The Einstein Shift.

Albert Einstein was a theoretical physicist. He used mathematics to solve problems and express new ideas, but he did not perform experiments to check his theories. Experimental work was left to others. Einstein's brilliant special theory of relativity in 1905 and general theory of relativity in 1916 proposed that space was composed of the three dimensions (length, width, and depth) plus time. The path of light moving through a gravitational field would be curved, he theorized, altering the perception of time. Stars are massive bodies, so big that space-time wraps around them.

Bending Light. As light travels from a distant startoward Earth, it bends as it goes around a nearer star in its path. This is because the nearer star is so massive its gravitational field bends light as it travels, causing the light to lose some energy in the process...