News You Can Bruise for 2006 August 26

(3) Sat Aug 26 2006 14:28 Transcendental Transneptunianism: Occasionally Sumana has transcendental experiences associated with revelations about the universe. Incredibly, I always manage to ruin these experiences by making some bonehead remark. I can't remember any of these remarks verbatim, but I have no trouble thinking them up and saying them when the need arises. I'd like to not do that next time because it really brings the transcendental party to a halt with a loud record-scratch sound.

I do know the source of these remarks: they stem from the eternal conflict between two philosophes in my mind. These are the hippy-dippy Carl Sagan atheist who says "You don't need God to have a good time, man; look at all the wonder in the natural universe!", and the cranky Richard Dawkins atheist who says "The wonder is all in your brain, you pothead! Not distributed throughout the universe!"

The Carl Sagan philosophe was formed in a transcendental experience I had when I was six years old. You know those charts that go on the walls in elementary school classrooms? Instead of putting a few of them on the walls, my kindergarten teacher, Jim Murchison, bought an enormous number of them. He punched holes in them and turned them into a huge flip chart. Every day or two he would flip over a sheet and reveal the new topic of discussion. One day he flipped over a sheet and I saw the solar system.

I'd surely been to the Griffith Observatory before then, but somehow I hadn't seen any pictures of the planets before this reveal. Jupiter, in particular, blew me away. Seeing drawings of the planets triggered my first and biggest transcendental experience. Since I always ruin Sumana's transcendental experiences it's only fair that I should ruin my own. Jupiter isn't transcendental; it just looks really creepy. It's a planet, a gasball.

What's more, the universe does not contain a magical kind of thing called a "planet". Planetness is a social construct. The solar system is not the sun and nine planets, as depicted on the flip chart of my youth. It's a fusing gasball, four non-fusing gasballs, a few million rockballs, a few billion snowballs, and a big dust cloud.

Recently, the International Astronomical Union decided to make a proper scientific definition out of the social construct "planet". This used to seem easy and even superfluous, but in recent years it's become clear that to judge every object in the solar system by a uniform standard of planetness, you must make a hard decision. Either Pluto is not a planet, or there are lots of Kuiper Belt objects which are planets on the same criteria as Pluto. These planets are very distant, mostly undiscovered, and not very interesting once discovered. There might be hundreds of these tiny boring planets. So the IAU created a definition that excludes these objects, including Pluto.

It's not nice to fool Mother Nature, but it's even less nice to naturalize Mother Social Construct. People are used to the planets being the non-fusing gasballs, four of the biggest rockballs, and Pluto. A lot of people got mad at what they viewed as a bunch of eggheads usurping their social construct. And now the eggheads are arguing amongst themselves about the definition. It's a huge mess.

The real problem with this definition is that, to get the "right" result, the IAU restricted the definition to apply only to our solar system. It's the Bush v. Gore of scientific definitions! They had to do this because extrasolar systems perform instant reductio on any attempt to turn "planet" into an objective concept. There are too many weird things in the universe. It would have been simpler if they'd just enumerated by fiat the eight things in our solar system that are "real" planets.

Astronomers have found things like two non-fusing gasballs orbiting each other in interstellar space. Are they planets? Only if we decide to call them "planets". What they are is big non-fusing gasballs that orbit each other. A gasball can have natural starness, but it cannot have natural planetness, any more than (as Michael Shermer says) it can have natural meaningness. This is what social constructs are for.

I personally don't care if Pluto is called a planet or not. My money is still on "alien disco ball". But if we must have a definition of planetness, it should recognize the inevitable subjectivity. If you don't do this, you need an artificial ban on discussing what might make an extrasolar object a "planet". Because sooner or later the smart-aleck universe will toss you a planet that doesn't meets the technical criteria, or (less likely) a non-planet that does. Then you have to tweak the definition and it's like adding epicycles to the Ptolemaic model of the solar system.