So, if we didn't have clocks there would be no time? What if there was nothing used to measure time, would there be no time, and what would be its referent then? — Sam26
Basically, yes! It is us who have constructed clocks, and the periodic processes accompanying them, like pendulums and metronomes, atomic vibrations, or orbital motions of celestial objects (showing not the amount of time passed but only the periodic motion we measure it by). Time as a periodic motion, put in relation to process that are going on in the world is not a property that existed before we mentally and practically constructed it. You can make a clock tick aside a physical process, reversible or irreversible, and say that the periodic motion has occured 536.78 times, but this will be the case only after the introduction of the clock. The clock has to be a reversible process, which is why it's so difficult to make one, as almost, if not all, processes are irreversible (which means it isn't possible to simply reverse all motion, which can only be done for the perfect, ideal clock).
So, quantified time is a human invention. You can mentally place a clock near all events, like is done in relativity or Newtonian mechanics. The processes you put the clocks next to take a number of periods. The number of periods is our invention, the processes are real. It turns out that some processes, when compared with reversible process of the clock, take more periods than others. If there would only be reversible processes there wouldn't be processes, there would be no irreversible processes next to which the clock could be positioned, and it are exactly these processes which can be meaningfully be quantized by time, as they evolve in one direction.
You can mentally reverse all motion in the universe, reverse time, but then the problem becomes that the end conditions become begin conditions, and the much bigger problem that you simply can't reverse momenta universally. You can do it mentally, or introduce a god, but reversing the process introduces initial conditions (the reversed end conditions) which are determined by the initial conditions when the process was still going in forward direction. Which means that you have to impose initial conditions which are reversed end conditions of the process you reverse. So the reversed end conditions become dependent on the initial conditions of the forward process, which is different from a forward process emerging from initial conditions only.
So while the quantified time, the number on the time axis, is a human construct, the processes it refers to are real, and
if you compare them with a clock, different events will read different times, and in relativity this proceeding of the clock, the quantity of time, will depend even on space and motion. The irreversible processes that are quantified contain amounts of time, and we also notice time without quantifying it. So time is not only the clock. It's not only the amount of periods, the number of seconds, clicks, or vibrations, that constitutes time. For time to have a meaningful existence, irreversible processes are needed. One can say that a reversible process has taken 10 seconds but then it's not clear if time ran forward or backward.
Something can take long, when it's boring, like what I write right now. People watch on their watch. Another 5 minutes... When having fun, the clock isn't looked on. Time over, when the end is there.
Something like that.
:cool: