Hi, so I just wanted some opinions on string theory, superstring theory, or M theory. Any of them would be fine probably, but M theory is the one I'm really curious about (since it's the latest and greatest, according to some of the books I've read). So the only opinions on M theory that I've heard are those of Michio Kaku and Brian Greene, but I wanted the opinion of people who are not as biased as them (whose lives' work is -besides popularization of science- string theory). I just don't see what's so special about it, and I'm not sure if it fits into the category of science. Because as Feynman said, science can be described with one sentence; "the test of all knowledge is experiment". As far as I can tell though, M theory hasn't been tested (forgive me if I'm wrong) and will be extremely difficult to test in the future. I've heard that its merits are that the mathematics are very beautiful and that it unifies all forces into one theory. It would be nice to have one theory, but (sorry to quote Feynman again) "we're exploring; we're trying to find out as much as we can about the world. People say to me: 'are you looking for the ultimate laws of physics?' No, I am not. I'm just looking to find out more about the world. And if it turns out there is a simple, ultimate law that explains everything, so be it, that would be very nice to discover. If it turns out it's like an onion with millions of layers and we're just sick and tired of looking at the layers, then that's the way it is. But whatever way it comes out, it's nature, it's there, and she's gonna come out the way she is. And therefore, when we go to investigate it, we shouldn't pre-decide what it is we're trying to do except to find out more about it!". Sorry for the long quote, I just love that guy and I think his wisdom in that quote really applies to what (I think) people are like with string theory (or M theory or whichever version you wish). I think that people are trying for some reason to decide that nature must be this way, nature must be symmetrical, and nature must have simple laws. Well, what if it's not like that?! I would really love the opinions of physicists, I'm just a teenager trying not to take everything that a few popular scientists say for granted. I don't know any of the math involved in the theory or anything, I just want to discuss its possible validity, its applicability to other problems in physics (so essentially the usefulness of it), and also my discomfort with the fact that people seem to be determined that what they think nature is should be right even if experiment does not say so yet.