Before I even venture into the maze, a question: what I'm meaning to do, is post a 'personal theory about relativity' that some guy told me. Now, it's quite ludicrous, even though the dear man tries to stick to the right principle. Which makes it hard for me, who is not really interested in relativity, to point out where the flaw of his argument lies. So: the purpose of this post would not be to vent a personal theory - but to rebute it. Is this allowed in this forum? Can I proceed? If not, a quick notice is enough, then I'll delete this post myself.