James Randi occasionally visited the offices of science journal Nature in the 1970s. He wanted to be sure we understood that a magician could duplicate all the phenomena – spoon-bending and more – that fascinated the public.
One such was to increase dramatically the response of a Geiger counter by concentrating on it. Randi brought in his own counter, focused on it and – lo and behold – it erupted with clicks, to our general astonishment. He then rolled up a trouser leg to reveal that he had strapped a radium watchface on to his knee. Raising it showered the counter with alpha particles. Point made.