Linear Algebra, 5th Edition

6.9* Einstein’s Special Theory of Relativity

As a consequence of physical experiments performed in the latter half of the nineteenth century (most notably the Michelson-Morley experiment of 1887), physicists concluded that the results obtained in measuring the speed of light c are independent of the velocity of the instrument used to measure it. For example, suppose that while on Earth, an experimenter measures the speed of light emitted from the sun and finds it to be 186,000 miles per second. Now suppose that the experimenter places the measuring equipment in a spaceship that leaves Earth traveling at 100,000 miles per second in a direction away from the sun. A repetition of the same experiment from the spaceship yields the same result: Light ...