"I believe in Spinoza's God who reveals
himself in the orderly harmony of what exists, not in a God who concerns himself with the
fates and actions of human beings."

The general theory of relativity, unlike quantum theory, was not rapidly developed after
Einstein showed the way. Gravity was now understood in a new way, but the equations were
difficult to work with. And the characteristics of the theory showed up clearly only
under extreme conditions, enormous densities or vast spaces or measurements of the highest precision.
Eventually technology caught up -- the modern Global Positioning System can pin down locations accurately
because it uses the equations of general relativity to adjust for effects of gravity and speed. But during Einstein's lifetime
only one such object was known: the universe taken as a whole.

In 1917 Einstein and the Dutch astronomer Willem de Sitter showed that Einstein's
equations could be used to describe a highly simplified universe. Other scientists
developed this model, adapting it to the real universe full of stars. They found
a difficulty: the model had to show the stars either all moving apart, as if
from a giant explosion, or all collapsing together upon each other. But Einstein
had found room in his equations for an extra mathematical term, the "cosmological
term" as he called it. He could adjust this term to give new model: an unchanging
model universe.

In 1929 the American astronomer Edwin Hubble discovered evidence that distant
galaxies of stars are moving away from our galaxy, and away from each other,
as if the entire universe were expanding. The original Einstein equations might
give an exact description of our universe after all. Quickly convinced by Hubble's
evidence, Einstein felt that his notion of a "cosmological term" was a mistake.
Other scientists withheld judgment, and debate over the cosmological term still
continues today. But most astronomers agree that with or without the cosmological
term, Einstein's equations give the best available language for a description
of the overall structure of the universe.

"I want to know how God created this world. I am not interested in this or thatphenomenon,
in the spectrum of this or that element. I want to know His thoughts; the rest are details."