Because we in Silicon Valley are newness junkies, it can feel like an act of sabotage to have memories, but, for better or worse, I have them. It’s been more than forty years since I co-founded the first company to make headsets and software for simulated experiences, and came up with familiar terms like virtual and mixed reality. Since then, virtual reality has flooded the public imagination in waves; back in the nineteen-eighties, for instance, it had quite a presence in movies, cartoons, TV s...