Maybe 10 years ago or so, nanotech was a hot topic in science fiction, and even some legitimate science (Feynman’s ‘room at the bottom lecture’ being often quoted).
Want a particular molecule? Just have the assemblers shove the atoms together in the right order.
Want a megastructure? A swarm of replicators will build it for you using local materials.
But we don’t seem to have heard much about it lately?
There is a lot of work going on in “nanotech” as fabricating materials at near atom-level precision. That actually describes modern microchips. But “nanotech” as tiny magic robots? Still a very, very long way off.
Mostly because advances are made in very, very small steps. :flees:
The problem with this is that it takes hundreds of years.
And yes, I did use present tense. We have swarms of replicators that build megastructures. We’ve always had them. They’re just a lot slower than the pulp authors describe.
True, and they reproduce themselves quite spontaneously. Unfortunately not all of them are very useful for any given project, and as you say, the cycle time is slow.