2. Galileo simply described this as the fact that an observer in motion sees things differently from a stationary observer We use this as a part of our everyday experience

3. German physicist Developed 2 theories on relativity 1. Special theory of Reality 2. General theory of Reality Believed that relativity teaches us the connection between the difference descriptions of one and the same reality

4.  Published in 1905 in Einstein's paper : On the Electrodynamics of Moving Bodies  Deals with things moving near or at the speed of light  Based on two postulates 1. The law of physics are the same in all inertial (non-accelerating) reference frames 2. The speed of light in free space is constant

5. Energy = mass times speed of light squared Einstein’s equation implied that tremendous energies were contained in small masses

7.  Published in 1915  Explains the force of gravity in terms of curving four dimensional space-time. According to Einstein the forces of acceleration & gravity are Equivalent.  This theory is based on one thing 1. That all physical laws can be formulated so it can be valid for any observer, regardless of the observer’s motion