This pipe on the RSPB reserve at Campfield Marsh reminded me of a black hole. What goes in can't come out - and a bonus is that gravity is the force pulling the water over the edge. The pipe edge would be the event horizon. It is so difficult visualising a black hole - it's a 3-dimensional star but also a singularity.Imagining a hole in the air in front of me is head-wrecking.
