the theory that space and time are not absolute concepts
Space and time can change when measured relative to an object moving near the speed of light—about 186,000 miles per second. Since relative motion is the key to Einstein’s idea, it is called the theory of relativity.
an artistic movement using fantastic and incongruous images
Surrealism, an art movement that sought to link the world of dreams with real life, was inspired by Freud’s ideas. The term surreal means “beyond or above reality.”
genre of American music that developed in the 20th century
A new popular musical style called jazz emerged in the United States. It was developed by musicians, mainly African Americans, in New Orleans, Memphis, and Chicago.
a long-term economic state with unemployment and low prices
Within months of the crash, unemployment rates began to rise as industrial production, prices, and wages declined. A long business slump, which would come to be called the Great Depression, followed.
a policy of pacifying an enemy by making concessions
On March 7, 1936, German troops moved into the Rhineland. Stunned, the French were unwilling to risk war. The British urged appeasement, giving in to an aggressor to keep peace.