I've never understood how one could be so sure about this. It seems to me all we need to program a human in a box is: 1. An atomic-level scan of a single human

I've never understood how one could be so sure about this. It seems to me all we need to program a human in a box is: 1. An atomic-level scan of a single human being. 2. A computer with program powerful enough to simulate all the atoms in a single human being and their interactions. If you can get this, you have a computer as smart as a human (modulo quantum effects, if those do indeed play any part in cognition. This would be a horribly inefficient way of doing it but I'd be very surprised if it were not possible to get a computer this fast in real life, or to conduct an approximated atomic level scan of a human being. It may not happen soon, but it would be truly shocking to me if it doesn't happen eventually, provided we do not destroy ourselves before reaching that technological level.