Originally Posted by
Jonathon Sullivan
Predictive power, yes, I agree. This brings us to the occasionally fuzzy distinction between observation and experiment. The theory of relativity makes certain predictions that can't be verified by setting up an actual "experiment" in the usual sense of the word, but such predictions have been verified by cosmological observations. You can argue that setting up the observation (with Hubble or LIGO or whatever) constitutes the "experiment," but I think you know what I'm getting at here. We can't actually set up a cosmic-scale gravitational lens or neutron star merger. But we can predict them and observe, and I do think that's science.
And then there's another issue: a line of scientific inquiry might make predictions that are testable in principle, but not in practice. Quantum gravity predicts a gravity boson (the graviton) and string theory predicts infinitesmal vibrating fundamental entities, but neither strings nor gravitons are, as far as I am aware, observable with any technology we could even hope to possess for millenia, if ever. So...are these lines of inquiry "science?" I'm inclined to say they are, but I understand that things are fuzzy at this level, and I understand the objections of those who say, for example, that string theory is more philosophy than science, at least for now.
And so now we're really off-topic.