Centuries from now, film historians will note that the early months of 2015 yielded not one but two movies about time travel: the teen-oriented thriller Project Almanac and Hot Tub Time Machine 2, which continues the story (such as it was) of 2010’s surprise hit Hot Tub Time Machine. While it seems unlikely that either of these titles will stand the test of (sorry) time, their near-simultaneous release provides an opportunity to look at the ways that movies have depicted the process of time travel—typically in ways that would earn them a failing grade from even the most lenient high school physics teacher.

Moving several rungs up on the educational ladder, any brief discussion of time travel needs to include the work of Gilles Deleuze, the French philosopher and metaphysician whose essays and books on a variety of topics—from schizophrenia to cinema—constitute one of the twentieth century’s most formidable portfolios of theoretical writing. He was prolific and perspicacious interpreter of other writers, including Marcel Proust, whose novel Remembrances of Things Past could be seen as a literary equivalent to his own writings on the relationship between different temporal states: for Deleuze (as for Proust) the past inhabited the present in the form of memory, and rather than attempting to move ourselves between points in time—the fantasy of fantasists and science-fiction writers born long before H.G. Wells—he suggested that existence itself was tantamount a kind of time travel. “The past and the future are not simply realms we might be able to visit,” he wrote. “They are processes fully implicated in our present ones.”

As any long-suffering philosophy major—or in my case former cinema studies specialist —can tell you, the moments of clarity in Deleuze’s writing are all the more blinding for being so fleeting. His brilliance is of the kind that requires a fair amount of intermediary explication, or else the kind of vivid illustrative examples that leap off the page—or perhaps the screen. While wading through selections from Deleuze’s monolithic 1983 volume Cinema-1: The Movement Image, it was helpfulto re-watch Chris Marker’s 1962 short masterpiece La Jetée—a work that goes unmentioned in the book yet perfectly demonstrates the author’s contention that cinema is not simply a series of still images but rather a “movement image” in which the motion itself is the key element. Of course, La Jetée is in fact a series of still images, but the moment near its midpoint where Marker’s snapshot aesthetic blurs into a movement-image—a shift that is literally over in the blink of an eye—demonstrates the difference between photography and cinema, and especially the latter’s capacity to more successfully evoke a sense of present tense, more potently than a semester’s work of lectures.

La Jetée is very much a Proustian work, and Marker’s fondness for the French author ran deep: hence the title of his amazing 2003 video Remembrance of Things to Come, another work comprised primarily of still photographs (by Denise Bellon). But even as La Jetée follows Proust’s lead by melancholically exalting nostalgia, it is itself a kind of primal scene of science-fiction moviemaking—ground zero for the modern time-travel film. For instance, its story of a man who survives the end of the world and is sent back in the past to locate information that will somehow help to avert the crisis will have the ring of déjà vu even for those who’ve never set foot in a film studies classroom or a cinematheque. La Jetée features nuclear apocalypse, a doomed romance between two lovers from different time frames and a fateful revelation tied to a childhood memory: throw in Arnold Schwarzenegger and some semi-automatic weapons, and you’ve got The Terminator (1984).

Had he chosen to file a lawsuit against the creators of The Terminator after the modestly produced action thriller unexpectedbecame one of the biggest independent hits of the 1980s, Marker would have had to get in line behind Harlan Ellison, the great science-fiction writer and crank whose Outer Limits episode “Soldier” was even more obviously an influence on James Cameron and Gale Anne Hurd’s script. The film’s distributor Orion quickly settled out of court with Ellison (against Cameron’s wishes) and The Terminator took its place as a modern classic, a heavy-metal shoot-em-up with just enough organic material—the holy trinity of brains, heart and nerve—underneath its gleaming surfaces (an inversion of the sculpted-skin-and-steel-bones physiognomy of its implacable antagonist). It’s uncertain whether James Cameron had seen La Jetée when he made The Terminator, and unlikely that he spent time in between takes slaving over translations of Deleuze, but he was smart enough to explicitly acknowledge the complexities of time-travel theory in his screenplay. Informed by her protector that he’s travelled back in time thirty years to protect her from a robotic hitman hoping to retroactively abort the baby she hasn’t even conceived yet, Linda Hamilton’s Sarah Connor grouses wearily: “a person could go crazy thinking about all of this.”

There are two kinds of time travel movies: those that want the viewer to go crazy thinking about the paradoxes in play, and those that try not to sweat it overmuch. La Jetée and Terry Gilliam’s affectionate quasi-remake 12 Monkeys (1995) are in the first category, as are The Terminator and its sequels: the gradual transformation of Arnold Schwarzenegger’s title character from a villain to a catchphrase-spouting hero didn’t alter the essentially po-faced nature of the material or its commitment to serious time travel paradoxes. Rian Johnson’s Looper (2011), about a man who ends up waging a pitched battle with his older self, belongs in this company as well. On the other side of the divide we find the likes of Hot Tub Time Machine (2010), in which the stakes are considerably less apocalyptic—what hangs in the balance is not the fate of mankind but rather the possibility of one group of friends getting laid on a high school ski trip.

The split is generic—between science-fiction movies and comedies. Occupying the middle of this Venn diagram is Back to the Future (1985), which hilariously indulged the primal fantasy of adolescents everywhere to spy on their parents’ younger incarnations while honoring the oldest rule of time travel fiction—the idea that interacting with the past will alter the shape of the present. Unlike its mid-80s contemporary The Terminator, Back to the Future actually goes to the trouble of visualizing the science of time travel, albeit in a deliberately (and amusingly) stylized way: under the direction of mad scientist figure Dr. Emmett Brown—Christopher Lloyd, evoking such great lab-coated quacks as Colin Clive’s Dr. Frankenstein and Jerry Lewis’ Nutty Professor—a sleek silver De Lorean is revved up to a great speed and then juiced with electricity, at which point it smashes through temporal barriers and arrives three decades earlier. The car zipping along hellaciously until it suddenly disappears is a great (movement) image, and it’s also a perfect analogue for the screenplay by Robert Zemeckis and Robert Gale, which insists on breakneck momentum from beginning to end so that the movie becomes a multiplex-friendly variation on the theory of relativity—time flies because we’re having fun.

Surprisingly, Back to the Future is not among the films name-checked in Project Almanac, which concerns a group of high-school kids who stumble across the remains of a government “temporal dislocation” project and restart it in a fit of youthful exuberance. “Who’s Doctor Who?” asks the popular girl of her geeky new pals. “What do you mean you haven’t seen Time Cop?” queries another boy incredulously to his friend, who later comments “I loved Looper.” (Naturally everyone in the group has seen The Terminator). At one point, a computer screen can be seen playing a DVD of Stephen Herek’s Bill and Ted’s Excellent Adventure (1989)—the gold standard of all teenage time-travel sagas (we might say it is the genre’s La Jetée).

The pop-culture sated protagonists of Dean Israelite’s Project Almanac mark it as a third kind of time travel movie—a self-aware mix of science-fiction and comedy whose characters have no excuse for the mistakes they’re making by meddling with temporal forces because they’ve all seen the same movies about why it’s such a bad idea. Project Almanac isn’t a very good movie—its found-footage conceit is much sloppier and less visually inventive than in Josh Trask’s excellent Chronicle (2012), whose low-budget, high-yield production model it surely seeks to emulate—but by making its teenagers science geeks instead of a befuddled layman like Marty McFly, it addresses the impetuousness of the time-traveling mindset.

Actually, Israelite’s wittiest scene actually has nothing to do with time travel and everything to do with the image of scientists in popular cinema. In it, the hero devises a homemade flying machine that he hopes will gain him admission to MIT—and like Icarus, it flies too high and crashes to the ground in a smoking heap. What goes up must come down, and while Project Almanac’s elaborately convoluted conclusion doesn’t rank with the classics that its makers have memorized along with their characters, the general theme of comeuppance is in keeping with the history of the genre. As usual, reckless scientists are punished for pushing things too far. So what are they supposed to do? Build a time machine and try to take it all back? Wasn’t that the problem in the first place? A person could go crazy thinking about all of this.