Freeman Dyson's review of Brian Greene's "Fabric of the Cosmos" was facinating...not because of the scientific problems that came out within it, but due to his thoughts on a sort of reductio ad absurdum within science. He comments that Brian Greene leaves a definite impression that it is just not right for their to be a big world and a small world (one operating off of general relativity and one from quantum mechanics). He repeats a couple of times that being a conservative, he doesn't see this as a detraction from science. The article is definitely interesting, and his point on quantum gravity is important to note (even if you disagree with his conclusion).
I do think, however, that he takes the whole idea too far. Regarding quantum gravity, he mentions that since there is no conceivable practical experiment for the existence of gravitons, then the theory must not have any physical meaning. In itself, this is a fine stopping point, but I think that Dyson wants us to go further and say that there will never be a conceivable practical experiment (which is a different ballgame altogether). I can understand that he is a conservative (self-proclaimed in the article, anyway) and does not want to say that the duality of our current system is wrong. That's fine...but the connections that allow us to further understand science are part of that reductio ad absurdum that I mentioned earlier. Just because we don't see something now is no reason to stop. Just because we dont' understand a particular topic doesn't mean that we never will. He brings up the example of either, but I would postulate that scientists at that time couldn't think of a practical experiment to test their theories on the light either. I would agree with him that we're probably not as close to the truth as Brian Greene might think, but I still feel bad for Dyson; he strikes me as a disillusioned scientist. And that's just depressing.
Also, his arugment during the debate with Greene that Chemistry, Biology, etc cannot be reduced to Physics is taking too big of a leap. Now, computational chemistry is still operating off of approximations of theories and cannot be said to be a predictor of truth within itself. And this is within a field that we supposedly understand. I disagree wtih Greene in that, atleast for now, even if we would discover this theory that would combine everything, approximation must still supercede calculation within science. We just don't have the computers that can make those leaps in logic yet. But I also disagree wtih Dyson's assessment, in that if we did find these equations, although there would be new advancements within Chemistry, Biology, etc, they would at that time become advancements in the understanding of the application of this theory of everything. In other words, the new jumpof Chemistry would just show us how we were misapplying the theory of everything beforehand.
So yeah, we need to be realists too and understand our current limits. But this doesn't mean that we can't at the same time optimistically reach past them with our imagination. It's the one thing that has allowed us to make the necessary jumps in logic that give our reductio ad absurdum process meaning.