The comments here are of a higher quality (due to top tier moderation) and generally the community is smarter and more in tune. I'd go with the HN consensus any day, over some random subreddit.

It is not some random subreddit, it is r/physics.

HN is a tech forum, plenty of smart people in there, but also plenty of people who think they know more than they really do. Lots of arrogance in here. I am guilty of it myself, and some of my posts got a lot of upvotes even though it was way out of my field of expertise. I try to get things right, fact checking and all that, but my opinion is certainly not worth that of an expert.

All that to say that on tech matters, I think HN is pretty good, because that's where the tech guys go. But for physics, I'd go for r/physics.