We know self-replicating nanomachines are possible because nature has already invented them. In biology, a single cell can duplicate and modify itself, to specialize for a specific purpose, like a neuron in the brain. There is no doubt that one day, humanity will gain this capability. Humanity’s nanomachines could be a hybrid of biological and man-made mechanisms or purely artificial, with mechanisms we discovered which surpass their counterparts found in nature. Imagine filling a bathtub with water, pouring in the raw materials, like: iron, silicon, copper and carbon; then waiting several days while your new laptop is grown. We could also have nanomachines in our blood, giving us accelerated healing and prolonging our life indefinitely. We could have nanomachines that break down fat and increase muscle mass which would be the end of gyms and cause explosive growth in the food services industry. You could even create a self-replicating nanomachine that will grow into an android, with an artificial intelligence or a blank slate that a human can transfer their mind into. Nanomachines could give us the ability to create backups of our minds and even transfer our minds from one body to another. We could have a self-replicating nanotechnological/biological colony infesting the entire crust of the Earth, mining every useful material with nano-miners, nano-refineries, nano-factories, etc. We would use any and all power sources, like fossil fuels, thorium, uranium, use radioactive waste in nuclear decay batteries, maybe even regenerative nano-scale fusion reactors. The subterranean colony could even infest all the trees, modify their chlorophyll and improve their efficiency, and siphon solar energy off all plant life. There could be subterranean power distribution network and raw material high ways. Then you could go into an artificial reality with all five senses, talk to your personal AI, have the AI design you something, then the subterranean colony builds it, and the dirt in your backyard starts moving, and a self-repairing motorcycle rises out of the ground.
Genetic Engineering will allow us to program nanomachines found in nature. We could modify a virus or bacteria to help repair our bodies or grow into a wetware laptop. We could have pumpkin patches growing cars. We could have supermarkets with thousands of seeds, which you can plant in your yard and grow anything imaginable. We could modify the human, to give it the ability to repair itself without nanomachines, cure all diseases, cure aging, improve memory recall, improve our ability to solve problems, limit the amount of fat stored, maintain a minimum muscle mass and anything else you can imagine. We could even have a mini-brain that is programmed with all scientific knowledge, with an intelligent immune system to combat engineered pathogens.
Whether we create our own nanomachines from scratch or learn to program nature’s or both; we will be opening a Pandora’s box of new capabilities.
Another possibility is the NanoFactory: