View full lesson: http://ed.ted.com/lessons/where-does-gold-come-from-david-lunney Did you know that gold is extraterrestrial? Instead of arising from our planet's rocky crust, it was actually...
========== In medieval times, alchemists tried to achieve
the seemingly impossible. They wanted to transform lowly lead
into gleaming gold. History portrays these people
as aged eccentrics, but if only they'd known that their
dreams were actually achievable. Indeed, today we can
manufacture gold on Earth thanks to modern inventions that those medieval alchemists
missed by a few centuries. But to understand how this precious metal became embedded
in our planet to start with, we have to gaze upwards at the stars. Gold is extraterrestrial. Instead of arising
from the planet's rocky crust, it was actually cooked up in space and is present on Earth
because of cataclysmic stellar explosions called supernovae. Stars are mostly made up of hydrogen,
the s...