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Factor (s) | Multiple | Symbol | Definition | Comparative examples & common units | Orders of magnitude |
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10−44 | 5.4×10-20 ys = 5.4×10-44 s: One Planck time tP = ≈ 5.4×10-44 s,[1] the time required for light to travel one Planck length, is the briefest physically meaningful span of time. It is the unit of time in the natural units system known as Planck units. | 10−20 ys, 10−19 ys (10−44 s, 10−43 s) | |||
10−24 | 1 yoctosecond | ys[2] | Yoctosecond, (yocto- + second), is one septillionth (short scale) of a second. | 0.3 ys: mean life of the W and Z bosons.[3][4][a] 0.5 ys: time for top quark decay, according to the Standard Model. 1 ys: time taken for a quark to emit a gluon. 23 ys: half-life of 7H. |
1 ys and less, 10 ys, 100 ys |
10−21 | 1 zeptosecond | zs | Zeptosecond, (zepto- + second), is one sextillionth (short scale)of one second. | 7 zs: half-life of helium-9's outer neutron in the second nuclear halo. 17 zs: approximate period of electromagnetic radiation at the boundary between gamma rays and X-rays. 300 zs: approximate typical cycle time of X-rays, on the boundary between hard and soft X-rays. 500 zs: current resolution of tools used to measure speed of chemical bonding[5] |
1 zs, 10 zs, 100 zs |
10−18 | 1 attosecond | as | One quintillionth of one second | 12 attoseconds: shortest measured period of time.[6] | 1 as, 10 as, 100 as |
10−15 | 1 femtosecond | fs | One quadrillionth of one second | cycle time for 390 nanometre light, transition from visible light to ultraviolet | 1 fs, 10 fs, 100 fs |
10−12 | 1 picosecond | ps | One trillionth of one second | 1 ps: half-life of a bottom quark 4 ps: Time to execute one machine cycle by an IBM Silicon-Germanium transistor |
1 ps, 10 ps, 100 ps |
10−9 | 1 nanosecond | ns | One billionth of one second | 1 ns: Time to execute one machine cycle by a 1 GHz microprocessor 1 ns: Light travels 12 inches (30 cm) |
1 ns, 10 ns, 100 ns |
10−6 | 1 microsecond | µs | One millionth of one second | sometimes also abbreviated µsec 1 µs: Time to execute one machine cycle by an Intel 80186 microprocessor 4–16 µs: Time to execute one machine cycle by a 1960s minicomputer |
1 µs, 10 µs, 100 µs |
10−3 | 1 millisecond | ms | One thousandth of one second | 4–8 ms: typical seek time for a computer hard disk 100–400 ms: Blink of an eye[7] 150–300 ms: Human reflex response to visual stimuli |
1 ms, 10 ms, 100 ms |
100 | 1 second | s | 1 s: 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.[8]
60 s: 1 minute |
1 s, 10 s, 100 s | |
103 | 1 kilosecond (16.7 minutes) |
ks | 3.6 ks: 3600 s or 1 hour 86.4 ks: 86 400 s or 1 day 604.8 ks: 1 week |
103 s, 104 s, 105 s | |
106 | 1 megasecond (11.6 days) |
Ms |
2.6 Ms: approximately 1 month |
106 s, 107 s, 108 s | |
109 | 1 gigasecond (32 years) |
Gs |
2.1 Gs: average human life expectancy at birth (2011 estimate)[9] |
109 s, 1010 s, 1011 s | |
1012 | 1 terasecond (32 000 years) |
Ts |
6 Ts: time since the appearance of Homo Sapiens (approximately) |
1012 s, 1013 s, 1014 s | |
1015 | 1 petasecond (32 million years) |
Ps | 7.1–7.9 Ps: 1 galactic year (225-250 million years)[10] 143 Ps: the age of the Earth[11][12][13] |
1015 s, 1016 s, 1017 s | |
1018 | 1 exasecond (32 billion years) |
Es | 312 Es: Estimated lifespan of a 0.1 solar mass red dwarf star. | 1018 s, 1019 s, 1020 s | |
1021 | 1 zettasecond (32 trillion years) |
Zs | 3 Zs: Estimated duration of Stelliferous Era. | 1021 s, 1022 s, 1023 s | |
1024 | 1 yottasecond (32 quadrillion years) |
Ys | 6.616×1050 Ys: Time required for a 1 solar mass black hole to evaporate completely due to Hawking radiation, if nothing more falls in. | 1024 s, 1025 s, 1026 s and more |
Factor (a) | Multiple | common units | orders of magnitude |
---|---|---|---|
10−50 | Planck time, the shortest physically meaningful interval of time ≈ 1.71×10−50 a | 10−50 a | |
10−24 | 1 yoctoannum | -- | 1 ya and less, 10 ya, 100 ya |
10−21 | 1 zeptoannum | -- | 1 za, 10 za, 100 za |
10−18 | 1 attoannum | -- | 1 aa, 10 aa, 100 aa |
10−15 | 1 femtoannum | -- | 1 fa, 10 fa, 100 fa |
10−12 | 1 picoannum | -- | 1 pa, 10 pa, 100 pa |
10−9 | 1 nanoannum | 1 second = 3.17 × 10−8 a ≈ 10-7.50 a | 1 na, 10 na, 100 na |
10−6 | 1 microannum | 1 minute = 1.90 × 10−6 a 1 hour = 1.40 × 10−4 a |
1 ua, 10 ua, 100 ua |
10−3 | 1 milliannum | 1 day = 2.73 × 10−3 a 1 week = 1.91 × 10−2 a |
1 ma, 10 ma, 100 ma |
100 | 1 annum | 1 average year = 1 annum (= 365.24219 SI days) decade = 10 anna century = 100 anna |
1 a, 10 a, 100 a |
103 | 1 kiloannum | millennium = 1000 anna | 103 a, 104 a, 105 a |
106 | 1 megaannum | epoch = 1,000,000 anna | 106 a, 107 a, 108 a |
109 | 1 gigaannum | aeon = 1,000,000,000 anna 13.7 Ga = 1.37×1010 a ≈ 13.7 billion years, the approximate age of the Universe |
109 a, 1010 a, 1011 a |
1012 | 1 teraannum | --- | 1012 a, 1013 a, 1014 a |
1015 | 1 petaannum | --- | 1015 a, 1016 a, 1017 a |
1018 | 1 exaannum | -- | 1018 a, 1019 a, 1020 a |
1021 | 1 zettaannum | -- | 1021 a, 1022 a, 1023 a |
1024 | 1 yottaannum | -- | 1024 a, 1025 a, 1026 and more |
The pages linked in the right-hand column contain lists of times that are of the same order of magnitude (power of ten). Rows in the table represent increasing powers of a thousand (3 orders of magnitude).
Conversion from year to second is year × 31 557 600 using the Julian year. Conversion from to is approximately . Example conversion; .
[a] ^ PDG reports the resonance width (Γ). Here the conversion τ = ħ⁄Γ is given instead.
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