alt Hacker NewsPretty much. If Pluto is a planet, then there are potentially thousands of objects that could be discovered over time that would then also be planets, plus updated models over the last century of the gravitational effects of, say, Ceres and Pluto, that showed that neither were capable of "dominating" their orbits for some sense of the word. So we (or the IAU, rather) couldn't maintain "there are nine planets" as a fact either way without grandfathering Pluto into the nine arbitrarily due to some kind of planetaceous vibes.
But the point is that millions of people were suddenly told that their long-held fact "the are nine planets, Pluto is one" was now wrong (per IAU definitions at least). And the reaction for many wasn't "huh, cool, maybe thousands you say?" it was quite vocal outrage. Much of which was humourously played up for laughs and likes, I know, but some people really did seem to take it personally.
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> But the point is that millions of people were suddenly told that their long-held fact
This seems to be part of why people get so mad about gender. The Procrustean Bed model: alter people to fit the classification.
I think most people who really cared about it just think it's absurd that everyone has to accept planets being arbitrarily reclassified because a very small group of astronomers says so. Plenty of well-known astronomers thought so as well, and there are obvious problems with the "cleared orbit" clause, which is applied totally arbitrarily. The majority of the IAU did not even vote on the proposal, as it happened after most people had left the conference.
For example:
> Dr Alan Stern, who leads the US space agency's New Horizons mission to Pluto and did not vote in Prague, told BBC News: "It's an awful definition; it's sloppy science and it would never pass peer review - for two reasons." [...] Dr Stern pointed out that Earth, Mars, Jupiter and Neptune have also not fully cleared their orbital zones. Earth orbits with 10,000 near-Earth asteroids. Jupiter, meanwhile, is accompanied by 100,000 Trojan asteroids on its orbital path." [...] "I was not allowed to vote because I was not in a room in Prague on Thursday 24th. Of 10,000 astronomers, 4% were in that room - you can't even claim consensus." http://news.bbc.co.uk/2/hi/science/nature/5283956.stm
A better insight might be how easy it is to persuade millions of people with a small group of experts and a media campaign that a fact they'd known all their life is "false" and that anyone who disagrees is actually irrational - the Authorities have decided the issue! This is an extremely potent persuasion technique "the elites" use all the time.
The problem is that re-defining definitions brings in chaos and inconsitency in science and publications.
Redefining what a "planet" (science) is or a "line" (mathematics) may be useful but after such a speech act creates ambiguity for each mention of either term -- namely, whether the old or new definition was meant.
Additionally, different people use their own personal definition for things, each contradicting with each other.
A better way would be to use concept identifiers made up of the actual words followed by a numeric ID that indicates author and definition version number, and re-definitions would lead to only those being in use from that point in time onwards ("moon-9634", "planet-349", "line-0", "triangle-23"). Versioning is a good thing, and disambiguating words that name different concepts via precise notation is also a good thing where that matters (e.g., in the sciences).
A first approach in that direction is WordNet, but outside of science (people tried to disentangle different senses of the same words and assign unique numbers to each).