In this lecture Prof Susskind discusses the fact that we are moving thru the background microwave radiation. He discusses directional bias due to Doppler shifting. He further discusses that there is a preferred frame of reference for the microwave background. Prof Susskind discusses that if two galaxies that are far apart, can have relative velocities greater than the speed of light, based on the Hubble’s law in flat space. We discuss Susskind’s inflation model, of a line of atoms that are stretched end to end. Prof Susskind discusses the process of atom additions to the line of atoms as the distance grows to a specific distance between atoms. Prof Susskind presents that this is a convenient way of thinking about inflation. We further discuss the mathematics of the general theory of relativity of expanding space-time. Prof Susskind presents the notion of the cosmic horizon. He discusses that the surface of last scattering is slightly closer than the cosmic horizon. Prof Susskind discusses how the proximity to the cosmic horizon yields a red shifted light. He discusses the fact that the surface of last scattering is approximately 1000 times red shifted, but not infinitely stretched. Prof Susskind presents the notion of vacuum energy.