A traveler-centered intro to kinematics by P. Fraundorf of Physics & Astronomy/Center for NanoScience at University of Missouri -St Louis (63121) Treating time as a local variable permits robust approaches to
kinematics that forego questions of extended-simultaneity, which because
of their abstract nature might not be addressed explicitly until a
first relativity course and even then without considering the dependence
of clock-rates on position in a gravitational field. For example we
here use synchrony-free ``traveler kinematic" relations to construct a
brief story for beginning students about: (a) time as a local quantity
like position that depends on ``which clock", (b)
coordinate-acceleration as an approximation to the acceleration felt by a
moving traveler, and (c) the geometric origin (hence mass-independence)
of gravitational acceleration. The goal is to explicitly rule out
global-time for all from the start, so that it can be returned as a
local approximation, while tantalizing students interested in the
subject with more widely-applicable equations in range of their math
background. Sections of this paper include: Note also that figure captions may often be accessed by either mousing-over or clicking-on a given figure. |