mjerne vremenske jedinice

[Adolf]

Neznam je li ovo dobro mjesto za postavljanje teme, ali neka mi netko kaže tko je izumio vrijeme kako znamo, mislim sekunda, sat? tko je prvi izmjerio sekundu? zašto je sekunda sekunda?

nigdje ove informacije ne mogu pronaći, majke mi

[Rain]

Sexagesimal (base-sixty) is a numeral system with sixty as the base. It originated with the ancient Sumerians in the 2000s BC, was transmitted to the Babylonians, and is still used in modified form nowadays for measuring time, angles, and geographic coordinates.

The division of the circle into 360 parts also occurred in ancient India, as evidenced in the Rig Veda:

Twelve spokes, one wheel, navels three.
Who can comprehend this?
On it are placed together
three hundred and sixty like pegs.
They shake not in the least.
(Dirghatama, Rig Veda 1.164.48)

The number 360 as the number of 'degrees' (i.e. smallest practical sub-arcs) in a circle, and hence the unit of a degree as a sub-arc of 1⁄360 of the circle, was probably adopted because it approximates the number of days in a year. Its use is often said to originate from the methods of the ancient Babylonians.[2] Ancient astronomers noticed that the stars in the sky, which circle the celestial pole every day, seem to advance in that circle by approximately one-360th of a circle, i.e. one degree, each day. (Primitive calendars, such as the Persian Calendar, used 360 days for a year.) Its application to measuring angles in geometry can possibly be traced to Thales who popularized geometry among the Greeks and lived in Anatolia (modern western Turkey) among people who had dealings with Egypt and Babylon.

The earliest trigonometry, used by the Babylonian astronomers and their Greek successors, was based on chords of a circle. A chord of length equal to the radius made a natural base quantity. One sixtieth of this, using their standard sexagesimal divisions, was a degree; while six such chords completed the full circle.

[blue bird]

The Egyptians had divided daytime and nighttime into twelve hours each since at least 2000 BC; their hours varied in length seasonally.

However, the use of sexagesimal systems became more common later. The Hellenistic astronomers Hipparchus (c. 150 BC) and Ptolemy (c. AD 150) subdivided the day sexagesimally and also used a mean hour (1⁄24 day), but did not use distinct smaller units of time, instead using fractions of an hour. The day was subdivided sexagesimally to at least six places after the sexagesimal point by the Babylonians after 300 BC, but they did not use sexagesimal smaller units of time. They used a double-hour, a time-degree lasting four of our minutes, and a barleycorn lasting 3⅓ of our seconds (the helek of the modern Hebrew calendar).[3]

In 1267 the medieval scientist Roger Bacon stated the times of full moons as a number of hours, minutes, seconds, thirds, and fourths (horae, minuta, secunda, tertia, and quarta) after noon on specified calendar dates.[4] Although a third for 1⁄60 of a second remains in some languages, for example Polish (tercja) and Arabic (ثالثة), the modern second is further divided decimally.

- sa Wikija