1. G. Chew:The Dubious Role of the Space-Time Continuum in Subatomic Physics, UCRL-10891 (1963).
2. A. Einstein:Meaning or Relativity (Princeton, 1953) (4-th ed.).
3. For the remarks to be made, it is unimportant that one can make clocks out of rulers or vice versa. One can trifle about the role of solids: use a vibrating drop for clock and an optical arrangement of drops as clocks, mirrors, and lenses for ruler, but a liquid is hardly different from a solid for the present purpose, and really solids in some sense cannot be so easily avoided if we also imagine our experiments to contain observers (3).
4. E. Schrödinger:What Is Life 1 (Cambridge, 1945).
5. The following is as taught 10 years ago, byN. Kroll.