Many a fine SF story uses science or technology merely as backdrop. Many a fine SF story presumes a technological breakthrough and explores its implications without attempting to predict how the thing might actual work.

The biggest fatal flaw in most fictional portrayals of nanotech - what sends those books arcing across the room - is ignoring that the nanobots need energy to do... anything.

One of the bedrock principles of physics is the conservation of energy. In this universe, energy can be neither created nor destroyed.

Edward M. Lerner Quotes