This volume collects the lectures on the foundations of physics given by eleven scientists at the University of Delaware. It is neither an anthology of disconnected items nor a smoothly running textbook but rather a progress report on a neglected yet vital area of basic physical research, namely foundations research. The investigation into the foundations of any branch of science is neither loose speculation nor popular science: it is an aspect of scientific research - in fact the deepest-searching part of basic research. Con sequently it must be carried out by the scientist himself. Thus whether the time concept is a numerical variable or a function, whether particle mechanics is the primary mechanical theory or a particular case of conti...