“A man with one watch knows what time it is, a man with two watches is never quite sure...” Clocks are devices that use Kinetic Energy, from some higher to lower Potential Energy level, at some rate. Your dial setting is purely human-arbitrary. In England they have 5 or more atomic clocks based upon number of vibrations/sec to keep “accurate time”. Even they wander off from each other w/o a master/slave linkup. So the timekeeper there suggested turning all but one of them off to save cooling energy.
Thus, you have to overcome the idea that there is an absolute “time” that can be measured. Time is a variable of Kinetic Energy release of over running/under running matter wavelength vs particle velocity. t=dKE=m or time is inertial mass or gravitational mass. Throw a baseball between your hands, you’re throwing matter wave force back and forth : accel is P>W and decel is W>P. Deceleration and weight are the same thing : over running matter wave Force.
Einstein bitterly resisted DeBroglie’s matter wave concept(spooky action at a distance)and thus died in 1955 still not knowing what time is. DeBroglie’s equations : Lambda(wavelength of fermion waves) = h/mv. That means matter waves(half of your physical existence)are some 20 orders of magnitude shorter than your visual 4000 to 7700 A light wavelengths. You don’t SEE them, you feel them as accel/decel in your sense of touch(haptics), your body is your “time-eye”...
DeBroglies equation for wave speed is U = C^2/v which blew Einstein’s mind, so they came up with this hokey group/phase cover story, and tried to make DeBroglie a “crazy aunt alice”, hopng he’d be forgotten, only vaguely referred to as the “wavefunction”. And hoping you’d think “wavefunction” meant EM waves.
The “marriage” equation is E=mc^2=hw where h is Planck’s quantum and w DeBroglie’s wave number. For fermions this means matter waves as flux-linking explains faster-than-light linked photons(the spooky action)and why the sun’s gravitational attraction on the earth isn’t 8 minutes c-retarded, it’s .001655 sec at 9 x 10^16 km/sec.
Matter waves, find a physics book and study up on them, they explain what time and gravity really are.