There’s a connective tissue keeping the Marvel Cinematic Universe together—and I’m not talking about the Infinity Stones. At an event last week in Los Angeles, Marvel and the Science and Entertainment Exchange held a panel discussion to talk about how science—and a lot of science fiction—continues to drive the franchise forward.

From the finely tuned senses of Black Widow to Captain America’s serum-enhanced strength, Marvel’s superhero movies are more grounded in science than you think. At least, these characters aren’t quite as unbelievable as they once seemed several decades ago.

For example, did you know that NASA is working on an Iron Man exoskeleton suit? Or scientists are dabbling in editing human DNA? Olympic athletes, meanwhile, are already displaying incredible feats of human strength. Pretty soon, scientists believe they’ll be able to pick and choose which enhanced abilities people have—from improved vision to resistance to cold.

In the 14 movies Marvel has released, the studio has built a consistent set of scientific rules, and it’s these set of rules that keeps the franchise grounded. Although Marvel isn’t completely beholden to the laws of physics, the world crafted by the filmmakers and storytellers creates a universe that’s not far off from our own. There’s a clear respect for science that acts as the MCU’s backbone.

Throughout the panels, there was one Arthur C. Clarke quote Marvel kept bringing up: “Any advance of technology looks like magic to other people.” The technology we have today would look magical to people a few hundred years ago. Imagine what humans will build in the next ten.

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As it applies to Thor and the people of Asgard, the notion of magic and science are one and the same. The Bifröst Bridge, which allows Thor to travel across great distances, draws a lot of parallels from the Einstein-Rosen Bridge, defined as the hypothetical topological feature that would fundamentally be a shortcut connecting two separate points in spacetime. In other words, a wormhole.

With Doctor Strange, Marvel is taking its biggest scientific leap yet by stepping into the world of mysticism and consciousness, and how we perceive the reality around us. While scientists are divided on theories about multiple universes, many agree that our senses aren’t advanced enough (yet) to detect the energy surrounding us.

The difficulty for Marvel in Doctor Strange was combining the title character’s background in medicine, which is very science-based, to that of consciousness, something scientists still don’t quite have a grasp on.

So how does Marvel introduce these elements while continuing to keep science consistent with the franchise? Well, admitting that science doesn’t always have all the answers, something that makes the world of Doctor Strange so fascinating.

Most scientists will tell you they have a very reductionist vision of the world, that humans are nothing more than their neurons, etc. Doctor Strange goes beyond that by taking a more philosophical approach.

Audiences have already accepted the franchise’s loose grounding in science. Now, it’s time for that science to open up new possibilities. The universe isn’t using actual science; they’re superhero movies, for crying out loud. But the scientific process is respected, allowing Marvel to build a plausible and consistent narrative that ties all the movies together.

Of course, there’s no purple alien hellbent on enslaving the universe with an Infinity Gauntlet (that we know of). But Marvel does a very good job of using scientific elements in a predominantly sci-fi world. And it’s a big reason why, 14 movies in, people return to the box office to see these films.