Glossary
contingency: The idea that many events (in history or the natural world) are
random and unpredictable.cosmic background radiation: Low energy radiation pervading the entire
Universe, released c. 380,000 years after the big bang, when the Universe
cooled suf¿ ciently for neutral atoms to form so that energy and matter could
separate; its discovery, in 1964, persuaded most cosmologists to accept the
big bang theory.cosmic evolution: A synonym for big history; history on all scales up to
those of cosmology.cosmology: Study of the history and evolution of the Universe.creation stories: Stories found in all human societies about the origins
of all things.Cretaceous event: The term used to describe the asteroid impact about
67 million years ago that led to the extinction of many species, including
the dinosaurs.cuneiform: A type of writing, common in ancient Mesopotamia, in
which symbols are made by pressing wedge-shaped cross sections of reeds
into clay.dark matter/dark energy: Studies of the movements of stars and
galaxies have shown that there must exist much more energy and/or
matter than we can observe; at present, astronomers have no idea what
either dark energy or dark matter consist of; one of the great mysteries of
contemporary astronomy.determinism: The idea, common in the 19th century, that general laws
determine the exact course of events so that if we had complete knowledge
of reality we could, in theory, predict the future.differentiation: The process by which, early in the Earth’s history, the Earth
melted to form a series of different layers, with the heaviest materials (mostly