The splitting of a heavy nucleus
This computer-generated image shows the transformation of a single sphere into two smaller spheres without any volume being lost. The process shown above is similar to that of nuclear fission, where a nucleus deforms and splits into two nuclei of similar (though unequal) size. This is, of course, an oversimplification, as the image does not show the neutrons and protons that make up the nucleus, or indeed the fast-moving neutrons that are emitted.