It’s called science fiction for a reason, as these stories of traversing the stars, traveling through time, or jumping into one another's dreams don’t always hold up to scientific scrutiny. The best sci-fi movies require audiences to suspend their disbelief and be whisked away to alternative worlds of technological advancement, unimaginable gadgetry, and far-fetched concepts that have their initial basis in real-world science. Just because a sci-fi film doesn’t make sense in the real world, that’s no reason it can’t be an insightful piece of escapism that offers unique and thoughtful insight into humanity’s endless pursuit of knowledge.

Some of concepts around time travel can often lead to paradoxical situations that result in viewers scratching their heads when they think about them too deeply. However, this is also part of the magic of filmmaking, as movies can explore ideas that real life rarely encounters and offer highly engrossing narratives of dinosaur theme parks or life on Mars. Just because a sci-fi movie doesn’t make complete scientific sense, that does not mean it should be dismissed by viewers.

15 Inception (2010)

Directed by Christopher Nolan

While the action heist stylings of Christopher Nolan’s Inception made for truly thrilling viewing, its concept of inserting oneself into other people’s dreams has absolutely zero scientific basis. The harsh truth was that Inception was fantasy through and through, as the only way of appearing in someone else’s dream is the good old-fashioned way of being stuck in their subconscious due to the everyday activity of the brain. While Nolan got a lot right about the mind and sleep in Inception, the rules that govern dreams are still something of a mystery as the depths of the unconscious mind continue to stump scientists.

14 Guardians Of The Galaxy (2014)

Directed by James Gunn

While the Marvel Cinematic Universe has always played it fast and loose with scientific accuracy, Guardians of the Galaxy truly took things to the next level as its galaxy-spanning alien creatures came in every imaginable shape or size. While it’s exciting to see a talking tree and a genetically engineered raccoon bounty hunter interact with one another, it would also be more exciting to see the scientific explanations about how all these things came to be. Guardians of the Galaxy was a creative exploration of the endless possibilities of the universe, but it should all be taken with a pinch of salt.

13 Déjà Vu(2006)

Directed by Tony Scott

The late, great filmmaker Tony Scott was responsible for some of the best action movies of all time, such as Top Gun and Crimson Tide, yet when he tackled sci-fi, he wasn’t exactly concerned with real-world accuracy. This was certainly the case for Déjà Vu, Scott’s time travel thriller with Denzel Washington that saw an ATF agent attempt to travel back in time to stop a terrorist attack in New Orleans before it happened. Time travel movies bend logic at the best of times, but the way Déjà Vu tried to explain itself through shaky science just left viewers scratching their heads.

12 Armageddon (1998)

Directed by Michael Bay

While a giant asteroid on a collision course toward Earth was scientifically possible, the idea of training oil drillers to be astronauts makes absolutely no sense. This was precisely what happened in Armageddon, which begged the question of why, if NASA wished to drill a role in an asteroid to save humanity, they would not instead train their engineering, computer science, or mathematics experts to learn how to be oil drillers. Although it was thrilling to watch Bruce Willis take on a mission to save humanity, it feels like NASA made things needlessly complicated for themselves.

11 Gravity (2013)

Directed by Alfonso Cuarón

The Best Picture nomination Gravity was a visually spectacular sci-fi film that took viewers on a death-defying journey of astronauts attempting to return to Earth after their space shuttle was destroyed. While Gravity got a lot right about the science of space, it was also packed with inaccuracies, as everything from the way debris would interact with their communications satellite to orbital parameters making it impossible to travel through the two spacecraft (via Washington Post.) These scientific liberties were taken in the name of good storytelling and helped keep Gravity entertaining and engaging throughout.

10 Interstellar (2014)

Directed by Christopher Nolan

The science behind Interstellar was thoroughly researched, as the theoretical physicist and Nobel laureate Kip Thorne acted as a consultant and executive producer on the film. But, like in most sci-fi movies, the facts don’t hold up to rigorous scrutiny, as aspects like the dire blight that was plaguing humanity were criticized by experts like astrobiologist David Grinspoon (via Mother Jones), who said it would take millions of years to reduce the Earth’s oxygen content. However, the most glaring error was Interstellar’s message that love transcends dimensions, a thought which, although sweet, holds no scientific weight.

9 Logan's Run (1976)

Directed by Michael Anderson

Logan’s Run was a 1970s dystopian classic based on the original novel by William F. Nolan that was set in a world where everyone was killed once they turned 30. While this was a powerful showcase of extreme solutions to the very real issue of overpopulation, the truth was that from a scientific point of view, this action causes more issues than it solves. Logan’s Run, at its core, misunderstands population density because if everyone were killed at 30, it would mean far too many children for the minority of adults left to with their limited time left alive.

8 Total Recall (1990)

Directed by Paul Verhoeven

Total Recall told a sci-fi story about a man who receives implanted memories of a fantastical adventure on Mars, although as it progressed, the lines between reality and fiction began to blur, and it was uncertain which version of the man was real. With Arnold Schwarzenegger as Douglas Quaid / Carl Ha, Total Recall was a fun-filled journey into sci-fi concepts full of inaccuracies. The most glaring issue was that in Total Recall, people had to pay for breathable air on Mars, a concept that an article on Medium explained does not make sense within the confines laid out in the film.

7 Prometheus (2012)

Directed by Ridley Scott

From Alien to Blade Runner right through to The Martian, Ridley Scott has directed several sci-fi classics that, although wildly entertaining, also feature their fair share of scientific issues. Perhaps the most glaring example of this was Scott’s Alien prequel Prometheus, which an article in Forbes stated left scientists baffled. From the improper movement of thousands-of-years-old specimens to the inaccurate depiction of objects moving at the speed of light, Prometheus was certainly a movie where audiences were required to suspend their disbelief.

6 The Matrix (1999)

Directed by the Wachowskis

The cyberpunk stylings of The Matrix work far better as a philosophical thought experiment than a genuine scientific possibility. While there’s merit to the idea that humanity lives within a simulation, the idea that machines use humans as energy sources contradicts the laws of thermodynamics. While The Matrix hinges on the idea that robots can run on human power, the simple truth is that this would be a wildly inefficient way to run a machine-led society, even if Morpheus asserted to Neo that humans produce “more bioelectricity than a 120-volt battery and over 25,000 BTUs of body heat.”