What makes the eye's pupils change size? Does scratching a coin make a machine more likely to accept it? Why does a copper bangle change colour periodically? Does the spinning of the Earth affect the top speed of a dragster? Does ice weigh less than water? Are glyconutrients beneficial for arthritis? And what makes a nose sweat more in winter than summer? join Dr Chris for the answers to these questions as well as news of how fungi and plants create their own free-market economies, and how scientists can reprogramme the immune system to combat cancer... Like this podcast? Please help us by supporting the Naked Scientists