>>13843138This is a good question, not sure about this myself. I have a vague idea you can recognize certain materials by shooting some xrays or microwaves or some precision rays at them, and we match the response to what we'd expect of a given material. There's a mechanical analog I think in terms of eigenmodes, you can excite a multi degree of freedom mechanical oscillator in different ways to get a certain kind of response, perhaps the first eigenmode if you the right frequency to hit. I'm guessing the case for testing molecules may be similar in spirit, except instead of using a hammer with a load cell to excite the system you'd use some kind or electromagnetic waves.
