# Orders of magnitude (time)

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Orders of magnitude (time)

## Seconds

Orders of magnitude (Time)
Factor (s) Multiple Symbol Definition Comparative examples & common units Orders of magnitude
10−44 5.4×10-20 ys = 5.4×10-44 s: One Planck time tP = $\sqrt{\hbar G/c^5}$ ≈ 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
31.6 Ms: approximately 1 year ≈ 107.50 s

106 s, 107 s, 108 s
109 1 gigasecond
(32 years)
Gs

2.1 Gs: average human life expectancy at birth (2011 estimate)[9]
3.16 Gs: approximately 1 century
31.6 Gs: approximately 1 millennium

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]
144 Ps: the approximate age of the Solar system[14] and the Sun.[15]
430 Ps: the approximate age of the Universe

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.

9.8 Zs:the lifetime of Brahma in Hindu mythology

1021 s, 1022 s, 1023 s
1024 1 yottasecond
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

## Years

Orders of magnitude (time)
Factor (a) Multiple common units orders of magnitude
10−50 Planck time, the shortest physically meaningful interval of time ≈ 1.71×10−50 a 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)
century = 100 anna
1 a, 10 a, 100 a
103 1 kiloannum millennium = 1000 anna 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 log 10 year to log 10 second is approximately log 10 year + 7.50. Example conversion; 1 year = 100 year = 100 + 7.50 seconds = 100.50 + 7s = 3.16 * 107s.

 Annum Geologic timescale Human timescales Logarithmic timeline Natural history Physical unit

## Footnotes

1. ^ "CODATA Value: Planck time". The NIST Reference on Constants, Units, and Uncertainty. NIST. Retrieved 2011-10-01.
2. ^ The American Heritage Dictionary of the English Language: Fourth Edition. 2000. Available at: http://www.bartleby.com/61/21/Y0022100.html. Accessed December 19, 2007. note: abbr. ys or ysec
3. ^ C. Amsler et al. (2009): Particle listings – W boson
4. ^ C. Amsler et al. (2009): Particle listings – Z boson
5. ^ esciencenews (2010)
6. ^
7. ^ Eric H. Chudler. "Brain Facts and Figures: Sensory Apparatus: Vision". Retrieved 2011-10-10.
8. ^ http://tycho.usno.navy.mil/leapsec.html
9. ^ CIA - The World Factbook -- Rank Order - Life expectancy at birth
10. ^ Leong, Stacy (2002). "Period of the Sun's Orbit around the Galaxy (Cosmic Year)". The Physics Factbook.
11. ^ "Age of the Earth". U.S. Geological Survey. 1997. Retrieved 2006-01-10.
12. ^ Dalrymple, G. Brent (2001). "The age of the Earth in the twentieth century: a problem (mostly) solved". Special Publications, Geological Society of London 190 (1): 205–221. doi:10.1144/GSL.SP.2001.190.01.14.
13. ^ Manhesa, Gérard; Allègrea, Claude J.; Dupréa, Bernard; and Hamelin, Bruno (1980). "Lead isotope study of basic-ultrabasic layered complexes: Speculations about the age of the earth and primitive mantle characteristics". Earth and Planetary Science Letters, Elsevier B.V. 47 (3): 370–382. doi:10.1016/0012-821X(80)90024-2.
14. ^ Bouvier, Audrey and Meenakshi Wadhwa, “The age of the solar system redefined by the oldest Pb-Pb age of a meteoritic inclusion”. Nature Geoscience, Nature Publishing Group, a division of Macmillan Publishers Limited. Published online 2010-08-22, retrieved 2010-08-26, doi: 10.1038/NGEO941.
15. ^ Bonanno, A.; Schlattl, H.; Paternò, L. (2008). "The age of the Sun and the relativistic corrections in the EOS". Astronomy and Astrophysics 390 (3): 1115–1118. arXiv:astro-ph/0204331. Bibcode 2002A&A...390.1115B. doi:10.1051/0004-6361:20020749.

[a] ^ PDG reports the resonance width (Γ). Here the conversion τ = ħΓ is given instead.