Scientists like putting things in boxes. They categorise things a lot. It’s one of those things they do along with measuring things a lot and formulating relationships between things they measure. They do all this to try and figure out things about the world
Some people seem to be a bit overly obsessed with this at the moment, and I wanted to post something about why I think scientists categorise things a lot.
Sometimes categorising things works really really well. Particle physics springs to mind. When a particle physicist sees an electron it looks exactly like all the other electrons, and it is easy to say ‘that particle fits in the category of electrons’.
In my old research area of astronomy it’s not always so clear cut, but most of the time it works well. You can look at a large collection of stars on its own and say ‘That’s a galaxy!’.
You can look at one object made up of a lot of stars and see that it shares a lot of things in common with another with a lot of stars, and say they’re both galaxies. You can subcategorise things into ellipticals, and spirals, and irregulars, and lenticulars, just as Hubble did and a lot of the time it’s nice and easy and helps you do your research.
Sometimes things don’t fit well into one box or another. A galaxy might be on the edge of one of those things or another. Or it might be a large collection of stars that’s not categorised as a galaxy. Or two galaxies have smashed together and you can’t decide quite if they’ve finished doing that and are still two galaxies or if they’re now one.
Sometimes even particle physicists find that some particle shows up that looks exactly like an electron, but weighs too much. They might make a new box for those particles and call them muons or tau particles, and have a bigger box for the collection of particles that includes them.
I think the reason we like to put things in boxes like this in science is that it makes it really easy to spot when something new and interesting comes along (like a muon, or a peculiarly lightweight galaxy or whatever) – an opportunity to learn something new about the world, and encourage you to rethink the way you’ve boxed things up. When something comes along that doesn’t fit neatly in your box, it’s a sign you should maybe change the way you’re thinking about things (because it is a box you created, even if things in nature have a propensity to climb into it, like the little guy pictured above). The boxes are not a ‘scientific fact’. The things you observe are, whether they fit neatly in your boxes or not.
It’s also ok I think to have more than one way to box things up, more than one way to define something, and sometimes you can sensibly reuse labels when the definitions broadly encompass the same collection of things. Even ‘alive’ and ‘dead’ as categories are sometimes not exactly defined, but we keep reusing those terms in all sorts of contexts despite definitions that sometimes has a thing classed as alive, and sometimes as dead. And that’s ok.
You can use different definitions at different times, as long as if you’re doing science you’re careful and you’re trying to learn new things about the universe, and as long as if you’re doing something else you think about why your chosen categorisations might be helpful, and (as you should when doing anything else) you’re kind and respectful to people and listen to them especially when they’re affected by what you’re doing, and try to make the world a little bit better. Or something like that. I’ve not terribly well defined that either, and that’s ok.
I think you probably know what I’m talking about.
I may not have worded things as best as I might, and comments are open, but comments may also be unceremoniously deleted if they don’t do the kind and respectful thing.