Sunshine Report:

Dick Nelson had a procedure in Michigan to drain fluid and he's doing OK. Calls or a card would be appreciated.

Speaker:

Tom Lagenstein

Gravity, Relativity  GP-B and GPS

Introduced by Walt McCullough

Tom has a career spanning 30+ years at Stanford performing Program Management, primarily associated with spacecraft development programs. He also manages the Stanford Center for Position, Navigation and Time and the Accelerator on a Chip International Program.

In 1687 Newton defined gravity as a force that attracts bodies to their center and is proportional to their masses. It happens instantaneously.

In 1905, Einstein developed the Special Theory of Relativity which was based upon the speed of light being constant, out of which came the formula E=mc2. This was in conflict with Newtons' definition and lead, in 1915, for Einstein to develop the Theory of General Relativity, in which gravity is defined as a field involving space and time, not a force.

In 1930, George Bernard Shaw honored Einstein as a "Maker of the Universe" at the Fabian Society.

In 1960 a thought experiment was conducted by three Stanford Professors (Schiff, Fairbanks and Cannon) that proposed that a gyroscope, put into a pristine environment (controlled for vacuum, electrical fluctuations and heat) could test Einstein's theory, the idea being that the gyroscope would experience presessioning due to geodetic effect and frame drawing, the effect of Earth spinning and dragging space with it. The gyroscope would need to detect .0001 arc second of deformation of space. The angle of this was described as an arc that separates by the size of the eye on Lincoln's memorial on a penny as viewed from Paris to NYC. But a "near perfect" gyroscope would need to be developed.

In the late 1980's a series of experiments were launched that eventually lead to a test in 2004.

Along the way as steps were taken that led to the test, several inventions were spun off, among them development of GPS as  navigational tool. This was initially designed by grad students, interested in navigating a small private plane that received signals from 4 satellite signals that provided the x,y,z and time coordinates of the position fix of the plane. This was eventually adopted by commercial airlines. 

The second spin-off was understanding that because the satellites were so crucial to navigation that GPS positioning error needed monitoring.

The third spin-off was the development of precision agriculture which has greatly increased the yield of agriculture with GPS aided tractors.

The test was finally launched in 2004, in which a number of highly precise gyroscopes were launched via satellite and their precessions were monitored. All of the data collected confirmed Einstein's theory was correct. It was a joint project between Stanford and NASA and was NASa's longest running project.

On an ending note, Tom Langenstein noted that  there is no Nobel prize for engineering, however there is a Queen Elizabeth Engineering Prize and 4 engineers won it for their work in GPS: Richard Swartz, Brad Parkinson, Jim Spilker and Hugo Fruehauf. It was noted that Jim Spilker, who attended the Community College of Marin, attended Stanford with a Rotary scholarship.

— Rachel Meyer, Ed.

Special thanks to Rachel for stepping up in a crunch and delivering Spinnings on short notice. — DS

Photographs by Peter Sortwell