I read a really interesting book called "The Science of Star Wars" once.
It didn't just say "that wouldn't happen" but it explained how it could happen if x, y and z.
The bit on Robots I found very interesting though it was written when bipedal robots were only just being realised so it's a little out of date now.
( MONO!, Tue 27 Sep 2011, 13:31, archived)