Pyramids and other exotic locales in the science-fiction movie "Jumper."
Everyone knows Anakin Skywalker can't really teleport himself to the Great Pyramids of Egypt, even though Anakin ... er, Hayden Christensen ... does just that in the movie "Jumper," opening Thursday. But isn't it possible to go through a wormhole in the space-time continuum? Wellllll, maybe - if you've got a galactic black hole's worth of power. Such are the issues that come up when science meets fiction, at the movie theater as well as in the classroom.
When scientists met up with Christensen and the director of "Jumper" at the Massachusetts Institute of Technology last month, neither side knew what to expect. But the result wasn't at all like the battle between the Jumpers and the Paladins in the movie. Both sides came away with that most sought-after Hollywood ingredient: a happy ending.
"The event was much more fun than I thought it would be," said MIT cosmologist Max Tegmark, who sat in a lecture hall along with quantum physicist Edward Farhi and a gaggle of students to watch a selection of scenes from the movie.
"It was actually an amazing experience. I was waiting to get shredded," said the movie's director, Doug Liman, a veteran of such big-name blockbusters as "The Bourne Identity" and "Mr. and Mrs. Smith."
In a telephone interview from Paris, where Liman was in the middle of a global publicity tour, the director recalled how he was thrown out of a physicist's office when he went looking for advice about teleportation. He was afraid the eggheads at MIT would react the same way, despite reassurances from the publicists.
"That just seemed like a recipe for disaster in terms of how I was going to come across," Liman told me. "But it was incredibly inspiring, because the physicists explained how they use movies to make physics more appealing and more magical."
Tegmark recalled that the affair had a party atmosphere, with some students sporting Darth Vader masks and lightsabers. "I remember thinking, 'Whoa, I never realized that MIT undergrads were such a bunch of groupies,'" he said with a laugh.
Getting technical about teleportation
The premise of "Jumper" is that the character played by Christensen somehow gains the power to teleport himself to distant locations, to get himself out of a jam or to save the girl.
Some of the advance publicity has compared the trick to quantum teleportation - but that would be wrong. As numerous bloggers have pointed out over the past couple of weeks, quantum teleportation is all about transferring information rather than beaming up in the "Star Trek" sense. In the movie (as well as the novel on which the movie is based), the main character doesn't know how he does what he does. And that suits Liman just fine.
"You don't have to understand why and how we do certain things," he told me.
Nevertheless, Liman said he does care about making scientific sense.
"I said that I was only going to take this one leap of faith," he said. "I tried to observe the laws of physics as best I could outside this one leap."
For example, Liman worked it out so that every time Christensen made a jump, the surrounding medium would whoosh in to take his place. "He has a certain volume," Liman explained. "If he's no longer there, something has to fill that space."
Another rule of the movie is that Jumpers have to enter a new reference frame with the same momentum they had when the left the previous reference frame. For example, let's say Christensen is in the middle of a fall from the top of the Empire State Building. "Yes, you can teleport away from that spot, but wherever you arrive, you will be traveling with that velocity," Liman said.
Limiting the liberties
Tegmark liked how Liman limited the liberties he took with basic physics. "He saw through things at a different level than the typical Donald Duck physics that you see," the physicist said.
"The main thing that he took liberties with was what we call energy conservation," Tegmark continued. "Einstein told us that E=mc2. In other words, matter is the same thing as energy. ... That means that a modest amount of matter, like you, corresponds to many, many megatons of energy. It's no small task to eliminate that from one place and put it in another place.
"If you turned yourself into energy, it would be like a hydrogen bomb had gone off," he said.
Let's say mad scientists had unlimited energy at their disposal (bwa-ha-ha!). It might be possible to bend space-time into an extradimensional wormhole and teleport to distant locations. But that would take some expertise - more expertise than the high-school dropout in "Jumper" could muster. And there would be a high price to pay.
"If you were able to somehow create a wormhole, when you try to jump through it, it would probably turn into a black hole - which kind of sucks," said Tegmark, fully aware of the double meaning.
The real-world physics behind the possibility of wormholes has been entangled with science fiction for decades. The concept was fleshed out by Caltech physicist Kip Thorne when Carl Sagan asked him to come up with a plausible way to get his heroine back and forth through space-time in the novel "Contact." To Thorne's surprise, he found that there was nothing in physics that absolutely ruled out the existence of wormholes, as long as you could get your hands on a huge amount of negative energy.
"Wormholes are probably not stable, but we still haven't been able to prove that in a convincing way," Tegmark said, "so there's still a slight possibility that lingers. People are looking into whether you can stabilize them with dark energy."
Science fiction and science fact
Tegmark said the best thing about science-fiction movies, even movies where the science is especially fictional, is that they spark more interest in science fact.
"As a scientist, often the hardest thing is not finding the right answer, but finding the right question - and science fiction is great for generating the right questions," Tegmark told me. "It's like when you're watching a movie and you say, 'It's obvious that that's impossible.' Then you realize, it's not so obvious why it's impossible. You start asking very basic questions about the nature of space and time."
That's how Einstein started along the path that eventually led to E=mc2 and more.
"It was precisely because Einstein was trying to understand the nature of time that we arrived at nuclear power," Tegmark said. "This goes to show that anything that stimulates basic research, even though it might seem completely useless, often has great applications."
So what's next? One of the fundamental issues surrounding wormholes is that they might (or might not) essentially work like time machines. There's even talk that microscopic time machines could be created later this year at the Large Hadron Collider.
That claim may be highly debatable - but Liman is already aware of the connection to time travel, which is a time-honored tradition in sci-fi cinema.
"I saved that for the sequel," Liman said. "That is definitely something that would be part of this, but it was too much for this story. I felt like it would have limited the depth to which I could explore this one idea."
To learn more about what Hollywood has done to scientific ideas over the years, check out Insultingly Stupid Movie Physics, the Cartoon Laws of Physics and the Bad Movies page at Phil Plait's Bad Astronomy Web site. If you have any other funny (or fantastical) examples of cinematic science, feel free to add them as comments below.
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