Comment by lavelganzu

It's been around long enough to have a Wikipedia page [1], which can give you the main facts & demographics. In short, it started in 2006 as a group blog for people interested in AI. This was long before LLMs, and it was expected among the readership that understanding the math of decision theory would be important to AI. This spiraled out into general interest in how to be more rational as humans, and LessWrong is largely responsible for rescuing Bayesian statistics out of the academic wilderness. Many jargon phrases that are now common in nerdy circles originated there as well. They invented the field of AI safety, and are unhappy about the poor state of AI safety at this time.

There are in-person meetups (primarily as a social group) in most large cities. At the meetups, there is no expectation that people have read the website, and these days you're more likely to encounter discussion of the Astral Codex Ten blog than of LessWrong itself. The website is run by a non-profit called LightCone Infrastructure that also operates a campus in Berkeley [2] that is the closest thing to a physical hub of the community.

The community is called "rationalists", and they all hate that name but it's too late to change it. The joke definition of a rationalist is by induction: Eliezer Yudkowsky is the base case for a rationalist, and then anyone who disagrees online with a rationalist is a rationalist.

There are two parallel communities. The first is called "sneer club", and they've bonded into a community over hating and mocking rationalists online. It's not a use of time or emotional energy that makes sense to me, but I guess it's harmless. The second is called "post-rationalism", and they've bonded about being interested in the same topics that rationalists are interested in, but without a desire to be rational about those topics. They're the most normie of the bunch, but at the same time they've also been a fertile source of weird small cults.

[1] https://en.wikipedia.org/wiki/LessWrong [2] https://www.lighthaven.space/