 In 1980, Terence Meaden, a meteorologist and physicist, proposed that the circles were caused by whirlwinds whose course was affected by southern England hills.As circles became more complex, Terence had to create increasingly complex theories, blaming an electromagneto-hydrodynamic "plasma vortex".The meteorological theory became popular, and it was even referenced in 1991 by physicist Stephen Hawking who said that, "Corn circles are either hoaxes or formed by vortex movement of air".