ABSTRACT
Postulate 1 of the special theory, the Principle of Relativity, states that the laws of physics are the same for all inertial (non-accelerated) observers. This postulate, as we saw in Chapter 19, is an extension of the Galilean Principle of Relativity that includes not only mechanics but also electromagnetism and optics; that is, all of physics at the time. This postulate means that there is no absolute inertial reference frame and uniform motion has to be referred to an inertial frame. No experiment performed inside a closed chamber in an inertial reference frame can reveal to us whether the chamber is at rest or in motion.
