When the filmmakers behind "Watchmen" wanted to understand the scientific principles behind the acclaimed graphic novel, they turned to a physics professor in Minnesota.

"They wanted to get enough of the science right that they could create an artificial reality that still felt real to the audience," said James Kakalios, a physics professor from the University of Minnesota who served as science consultant on the "Watchmen" film.

Kakalios is known among his colleagues for research in experimental condensed matter physics, but to his students, he's the professor who teaches about the comic books he loves. By relating scientific principles to the various superheroes who utilize them, Kakalios not only developed a comic-based science class for the freshmen he teaches, but used his research to write the book "The Physics of Superheroes."

"A lot of comic book stories, especially going back to the Silver Age, tried to be what used to be called 'hard' science fiction. They were trying to have one impossible aspect, but have everything else be as realistic as possible," the professor explained. "So they tried to put these little bits and nuggets of science into the story whenever possible."

Kakalios points out that, for example, the DC Comics speedster the Flash is constantly doing things with his "superspeed," a concept that requires a suspension of disbelief. But if the character has to knock someone down without touching him, he'll run very fast and create a shock front, which is a real scientific concept.

"By going through this while teaching my students, I was able to actually construct an entire physics book written for a general readership where all the examples came from, for the most part, correct applications of physics found in superhero comic books," Kakalios said.

So when the creators behind the "Watchmen" movie asked the National Academy of Sciences for a consultant to help them translate the acclaimed graphic novel to film, they looked no further than Kakalios and his superhero expertise.

"The National Academy called me and said, have you ever heard of this thing called 'Watchmen'?" Because they'd never heard of it. After I was done vibrating like a gong I said, 'Uh, "Watchmen?" Yeah, I've heard of it,'" he said with a laugh.

Much of his consulting involved the science behind Dr. Manhattan, the "Watchmen" character whose powers are based on quantum physics. But the professor began working with filmmakers all the way back in the pre-production stage, lending his expertise to everything from the movie's set designs to the psychology of the characters.

"Alex McDowell in particular, the production designer, and the other art designers would say things like, 'What would a physics lab look like in 1959?' or 'What would it look like in 1985?' and 'Early in the story we see Dr. Manhattan working on some apparatus. What is he doing here?'" he said. "They flew me up to the set, they showed me things, we talked about how certain things would work.

"And then they were also interested in the psychology of scientists and how we would interact with other people," Kakalios said. "One of the things that, sadly, is accurate in the story is that when we see, sometimes, students get depressed or start having trouble with the stresses of their life, they hone in on their research, and they focus on that to the exclusion of practically everything else. It's the one thing that they feel they have some control over. And so, you see this also with Dr. Manhattan's attitudes and behaviors. He kind of just retreats into his research more and more."

In the graphic novel, Dr. Manhattan gets his powers from having his atoms torn apart in an "intrinsic field subtractor," but he's able to put himself back together, transforming into a being powered by quantum mechanics. He can exist in more than one time and place, and he can teleport himself as far away as Mars.

"Even though the movie and the graphic novel don't get into the minutia of how his powers work, [the filmmakers] were interested in how do they work?" Kakalios said. "Obviously, it's not possible, but if you made one suspension of disbelief -- if you had one miracle exemption from the laws of nature -- what would this be like?"

Kakalios talked with everyone from the actors to stunt people to special effects designers about what Dr. Manhattan's powers might look and feel like in real science. He theorized about things like what would make the character have blue skin, how he might be able to teleport, and what would give him the ability to be in multiple locations.

"There were some things that they said, could he do this? Could he do that? And there are some things he's shown doing that, even under the broad brush of quantum mechanical powers, just don't fly," he said. "They talk about things like, he says I can transmute the walls to grass. I think in the movie he's shown turning missiles into butterflies or something like that. I can understand him having control of his own body, and even within quantum mechanics, being aware of past, present and future at the same time. But some things don't fall within that realm."

Yet Kakalios said his advice about scientific fact was only meant to provide support for the story, not to change it.

"'Watchmen' is a unique situation because the graphic novel is so revered that I think they used that much more than any other source, and they were very mindful of any deviation," he said. "In an open-ended story like "Iron Man," where it's only loosely based on a few storylines, there's a little room for updating and modification. But that wasn't the case with 'Watchmen.'"

"You literally could not swing a dead cat without hitting a copy of 'Watchmen' on the set in Vancouver. It was everywhere. So at the end of the day, if they had to make a balancing act between upsetting a million rabid 'Watchmen' fans or upsetting a physics professor from Minnesota," he laughed, "I think I know which one they're going with.

"I know which way I'd go, and I am the physics professor from Minnesota," he said.

And much of the science-based discussion Kakalios had with filmmakers never made it to the screen. "Zack Snyder, Alex McDowell, all the filmmakers wanted to know what was behind the story, even if it was never in the film. The phrase that really stuck with me was, 'We want to know what's around the corner at the end of the hallway, even if the audience doesn't go down that corridor.' They wanted to know the foundations, the reasons for things, so they would do a better job creating an artificial reality."

For a self-admitted geek like Kakalios, the experience of working on the film gave him enjoyment on two levels: As a scientist who could appreciate the references to physics within the story, but also as an avid comic book reader who loved having one of his favorite graphic novels adapted by Hollywood.

"It was fantastic. I talked to everyone from Debbie and Zack Snyder to Billy Crudup, and they were all super nice, super friendly. Billy Crudup actually knows his science. And they were interested in anything that I'd have to say and very enthusiastic about the film," Kakalios said. "Like all of us geeks, these are people who are smart, with wide-ranging interests. They are comfortable in their skins. They like what they like, and there's nothing to feel guilty about. And among those interests, as they worked on the film, they were interested and fascinated by real science, and they cared about bringing "Watchmen" to film. And so it was a pleasure talking to them and dealing with them."

After the National Academy of Sciences matched Kakalios with the "Watchmen" filmmakers, the organization put together the Science and Entertainment Exchange, which acts as an intermediary between Hollywood and scientists. One of the goals is to encourage the public to view the world through science, something that Kakalios will happen with audiences who see "Watchmen".

"At the end of the day, I'm not looking for a movie to be 100 percent scientifically accurate. I'm not going to movies with a pad of paper and a calculator and saying, 'Ooo! My physics sense is tingling!'" he laughed. "But if they can do something right, it's like catching a little inside joke. It's like a little inside reference. And who knows? Maybe the audience will learn a little something about science."