825.2 the need for change and th postulates of the special theory @the fundamental laws of physics are the same for observers in all inertial reference frames No frame is preferred. Descriptions of what happens as a result of the laws of physics may different from one inertial reference frame to another, but the underlying fundamental physical principles and laws are the same Glileo assumed that the laws of mechanics were the same in all inertial reference frames Einstein extended that idea to include all the laws of physics. 8 25.3 consequences of Einsteins postulates 1. Time dilation Mirror Event 1: emission of the pulse 0,y=0,x1=0,1 Event 2: reflection of the pulse Event 2 x2=0,y2=l1,z=0,t2=l/c Event 3: detection of the pulse x3=0,y3=0,z3=0,t3=2l/c Time interval: At=To=2Lo/c Proper time interval12 2the fundamental laws of physics are the same for observers in all inertial reference frames. No frame is preferred. Descriptions of what happens as a result of the laws of physics may different from one inertial reference frame to another, but the underlying fundamental physical principles and laws are the same. Glileo assumed that the laws of mechanics were the same in all inertial reference frames. Einstein extended that idea to include all the laws of physics. §25.2 the need for change and the postulates of the special theory §25.3 consequences of Einstein’s postulates 1. Time dilation 0l 0 τ s′ Event 1: emission of the pulse 0, 0, 0, 0 x1 ′ = y1 ′ = z1 ′ = t1 ′ = Event 2: reflection of the pulse x y l z t l c 2 2 0 2 2 0 ′ = 0, ′ = , ′ = 0, ′ = Event 3: detection of the pulse x y z t l c 3 3 3 3 0 ′ = 0, ′ = 0, ′ = 0, ′ = 2 t l c = 0 = 2 0 Time interval: ∆ ′ τ Proper time interval