Talk detail

Participant	Everitt, C W Francis
Institution	STANFORD UNIVERSITY - 452 LOMITA MALL - STANFORD - CALIFORNIA - USA

Session	HR1	Accepted	Yes	Order	1	Time	14:00 - 14:35	35'
Talk	Oral abstract	Title	Discovery of Maxwell's Equations
Co-authors
Abstract	Maxwell's amazed discovery of the link between electromagnetism and light was announced just 150 years ago in Jan 1962. This, his second paper, was followed by 3 more and then in 1873 by the massive 2 volume Treatise on Electricity and Magnetism. Much remained to be done. Not until 1888, 26 years later, did Hertz discover radio waves. What is so striking about the 5 papers is that each presents a complete view of the subject radically different from the one before. I shall say something about each, emphasizing in particular Maxwell's most unexpected idea, the displacement current, so vastly more interesting than modern textbooks say. Beyond lie other surprises. The concept of gauge invariance and the role of the vector potential in defining the canonical momentum of the electron go back to Maxwell, as do the distinction between axial and polar vectors, and the new operational concepts curl, divergence, and gradient. Most intriguing for us may be that it was he that introduced the term 'relativity' into physics and on 3 separate occasions gave deep thought on how to incorporate gravity into field theory.

Session	SG4	Accepted	Yes	Order	9	Time
Talk	Oral abstract	Title	Closing Comment
Co-authors
Abstract	Tests of General Relativity take two forms: observational and controlled physics experiments. Both have value and challenges, above all the challenge of identifying and removing every significant systematic error. An attractive aspect of Gravity Probe B was the range of cross-checks secured by having four independent orbiting gyroscopes with different but related known operating conditions. Confidence is high that the three unexpected effects discussed by earlier speakers are now completely understood and removed, and that no other unknown disturbance exists.

Session	PS	Accepted		Order		Time
Talk	Oral abstract	Title	Space as the Testing Ground for Fundamental Physics
Co-authors
Abstract	Space enables new experiments in General Relativity and other regions of fundamental physics in 8 distinct ways. I shall illustrate the richness of opportunity by reviewing a number of existing and future flight missions with comments on the complications as well as the simplifications brought about by Space. Essential to it is building strong collaborations with engineers. Strangely, one often finds engineers doing the physics and physicists the engineering.

Session	SG1	Accepted	Yes	Order	14	Time	18:00
Talk	Oral abstract	Title	STEP: Satellite Test of the Equivalence Principle
Co-authors
Abstract	The STEP Satellite Test of the Equivalence Principle, advanced as a joint NASA/ESA mission, aims to test the equivalence of gravitational and inertial mass in four pairs of suitably configured cylindrical test masses to an accuracy at or beyond 10^-18. It depends on a combination of space and cryogenic technologies, many of them already proved on-orbit in Gravity Probe B. Prototype flight hardware exists. The program status and plans for future flight development will be discussed.