It takes years to make a movie, with hundreds, sometimes even thousands, of people working together.

Amid the strain of budgets, creative disagreements and other aspects of the filmmaking process, small details fall by the wayside.

Realism can be one of the casualties of the process. Who hasn't watched a film and thought, "Come on, that's not possible"?

Films are ultimately meant to entertain, and "the rule of cool” — the idea that what's fun and entertaining is most important — often wins out over plausability.

But sometimes a special group will be called in to make sure the movie gets it right: science consultants.

For many of these professors and researchers, science fiction is the go-to genre.

"The difference between science fiction and fantasy is that science fiction has a basis in actual science," said Mohamed Noor, a biologist at Duke University, who has consulted for two seasons of "Star Trek: Discovery." "[Our job] is to make it so that basis in reality is as accurate as possible."

In practice, that means ensuring ideas presented in the show are either consistent with scientific principles or that a hypothesis about what might be possible in the future is also grounded in current science.

Hard science in fiction

In one episode, the "Discovery" writers were looking for a new alien species with a mysterious disease that would be extremely difficult to cure.

Noor suggested using prion diseases.

These extremely rare diseases are caused by protein mutations in the brain that eventually cause the body to shut down. Bovine spongiform encephalopathy — better known as mad cow disease or BSE — is a fatal, real-world example.

"There is no good cure right now existing [for BSE]," Noor told DW. "So it's not that crazy that maybe in a few hundred years from now, there still wouldn't be a good cure for it. I suggested prions as the concept and then a whole bunch of specific pieces for it."

But consultants don't always win out in the writers' room. When he was called to help conceptualize an alien species foreign to human understanding in every way, he suggested a race that uses chemical communication, similar to the way in which dogs communicate via scents. Noor's premise would require the human characters to somehow release chemicals to interact with aliens.

In the end, the writers deemed the concept too complicated.

"Ultimately, story does trump science," Noor said. "If somebody has to do something that's just not possible, I'll get them as close as possible.

"But then the rest is ‘future scientific advances we haven't discovered yet.'"

Do viewers want real science in their fiction?

A 2017 poll conducted by the Pew Research Center found on-screen portrayal "makes no difference" for 72% of science fiction viewers in their understanding of science.

But Noor said he is convinced that an accurate portrayal is still important for audiences.

"People watched 'The Martian' and were very excited," Noor said. "There was a lot of dialogue online about how just about everything that was shown in that exciting movie was realistic. 'Interstellar' is another example."

For "Interstellar," Nobel laureate and theoretical physicist Kip Thorne used his own theories to create that film's depictions of black holes.

Jim Green, former chief of NASA's space science data operations office, helped "The Martian" earn praise for its realistic depictions of life alone in a Mars station.

Both films were also box-office hits, earning hundreds of millions of dollars globally and critical acclaim, along with several Oscar nominations. Interstellar even won the Oscar for best visual effects.

Noor compared the differences in degrees of realism that these films provide to a buffet: Everyone gets to pick their preference.

"I'm sure there are some fans who don't really care … but there are some who really do appreciate it and really want to understand it," he said.

Does science in film have educational value?

The United States continues to drop in grade school science test scores, according to data from the Netherlands-based International Association for the Evaluation of Educational Achievement. US fourth graders are now nine points below 1995 levels, when the study was first run.

At the same time, adolescents and adults are turning away from established media outlets and toward social media for news and information, which prioritize entertainment over educational value.

Science consultants, therefore, see their work not just as passion but as a duty to help engage the public through any medium.

"There are people who are going to go and become ornithologists or scientists in whatever shape or form. That's great," Noor said. "Not everybody's going to do that. And if we just accept the fact that not everybody's going to do that, then what are other ways we can get them excited?”

At Duke, he's incorporated Star Trek into his curriculum, using the fictional series as examples for evolution and genetic theories. He also takes these lectures on the road with him to conventions, hoping to inspire fans to explore real-world science. 

The strategy of fictional media inspiring real decisions has worked in the past — in an interview with PC Mag,  Green even mentioned the original Star Trek series as inspiring him from an early age to get interested in science.

"There's a reason why we call it 'pop culture' — the ‘pop' is for ‘popular,'” says Noor. "If I can leverage that popularity and get them excited in science, I think all is good."

Edited by: Matthew Ward Agius