS, NBC, Fox) bumps two Christmas specials from the network schedule. The new “Disney Prep & Landing” and the 1965 classic “A Charlie Brown Christmas,” originally slated for tonight, will be seen next Tuesday.

• ABC continues a peculiar network tradition of hanging on to sitcoms long past their expiration date. “The Drew Carey Show” sustained the network during its lean pre-“Millionaire” days, and ABC rewarded “Drew” by running it from 1995 to 2004, even though it wasn’t all that funny after, say, 1997.

“According to Jim,” a sitcom that seemed ancient and dated when it debuted in 2001, continued on the Alphabet Network until this very spring.

And now “Scrubs” (ABC), a series left for dead by NBC some years back, returns for its ninth season tonight. In the first episode (8 p.m.), the old gang returns to the old hospital to teach. In the second (8:30 p.m.), J.D., Turk and Kelso play matchmakers.

Like many shows long in the tooth, “Scrubs” faces personnel changes. Zach Braff, the star of the series, is scheduled to be phased out as “Scrubs” moves its focus to a younger set of interns, students and knuckleheads. Hey, this worked for “ER,” and that ran for 15 years.

• “Sci-Fi Science: Physics of the Impossible” (9 p.m., Science) explores areas where emerging technology might soon realize cinematic fantasies of light sabers and time travel.

Host and author Michio Kaku (“Physics of the Impossible,” Doubleday, 2008) discusses how these fantasies could become part of everyday reality. He will devote each episode to describing ways each fantastic invention could be built.

He incorporates interviews with cutting-edge scientists to determine which technologies are feasible and which will remain in the realm of fantasy.

Like many professional scientists, Kaku has more than a casual interest in science fiction, claiming that the literary and cinematic genre “helped inspire me to become a theoretical physicist.”

• Carrie Underwood performs old hits and new numbers from her latest album, “Play On,” on “Invitation Only” (8 p.m., CMT).

• The third time is not exactly the charm for the 2006 holiday comedy “The Santa Clause 3: The Escape Clause” (7 p.m., Family). The franchise, begun back when Tim Allen was star of “Home Improvement” (another long-running ABC sitcom) can handle only so many incarnations.

Tonight begins the Family Network’s “25 Days of Christmas.” For the record, the spate of Christmas movies it has already aired was merely the 25-day buildup to the 25-day of “Days.” Can an all-year Christmas network be far behind?

Tonight’s other highlights

• A marathon awaits the contestants on “The Biggest Loser” (8 p.m., NBC).

• A missing drone demands attention on “NCIS: Los Angeles” (8 p.m., CBS).

• Eight talents with various disabilities compete on the import “Britain’s Missing Top Model” (8 p.m., BBC America).

• The overpaid appear in their undergarments on “Victoria’s Secret Fashion Show” (9 p.m., CBS).

• A body discovered four months ago seems to have been dead for four years on “The Forgotten” (9 p.m., ABC).

• A plot to remove Ethan and the League faces problems on “Sons of Anarchy” (9 p.m., FX).