As promised, photos from Paris and the "Invisible Universe" meeting. Here is the view from UNESCO headquarters, the conference site. The parade ground lies in front of Ecole Militaire, where French officers are trained.
Eiffel Tower from Champ Du Mars. In 1783 the Montgolfier Brothers launched their first manned balloon from this site. Since radios were introduced a century ago, the tower has been a natural site for transmitting antennas. Signals radiate outward at the speed of light. Space and Time are one phenomenon, also related by the speed of light. If an event is outside this expanding sphere, its separation is spacelike-the tower's signal is too late to affect that event. If you are "within the sound of my voice" our separation is timelike, literally a matter of time. From this simple principle (without a fixed c) one can derive all the equations of the Lorentz tranformation.
Wednesday the scientists took a boat tour down the Seine and around Ile St. Louis. A long day of meetings leaves one worse for wear. On a hot Summer night crowds gathered around the riverbanks. In the cafe atmosphere of Paris, scientists discussed new ideas like a changing speed of light.