Ask HN: Where do mathematicians/physicists hang out? / How to learn math?

I've recently taken a big interest in math and physics again. I'm 35 and haven't touched any of it since middle school, 20 years ago, and I'm trying to learn in the direction of geometry and physics.

I'm trying to change my internet habits and would like all my habits to revolve around math and physics and learning. Instead of reddit & youtube, going on /sci/, physicsforum etc.

I still have no real idea where to start, I've been reading and doing exercises from Kiselev's "Geometry" [0] and Israel Gelfands "Algebra".

How does an old fart like me with a bunch of spare time genuinely get into math? I don't even know basic notation.