Ars Technica: Fracking--the use of hydraulic pressure to crack layers of shale that hold oil and natural gas--is controversial. Thats one thing we know about a debate that mainly focuses on what we dont know. The most common concern is the contamination of drinking water, either by the chemicals used in the fracking fluid or by liberated natural gas. And this issue has entered the public consciousness through media like the film Gasland and its imagery of flaming faucets--though almost 40 percent of people in...