That is certainly a thing. But on HN, we really do have topical trends. When an article gets popular, and piques our interest, people keep researching it. And finding related topics and articles, and those also get posted. We also see it impact the "Show HN" posts - before coronacrisis, we were seeing so many curated job postings sites that it got to be a bit of a joke. Just in the last couple week, we've see an uptick in blogging tools, and in the past couple days, an uptick in data gathering sites for police action. Trends do exist.

They sure do. Is there a "HN trends" tool you're aware of?

Not that I recall... but with all the people who participate here, I wouldn't be surprised if someone has a project along those lines in some stage of development. If not, it could be a fun project to try.

I stand [partially] corrected. Searching through the archives, I find the term first appeared on HN 4 years ago, with a few mentions a year, ever since. But there's definitely been a cluster of mentions over the past month or so:

https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

Sure, but there's also culture and things go in and out of fashion and ideas go varying level of viral, too. I have certainly seen a post become popular and decide that an essay I read which has some passing similarity might likewise be too. So I post it, and someone links it on Facebook, and we run in similar internet circles and it hits you twice in different ways.

To some extent that applies.

In this case a strange new word like Zettelkasten also caused me to look it up the first time i saw it. Which was sometime this year.

I.e. had it been appearing everywhere before, I would have looked it up earlier.