The Greatest Advance Since the Wheel? Horizon : Season 11 Episode 29

Sixty years ago a Dutch scientist discovered a phenomenon that overturned the electrical rule book. By cooling certain metals to incredibly low temperatures he found they could continue to carry an electric current for ever, even when the power supply was switched off. Today, developments of these metals - called superconductors-have led to trains that fly, magnets that could depollute rivers and machines that promise cheaper power.