Is the Wormhole in 'Interstellar' Possible?

Sci-fi fans who hope humanity can one day zoom to distant corners of the universe via wormholes, as astronauts do in the recent film 'Interstellar,' shouldn't hold their breath.

Sci-fi fans who hope humanity can one day zoom to distant corners of the universe via wormholes, as astronauts do in the recent film "Interstellar," shouldn't hold their breath.

Wormholes are theoretical tunnels through the fabric of space-time that could potentially allow rapid travel between widely separated points - from one galaxy to another, for example, as depicted in Christopher Nolan's "Interstellar," which opened in theaters around the world earlier this month.

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While wormholes are possible according to Einstein's theory of general relativity, such exotic voyages will likely remain in the realm of science fiction, said renowned astrophysicist Kip Thorne of the California Institute of Technology in Pasadena, who served as an adviser and executive producer on "Interstellar." ['Interstellar': A Space Epic in Pictures]

"The jury is not in, so we just don't know," Thorne, one of the world's leading authorities on relativity, black holes and wormholes, told Space.com. "But there are very strong indications that wormholes that a human could travel through are forbidden by the laws of physics. That's sad, that's unfortunate, but that's the direction in which things are pointing."

The major barrier has to do with a wormhole's instability, he said.

"Wormholes - if you don't have something threading through them to hold them open - the walls will basically collapse so fast that nothing can go through them," Thorne said.

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Holding wormholes open would require the insertion of something that anti-gravitates - namely, negative energy. Negative energy has been created in the lab via quantum effects, Thorne said: One region of space borrows energy from another region that didn't have any to begin with, creating a deficit.

"So it does happen in physics," he said. "But we have very strong, but not firm, indications that you can never get enough negative energy that repels and keeps the wormhole's walls open; you can never get enough to do that."

Furthermore, traversable wormholes - if they can exist at all - almost certainly cannot occur naturally, Thorne added. That is, they must be created by an advanced civilization.

And that's exactly what happens in "Interstellar": Mysterious beings construct a wormhole near Saturn, allowing a small band of pioneers, led by a former farmer named Cooper (played by Matthew McConaughey) to journey far afield in search of a new home for humanity, whose existence on Earth is threatened by global crop failures.

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Anyone interested in learning more about the science of "Interstellar" - which also features gravitational time dilation and depictions of several alien planets orbiting close to a supermassive black hole - can check out Thorne's new book, which is called, appropriately enough, "The Science of 'Interstellar.'"

Wormholes have been a staple of science fiction for decades. Interestingly, Thorne said that one of the genre's most famous titles helped inspire scientists to try to better understand the hypothetical structures.

"The modern research on the physics of wormholes largely stems from the movie 'Contact,' from conversations I had with [renowned late scientist] Carl Sagan - actually, when he was writing his novel 'Contact,'" Thorne said.

"Contact" features traversable wormholes. The novel came out in 1985, while the movie (which also stars Matthew McConaughey, apparently a wormhole connoisseur) was released in 1997.

More from SPACE.com:

'Interstellar' Trailer Reveals Potentially Habitable Worlds | Video How Interstellar Space Travel Works (Infographic)

The Science of 'Interstellar' Explained (Infographic)

Originally published on Space.com. Copyright 2014 SPACE.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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.

Frequency (2000)

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.

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.

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."

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.

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.