Definition of Science Fiction

Perhaps one of the most versatile genres in films, television, books, artwork and any number of things today is science fiction. Many times I have seen a sci-fi movie filed under comedy or drama. That is one of the major things that has led to my love for science fiction, the simple fact that it can be so much more than just science fiction. I would like to present a definition of what science fiction is in this paper. My definition will not be exact, because so many people have a different idea of what counts as sci-fi and, not only that, but we may have found yet another venue for science fiction by the time this paper is complete. In order to define what science fiction is and to support my definition, I am going to give some examples of stories that I think fall into this genre first and then give a semi-solid definition of what I think science fiction is.
The first example of science fiction I'd like to take a look at is Alien. A prime example of straightforward science fiction would be this movie. Space miners (or merchants…something like that) are awakened from their cryogenic sleep-state much earlier than was originally planned. A distress/warning beacon on an unfamiliar planet caused their ship to awaken them so that help could be dispatched. Of course, it turns out to be a ship that was taken over by the Aliens and the Earthlings' ship was soon to be infested. No questions about this one; it is most definitely science fiction. Humans meeting up with aliens and, of course, space travel, instantly places this film into the science fiction category.
Another example of science fiction, and one that proves science-fiction's elusive nature, is Tarzan. This is a fantastic example of a popular story that nobody would normally think of as being sci-fi. Everyone knows the story: A baby is lost in the jungle, raised by apes, and then is discovered years later by some jungle-adventurers. It sounds sort of questionable as to whether this should be considered science