The relationship between energy and mass came out of another of Einstein's ideas, special relativity, which was a radical new way to relate the motions of objects in the universe. At one level, the equation is devastatingly simple.
Time and Tools. The most obvious difference between a cake and a cupcake is size, which depends on the container in which the dessert is prepared. Cakes are baked in large pans, usually round or square, and take half an hour or more to bake fully. Cupcakes, on the other hand, are baked in tins with several cups. Each cup is much smaller than a large cake pan, so a batch of cupcakes usually takes only about 15 minutes to bake.
Of course, it takes about 10 minutes to put them together and preheat the oven; then you wait 10 minutes after they're out of the oven to take them out of the muffin pans; then you have to let them cool completely before frosting (or the frosting just melts into the cupcakes) and then the time to actually frost them.