“Write what you know.” I’ve heard it a gazillion and three times. I still don’t believe it. If you write what you know, you never learn anything (k)new.
What if you just read what you knew? It’d be really boring and we’d all still be reading what we read in the 4th grade. What if you never met anyone new and just stayed with the friends you knew. Sure, you’d have some great lifelong friends, but you’d never have the chance to meet people from other places or find someone you with whom you really connect. Isn’t that kind of the same thing?
Probably what was meant all those gazillion and three times is if you get stuck or can’t find your way out of a story or a sentence you should write what you know and that will help the writer. However, as a writer and even as a copywriter, I can immerse myself into a different subject and become an ‘expert.’ Obviously, three weeks of learning and researching doesn’t qualify you to run a lab and conduct forensic testing, but you can learn quite a bit if you expand your horizons.
So I say write what you don’t know and then you can learn what you didn’t know. Isn’t that way more fun?