An ideogram signifying the
modern Western conception of the smallest part of matter, the atom. As such it has become a symbol for
uranium, the element
mainly used for producing nuclear power in plants, and plutonium for nuclear bombs. This sign
also stands for nuclear research, nuclear physics, and nuclear
In this and the two preceding entry signs the ellipses represent the electrones' orbits around the nucleus, which is symbolized by the point in the center of the ideogram.
Compare with , a sign used in physics for nuclear charge, and with a sign for galaxy, .
It is interesting that when illustrating the smallest and the largest entities of matter Western ideography uses the same basic sign structure, which is also the structure used to indicate nothingness (as the sign for zero). This is another illustration of the law of the polarity of meanings of elementary graphs.