Overview: Two protons next to each other in an atomic nucleus are repelling each other electromagnetically with enough force to lift a medium-sized labradoodle off the ground. Release this energy and you have, well, you have a nuclear explosion. Just as well there's an even stronger force than the electromagnetism holding our nuclei together. But it's not the strong force, as you might have imagined. At least not directly. Nuclei are held together by a quirk of nature, without which we would have no complex atoms, no chemistry, and certainly no labradoodles.