Tom- Teleporting/portalling to provide unlimited energy resources would destroy the equilibrium humans have with the environment. Limited energy is what currently provides an upper bound to our exponential growth. Remove that and our population rockets until some other limit is reached. I don't know what that would look like, but it would be nasty and make the instigator quite evil.,(reply>), population growth models disagree with your theory. Populations of people stop expanding once they become developed (because children become a burden and therefore people have far fewer of them).