The idea in “Timeline” is that since the fax machine transports documents from one place to another, it should be possible to transport people the same way. Somehow the movie overlooks that when you fax something, you’re not sending the ACTUAL thing over the phone lines; the original stays where you are and a COPY is sent. So if the science is the same, then they should be sending COPIES of people to far-off places, and the actual people should stay behind. But of course that’s not what happens, they send the actual people, by breaking down their atoms and rebuilding them somewhere else, apparently believing this is what fax machines do. But in the process of transporting people, they encounter a wormhole that takes them back to April 4, 1357, in Castlegard, France, on the very day of a pivotal battle between the French and the English!

“Timeline” is the sort of easy-going potboiler that you can sit back and enjoy because, despite being hopelessly stupid, it at least refrains from being irritating or boring. (Truly awful movies are usually one or both of those.) It’s a thick, meaty slab of badness with no irony or cynicism, the kind of earnest Saturday-matinee material that is best enjoyed with a cadre of light-minded friends. I’m not a drinker myself, but I can imagine the benefits of imbibing before or during the viewing of “Timeline.”

It’s a company generically called International Technology Corporation that has devised this human-fax-machine-turned-time-machine, and they’ve sent archeologist Edward Johnston (Billy Connolly) back there, perhaps accidentally (I don’t recall), and now he’s stuck there. His son, Chris (Paul Walker), a dude-speaking non-archeologist who professes early on that he hates The Past, making him the first movie character I am aware of to declare The Past as his enemy, is eager to rescue him. He’s accompanied by people from Dad’s digging expedition: pretty Kate (Frances O’Connor), who’s the reason Chris ever shows up at the digs; rugged Andre (Gerard Butler); and French Francois (Rossif Sutherland), needed for translation purposes. Oh, International Technology Corporation sends along two Marines, too, but you know what’s going to happen to them.

They’re all sent back in time with little medallions that, when pressed, will bring them home again. They have only six hours in which to find the professor; after six hours, it’s TOO LATE! Or something. (I am fond of movies with arbitrary deadlines.)

So then we’re in the 14th century, or at least the movie version of it, where everyone practices good dental hygiene and bathes often and where the French have all learned English and where the English speak not Chaucer-esque Middle English, but more like Victorian English, Sherlock Holmes-style. (Given the setting, thoughts of Monty Python are unavoidable.) Our heroes instantly run afoul of both the French and the English, each group thinking they’re spies for the other, and some of them get killed. Not Andre, though, who hooks up with Lady Claire (Anna Friel), whom we’ve already been told plays a pivotal role in tonight’s battle.

Ah, the goofiness of it all! There’s dubious science, questionable history and outlandish accents oozing from each of the film’s orifices. Paul Walker’s surfer-boy dialect causes everything he says to sound ridiculous, even basic statements such as, “It is a nice day.” When he remarks that rescuing his dad should be easy due to having 700 years of knowledge over his captors, all I can think is, “Yeah, you’d think so, wouldn’t you?” He inspires little confidence even in his ability to perform simple tasks.

The director is Richard Donner, who gave us “Superman,” “The Goonies” and the “Lethal Weapon” movies. His track record for entertaining action films speaks for itself, and I doubt he or anyone involved with “Timeline” imagined that anything special was being produced. The film is not overly ambitious, but neither is it lazy. It works hard at its dumbness, and it’s eager to please. For what it’s worth, it’s probably the most enjoyable bad movie of the year.

C (1 hr., 56 min.; PG-13, one F-word, some mild profanity, a lot of non-bloody sword- and arrow-related violence.)