Dear Rob and Eckard,
I find this Q and A session quite fascinating. As you both know, I am focused on the possible physical consequences of Tajmar's measurement of a gravito-magnetic field that, in coherent circumstances, exceeds the expected field strength by 31 orders of magnitude. The associated G and C fields are 'analogous' to the electro-magnetic E and B fields and this is conceptually quite useful.
For purposes of relating gravito-magnetism to some of your above statements, I'd like to point out that G has dimensions L/T^2 while C has dimension 1/T, where l is length and T is time. Thus G has units of 'acceleration' and C of 'frequency'.
This relates to Rob's comment that "a positive frequency corresponds to an increasing phase angle, [and] if a second hand rotates clockwise, it is said to have a frequency of +1 cycle/minute. But if it rotates counter-clockwise, it is said to have a frequency of -1 cycle/minute. [and] Counting downwards is every bit as "real" as counting upwards."
Yes, one can 'count' downwards. But can the clock run backwards? The mechanical clock can do so, but the C-field cannot. It is a 'left-handed' rotation [accounting for neutrino and other asymmetries] and cannot 'run backward'. In my previous FQXi essay I propose that the C-field established the first cyclical phenomena in the universe, and hence the first instance of the appearance of 'time' in the universe.
Eckard notes that "While time is commonly considered a basic physical quantity," he does not have a problem with "the alternative choice of frequency as a basic physical quantity. Neither the measurable (elapsed) time nor the measurable frequency may change their sign." It is exactly this basic physical quantity that the C-field represents.
Eckard also noted "Dirac was not horribly wrong when he meant that there is no negative frequency in reality."
In "Quantum Mechanics: Myth and facts", Nikolic discusses the fact that relativistic Klein-Gordon equation has solutions with positive and negative frequencies, while the non-relativistic Schrodinger equation has only positive frequency solutions. My current essay relates this QM wave function to the left-handed C-field, and establishes a physical, not a mathematical, reason to throw away the negative frequency solutions of the Klein-Gordon equation.
Thus, in addition to Rob's explanation that, while the mathematical equations exhibit time symmetry, the required initial conditions do not, in the case of the C-field, even the basic equation is asymmetric, as the circulation is clearly left-handed.
While it is impossible to lay out a theory of time symmetry in a comment, I have included more relevant information in my last two FQXi essays, and I suggest that this is the actual physical underpinning for the fact that time does not run backward.
Thanks for exploring these issues.
Edwin Eugene Klingman