The model of 10 or 11 dimensions is much more than sci-fiction, as many scientists believe that they apply to the real world.
No one said the existence of extra dimensions is science fiction, read the posts. However, if you're going to try to explain something as complicated as string theory than it should come from a credible source, like an expert in string theory, not a science fiction writer. What's presented on that website is speculation, not an accepted theory, even though he borrowed some of his ideas from actual scientific theory.
One can not understand string theory (or any complex scientific theory) from reading a website like wikipedia. You have to start from the beginning, studying the basics like classical physics, and moving upwards from there. You can read, pop-sci books targeted towards the layman, which can give you an idea about what the theory is about, but you certainly won't attain the knowledge to debate the subject, or use it to prove/disprove the existence of life/god, like they're trying to do in the other thread.