aarondubrow writes "Imagine a metal that 'remembers' its original, cold-forged shape, and can return to that shape when exposed to heat or a magnetic pulse. Like magic out of a Harry Potter novel, such a metal could contract on command, or swing back and forth like a pendulum. Believe it or not, such metals already exist. First discovered in 1931, they belong to a class of materials called 'shape memory alloys (SMA),' whose unique atomic make-up allows them to return to their initial form, or alternate between forms through a phase change."
The perversity of nature is nowhere better demonstrated by the fact that, when
exposed to the same atmosphere, bread becomes hard while crackers become soft.