Scientists have demonstrated a noninvasive technique that uses light to reveal the hidden contents of chicken eggs, potentially helping to curb the meat industry's practice of killing billions of male chicks at birth. The study, published in Newton, found that when light enters an intact bird eggshell, it bounces back and forth many times, with photons traveling as far as 2 meters (6.6 feet) within a chicken egg's tiny, 4-centimeter (1.6-inch) interior.