Albert Einstein developed the _______ during the years 1907 to 1915.

Directions: Read the given passage and answer the question that follows.

Albert Einstein is perhaps the most famous scientist of all time. Both his image and brilliant work on theoretical physics live on today and he serves as an inspiration to young scientists around the world. Albert Einstein was born on the 14^th of March 1879 and died on the 18^th of April 1955. Born in Germany to a Jewish family, Einstein made many contributions to the field of theoretical physics. Even when very young, Einstein showed great ability in both math’s and science. He was naturally curious and had a brilliant and analytical mind. He produced perhaps one of the most famous equations ever: E = mc² (energy equals mass multiplied by the speed of light squared). He is also well known for his theory of relativity. Special relativity being introduced in his 1905 paper “On the Electrodynamics of Moving Bodies” before Einstein developed the theory of general relativity between the years of 1907 and 1915. Einstein won the 1921 Nobel Prize in Physics for his work on theoretical physics. He worked on many other influential theories and projects including: the deflection of light by gravity, the quantum theory of atomic motion in solids, Brownian motion, an explanation for capillary action and much more.