The world is experiencing a "negative feedback loop" as commodity prices fall, according to Goldman Sachs. What's more, this loop is a huge story decades in the making — and there isn't a country on the planet that won't be impacted. Lets go back to last week, when prices for all kinds of commodities — including gold, oil and all manner of metals and agricultural products — fell in concert. For some of these commodities, it marked the dramatic acceleration of a year-long trend. Slowing Chinese demand for raw materials has pushed the Bloomberg metals index down 25%. Liquidity is low. Cash is in shorter supply. ... (full story)