With machine intelligence and other technologies such as advanced nanotechnology, space colonization should become economical. Such technology would enable us to construct “von Neumann probes” – machines with the capability of traveling to a planet, building a manufacturing base there, and launching multiple new probes to colonize other stars and planets. A space colonization race could ensue. Over time, the resources of the entire accessible universe might be turned into some kind of infrastructure, perhaps an optimal computing substrate (“computronium”). Viewed from the outside, this process might take a very simple and predictable form – a sphere of technological structure, centered on its Earthly origin, expanding uniformly in all directions at some significant fraction of the speed of light. What happens on the “inside” of this structure – what kinds of lives and experiences (if any) it would sustain – would depend on initial conditions and the dynamics shaping its temporal evolution. It is conceivable, therefore, that the choices we make in this century could have extensive consequences.

Nick Bostrom, ‘The future of humanity’, in J. K. B Olsen, S. A. Pedersen & V. F. Hendricks (eds.), A Companion to the Philosophy of Technology, Oxford, 2009, pp. 555-556