Theories of Space and Time (HET605)

Relativity on Earth

Almost everybody who has studied physics, read a mass-market science magazine, or visited an Internet science forum is aware of Einstein's theories of relativity. In 1905 Einstein published the Special Theory (hereafter SR) that presented an elegant approach to explaining some of the more puzzling experimental results of the 19th century electromagnetic experiments. Not content with that achievement, Einstein published his General Theory (GR) in 1915, extending the concept of relativity to encompass gravitation. Einstein did not concentrate on tweaking existing theory to suit the experimental data of the day, rather he looked for an elegant framework that could encompass all of the phenomena of electromagnetism and gravity. Despite Einstein's lack of reference to experiment his theories are testable. Numerous tests are possible for predicted effects such as: time dilation, length contraction, and Doppler shifts from SR, and gravitational lensing, time dilation, and reddening from GR. Many of the experiments rely on astronomical or astrophysical observations, but some tests of both SR and GR are possible within the confines of Earth and its immediate surrounds. This essay will describe several Earthly experiments that have been performed to validate Einstein's work.
Relativity on Earth Essay PDF

The Global Positioning System

Arguably one of the most useful global benefits provided by the U.S. Department of Defense (DoD) has been the Global Positioning System (GPS). The GPS provides worldwide ability to pinpoint positions, including altitude, to within a few tens of metres. The general theory of operation for GPS is relatively straightforward but the implementation must take into account a number of effects related to the special and general theories of relativity. This project describes the GPS and how relativistic effects are accommodated within it.
The Global Positioning System Project PDF