Theories of the Universe The Forces You Already Know Theories of the Universe Forces, Particles, and Some Cosmological Glue Size in the Microcosm The Forces You Already Know The Particle Zoo The Last Train to Quarkville Cosmonotes It's interesting that the fundamental forces of the universe happen to manifest as the number 4. If you remember back to the first section when I discussed the role of certain numbers, such as 4 and 7, which were used by ancient cultures to define the cosmological structure of their universe, the tribal Native American people believed that “the Great Spirit caused everything to be in fours.” Maybe they already knew something that has taken science centuries to find out. There are only four forces that are known to operate between elementary particles. Two of these we just covered, the strong force and the weak force. The other two, gravity and electromagnetism, are familiar to us because, not only have we covered them, but they also operate in the everyday world. Gravity is the weakest of the four forces and was the first to be discovered. But even though it is the weakest of the four, its range is infinite, while the strong and weak forces are limited in range to the nucleus of the atom. Electromagnetism is much stronger than gravity, but both electricity and magnetism come in two varieties—positive and negative charge, north and south poles. These varieties tend to cancel each other out, reducing their overall influence. But as you know, Maxwell combined these two separate forces into one: electromagnetism. This force holds atoms together (electrons in their probable positions around the nucleus) as well as molecules, but is overcome by the strong force that binds the nucleus together. This all might be explained a little better by the following chart. You can compare the four forces and their relative strengths.