The role of electrons in aiding the flow of electricity is well known. But as explained in Chapter
2-1 (The Tiniest Units), they are subatomic particles that surround the nucleus of an atom. In addition, electrons were the first subject of in-depth research into the properties of quanta.

This came about as a result of the following phenomenon. When electrons, which surround the nucleus of an atom, receive energy from external sources, they enter a special state, known as an excited state. Then, when the electrons return from this excited state to their original state, they discharge energy in the form of light. This was explained in detail in the section "What is Light?" The quantities of energy exchanged at this time are not continuous units, but discrete units (or packets) of energy.

According to our perception of the normal scale of things, it is, in principle, possible to measure continuous quantities with extreme precision. This is possible when measuring water, for example, providing there are viable methods of measuring intermediate quantities as precisely as we want, such as volumes of 1.2495...cc, or lengths of 12.514...cm. Of course, the same kind of thing applies to energy as well. However, no matter the degree of precision with which we investigate energy, the quantities of energy discharged by electrons always increase and decrease in discrete units. In other words, there are no intermediate units.

This property found in quanta is virtually unrecognized in substances that fall within the normal scale. But when we think of things on the scale of sub-atomic particles, it starts to assume considerable influence. This is one reason why there are phenomena that occur in the nano-scale world that do not fit the logic of the normal scale.