Reality+: Virtual Worlds and the Problems of Philosophy

by David J. Chalmers

To simulate where we’ve been, the people we interact with, and the media we read and watch, it will need to simulate a fair amount of our planet, and it will need reasonably detailed simulations of the Sun, Moon, and other planets (of which we now have detailed images). We’ll need a decent simulation of at least the visible stars and galaxies, and of background radiation and other observable phenomena. The simulators will need to be ready to expand the simulation—for example, if we travel to the stars or acquire new ways of getting information from them. Expandable simulations are already familiar in video games such as No Man’s Sky, in which new planets are algorithmically generated as players travel to them. Sophisticated simulators may be masters of these techniques, knowing just where a local simulation can cut corners. Something similar goes for using shortcuts to simulate the microscopic depths of the world. In some contexts, a simple Newtonian physics of macroscopic objects may be all we need, but there are many contexts for which more is needed. Many observable properties of ordinary objects depend on chemistry, which itself depends on quantum mechanics, so it will be difficult to simulate macroscopic objects really well without going very deep. Making our simulation consistent with the observations of scientists about atomic physics and the like will require even more work. Perhaps not every last detail will have to be simulated. Some low-level details may never s...