You’ve probably seen the aftermath of an EMP in popular culture. Remember in “Ocean’s 11,” when they gang needed to shut power off in Las Vegas to break into the casino’s vault? They used an EMP, hidden in the back of a cargo van. Or in “Broken Arrow” — an EMP knocks a helicopter out of the sky.

That’s fiction, though. That’s not how it works. And as it turns out, the scenarios proposed by Santorum and Carson are pretty close to fiction, too.

Dr. Yousaf Butt is a senior research fellow at National Defense University who has written about the threat posed by EMPs. Such as it is. When we spoke by phone on Friday, Butt didn’t seem particularly alarmed at the idea that Iran was planning to incapacitate every car on Interstate 80.

“I’m not trying to minimize the vulnerability. The vulnerability is there,” Butt said. “I’m just saying the threat, if it’s being cast as a rogue nation or a terrorist trying to do this, it seems like a difficult way for them to achieve harm.”