Special Relativity 4 - Einstein's Speed of Light Principle ("Principle 2")

          @misc{ scivideos_PIRSA:08080063,
            doi = {},
            url = {https://pirsa.org/08080063},
            author = {Epp, Richard},
            keywords = {},
            language = {en},
            title = {Special Relativity 4 - Einstein{\textquoteright}s Speed of Light Principle ("Principle 2")},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2008},
            month = {aug},
            note = {PIRSA:08080063 see, \url{https://scivideos.org/pirsa/08080063}}
          }
          

Abstract

Repeating the experiment from SR-3 using light rather than sound, and understanding what Einstein assumed regarding the speed of light.
Learning Outcomes:
• How to draw a spacetime diagram that represents the sending and receiving of a light signal.
• Understanding that Einstein's Speed of Light Principle: "For an observer at rest, the speed of light is c, independent of the motion of the source" is natural and easy to believe.
• Interchanging the words observer and source we arrive at Principle 2*: "For a source at rest, the speed of light is c, independent of the motion of the observer," which Einstein did not assume, because it is very hard to understand how it could be true.