An animal that embarks on forming states without greatly restricting egoism will perish.

Erwin Schrödinger

Figure 7.0. Old Woman Dozing by Nicolaes Maes (1656), Oil on canvas. Royal Museums of Fine Arts, Brussels.Atoms and molecules with unpaired electrons, called free radicals, are responsible for many diseases including old age. Their motion is governed by quantum mechanics.Although a cell (the smallest unit of life) largely consists of four types of molecules (nucleic acids, proteins, lipids, and carbohydrates), atoms and ions (atoms that have gained or lost one or more electrons) play a crucial role inside an organism. For example, many chemical reactions in biological systems involve a proton (H+) transfer, and therefore their rates depend on the concentrations of H+. Because the correct rate of these reactions is crucial to maintain life, the wrong H+ concentration can result in illness and even death.A free radical is another example. It is any atom or molecule that has a single unpaired electron in an orbital of its outer shell. An orbital needs two electrons to be complete, and the atom experiences instability due to the lack of a missing electron. In order to gain stability, the atom (free radical) has a very strong tendency to rip an electron from neighboring atoms and molecules. So, most biologically relevant free radicals are highly reactive, and therefore they can participate in unwanted side reactions resulting in cell damage and even ...

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