Time

Is Time the fourth dimension of space?

The measurement of time began with the invention of sundials in ancient Egypt some time prior to 1500 B.C. However, the time the Egyptians measured was not the same as the time today's clocks measure. For the Egyptians, and indeed for a further three millennia, the basic unit of time was the period of daylight.

Linear Time

The measurement of time began with the invention of sundials in ancient Egypt some time prior to 1500 B.C. However, the time the Egyptians measured was not the same as the time today's clocks measure. For the Egyptians, and indeed for a further three millennia, the basic unit of time was the period of daylight.

Hour

Daylight using a shadow clock such as in antient Egypt split it into 10 division's (hours) adding 1 hour each for twilight in the Morning and evening

As Egypt is near the equator one day and one night became 24 hours.

Minutes

60 is easy to count on your hands if you count on one hand the 3 knuckles on each finger you can count to 12 and then on the other hand each finger gives 5x12 = 60 for all five fingers

12x5 = 60

Second

In 1000, a Persian scholar named al-Biruni first termed the word second when he defined the period of time between two new moons as a figure of days, hours, minutes, seconds, thirds, and fourths. The minute was the first subdivision of the hour by 60, then the second, and so on.

The first timekeepers that could count seconds accurately were pendulum clocks invented in the 17th century. Starting in the 1950s, atomic clocks became better timekeepers than earth's rotation, and they continue to set the standard today.

Currently, one second is defined as “9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom”. ... It was called the ephemeris second, and was simply a fraction of a year, as defined by Newcomb's tables.

arrow of time: the fact that the past is different from the future.

Time Dilation

In physics and relativity, time dilation is the difference in the elapsed time as measured by two clocks. It is either due to a relative velocity between them (special relativistic "kinetic" time dilation) or to a difference in gravitational potential between their locations (general relativistic gravitational time dilation).

Time dilatation and gravity