Most time travel movies disregard the mathematical and quantum physics that would govern such a phenomenon. Writers and directors often include time-travel concepts that serve their narrative while ignoring those that don't, leading to logical inconsistencies. For instance, in Back to the Future Part II, the inability of Marty and Jennifer to meet their future children is attributed to their absence from the timeline for 30 years, a concept that raises further questions when examined closely.
However, a select few films manage to incorporate plausible scientific grounding, either through extensive research into quantum physics or by building their stories around its principles. These rare examples offer a more scientifically coherent approach to the concept of time travel.
Interstellar
Christopher Nolan's 2014 epic, Interstellar, stands out for its detailed exploration of quantum physics. Developed in conjunction with theoretical physicist Kip Thorne, who also served as a scientific consultant, the film delves into concepts like black holes and time dilation. In its climax, astronaut Cooper enters a black hole and finds himself in a 'tesseract,' a construct enabling him to communicate with his daughter in the past. While the tesseract is explained as a creation of future humans, it serves to explore theoretical possibilities of time travel and the enigmatic nature of black holes.
Planet of the Apes
The original 1968 film, Planet of the Apes, employs a scientifically plausible form of time travel: forward progression through time dilation. This phenomenon occurs when traveling at speeds approaching the speed of light, causing time to pass slower for the traveler than for those on Earth. Astronaut George Taylor, after a mission at near-light speed, crash-lands on a planet that is revealed to be Earth in the distant future. This concept of forward time travel is scientifically accepted, unlike backward time travel, which is considered largely impossible by many physicists.
Avengers: Endgame
Despite its fantastical elements, Avengers: Endgame earns recognition for avoiding a common, flawed time travel trope: altering the past to fix the future. Instead, the Avengers retrieve items from the past to use in the present, a concept that, according to Hulk, does not alter the timeline but rather branches it off. This aligns with physicist David Deutsch's proposal and the Many Worlds Interpretation of quantum mechanics, which suggests that altering the past creates new, parallel timelines. The film's use of the quantum realm for time travel, where time operates differently, acknowledges the complex nature of physics.
Primer
Shane Carruth's 2004 low-budget film, Primer, is renowned for its intricate and scientifically rigorous depiction of time travel. Written and directed by Carruth, who has a background in mathematics and software engineering, the film follows two engineers who accidentally discover how to travel backward in time. They construct a device that allows for limited time jumps, adhering to strict parameters. The film's time travel mechanics are based on Feynman diagrams, which illustrate subatomic particles moving forward and backward in time simultaneously. Primer's complex dialogue and adherence to its own established rules have made it a subject of intense analysis and interpretation for over two decades.
Predestination
Based on Robert A. Heinlein's 1959 short story '—All You Zombies—,' the 2014 film Predestination rigorously explores the concept of a causal loop, a paradox often warned about in time travel narratives. The story centers on a character who, through time travel, impregnates their younger self, resulting in a child who is also the progenitor of the traveler. This narrative avoids altering timelines by presenting a self-contained, unchangeable loop. While not strictly depicting a scientifically accurate method of time travel, Predestination serves as a profound examination of why such temporal paradoxes fundamentally challenge the logic of time travel stories.