[GoC]

Time is just a measurement of reaction rates relative to other reaction rates It is fundamental motion c that regulate the reaction rate in a frame. A clock measures the available energy c minus the kinetic energy used from c. c energy is not able to be viewed directly because we would need something faster than c to measure directly. We only can measure indirectly with the speed of light. Energy is only a dimension of size very small.

[guest4091]

From the archive:

What is time?

The operational definition of assigning a time to an event as mentioned by A.E. in the 1905 paper is essentially what it is, and how it's been done since humans appeared.
It is a correspondence convention, i.e., assigning events of interest to standard clock events, a measure and ordering of activity, with 'time' always increasing/accumulating.
It is an accounting scheme developed out of practical necessity, for human activities like agriculture, business, travel, science, etc. The unit of measure for time initially referred to relative positions of astronomical objects, stars, sun, and moon, which implies earth rotations and earth orbits. The year equates to the periodic motion of the earth relative to the sun, the month, the moon relative to the earth, and the day, the earth rotation relative to the stars. All units of time are by definition, involving spatial motion or distance. The clock further divides the day into smaller units of measure. The reference in the 1905 paper of the watch hand to a position on the watch face involves nothing more than counting hand cycles (hand motion of specific distances representing subdivisions of a day). Current scientific research requires clocks that generate smaller and more precise periods than those of the past. The second is defined as n wave lengths of a specific frequency of light. Note "n wave lengths" is a distance, but labeled as "time".

If we use a light based clock to time the speed of an object along a known distance x, what are we actually doing?
We are comparing the simultaneous motion of an object to the motion of light for a duration (number of ticks). The result is a ratio x/s = vt/ct = v/c or speed. It should be obvious that the ticks serve to correlate the positions of the object with the positions of the light signal, for simultaneous comparisons. If you use Minkowski spacetime diagrams the vertical scale is not 'time', but ct, light path distance, i.e. they plot speed. You 're comparing apples to apples.
In summation: A clock provides a beat or rhythm to coordinate events.
The clock used in music is a metronome. Whether it ticks fast or slow, the same amount of music is played.

quotes by the author of SR
From 'The Meaning of Relativity', Albert Einstein, 1956:
page 1.
"The experiences of an individual appear to us arranged in a series of events; in this series the single events which we remember appear to be ordered according to the criteria of "earlier" and "later", which cannot be analyzed further. There exists, therefore, for the individual, an I-time, or subjective time."
page 31.
"The non-divisibility of the four-dimensional continuum of events does not at all, however, involve the equivalence of the space coordinates with the time coordinate."
page 32.
"Finally, with Minkowski, we introduce in place of the real time co-ordinate l=ct, the imaginary time co-ordinate..."

time and perception
Subjective time requires memory, which allows a comparison of a current state to a previous state for any changes, which lends itself to an interpretation of time flowing. Patients with brain damage to specific areas involved in maintaining a personal chronology, lose their ability to estimate elapsed time, short or long term. Consider the fact that people waking from a comatose state, have no memory of how much elapsed time, whether hrs, days, or even years.
Consider one of the greatest misnomers ever used, 'motion pictures' or  'movies', where a person observes a sequence of still photos and the mind melds them to produce moving objects where there is no motion. These cases show time as part of perception. SR then alters perception via motion.

misc.
It was Minkowski who advocated the mathematical manipulation of the expression for the invariant interval from an equality to a generalized form of four variables, producing spacetime.

Mathematical descriptions that express a behavior as a function of time, are misleading when the time is interpreted as a causative factor. The time of an event must be assigned after the event occurs!

No objective or universal 'time' has yet been discovered, thus it remains subjective and  variable with observer motion per SR. It is a measure of activity, and that's what science does, it measures things.

It's intangible, so we will never have "time in a bottle".

To Yahya; the spacetime diagram or similar graphic, using (x, ct) axes is based on the standard c. Light speed is accepted as an upper limit and as universal. No need to reinvent it.

[GoC]

Clocks measure c energy - kinetic energy. Universal time is c distance but we can never properly measure the amount of kinetic energy being used in a frame.

[guest4091]

Clocks measure c energy - kinetic energy. Universal time is c distance but we can never properly measure the amount of kinetic energy being used in a frame.

I'll agree with you in part; energy can be calculated from the time, but that's not the design purpose of a clock, no more than a ruler measures momentum, but can supply distance data for that purpose.

[GoC]

Yes, it is all interconnected and relative. c is the total available energy E while mass is the kinetic energy being used from c. Just like a ruler a clock is just a measurement. .Momentum is a result from measurements. A clock measures distance for an interval. It can be an electron (mechanical) or a photon but they both measure the same E-Kinetic e of a frame. In GR its dilation of energy c for a less dense energy per volume of space. In SR its c volume of space traversed. This increases the kinetic portion of energy to c where it becomes all kinetic and no clock measurement for electron cycle or photon cycle between mirrors.

[Quantum Antigravity]

Is time just a mathematical artefact? 
 
In my opinion, time, in physics, is just a mathematical artifact,
because :
 

• it is experimentally un-detectable ;
  
• it cannot be neither continuous, nor discrete.

see:  Fqxi.org/data/essay-contest-files/Schlafly_fqxischlaflynomath_1.pdf
 
According to Einstein's GTR, time does not pass, nor flow ;
time in GTR is just the 4-th dimention of stationary space.
 
So, why do we have this experinece of time passing
along with its consequences, like aging?
   
Because the passage of time is intimately related to mind (consciousness) :
 
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[Yahya (OP)]

So, why do we have this experinece of time passing
along with its consequences, like aging?
   
Because the passage of time is intimately related to mind (consciousness) : [/size]
 

I (in my opinion ) totally agree with this point , time is just a feeling, I noticed that  a constant speed of something exists inside our minds ,  we interpret constant speed and distance elapsed as time, as I said before constant speed can just be compared with c , the thing we interpret as time is the distance traveled inside our minds, our minds can't measure distance inside them, they just interpret it as time, if I am not delusional , when I measure time in my mind I feel something moving with a constant speed and spending more something if it took much time and less something if took little time , this something is in fact distance but my mind interpret it as time, does anyone feel this when trying measuring time and comparing between long periods and short periods?

[Yahya (OP)]

think of a clock of constant speed V and it elapses distance of S , then time is just : T=S/V
this equation : v=ds/dt , we can substitute dt=dS/V, the full equation will be:

v=ds/dt=V(ds/dS) or v=C(ds/dS) because the speed of the clock (V) is constant everywhere . the capital S is the distance traveled by the clock, which can be equivalent to time in any equation on earth.

[Yahya (OP)]

notice : in the above equation , speed= length/length , which should not have unit , exactly! as I defined speed to be xc, v=xc , x is just a number , and c is also a number that is speed of light. speed does not have a unit it is related to c.