David Chalmers, a professor of philosophy and neural science at NYU, has been studying the potential of life in VR for years, long before Mark Zuckerberg promised to build virtual worlds that make people “feel present” and totally immersed. And in a new book, he says he believes that while it’s already possible to have good experiences in virtual reality, they’re still not that common.

Designers and engineers focused on building the metaverse will likely be cheered by the first part. But Chalmers also has a sharp sense of what today’s virtual worlds lack, and he’s far less inclined to paper over those gaps than your typical AR/VR optimists. People like Zuckerberg believe the metaverse could be mainstream in a decade’s time; in an interview with Reality Check, Chalmers said he fully believes it’s “going to be quite disappointing” for at least that long.