How much the united states changed between the great depression and the postwar era, when the country had become an economic powerhouse

The United States changed dramatically for the better economically between the Great Depression and the postwar era, since the World War spurred production on an unprecedented scale, which meant that many poor people were put to work and had higher incomes. 

The law of gravity was his main contribution. Main scientists had observed planets moving around the sun but this theory finally explained why.