This installation in the park at Ambleside reminded me of when I taught the Turning Points in Physics module in the NEAB A Level specification in the late 90s. It included the discovery of the electron, quantum physics, special relativity and low temperature physics. The quantum theory has since become part of the main AQA syallabus. The current content is here. It has changed a bit since NEAB became AQA. No low temperature physics anymore. Why turning points? I suppose that physics really did change direction in terms of its focus with relativity and quantum theory. I suppose I've always thought of each discovery as a threshold to a new world of thought - a kind of forward motion rather than a turn. Interesting to reconsider.