  We present the theory of special relativity here through the lens of
differential geometry. In particular, we explicitly avoid any reference to
hypotheses of the form "The laws of physics take the same form in all inertial
reference frames" and "The speed of light is constant in all inertial reference
frames", or to any other electrodynamic phenomenon. For the author, the
clearest understanding of relativity comes about when developing the theory out
of just the primitive concept of time (which is also a concept inherent in any
standard exposition) and the basic tenets of differential geometry. Perhaps
surprisingly, once the theory is framed in this way, one can predict existence
of a "universal velocity" which stays the same in all "inertial reference
frames". This prediction can be made by performing much more basic time
measurement physical experiments that we outline in these notes, rather than
experiments of an electrodynamic nature. Thus, had these physical experiments
been performed prior to Michelson-Morley type experiments (which, in principle,
could have been done in any period with precise enough time keeping
instruments), the Michelson-Morley experiments would simply give us an example
of a physical entity, i.e., light, which enjoys this special "universal"
status.
