Traditional and Modern Methods of Navigation

Atomic Clocks

In this course, Professor David Wineland (University of Oregon) discusses atomic clocks. In the first mini-lecutre, we compare traditional and modern methods of navigation, where we see that precision in a clock’s ‘tick rate’ is essential for modern satellites and GPS. In the second mini-lecture, we discuss how a basic, mechanical clock (such as a pendulum clock) works, compare these clocks with atomic clocks, explain how to make an atomic clock with lasers/masers, and discuss why atomic clocks are so accurate and reliable. In the third mini-lecture, we introduce the concept of holding, or trapping, a single atom (or ion) and how this can be used to detect atomic transitions between the energy levels of the atom. The fourth mini-lecture discuses further effects on atomic clocks, notably gravitational-potential redshifts, and notes future uses of atomic clocks.

Traditional and Modern Methods of Navigation

In this mini-lecture, we discuss methods of navigation, focusing in particular on: (i) how to determine your latitude (North-South position) using traditional methods, such as determine the angle between the the Earth’s surface and a fixed star; (ii) how to determine your longitude (East-West position) using traditional methods, which is similar to that used for determining latitude except that the time of day is needed to account for Earth’s rotation; (iii) how to calculate the error in your position due to your error in time; (iv) some historical context on the Longitude Act of 1714; (v) modern navigation using satellites, which requires the clock on the satellite and clocks on Earth to be synchronised; (vi) an error calculation exemplifying the error in the distance between the Earth and the satellite; (vii) the clock’s ‘tick rate,’ or frequency, precision that is needed for accurate use of satellite navigation; and (viii) the global positioning system (GPS).