Geology 109, General Oceanography
Spring 1996, Learning Community Section
Unit 1, Topic 1a, The Origin of Matter

The Path to the Present?

Astronomers generally agree that 10 to 20 billion years ago, the cosmos began in a gigantic explosion, the Big Bang. From this event emerged the basic particles (atomic physicists have names for them like quarks and leptons, subatomic particles which we will not be concerned with) that quickly assembled into the building blocks of matter (atomic nuclei orbited by electrons). In reference to the figure we will be concerned with the nucleons (protons and neutrons), the electrons, nuclei, atoms, and solar system origins.

Then the lightest atoms - hydrogen and helium - accumulated into clumps. Within these clumps the intense gravitational pressure caused nuclear fusion, the spark that ignites stars. Stars gathered by the billions into large clusters called galaxies (The Earth is in the Milky Way galaxy).

Finally, after billions of years, the star evolution events generated heavier elements such as silicon and iron, carbon and oxygen, the basic building blocks our planet and the life forms which inhabit it.

In this model, the Big Bang is the root of all matter and life.