Texas ranching has been under economic siege almost since it began. It has always offered an opportunity to make a small fortune, nowadays by starting with a large one. Yet for all its flaws, ranching is addictive. So is abandoning ranching. “The Big Empty,” a novel by Loren Steffy, steals one of the classic tropes of Texas letters: modern technology displacing ranching. The oil industry is the traditional disrupter. Set at the dawn of the 21st century, Steffy makes high tech, computers, and the internet ranching’s competitor. He adds a spin. The ranchers are rooting for high tech to win. Conquistador is a dying West Texas cattle town. While not at the end of the world, on the flat West Texas plains it might as well be. Ranching is fading as a business. Conquistador’s residents are desperately seeking new industry to draw jobs there. They even tried getting the state …