Friday, January 14, 2011
Is gravity a strong or weak force? We think it's strong, seeing it holds moons in orbit, but it's actually rather weak, as eraser-sized magnets can overcome the gravity of the entire Earth when it lifts a paper clip off the ground. Yet gravity is so prevalent because electromagnetic forces are self-neutralising; sometimes they attract, and sometimes they repel. Meanwhile, nuclear forces operate at atomic distances, whereas gravity interacts across the universe.