Theory of Relativity (Galilean Transformation and Velocity of Light) Lecture-4

Theory of Relativity

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4.Galilean Transformation and Velocity of Light The Galilean transformation successfully explained the invariance of laws of Newtonian mechanics in different inertial frame. No experiment in physics carried out in a single inertial frame can tell us that our frame is at rest or moving with uniform velocity. Let me remind you that our earth moves with a velocity of 30 Km/sec with respect to space in a nearly circular path around the sun. There is no preferred inertial frame for the laws of mechanics to hold true.               According to Maxwell's electromagnetic theorem, the velocity of light in space is                       =          ( - permeability and permitivity of free space ) It was believed that light travels with above velocity in a medium called ether, which is inertial with respect to sun.              According to Galilean transformation (v'=v-V),  for an observer in a S'-frame moving with velocity V  would measure the velocity of light pulse ranging from c-V to c+V depending upon the relative direction of c and V. But according to Maxwell's equation, the velocity of light is constant in empty space/vacuum. The consequence of above observation has following possibilities: