Hi Warren and Everyone!
I have been asking the question "What is Time?" for many Years. 
Time like Gravity is still undefined officially.
Time seems intimately connected to what Physics or Thermodynamics refers to 
as Entropy.  Entropy being the increase in disorder that takes place in any 
physical process or chemical process; this being characterized by a loss of 
heat into the universe at large.  I believe that Entropy is in a sense, a 
measure of Time,  that clocks on the surface in only one direction as Time 
does.  
Any understanding that we have of Science comes through very strict 
definition of terms.
Time might then initially be defined as the average or mean increase in 
disorder of energy in space.  This could then be considered in different size 
volumes and would allow for Time to vary slightly according to different 
dispersions of Energy in Space.
dt = K dE/dV  might be an initial starting point.  dt = differential or small 
unit of time
                                               dE = change of Energy
                                               dV = small unit Volume of Space
                                                K  = a possible constant(as 
needed)
Hence the cycling of Time would be dependent upon the average or mean ratio 
of the density or amount of Energy confined in a given Volume of Space during 
its dispersion.  
Energy Concentration in a given Volume of Space Seems to be related to 
Temperature as Well. 
This phenomena seems to be born out in Human experience.  Young children have 
a higher average temperature and Time seems to be moving faster subjectively. 
 As we age our internal clock or sense of Time seems to slow down as our 
average body temperature decreases.  The older we get the greater the 
disorder we experience in the body as well, until complete disorder and death 
occurs, resulting in a final cooling to the ambient Temperature of the 
surrounding universe.
My most current theory sees the Universe or Third Dimension of Energy/Space 
being enclosed in a gigantic Magnetic Bubble.  Its as if the Universe is a 
giant singularity like an instrument, say a guitar being strummed.  This 
Process or waveform of the strumming then inturn controls the interaction of 
Energy /Matter in Space resonating in complex interference/fractal patterns, 
which intern controls the average or mean dispersion of Energy in Space.   
This cyclic strumming would then be called Time as it interacts with the 
Three Space universe.  Entropy would then be the direct result of this 
strumming or cycling that we would call Time.
I would suggest that this Time/Strumming is a Non-Third Dimensional energy 
such as a Scalar Energy Wave that would act directly and indirectly upon the 
Universe/Singularity Magnetic Bubble as if through sympathetic resonance, and 
Holographically upon each particle of matter in the universe.  The creation, 
birth or entry of an object into Three Space would then impart a 
charactoristic Imprint pattern upon such a Matter/Energy form directly 
related to its position in Three Space and the charactoristic Energy/Space 
dispersion/interference  patterns relative to its position.  This Imprinting 
would in turn be down to the quantum level and beyond.
R.E.Cathey