Your comment about "hand waving" reminds me of something I read about the Star Trek writing team. The story was they would come up with the plot they wanted regardless of any scientific concerns. Then they'd insert a crisis with some system of the ship and write dialog like, "Captain, the tech isn't working. But I think we could try teching the tech..." And later on they'd pay an engineer or a physicist to put in some more convincing jargon.

You're right - the more science we really know, the harder it is to pull this off.