There is no limit to complexity. There are still many many mysteries to solve about life, intelligence, and more generally about complex chemical processes. E

There is no limit to complexity. There are still many many mysteries to solve about life, intelligence, and more generally about complex chemical processes. Energy efficiency has a limit that we are very far from reaching (how to harvest all of the sun energy productively? without ruining life?) Human systems: how to reduce waste, make transit faster, make people happier, avoid violence, etc. I can't think of it all, but no we will not run out of things to discover/invent.