Why can't energy be created or destroyed?

Can any organ get cancer? Why do mints make water feel cooler? Why do cockroaches face upwards when they die? What causes eye twitch? What's the best exercise after a hip replacement? How would high water pressue affect the body? Why is extreme cold as painful as extreme heat? Plus, developments are made with the first human head transplants... Like this podcast? Please help us by supporting the Naked Scientists