There was a time when seeing was believing — but that’s changing, thanks to new technology that’s elevating fakery to a whole new level. In an ever-growing world of synthesized realities, how do we tell what’s real from what’s fake? And when and why does it matter?

We explore that question on this episode, with stories about deepfakes — a new kind of fake video, powered by artificial intelligence; lab-grown meat in our pets’ food; and fake laughter.

Also heard on this week’s episode:

• Reporter Susie Armitage explores fake laughter in its natural habitat — comedy open mics. We hear about how up-and-coming comics learn to tell real laughter from fake, and how our evolutionary past explains that ability… along with our tendency to chuckle when things aren’t remotely funny.
• What happens when a piece of information shatters everything we believe to be true? Reporter Molly Schwartz explores that question with the story of Austin Lane Howard, a devout Jehovah’s Witness whose doubt eventually pulled him away from the church.
• We talk with Lydia Pyne, author of “Genuine Fakes,” about everything from lab-grown diamonds to replicas of famous historical sites.