'Stranger Things': How Realistic Are Parallel Worlds?

The hit new series "Stranger Things" is more than just the 1980s throwback we've all been waiting for. In fact, the kids soon realize that the spooky occurrences may actually be stemming from interactions with an alternate world. While a sinister parallel universe like the one on the show "Stranger Things" may not be hovering over our own, the basic idea of an alternate world echoes concepts of multiverses that theoretical physicists have proposed for decades, experts say.