I worked in an aerospace startup for seven years, and while not an expert I really know my way around some spacey stuff. People speaking authoritatively about that on HN also make me cringe, I rarely intervene because they almost always engage in a discussion about how they are right even when I send references to papers and book chapters. In Reddit it's even worse.

With law and politics I feel there's a similar attitude going around but it's of course more an up for debate topic.