
Originally Posted by
Nereid
This points to another aspect that we have touched on but not explored much in this thread: scope.
Do hypotheses get to be falsified? theories? ideas? concepts? models? laws?
An experiment or observation may be quite clear-cut: Mercury's perihelion moves in this way (with stated uncertainties/error bars), the atomic clocks aboard the planes differed by this many seconds when they got back home, the A, B, C and D images of the distant quasar varied over time in this way, and so on. But how do these clear-cut results relate to GR (for example), or CDM?
I think a good example is the Pioneer anomaly: analysis of the tracking data shows an unmodeled acceleration of {value and direction; uncertainties}.
So something is a bit off, or odd ... but what?
Enter hypotheses, which are very specific, quite narrow in scope, and as fully quantitative as we can make them - they provide clear guidance, or pointers, on what to do on Monday when we get to the lab, because they are eminently testable (albeit sometimes more in principle than in practice).
As a general rule, the things to be tested first are what's in textbooks - on Monday you build models using standard physics.
Suppose you've done that, written papers, chatted over coffee (or something else) at meetings, etc, etc, etc, and the day comes when models built on standard physics have all been ruled out; what then? Time to sketch some ideas for new physics? which will be severely tested in the crucible of your colleagues sharp minds (and, often, tongues) ... modify, re-state, get the idea torn to ribbons again, repeat. Maybe one day a theory emerges ... what then?
Can we say that "neutrinos" were such a theory, from the 1930s? or is that too grand a word?
Certainly neutrino flavours/oscillations were a theory long before 2001!
Is MOND a theory?
Is CDM a theory (non-baryonic CDM, whether collisionless or not)?
Are 'gap fillers', or 'place holders' in some kind of limbo, neither hypotheses nor theories? extremely useful but not really falsifiable? They are undoubtedly convenient as shorthands, if nothing else!
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