Ever heard of hydraulic fracturing, a.k.a. fracking -- the controversial practice of extracing natural gas and oil from rock by pumping highly pressured water and other liquids under the Earth? If not, you're in good company. A whopping 35 percent of some 2,400 in a representative sample of the U.S. conducted by the University of Texas Austin had "never heard of" the process, while another 28 percent "were not familiar" with it, meaning that 63 percent of the nation doesn't know what the process is. "We are left with a highly controversial topic that few Americans understand," writes Sheril Kirshenbaum, UT Energy Poll director.