Congress has always had a soft spot for "experts' who tell members what they want to hear, whether it's supply-side economists declaring that tax cuts increase revenue or climate-change skeptics insisting that global warming is a myth. Back in May, Michael Masters, a hedge fund manager, made a big splash when he told a Senate committee that speculation is the main cause of rising prices for oil and other raw materials. He presented charts showing the growth of the oil futures market, in which investors buy and sell promises to deliver oil at a later date, and claimed that "the increase in demand from index speculators'