Someone linked it in the comments over there, but I think it's worth reposting here, "The Edges of Our Universe" by Toby Ord (https://arxiv.org/abs/2104.01191 h

Someone linked it in the comments over there, but I think it's worth reposting here, "The Edges of Our Universe" by Toby Ord (https://arxiv.org/abs/2104.01191 https://arxiv.org/abs/2104.01191), which goes over a number of different radii of this form that one could define.