A scientific analysis of famous time travel stories

The origins of our fascination with time travel

Humans have been captivated by the prospect of leaping forward and backward in time for thousands of years. Georgia Institute of Technology Science Fiction Studies Professor Lisa Yaszek recounts how the concept has been utilized by storytellers from 400 BCE to modern-day to explore our relationship with the supernatural, technology, and the past. In a way, this historical recounting is a journey through time.

Tips for writing time travel stories

Are you thinking of writing a story that involves time travel? You might want to read this guide first. It offers questions to consider, mistakes to avoid and strategies to employ to ensure you avoid paradoxes, plot holes and implausibilities.

The earliest mention of time travel

Time travel has fascinated humans for centuries. It appears in myths, literature, and science fiction. One of the earliest examples comes from the 400 BCE Hindu epic Mahabharata, describing time dilation long before Einstein’s Theory of Relativity. By the 19th century, stories introduced machines enabling time travel—setting the stage for modern sci-fi.

Five potential ways to achieve time travel

While the author discounts the possibility of traveling to the past, it lays out five hypothetical modes of catapulting into the future: speed, gravity, suspended animation, wormholes, and light. Each has some scientific basis, but none are realistic for humans. Read the article to learn where they offer promise and where they fall short.

Is time travel really possible?

The laws of physics, as currently understood, don’t categorically reject the possibility of time travel. But, scientists are skeptical, especially when it comes to traveling to the past. Hopping between past, present and future would require the world to have some wacky yet-to-be-discovered physical properties like negative mass, negative energy, and infinite density. Time travel also introduces philosophical questions about free will, causality, and chronology.

What Stephen Hawking said about time travel

When renowned theoretical physicist Stephen Hawking did not rule out the possibility of time travel in his posthumous book Brief Answers to the Big Questions, many hopefuls got excited. But, unfortunately for them, Hawking believed that yet-to-be discovered laws of physics will prove time travel impossible. This piece outlines some practicalities about the speed of light and wormholes that lend way to Hawking’s prediction.

Branching timelines are allowed and resolve grandfather paradoxes in physics

According to quantum physics, traveling back in time to kill one's grandfather would not cause a paradox because time travel would bring one to a new timeline, where the person killed is not one's grandfather. Alternatively, causality would not be violated because the universe would prevent the murder from occurring.

Because some models of the universe do not incorporate time, it may be an emergent property born from our limited perception of the universe, rather than a fundamental property of reality.

The science behind the movie 'Interstellar'

Christopher Nolan's 2014 sci-fi action film "Interstellar" relies on real science for its wild space-time travel. This infographic dives into the physics basis of the fictionalized Gargantua black hole, the relativity effect, and more.

According to special relativity, time travel cannot change history

Although time travel is allowed—because all moments of the past, present, and future exist simultaneously and are locked in place—you will be unable to alter events beyond those that you changed because you were there before your travel to the past, including doing something to change your existence.

One 'Harry Potter' fan fiction deals with cognitive science and philosophy

Eliezer Yudkowsky's "Harry Potter and the Methods of Rationality" is not your typical fan fiction: It uses JK Rowling's fictional universe to wrestle with rationalist philosophy and the physics behind the magic taught at Hogwarts. The book went on to become popular in Silicon Valley, especially in the effective altruism movement.

Listen to an academic analysis of the 'Wizarding World of Harry Potter'

Potterversity examines the Harry Potter series through an academic lens—inviting scholars from diverse fields to uncover new interpretations and deeper meanings within the book series.

Experimenting with space-time

Einstein's theory of general relativity—that mass literally bends space and time—can be difficult for the human brain to imagine. This interactive resource lets you create celestial objects, imagine their effect on space-time, and see how they interact with each other (best viewed on desktop).

The grandfather paradox of time travel

If you went back in time and killed your grandfather when he was a child, what would happen to you? One of your parents would never be born, so you wouldn't be born either. But, if you're never born, how could you kill your grandfather in the first place? This so-called grandfather paradox is something physicists, philosophers and sci-fi writers constantly ponder. Read the piece to learn how they've been trying to reconcile it.

Translating ‘Harry Potter’ required creativity across 60+ languages

This Vox video explores how translators adapted JK Rowling’s wordplay, invented spells, and cultural references—reimagining names and magical terms while attempting to preserve humor, rhythm, and meaning for readers around the world.

The underlying fabric of the universe—spacetime—changes shape in the presence of mass and energy, which affects measurements of space and time.

How 'Star Wars' changed science fiction

The popularity of "Star Wars" shifted the market away from the more literary, and sometimes cynical, science fiction of the 1960s and '70s. In the wake of George Lucas' space opera, publishers and studios wanted similarly optimistic adventure stories. In time, though, writers like William Gibson would react against that and, in turn, create the "cyber punk" subgenre.

Understanding time dilation

The faster you go, the slower time ticks for you. And the stronger the gravitational field acting on you, the slower time ticks for you. These phenomena – collectively called time dilation – were first explained by Albert Einstein’s theories of general and special relativity. In this 11-minute video, beloved astrophysicist Neil deGrasse Tyson explains them to comedian Chuck Nice.

The wave nature of matter can produce phenomena like negative time and retrocausality

Within quantum mechanics, matter simultaneously exists as both fixed particles and extended waves, allowing it to emerge across barriers—just as sound travels through walls—before it fully enters the obstacle. The resulting measurements can show that particles spent negative time within a barrier, with the future occurring before the past.

According to the special theory of relativity, because the passage of time depends on how quickly objects move through space, people will not agree on the order of events they observe if they are moving at different speeds.

Einstein and the fourth dimension

How Einstein's greatest theoretical achievement contains a simple but mind-bending proposition—the dimension of time is physically connected to the three observable spatial dimensions.

The calendars of the 'Lord of the Rings'

JRR Tolkien's epic fantasy trilogy "The Lord of the Rings" is a seminal work in the history of literature partly due to its creator's obsessive focus on systematic detail—including the calendars used in the world. Take a fantastic dive into the minutiae of Tolkien's creation by learning the different approaches to time organization in the Shire or Rivendell with this dense, comprehensive resource based on Tolkien's appendices.

Einstein’s theory of special relativity

Special relativity, formulated by Einstein, describes how space and time are linked for objects moving at constant speeds. It states that the speed of light is constant for all observers, leading to time dilation (moving clocks run slower), length contraction (moving objects shrink), and mass-energy equivalence (E = mc²). This video breaks down how motion and time are fundamentally related.

Imagining how genetics works in 'Harry Potter' and how muggle-born Hermione is a witch

Dr. Robert Pyatt, director of Sanford Health’s medical genetics lab, talks through real-world genetics scenarios in the Harry Potter series, from the Weasley's red hair and freckles to why Hermione, a witch, could be born to "muggle"—or nonmagical—parents.

Time crystals are systems of atoms organized into periodic patterns of motion

Unlike traditional crystals—whose atomic structures cause them to look identical no matter how you look at them in space—time crystals exhibit this behavior through time, where the motion of atoms will bring them to the same positions relative to one another regularly.

Go behind the scenes of the making of the ‘Harry Potter’ films

See a rare look at how the beloved series was brought to life—from set design and visual effects to interviews with cast and crew who shaped the wizarding world on screen.

With his dry wit, Stephen Hawking warns of AI dangers and explains imaginary time

In this comedic interview with John Oliver, Stephen Hawking discusses his groundbreaking work in theoretical physics, his views on AI, and Oliver's chances of dating Charlize Theron in the multiverse—all with his trademark voice and humorous tone.

Wormholes, though unstable, would offer a theoretical shortcut through spacetime

These hypothetical distortions in the fabric of spacetime may connect vast distances across or even between universes. While science fiction often portrays them as traversable tunnels, the energy and matter required to keep a wormhole open defy current physical understanding.

What is space-time?

Space-time is a complex subject, but this Livescience article makes an effort to disentangle the topic. Somewhat akin to a sheet of rubber that can be warped and bent in parts, space-time is a bit more involved that that. However, the analogy makes this and other aspects of the concept simpler to grasp.

Visualizing Einstein's special relativity

Before Einstein developed his theory of general relativity, he worked out what is known as special relativity—or why time is experienced different for different observers. The breakthrough rests on his theory that light travels at a constant...

Neil deGrasse Tyson explains wormholes and black holes

Much of the film Interstellar is centered on the existence of a wormhole and black hole, which happen to be two of the most perplexing things in the universe. Astrophysicist and StarTalk Radio host Neil deGrasse Tyson explains how wormholes and black holes work in real life in this two-minute video.

Imagine thousands of alternate histories of the world

AlternateHistory.com has hosted fan-written "what if" timelines, discussions, and speculative fiction since 2000, making it the largest online gathering of alternate history enthusiasts, with over 10,000 active members and a wiki cataloging hundreds of user-created scenarios. Two highlights to pique your interest: what if the Vikings had settled North America? What would have had to happen for the storyline of George Orwell's "1984" to come true?

A scientist debunks theories for why aliens might invade Earth

While TV and films offer common tropes for why aliens would invade Earth, many of those reasons aren't actually feasible. For example, a species with technology advanced enough to allow it to travel between planets likely doesn't need to enslave flawed humans to carry out its labor.

Explaining the many-worlds interpretation

A mind-bending, jargon-free account of the popular interpretation of quantum mechanics, helping to explain how something can be in two states at once.

Lewis Carroll's 'Alice's Adventures in Wonderland' turned the fantasy genre upside down

A lot of 19th-century British fantasy was often stiff; its children’s literature was often overly didactic. Carroll’s novel—about a young girl who falls into an unusual world full—was neither, offering vivid, psychedelic imagery and seemingly nonsensical word games.

No one showed up to the party for time travelers organized by Stephen Hawking

In 2009, Hawking hosted a reception but only sent out invitations afterward, hoping that time travelers from the future would attend and prove time travel possible. He later joked it was "experimental evidence" that time travel doesn’t exist.

Fantasy and science fiction are distinct genres, though they sometimes overlap

Fantasy stories take place in universes where magic exists; science fiction stories take place in universes that are still grounded in the physics of our world. In science fiction, supernatural powers have scientific explanations. Think of “Spiderman”: Peter Parker gains his powers after being bitten by a radioactive spider.

Understanding how and when time began requires a theory of quantum gravity

Rewinding the universe to the big bang compresses all matter, energy, space, and time into a single point, necessitating a model that combines general relativity with quantum mechanics. Although physicists understand time to have begun when the universe did, a clear understanding of the mechanisms involved remains unclear.

Why mythologist Joseph Campbell loved 'Star Wars'

Joseph Campbell, the literature professor who wrote about the power of mythology, suggested that "Star Wars" was a powerful modern myth that used classic archetypes to communicate a universal message.

'Harry Potter' became one of the most successful franchises in history

What began as a story written in cafés by an unknown author grew into a global phenomenon—spanning seven books, eight films, theme parks, and video games—reshaping modern popular culture.

The world's different calendars, explained

The calendar we use to mark the days, months, and year can feel set in stone, but the history of calendars shows these organization systems can and do change. Parse the fascinating, complex details of the Gregorian, Julian, Chinese, Hebrew, and many more calendars in this comprehensive, well-executed explainer video.

JRR Tolkien believed fantasy literature was an entirely different world

Tolkien effectively invented modern fantasy, which often relies on an intricate universe, complete with its own languages, cultures, lifeforms, physics, and systems. When an author did this effectively, he called it “Faërie”—a sort of enchantment that transports the reader into the fictional world.

Quantum mechanics and general relativity—two of the most successful explanations of the physics seen across the universe—are logically incompatible with one another because they use contradictory models for space and time.

George Lucas used Joseph Campbell's 'hero's journey,' a narrative structure that encompasses the common characteristics of multiple cultures' mythologies, to revise 'Star Wars.'

Time disappears when encompassing all quantum configurations across the universe

The Wheeler-DeWitt equation, a modified version of the Schödinger equation—the formula that describes the evolution of the quantum configuration of a system—describes the quantum state of space-time across the universe. The transformation causes the variable of time to disappear, suggesting it is not a fundamental, physical parameter of the cosmos.

The art of miniature sets in Hollywood

Many films utilize meticulously designed miniature sets to produce scenes that would otherwise be too big to film. While artsy filmmaker Wes Anderson is well-known for reviving this technique in an idiosyncratic style, more mainstream films like "Star Wars" and "Inception" rely heavily on small-scale sets filmed in such a way as to make them appear normal-sized. This nine-minute video breaks down how it all works.

How science explains déjà vu

Take a fun look at the science explaining the odd experience of déjà vu, which some theories suggest is actually a sign of a healthy brain.

Visualizing the highest-grossing movie franchises from 1979 to 2019

A few dozen major movie franchises have dominated the box office in recent decades, including "Star Wars," "Harry Potter," "Lord of the Rings," and Marvel. This video shows the change from quarter to quarter in gross revenue for each movie franchise over the decades.

Four directors shaped the evolving tone of the ‘Harry Potter’ films

Across eight movies, Chris Columbus, Alfonso Cuarón, Mike Newell, and David Yates each brought a distinct vision—from early wonder to darker maturity—charting the series’ shift from children’s fantasy to coming-of-age epic.

Take a tour of Charles Dickens' London

Much of Dickens' fiction concerns Victorian London and its people. This tour of the city, led by Dickens biographer Simon Callow, walks you through significant sites, like the place where Dickens' parents were married, the shoe-blacking factory where he worked as a boy, and the place where he created his first magazine.