We have all grown up and, over our formative years, we have understood the measurement of time. However, time flies by so the saying goes so not to many young people or the older generation give much thought to it.
We understand that time is shown on sundials, on our watches, on our smart phones, on TV, on station clocks and we have day and night to prompt us whether we are in a before noon, or after noon, mode .
However, if we take all that we know about time and remove some of the understandings we may come to another conclusion
Let us make some very big assumption, as follows, on the basis that our universe did not develop as it did. Let us assume:-
a) The Earth does not rotate
b) The Moon does not exist
c) The Sun does not exist
d) The Planets do not exist
e) The Earths trajectory is in a straight line through space,
f) However, life has developed on earth notwithstanding these huge assumptions.
As life developed and humans started to look around, with radar for eyesight, there would be no day and night, there would be no shadow and therefore no sun dials. There would not be the opportunity to divide the 360 degree rotation of the earth into a convenient 24 sectors and give each sector a number between 1 and 24. There would not be a cycle around the sun to give a start and end to a cycle i.e. how long is a piece of string.
Life, being full of challenges, a man and woman would see that the man going from the next cave to another, over the hill and back, led to conflict in the cave, as the man had been out of sight and doing what men do whilst the woman was cooking. There was no watches, no clocks indeed no measurement of the space between events.
As the earth sped through space, in an African village a man climbed to the top of a tall palm tree and cut a palm nut from the tree. He dropped the nut and at the same moment his knife fell out of his hand. The nut and the knife fell to the ground watched by his woman. Later the woman remarked about the two items hitting the ground at exactly the same moment. They discussed this and decided to try an experiment, later, after they had slept.
When they awoke they collected stones of different sizes and hauled them to the top of the palm tree. The man then dropped two stones, of different sizes, at the same moment and both the man and the woman agreed the stones hit the ground at the same moment.
The man had many stones, maybe 200 at the top of the tree for the experiment. When the man in the next cave came out of his cave and started to walk to the stream, which was 200 paces from his cave entrance, as the man started to walk to the stream the man at the top of the Palm tree dropped a stone. The instant the falling stone hit the ground the man dropped a second stone and he continued to drop stones in a similar way until the other man had reached the stream.
The man at the top of the tree, then, climbed down and looked at all the stones on the ground and then looked at the neighbours cave entrance and then at the man at the stream. He realised he had made a measurement of some description. The Palm tree was 32 ft tall and the distance from the cave to the steam was 100 paces which he thought was about 300 ft.. He calculated that for each stone dropped the walking man had moved towards the stream a distance of 7ft.
After sleeping again he come to the conclusion that for every tree length travelled by a stone the walking man had covered a distance of 7 ft
Therefore 7 ft( horizontal ) per tree length (vertical) was a speed.
The next action was to make up a new name for this length which after the village elders agreed would be called a “second”. This fits in nicely with 32ft per second per second the acceleration due to gravity which was later calculated by Newton
Under the assumptions made the only constant that could be observed would be the effect of gravity. But this would be for plant Earth. Should another alien race be on a much larger planet and, under the same assumption, their xx ft per tree length speed would not be the same, as the effect of their gravity would be different. Accordingly, the acceleration due to gravity on the alien planet would give them a different “second”.
As other alien planets evolved their own developed “seconds” would be of specific length and therefore any measurement of time would vary according to the gravity forces local to the observer
All the above is trying to show that time, as we understand it, is simply a convenient of measuring the “space” between events and the events are relative to earth as the base point. Space in this context is a distance.