Maybe Not Quite 6.6 Billion

As I hinted in the previous page, the ratio of 6.6 billion-to-one is the result of 100% conversion of matter to energy. Using chemical energy such as digesting food is easy, but not very efficient. When careful experiments are done to prove Einstein right using chemicals, they require far more delicacy than is available, which is why Einstein discovered his formula instead of Lavoisier or one of that crowd. Incidentally, "burning" chocolate chips or burning coal, gasoline, or wood is so close, energy wise, that in the context of nuclear energy it's barely worth making the distinction.

So, to summarize:

Chemical Energy is inefficient but easy; Total Conversion, at least on earth, is impossible.

Which brings us to Nuclear Energy—Fission and Fusion

Although there are energetic reactions whose magnitude lies between chemistry and fission/fusion, we'll ignore them here for simplicity and grace.

Nuclear fusion energy production is the result of atomic nuclei combining. Nuclear fission energy production is the result of atomic nuclei coming apart. Why isn't that a contradiction?

Because they're accomplished by different atoms!

Of course you remember the Periodic Table of the Elements, a copy of which resides on the wall of every chemistry classroom in the world. This table starts with hydrogen, the lightest and most abundant element in the universe, in its upper-left corner. Hydrogen has an atomic number of one, that number reflecting the number of protons in its nucleus. The element Uranium, which is a very heavy, metallic element, has 92 protons in its nucleus, with a corresponding atomic number. It resides near the bottom of the Periodic Table. All elements have isotopes which relate to the number of neutrons in their nuclei. Uranium has two familiar isotopes, 235 which is fissionable and used in atomic reactors, and 238. Hydrogen has three isotopes each of which has its own name since they're so different. Normal hydrogen has no neutrons. Deuterium has one neutron and, when combined with oxygen as D2O instead of H2O, makes "heavy water." Finally, the hydrogen isotope with two neutrons is called tritium, and it's radioactive. They used to make watches with tritium backlights which glow in the dark. The two heavier isotopes figure prominently in fusion reactions.

With this background, we come to the term "binding energy."

It relates to the energy that holds the protons and neutrons of a nucleus together. The mass of a nucleus is less than the mass of its constituent particles. Remembering that mass and energy are equivalent, splitting a heavy nucleus (fission) or combining the protons and neutrons of different isotopes of hydrogen into a heavier nucleus (helium) releases energy.

As a rule, very light elements can fuse comparatively easily, and very heavy elements can break up via fission very easily; elements in the middle are more stable and it is difficult to make them undergo either fusion or fission in an environment such as a laboratory. When either happens, energy is released and the mass of the resulting elements is decreased.