Prices of a stock will move throughout the day. Investors generally buy a stock they feel is undervalued, and sell a stock they feel is overvalued. For instance, if the price of AAPL is $600 dollars, it means the cost to purchase one share of Apple is $600 dollars.
Einstein quickly realized (or had known all along) that his new theory of gravity was really a theory of the cosmos. In 1917, he wrote a famous paper applying general relativity to the universe as a whole. Today that paper stands as the foundation for modern cosmology.
Original theory of relativity: Galileo Galilei. The theories of general and special relativity: Albert Einstein. Albert Einstein developed the theory of relativity. Albert Einstein developed the theory of relativity between 1907 through 1915. It was further developed by Max Planck, Hermann Minkowski, and others. If you are referring to the theory of relativity it would be Albert Einstein.