Marty McFly (Michael J. Fox) in the "hoverboard" scene from Back to the Future II when he travels forward in time to 2015 to avoid a temporal catastrophe.
Image credit: Sara Hayward/Getty Images
Top 5 Time Travel Methods from the Movies
Oh, how we often long to travel back in time and change our pasts, to stop some horrible event, to rewrite history. Movies often indulge and inspire us with their time travel adventures, but how many of these have any basis in real science? Let's, for this purpose, ignore how much the movies tug at the heartstrings, entertain us, or tickle our funny bone. We can never forget great ones like "Back to the Future," "Bill and Ted's Excellent Adventure," "Time Cop" and many others. But this is a focus on how the heck we are going to get these movies to come true. Ron Mallett, professor of physics at the University of Connecticut and author of Time Traveler: A Scientist's Personal Mission to Make Time Travel a Reality, has spent his whole career studying the possibilities of time travel and he weighed in on what aspects of the movies are on the edge of possibility and which ones are not. Derived from the expertise of Mallett, here are the top five time travel movies ranked on their basis in science and their true feasibility. Sorry "Hot Tub Time Machine", you didn't make the cut.
Image: Frank (Dennis Quaid) communicates with
Frank Sullivan, played by Dennis Quaid, communicates with his son John (Jim Caviezel) 30 years into the future through a radio. They work together to save Frank's life and to find John's mother's would-be-killer. Frequency's time travel is largely based around an unusual environmental phenomenon in the aurora borealis. This solar disturbance causes Frank's radio to send its signal to the same radio in the future, where John now has it in the same home. The idea that the energy from a solar disturbance could alter spacetime in some way that sends radio waves through time is very much outside the realms of possibility. The aurora borealis could never produce that much energy and if it were to do so, there would likely be some disastrous side effects. But being outside the realms of possibility isn't a problem when it comes to sci-fi time travel. However, Brian Greene, physicist and author of several books including The Elegant Universe, was a consultant for the film, so his input certainly gave the movie some extra weight as far as feasibility goes.
Image: An artist's rendition of a wormhole. C
Déjà Vu (2006)
After a ferry bombing, Agent Doug Carlin (Denzel Washington) joins forces with a special team that has technology to see four days into the past. This technology turns out to be a "time window" which Carlin convinces them to use as a time machine and send him into the past. He ends up saving the ferry from the bomber, played by Jim Caviezel. This is a stretch and would involve technology and an understanding of wormholes that we just don't have right now. The "Snow White" project, as it's called in Déjà Vu, somehow controls wormholes or what they call a "time window" to travel through time and space. Wormholes, also called Einstein-Rosen bridges, are a valid theoretical method for time travel, but solely theoretical. Their existence has never been proven and requires something called "exotic matter" to keep them stable. Yet, Mallett says that any movie involving theories of Einstein for time travel is more feasible than those that do not. The movie takes the theory to the extreme in a way that is very entertaining and smart. Brian Greene, who consulted in "Frequency," was also a consultant for "Déjà Vu". You definitely need a theoretical physicist to keep all the timelines straight in this one.
Image: H. George Wells (Rod Taylor) fires up
The Time Machine (1960)
H.G. Wells wrote the original book and the movie's lead character is named H. George Wells (Rod Taylor) after him. He uses his machine to travel from the year 1900 through the future seeing two world wars and accidentally ending up in the year 802,701, where he finds a future people who he tries to help. Mallett has this high on his list (of course he says the book is even better) because it's the only movie that accurately states time as a fourth dimension. Although in modern relativistic physics, space and time are combined into one metric called "spacetime." The machine itself; not so feasible. A chair with spinning parts and a lever that controls time travel is something today's scientists have yet to find viable. It's quite miraculous that the fictional H. George Wells was able to invent it in the early 1900s. Another positive note for this version: it does not have him traveling to the past beyond the invention of his machine. The movie doesn't explain this rule, but it does follow the true physics of time travel. Mallett says, "Since it is the device that creates the effect, then is not possible to go back before the device was created."
Image: The bridge of the Enterprise in Star T
Star Trek (2009)
Time travel is featured in the "Star Trek" series many times, but the way the most recent movie dealt with time travel makes it very easy to understand without having to be a physics expert. "They actually brought in a number of current ideas," says Mallett. The movie's use of parallel universes is done very well and explained very well. There is a valid scientific theory in quantum mechanics that says there are many parallel universes. Plus, when you go back into the past you actually arrive in the past of a parallel universe, where you can change the future of that universe, but in your time those things have already happened. It's also important to know that once you are in this alternate reality you cannot, as another time travel movie suggests, go back to the future. Black holes are a very popular method for sci-fi time travel and one that could actually be possible. Einstein's general theory of relativity basically says that gravity effects time and since black holes have gravity so strong that light can't even escape, they create the possibility for time travel. If you were able to get close to a black hole, time would slow down. When you escaped, time outside would have passed a lot more quickly. Making things more complicated, when the black hole is rotating, it can cause time to be twisted into a loop that allows you to go into the past. That still leaves some scientific flaws in the movie, but nobody's perfect. It was still one of the most (if not the most) entertaining "Star Trek" movies.
Image: Charlton Heston finds himself in front
Planet of the Apes (1968)
Put briefly, astronaut Taylor (Charlton Heston) unknowingly goes on a journey to a future Earth where apes have guns, don't believe in the possibility of flight, and rule the planet. Humans are still around in this future, but are mute and quite unintelligent. The best thing about this movie is that they talk about real scientific theories in explaining how they traveled through time. "According to Dr. Hasslein's theory of a vehicle traveling near the speed of light, the earth has aged nearly 700 years since we left it, while we've aged hardly at all," says Taylor in the opening scene of the movie. Actually, it's based more on theories of a man named Albert Einstein. His special theory of relativity says that time for a moving clock slows down. In 1971, the Hafele-Keating experiment proved this with very accurate atomic clocks. One was on Earth and another was flown around the world on a passenger jet. When the jet landed, the clock on the jet was about 50 nanoseconds behind the one on Earth, just like Einstein predicted in 1905. "This means, for a space traveler traveling close to the speed of light, that this effect will happen dramatically. A few years will pass for those on board, but when the rocket lands, decades will have passed on Earth," explains Mallett. So as Heston and his crew travel near the speed of light, they would in fact be traveling through time relative to those of us on Earth. Getting a ship close to the speed of light is the practical challenge in this case, but very plausible in theory. The portion of the movie in which apes control the planet is a little more questionable.
After carrying out the first search for evidence of time travelers using social media networks, a pair of physicists have turned up empty handed. This search for "prescient" messages online has yet to be picked up by a peer-reviewed journal, but the media has jumped on the news nonetheless.
Although I filed this research under “There’s too much cool sciencey stuff coming from the American Astronomical Society meeting in Washington, D.C. this week for me to find the time to write about time travel,” I’ve received a few emails pointing me to this work. So, as it’s Wednesday,* here we go.
Prescience in the Search Engine
The crux of the study by astrophysicist Robert Nemiroff and physics graduate student Teresa Wilson from Michigan Technological University is that they carried out an unprecedented search of the Internet for any signs of prescient knowledge of future events. Of particular interest was any mention of “Comet ISON” or “Pope Francis”. The idea is that should time travelers travel back in time from the future and arrive before Comet ISON was discovered (in September 2012) or before Pope Francis was elected head of the Catholic Church (in March 2013), they might have accidentally (or otherwise) let slip about these future events on an Internet-based platform. Both search terms were considered unique enough for there to be a very low chance of false positives.
Searching for prescient information on the Internet proved to be a somewhat tricky affair, however.
For example, using Google Search to tease out prescient mentions of “Pope Francis” or “Comet ISON” turned out to be “unreliable.” As did Google’s competitor Bing.com. The researchers then turned to social media for help. They carried out searches of all the popular social sites including Facebook, Twitter and Google+. Facebook, however, was another unreliable source of prescient messages as the platform allows back-dated messages to be published.
Twitter, it seems, reigned supreme. Yay Twitter.
“Our most comprehensive search for potentially prescient Internet content was achieved using the microblogging Internet platform Twitter,” they wrote.
Assuming our temporal travelers were social media savvy, Nemiroff and Wilson found that hashtags (“#”) were an especially useful tool for their hunt. They therefore tried to weed-out any mention of #cometison or #popefrancis before the events themselves occurred.
“No clearly prescient content involving ‘Comet ISON’, ‘#cometison’, ‘Pope Francis’, or ‘#popefrancis’ was found from any Twitter tweet — ever,” they concluded.
Interestingly, they also rummaged through search queries (i.e. queries typed into search engines by Internet users) to see if anyone was looking for information about “Comet ISON” or “Pope Francis” before the events occurred. This search also turned up zero definitive prescient candidates.
Come to my Party, Yesterday
Finally, they also tried to actively engage time travelers on Twitter. In September 2013, the hypothetical time travelers were asked, via an Internet forum bulletin, to tweet one of two hashtags on August 2013 — one month before the bulletin was sent out. Time travelers were requested to tweet either #ICanChangeThePast2″ or “#ICannotChangeThePast2″ — the first would be tweeted if the author’s past could be altered and the second would be tweeted if the author’s past could not be altered. A similar strategy was used by Stephen Hawking in 2009 who advertised a “Time Travelers Party” but only advertised the event after the party had taken place. Nobody — no candidate time travelers or random party crashers — turned up. Good effort though, Stephen.
This is the very basis of the “Grandfather Paradox” that posits that if reverse time travel were possible, could you go back in time and kill your grandfather. In this scenario, would you cease to exist in that timeline or would you cease to exist in another timeline? You remember when Marty McFly’s hand starts to disappear during The Enchantment Under The Sea dance in “Back To The Future”? That paradox.
Using both passive and active means to find evidence of time travelers, no strategy turned up evidence of time traveler activity. “No time travelers were discovered,” they wrote. “Although the negative results reported here may indicate that time travelers from the future are not among us and cannot communicate with us over the modern day Internet, they are by no means proof.”
Time Travelers: Not So Smart?
Although this Internet search was fun, and it demonstrates a potential strategy for teasing out prescient knowledge of events using social media, its limited scope greatly reduced any hope of success even if time travelers are out there. The study assumes that, a) travelers from the future want to be discovered or, b) they are careless to let slip about two specific future events. Both options I find difficult to swallow.
If the first option is true, and they used their future knowledge to be discovered, one would have to question their motives and/or sanity — aren’t they breaking some time traveling “code of ethics”? If b) is true, the intellect of our future selves could be called into question. If they can’t keep quiet and avoid babbling on social media, how the heck did they had the smarts to build a time machine in the first place?
Also, why would time travelers just pop onto the social web and start tweeting? No doubt they’d have the ability, but it’s hard to see what they’d get from it — apart from giggling at Justin Bieber’s “I’ve retired at 19″ tweets and lamenting that even in the year 2082, Biebs is still singing his little heart out and peeing into mop buckets.
And, why now? Sure, we think we’re important and our era is unbelievably epic, but in the grand scheme of things, over tens (or hundreds) of thousands of years of civilization (from the past to the undefined future) — not to mention all those billions of years when humans weren’t roaming around and polluting the planet — the early 21st century may not be all that.
Perhaps all the “cool” time travelers travel back to see the dinosaurs to experience the gritty Jurassic era; or explore ancient Rome to find out if Julius Caesar really was a tyrant or just misunderstood; or hit up the rowdy pubs of London during the Industrial Revolution? The problem with humans is that we all think we’re special, that this time in history is special and we are the specialest of all special entities in all of human history.
What if our future selves think we’re all a bit “meh” and crossed off the 21st century as a snooze fest? Assuming that these time travelers are even human! So many questions.
Scouring the Internet for prescient knowledge probably isn’t very reliable anyway. If we were to scale this up, research hundreds or even thousands of search terms that could have only been thought up right at the time of a specific event and devoted a supercomputer (or a distributed computer effort SETI@home style) to trawl the web for “prescient candidates,” the sheer number of false positives would likely cause the system to unravel. (Although, looking at the rapid advancement of computing, it’s not that inconceivable that we might build some form of artificial intelligence that can pick through the web, searching for messages from John Connor. Wait a minute.) The Internet is not infallible, after all, regardless on how full-proof the researchers think data from Twitter is.
Limitations of this study aside, traveling back in time isn’t thought to be physically possible anyway; only forward time travel is possible (and, actually, surprisingly easy) — unless you do some fancy stuff with wormholes. Time travel is therefore likely to remain firmly in the realms of science fiction. Also, there’s that inconvenient idea that even if reverse time travel were possible, you’d only be able to travel back as far as when the time machine was first constructed. Bummer.
All that said, if you are reading this and you’re from the future, please send me an email with 1) next week’s lotto numbers, 2) the next 10 years of Superbowl winners and, 3) blueprints for the warp drive, that would sure come in handy around about now. Thanks.
*Just kidding, it’s Tuesday.
Publication (pre-print): “Searching the Internet for evidence of time travelers”, Robert Nemiroff & Teresa Wilson, 2013. arXiv:1312.7128 [physics.pop-ph]
UPDATE 1 (Jan. 10): I've just received my first email from a time traveling candidate! (Hi, 'Eli') Not sure if he's the real deal, but let's put it this way, I'll be betting on the next ten Superbowls.