Scientific American: Where some are planning walls, others are planning windows. Or rather, pipelines. Across the dusty 1,954-mile border between Mexico and the United States, international companies are gearing up to spend more than $10 billion on thousands of miles of steel tubes carrying cheap natural gas from Texas to hungry markets on the other side of the Rio Grande. The recent surge in natural gas investment is just one element of the colossal changes underway in Mexicos energy portrait. Fracturing monopolies,...