Since tech wizard Jaron Lanier made virtual reality popular in the 1990s, many claims have been made about its transformative power. Most of these have proved to be hype and VR remained little more than a fad, popular with video gamers. But in his new book, VR: Experience On Demand, Jeremy Bailenson, founding director of the Virtual Human Interactive Lab at Stanford University, insists that VR is at last coming of age, with new applications from conservation to the treatment of PTSD.

When National Geographic caught up with him by phone from Stanford, Bailenson explained how VR is now being used to raise awareness about climate change, help quarterbacks memorize plays for the NFL, and even help first 9/11 responders