The second, the base unit of time in the International System of Units (SI), has roots dating back to ancient civilizations. Originally defined through astronomical events, the second was once 1/86,400 of a day, based on Earth’s rotation. However, the Earth’s rotation isn’t perfectly consistent due to gravitational interactions and geological activity, making this measurement imprecise for modern needs.
Today, the second is defined by atomic perfection: it is the duration of 9,192,631,770 periods of the radiation corresponding to a specific transition in the cesium-133 atom. This definition, adopted in 1967, takes advantage of atomic clocks, which can measure time with incredible accuracy, losing only about a second every hundreds of millions of years. Such precision is essential for technologies like GPS, telecommunications, and the synchronization of global networks.
The concept of an hour as a unit of time has its roots in ancient Egypt, around 1500 BCE, when sundials were used to divide daylight into 12 equal parts. This uneven division, which varied with the seasons, was later standardized by the Greeks and Romans. The 24-hour division we use today first appeared in the late 13th century, influenced by the development of mechanical clocks in medieval Europe.
Interestingly, despite its seemingly mundane nature, the hour is deeply intertwined with human culture and religion. For example, in Christianity, the canonical hours mark specific times of prayer throughout the day, a practice dating back to the early Middle Ages. Even today, the hour impacts how society organizes work, entertainment, and rest, shaping our daily lives in profound ways.
Seconds | Hours |
---|---|
0
s
|
0
h
|
50
s
|
0.0138889
h
|
100
s
|
0.0277778
h
|
150
s
|
0.0416667
h
|
200
s
|
0.0555556
h
|
250
s
|
0.0694444
h
|
300
s
|
0.0833333
h
|
350
s
|
0.0972222
h
|
400
s
|
0.111111
h
|
450
s
|
0.125
h
|
500
s
|
0.138889
h
|
550
s
|
0.152778
h
|
600
s
|
0.166667
h
|
650
s
|
0.180556
h
|
700
s
|
0.194444
h
|
750
s
|
0.208333
h
|
800
s
|
0.222222
h
|
850
s
|
0.236111
h
|
900
s
|
0.25
h
|
950
s
|
0.263889
h
|
1000
s
|
0.277778
h
|
1050
s
|
0.291667
h
|
1100
s
|
0.305556
h
|
1150
s
|
0.319444
h
|
1200
s
|
0.333333
h
|
1250
s
|
0.347222
h
|
1300
s
|
0.361111
h
|
1350
s
|
0.375
h
|
1400
s
|
0.388889
h
|
1450
s
|
0.402778
h
|
1500
s
|
0.416667
h
|
1550
s
|
0.430556
h
|
1600
s
|
0.444444
h
|
1650
s
|
0.458333
h
|
1700
s
|
0.472222
h
|
1750
s
|
0.486111
h
|
1800
s
|
0.5
h
|
1850
s
|
0.513889
h
|
1900
s
|
0.527778
h
|
1950
s
|
0.541667
h
|
2000
s
|
0.555556
h
|
2050
s
|
0.569444
h
|
2100
s
|
0.583333
h
|
2150
s
|
0.597222
h
|
2200
s
|
0.611111
h
|
2250
s
|
0.625
h
|
2300
s
|
0.638889
h
|
2350
s
|
0.652778
h
|
2400
s
|
0.666667
h
|
2450
s
|
0.680556
h
|
2500
s
|
0.694444
h
|
2550
s
|
0.708333
h
|
2600
s
|
0.722222
h
|
2650
s
|
0.736111
h
|
2700
s
|
0.75
h
|
2750
s
|
0.763889
h
|
2800
s
|
0.777778
h
|
2850
s
|
0.791667
h
|
2900
s
|
0.805556
h
|
2950
s
|
0.819444
h
|
3000
s
|
0.833333
h
|
3050
s
|
0.847222
h
|
3100
s
|
0.861111
h
|
3150
s
|
0.875
h
|
3200
s
|
0.888889
h
|
3250
s
|
0.902778
h
|
3300
s
|
0.916667
h
|
3350
s
|
0.930556
h
|
3400
s
|
0.944444
h
|
3450
s
|
0.958333
h
|
3500
s
|
0.972222
h
|
3550
s
|
0.986111
h
|
3600
s
|
1
h
|
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