One can imagine that a few curious 23rd-century simulators mightfocus on the early 21st century. Let’s suppose the simulators live in aworld in which Hillary Clinton defeated Jeb Bush in the US presiden-tial election of 2016. They might ask: How would history have beendifferent if Clinton had lost? Varying a few parameters, the simulatorsmight go so far as to simulate a world where the 2016 victor was DonaldTrump. They might even simulate Brexit and a pandemic.

These temporary limitations will pass. The physics engines thatunderpin VR are improving. In years to come, the headsets will getsmaller, and we will transition to glasses, contact lenses, and eventuallyretinal or brain implants. The resolution will get better, until a virtualworld looks exactly like a nonvirtual world. We will figure out how tohandle touch, smell, and taste. We may spend much of our lives in theseenvironments, whether for work, socializing, or entertainment.