To provide a place for us (theoretical physicists) to talk in public, to each other and whoever wil listen, about our current (often unformed) thoughts on theoretical physics, and
To provide a semi-private space for us to post current ongoing research, to get it out of our heads, and to discuss it with each other, in a forum that is closed enough that we should not have to worry about idea-poaching, as we'll know exactly who is reading it if we post "friends-only" here (as an alternative to the way some of us have done in the past, where we just make such posts in our own journals).
For these ends, the community is designed so that at present, anyone can post to this community, whether they are members or not, and posting access is unmoderated (for now, if there's abuse...). Members can read friends-only posts in the community. For reasons of academic privacy, membership will be basically by word of mouth: people who know someone in this community well enough to be trusted with ongoing, unpublished research, are welcome to send an email to one of the maintainers and be invited (although you don't need member access to post here, as mentioned above).