This entry is entitled with an oxymoron to represent a phenomenon that hard core science fiction lovers must perpetually endure. If part of the draw of sci-fi is allowing one to imagine extraordinary things that might in fact be possible, a skillful author will try to narrow his material within the confines of rational believability, or at least try to convince us that the material is believable. Yet so often we see things that are utterly preposterous and we are asked to simply accept it on face value, placing our objections on the shelf. In fact, many authors will use the same concepts over and over again, assuming that some earlier work has already convinced the readers/viewers of its rationality and they can just piggyback their way into it. Well, I hope some future authors will encounter this entry in my blog and see just how difficult it is to create a truly nonsense-free sci-fi story.
There's a bit of toungue-in-cheek in that last paragraph because I know that you can enjoy science fiction without being convinced it's all actually possible and many folks don't even care about it. But I, like my Dad, studied physical sciences in college and even taught the subject for a little while, so I have tendency to be bothered by these things more than others. There's not enough room here to expound on each topic, so below is a list of recurring sci-fi literary elements that never registered on my possibility meter. I intend to expand it as time goes on and then turn them into links to entries which explain them in more detail. I have no idea how long the list will become.
Backward Time Travel
Faster Than Light Travel (Warp, Hyperspace, etc.)
Miniaturization (as in shrinking things)
Mind Viewing Machines (or aliens constructing images from someone's thoughts)
The next list are items that are in the realm of possibility but highly suspect or of such low probability as to be ridiculous:
English Speaking Aliens (on first contact)
Force Fields (and Tractor Beams)