Silicon Valley billionaires literally want the impossible

It's long been the stuff of science fiction: humans achieving immortality by uploading their consciousness into a silicon virtual paradise, ruled over by a benevolent super-intelligent AI. Or maybe one dreams of leaving a dying Earth to colonize Mars or other distant planets. It's a tantalizing visionary future that has been embraced by tech billionaires in particular. But is that future truly the utopian ideal, or something potentially darker? And are those goals even scientifically feasible?