Wiki offers theories but no certainty. Googling gave the same results. ISTM that in today’s day of micro-this and nano-that, we should be able to determine once and for all what is causing the vibrating. Or are scientists just not that curious?
As The Perfect Master mentioned, you can really only know how a cat purrs by examining the interior of its throat while it’s purring. Cats tend not to like that. Mebbe you could do the equivalent of a PET or CAT scan (heh) on a living feline while it purred, and develop some kind of three-dimensional computer model of how purring works? I dunno. Perhaps some things were just meant to remain mysteries.
Who would fund it? Running scans isn’t exhorbitantly expensive, but it’s not cheap either. Especially when you’re trying to arrange a cat in the scanner and make it happy. I’ve never had a scan, but I’ve heard that they’re noisy. It could put a cat’s purr right off.
They’ll probably eventually catch it while they’re scanning a cat for something else. Just like the first migraine event caught on scan.
That’s the first problem…
Well, how often do they scan cats for something else? Cats freak out when you put them in some strange place. It doesn’t seem viable to me.