First, the good news. Time travel isn’t necessarily forbidden by the laws of physics. In fact, the mathematics underpinning Albert Einstein’s theories of relativity offer up possibilities via the likes of wormholes and curved spacetime that might allow someone — or more likely something — to make a journey back into the past. Not that anyone really knows how you’d do it — or if it’s even possible at all.
Luckily for sci-fi writers, there’s rarely any need to worry about backing up their ideas with facts. Over the years, they’ve come up with numerous ingenious ways to negotiate the space-time continuum, from iconic cars and spaceships slingshotting around stars, to heavily-modded telephone boxes and even — we’re sorry to say — a time machine built into a hot tub.
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1. Flux Capacitor
As seen in: “Back to the Future” (1985)
Doc Brown never really gets into the science of the Flux Capacitor — all we really need to know is that this cobbled-together component is “what makes time travel possible”. But when this unassuming glass box is installed in a car — preferably stainless steel, it aids with “flux dispersal”, apparently — you can rest assured that you’re going to see some serious s**t.
There are drawbacks, of course. Getting your DeLorean serviced is not as easy as it once was, you need enough road to get up to 88mph, and — unless you’ve had a Mr. Fusion generator installed — you’ll require some plutonium if you’re going to generate the 1.21 gigawatts required to traverse the fourth dimension. A small price to pay, perhaps, if you want to meet your parents when they were kids.
Other time-traveling cars are available, including the Volkswagen Beetle and Cadillac Eldorado driven by Austin Powers.
2. TARDIS
As seen in: “Doctor Who” (1963-present)
Arguably the most powerful and sophisticated time machine of them all, a Time Lord’s TARDIS (it stands for Time And Relative Dimension In Space) makes hopping around the space-time continuum as easy as going to the shops in your car.
Despite the show’s efforts to explain away a TARDIS’s functionality with black holes and the Time Vortex, its abilities are best regarded as magic. Any place or time in history (or the future) is at your disposal when you’re the owner of a TARDIS, a vehicle that has the uncanny ability to blend into its surroundings — assuming, of course, a faulty chameleon circuit hasn’t condemned you to a permanent phone box exterior.
The future dudes in “Bill and Ted’s Excellent Adventure” also decided that phone boxes made for bodacious time machines — though their version was most definitely not bigger on the inside.
3. Stellar slingshot
As seen in: “Star Trek” (1967-present)
Captain James T Kirk’s famous voiceover never talked about “time: the final frontier”, but the Enterprise and its successors have set coordinates for the fourth dimension on numerous occasions.
Sometimes known as the “light speed breakaway factor”, Starfleet’s preferred time travel technique involves accelerating to maximum warp before performing a slingshot maneuver around a star (or other body with a strong gravitational field). This subsequently sends the starship forward or backward in time, while occasionally (and inexplicably) transforming your shipmates into freaky clay heads.
The calculations required to reach your destination are mind-bogglingly complex, which is why you need a Spock (see Original Series episodes “Tomorrow is Yesterday”, “Assignment Earth”, and 1986 movie “The Voyage Home”) or a captive Borg Queen (“Picard” episode “Assimilation”) to make it work.
This complexity is presumably why the Borg opted to unveil a more user-friendly time travel solution, namely “chronometric particles”, in “First Contact”.
4. The Quantum Realm
As seen in: “Ant-Man & The Wasp: Quantumania” & “Avengers: Endgame” (2019)
Unfortunately, the convenient time travel rules seen in “Back to the Future” — don’t interact with your past/future self, don’t bet on future sporting events — no longer apply in the MCU, where messing around in the past does not change the future.
The Avengers do, however, have access to the Quantum Realm, the sub-atomic domain where time starts to behave in weird, non-linear ways. It’s all kind of random, but luckily Earth’s Mightiest Heroes also turn out to be Earth’s Brainiest Heroes when Tony Stark works out how to circumvent potential issues with quantum fluctuations, the Planck Scale, and the Deutsch Proposition.
In layman’s terms? Iron Man builds a “time-space GPS” capable of getting the team when and where they need to be — as long as they have enough Pym Particles (the mass-altering fuel for Ant-Man’s suit) to make the round trip.
5. Time Displacement Chambers
As seen in: “The Terminator” (1984-present)
With flesh-and-blood commander John Connor proving to be a thorn in its silicon side, malevolent AI Skynet builds time displacement equipment to open up a new frontier in the human/machine war — the past.
Although we don’t see the machinery at work in the first two movies, later “Terminator” outings reveal a mass of spinning metal that zaps anything inside it to a predefined point in the past or future, with the goal — again countering the rules laid down by “Back to the Future” — of altering the timeline.
As an important side note, the device only works if you’re covered in living tissue — or a shapeshifting cyborg constructed from mimetic polyalloy — so you need to be comfortable with the fact you’ll be arriving in a new time period as naked as the day you were born.
6. General relativity
As seen in: “Interstellar” (2014)
Is this technically time travel? Possibly not, though Einstein’s theory of General Relativity does have some time-travel-like consequences.
In “Interstellar”, the intense gravitational field of a black hole named Gargantua dilates time for the crew of the Endurance mission, meaning that mere hours on the surface of an alien world are equivalent to years back on Earth. When intrepid pilot Coop is eventually reunited with his daughter, Murphy, he’s skipped decades while she’s now significantly older than he is — in effect, he’s travelled to the future.
Special Relativity also comes into play in the ’80s Disney movie “Flight of the Navigator”, where a kid is abducted by an alien spacecraft in 1978 and — after a quick faster-than-light jaunt to the planet Phaelonn — wakes up in 1986. Luckily, the boy’s sophisticated spaceship buddy Max also has the time travel smarts to take him home again.
7. Time inversion
As seen in: “Tenet” (2020)
Lots of people — including writer/director Christopher Nolan — will tell you that the time inversion in “Tenet” isn’t technically time travel. We disagree, seeing as the tech can transport you into the past and back again.
It works by flipping entropy, the amount of disorder in a system, which — according to the second law of thermodynamics — always tends to increase. In other words, stepping through one of the Turnstiles in “Tenet” allows you to experience time in the opposite direction to everybody else, meaning that your future is their past, and vice versa.
There are drawbacks, however. There are no shortcuts — your journey through time must, by definition, unfold in real (albeit reversed) time — and it’s really, really hard to get your head around the mechanics of the situation. Similarly themed “Red Dwarf” episode “Backwards” was a lot easier to follow.
8. “The Box”
As seen in: “Primer” (2004)
Jeff Bezos famously launched Amazon from an ordinary garage. In “Primer”, two ordinary guys go one step further by building a time machine in their spare time.
As you’d expect from a film that cost less than $10,000 to make, the device makes the Flux Capacitor look like the pinnacle of sophistication. Even so, it’s big enough to accommodate a human time traveler, and it actually works. The only problem is, negotiating and understanding the subsequent paradoxes — which writer/director Shane Carruth made little effort to simplify — requires a PhD in high-level physics.
“Safety Not Guaranteed” takes a similarly DIY approach to a complex problem.
9. Closed loops
As seen in: “Looper” (2012)
The time travel in “Looper” is limited but extremely effective. With the tech outlawed soon after its creation in 2074, it fell into the hands of the criminal underworld, who use it as an untraceable method for disposing of people they don’t like — send the victim 30 years into the past and, the theory goes, their body will never be discovered.
The drawback, of course, is that the only journey you can make is between 2074 and 2044, vastly reducing opportunities for time tourism. Also, the eponymous Loopers (assassins in the past hired to kill people sent back from the future) know they’ll be bumped off as soon as they’ve gone the long way round to 2074, thereby closing the loop. It’s brutal, but nobody can say the system doesn’t work.
10. Anomalies
As seen in: “Primeval” (2007-2011)
These gateways through space and time are too random and sporadic to provide a useful method of temporal travel. They do, however, have a habit of transporting dinosaurs into the present day, which is handy if you want to recreate “Jurassic Park” in the UK.
Similar portals are a convenient way of getting from point A to point B in the spacetime continuum, and a riff on the notion of wormholes/Einstein-Rosen Bridges. Notable examples include the Guardian of Forever in “Star Trek”, the time travel device in “Continuum”, and the gateway that transports new soldiers to a future conflict in “The Tomorrow War“.
It’s also pretty close to the time-travel side effects of Third Energy in the “Dino Crisis” games, which, wouldn’t you know it, also brought dinosaurs to the present day.
11. Quantum Leap Accelerator
As seen in: “Quantum Leap” (1989-1993)
Found in a top-secret facility beneath a mountain in the New Mexico desert, this experimental time-travel tech sent its inventor, Dr. Sam Beckett, on a frustratingly random journey through space and time.
There were caveats, however: he could only “leap” to dates within his own lifetime (with the odd exception), and had to inhabit other people’s (or chimpanzee’s) bodies while he was there.
And unlike other famous time travelers who are strictly forbidden from meddling with history, Beckett needs to alter the timeline (for the better) if he’s going to make his next leap.
12. Mutant powers
As seen in: “X-Men: Days of Future Past” (2014)
Why waste your time building a fancy time machine when mutant powers can do the job just as easily?
In “X-Men: Days of Future Past”, Kitty “Shadowcat” Pryde’s teleporting abilities are repurposed to transport Wolverine’s consciousness from 2023 back to his 1973 self. In Chris Claremont’s original comic, it was Pryde herself who made the journey, but the mission remains the same — altering the past to avert a mutant apocalypse.
In “The Umbrella Academy”, fellow teleporter Number Five also possesses superpowers that allow him to travel through time. He’s subsequently head-hunted by the Commission to help monitor the timeline.
13. Alien blood
As seen in: “Edge of Tomorrow” (2014)
Exposure to the blood of an alien invader — specifically one of the Mimics’ Alpha leaders — traps cowardly military PR guy Major William Cage in an inescapable time loop.
It’s more a cool plot device than a logical explanation, though it’s no more ridiculous than the cave in “Palm Springs” and whatever it is in “Groundhog Day” (a magical rodent?), which induce similar déjà-vu-inducing qualities.
14. A stone circle
As seen in: “Outlander” (2014-present)
The stone circle that transports World War II nurse Claire Randall back to the 18th century may just be a marker for a pre-existing region of magical properties in the Scottish Highlands.
Its powers also appear to act on a few lucky (or unlucky, depending on your point of view) individuals. Either way, this is another time travel technique best written off as unadulterated sorcery.
15. A cyberpunk raincoat
As seen in: Good Luck, Have Fun, Don’t Die (2026)
If Sam Rockwell thinks this is the best way to time travel, who are we to argue? That man is a treasure.
Known only as The Man from the Future, Rockwell’s character zaps back from the future and lands in a Norms diner, looking to assemble a dream team to stop the AI apocalypse. And, somehow, he succeeds despite looking like a wet-weather averse suicide bomber.
His time machine is constructed from a see-through raincoat, an angry piggy backpack, a bunch of wires and tubes, and every sci-fi-looking gizmo and doodad the prop department could hot-glue to it.
He claims that it’s “the height of f***ing fashion” where he’s from… we’re not so sure about that, but it’s a rad piece of costume design.
16. A hot tub
As seen in: “Hot Tub Time Machine” (2010)
Yes, this is actually a thing in an actual movie. Some things just defy explanation. Seriously, what the hell were they thinking?
