Einstein and Gravitation
Albert Einstein once said in the patent office at Bern when all of a sudden a thought occurred to me: ‘If a person falls freely, he will not feel his own weight.I was startled. This simple thought made a deep impression on me. It impelled me toward a theory of gravitation.
Thus Einstein tells us how he began to form his general theory of relativity, The fundamental postulate of this theory about gravitation (the gravitating of objects toward each other) is called the principle of equivalence, which says that gravitation and acceleration are equivalent. If a physicist were locked up in a small box as in, he would not be able to tell whether the’ box was at rest on Earth (and subject only to Earth’s gravitational force). or accelerating through interstellar space at 9.8 m/s2 (and subject only to the- force producing that acceleration.