[quote author=“alexdiaz”]my only gripe was the comment he made about scientists like him (paraphrasing) ‘wasting their time’ on coming up with definitions for things like ‘planets’.
clear and coherent language, esp. definitions make science more powerful.
Quite right, alexdiaz. But I think the point he was making (and I’ve heard other scientists like Phil Plait say the same thing, on the recent Skepticality podcast) is that what we consider a ‘planet’ and what not just isn’t an interesting scientific issue.
For example, being an electron is an interesting scientific issue, since electrons have certain masses, charges, spins, et cetera; they enter into laws. If we could find out that our definition of ‘electron’ was somehow flawed, that would be of great consequence.
But being a planet just isn’t the same sort of thing at all. There is no confusion about Pluto’s (gross) properties—mass, velocity, albedo, composition, accompanying moon, etc.
In this sense, “planet” is sort of like the early notion of “atom”, which the ancient Greeks believed was a particle that couldn’t be split farther. It’s basically an archaic notion that doesn’t fit well with our more modern, scientifically inspired concepts: planets aren’t the god-like ‘wanderers’ of old. Atoms aren’t the smallest, unbreakable parts of things.
So debates over the nature of such basically archaic concepts are more for ‘public consumption’, since the person in the street cares deeply about what is an atom and what is a planet. The physicists who deal with these things don’t care so much because they see through the complexities that these notions are not necessarily very helpful, except in more-or-less standard cases.