There is mathoverflow.net and its meta site as math researcher hangouts, plus ncatlab.org for category theory, and various sites, blogs, mailing lists etc. for other fields.
You might also like Bill Thurston's famous article "On Proof and Progress in Mathematics", which says not so much that math is social, but that human mathematicians want personal understanding of mathematical truths. So black box computer-checked but human-incomprehensible proofs aren't of that much appeal.
It's telling how you can tell the article was written by a mathematician, apart from the obvious fact that it's about mathematics. I'm talking about the structure. For example:
"How do mathematicians prove theorems? This question introduces an interesting topic, but to start with it would be to project two hidden assumptions:
(1) that there is uniform, objective and firmly established theory and practice of mathematical proof, and
(2) that progress made by mathematicians consists of proving theorems"
It reminds me of a joke I was told by my math teacher when I was at school about how mathematics shapes your thought (I may do a poor translation):
An air balloon traveller encounters very dense mist and gets lost and so is forced to descend to the ground, where he finds a guy taking a walk. The traveller asks the guy "Excuse me sir, could you tell me where am I?" The guy, after a very long pause answers "You are on a balloon". The traveller smiles and says "You are obviously a mathematician". "How do you know?" asks the guy to which the traveller replies. "Easy, there are three very good reasons. The first one is that you took a long time to answer, obviously considering just the facts and proceeding with strict logic. The second one is because the precision of your answer. And last but not least because your answer is useless"
There are variatons on this joke that are even more apropos to HN, for example:
A man is flying in a hot air balloon and realizes that he is lost. He reduces height and spots a man down below. He lowers the balloon further and shouts, "Excuse me. Can you help me? I promised a friend I would meet him half an hour ago, but I don't know where I am."
The man below says, "Yes. You are in a hot air balloon, hovering approximately 30 feet above this field. You are between 40 and 42 degrees north latitude, and between 58 and 60 degrees west longitude.
"You must be an engineer" says the balloonist.
"I am", replies the man. "How did you know?"
"Well..." says the balloonist. "Everything you told be was technically correct, but I have no idea what to make of your information and the fact is I am still lost."
The man below says, "You must be a Manager"
"I am", replies the balloonist. "How did you know?"
"Well..." says the man. "You don't know where you are, or where you are going. You made a promise which you have no idea how to keep, and you expect me to solve your problem. The fact is you are in the exact same position you were in before we met but now it is somehow my fault."
A little further off-topic. I knew (well) a mathematician who most of the department thought a bit odd, and he was. If you asked him "how are you?", he would take longer than is usual to respond. I fairly quickly realised it was because he considered that nicety as an actual question and gave a considered response.
You can also tell that the article was written by a mathematician by noticing that the author is Bill Thurston, a very famous mathematician, who we sadly lost a couple of years ago. He was amazing. I guess it never would have occurred to me to identify the writing style as mathematician-like in its own right, since I was expecting it to be what it was.
You might also like Bill Thurston's famous article "On Proof and Progress in Mathematics", which says not so much that math is social, but that human mathematicians want personal understanding of mathematical truths. So black box computer-checked but human-incomprehensible proofs aren't of that much appeal.
https://arxiv.org/abs/math/9404236