Plunging oil prices have been big news over the past year. Since mid-summer 2014, the price for benchmark West Texas Intermediate (WTI) crude has fallen from $105 to $48 per barrel. But it's not just the price of petroleum that has plummeted. The prices of lots of other industrially important commodities have also been dropping. Reason Science Correspondent Ronald Bailey explains that the run up in commodity prices is the upswing part of an expansionary economic super-cycle that has peaked. We are likely now on the downward slide to greater resource abundance and lower prices for at least the next ten to fifteen years.