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Orders of magnitude (time)

An of time is (usually) a prefix or decimal order-of-magnitude quantity together with a base , like a or a million years. In some cases, the order of magnitude may be implied (usually 1), like a "" or "year". In other cases, the quantity name implies the base unit, like "". In most cases, the base unit is or years. Prefixes are not usually used with a base unit of years, so we say "a million years", not "a megayear". Clock time and time have duodecimal or sexagesimal orders of magnitude rather than decimal, i.e. a year is 12 months, and a minute is 60 seconds.

The smallest meaningful increment of time is the Planck time, the time light takes to traverse the Planck distance many decimal orders of magnitude smaller than a second. The largest realized amount of time, given known scientific data, is the age of the , about 13.8 billion years - the time since the as measured in the cosmic microwave background rest frame. Those amounts of time together span 60 decimal orders of magnitude. Metric prefixes are defined spanning 10−24 to 1024, 48 decimal orders of magnitude which may be used in conjunction with the metric base unit of second. Metric units of time larger than the second are most commonly seen only in a few scientific contexts such as observational astronomy and materials science although this depends on author; for everyday usage and most other scientific contexts the common units of minutes (60 s), (3600 s or 3.6 ks), days (86 400 s), weeks, months, and years (of which there are a of variations) are commonly used. Weeks, months and years are significantly variable units whose length crucially depends on the choice of calendar and is often not regular even with a calendar, e.g. leap years versus regular years in the . This makes them problematic for use against a linear and regular time scale such as that defined by the SI since it is not clear as to which version of these units we are to be using. Because of this, in the table below we will not use weeks and months and the year we will use is the Julian year of astronomy, or 365.25 days of 86 400 s exactly, also called an annum and denoted with the symbol a, whose definition is based on the average length of a year of the which had one every and always every 4 years against common years of 365 days each. This unit is used, following the convention of geological science, to form larger units of time by the application of SI prefixes to it at least up to giga-annum, or Ga, equal to 1 000 000 000 a (short scale: one billion years, long scale: one milliard years).

Contents

Less than one second One second and longer See also Footnotes External links

Less than one second

https://en.wikipedia.org/wiki/Orders_of_magnitude_(time) 1/7 03/08/2018 Orders of magnitude (time) - Wikipedia

Unit Multiple Symbol Definition Comparative examples & common units (s)

10−20 ys = 10−44 s: One Planck time t = Presumed to be the shortest P theoretically measurable time ≈ 5.39 × 10−44 s[1] is the briefest −44 10 1 Planck time tP interval (but not necessarily the shortest increment of time - see physically meaningful span of time. It is the unit quantum gravity) of time in the natural units system known as . 156 ys: mean lifetime for the decay of a Higgs Yoctosecond, (yocto- + second), −24 1 yoctosecond [2] Boson, the quantum of energy in the field which 10 ys is one septillionth of a second gives elementary particles their masses 2 zs: representative cycle time of gamma ray Zeptosecond, (zepto- + second), radiation released in the decay of a radioactive 10−21 1 zeptosecond zs is one sextillionth of one second atomic nucleus (here as 2 MeV per emitted ) 12 attoseconds: best timing control of laser 10−18 1 attosecond as One quintillionth of one second pulses.[3] 1 fs: Cycle time for 300 nanometre light; ultraviolet light; light travels 0.3 micrometres −15 (µm). 10 1 fs One quadrillionth of one second 140 fs: have localized onto individual bromine atoms 6Å apart after laser dissociation [4] of Br2. 1 ps: mean lifetime of a bottom quark; light travels 0.3 millimeters (mm) 10−12 1 ps One of one second 1 ps: lifetime of a transition state 4 ps: Time to execute one machine cycle by an IBM Silicon-Germanium transistor 1 ns: Time to execute one machine cycle by a 10−9 1 ns One of one second 1 GHz microprocessor 1 ns: Light travels 30 centimetres (12 in) 1 µs: Time to execute one machine cycle by an Intel 80186 microprocessor 10−6 1 microsecond µs One of one second 4–16 µs: Time to execute one machine cycle by a 1960s minicomputer 1 ms: time for a neuron in human brain to fire one impulse and return to rest[5] 10−3 1 ms One thousandth of one second 4–8 ms: typical seek time for a computer hard disk 18–300 ms (=0.02–0.3 s): Human reflex response to visual stimuli 1 16.667 ms period of a frame at a frame rate of −2 10 centisecond cs One of one second 60 Hz. 20 ms: cycle time for European 50 Hz AC electricity

1 −1 [6] 10 decisecond ds One tenth of a second 100–400 ms (=0.1–0.4 s): Blink of an eye

One second and longer

In this table, large intervals of time surpassing one second are catalogued in order of the SI multiples of the second as well as their equivalent in common time units of minutes, hours, days, and Julian years.

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Unit Multiple Symbol Common units Comparative examples & common units (s) 1 60 s: one minute (min), the time it takes a second hand to cycle 101 das single seconds decasecond around a clock face 260 s (4 min 20 s): average length of the most popular YouTube videos as of January 2017[7] minutes 1 555 s (9 min 12 s): longest videos in above study 102 hs (1 hs is 1 min 40 s) hectosecond 710 s: time for a human walking at average speed of 1.4 m/s to walk 1 kilometre

1 ks: record confinement time for , specifically antihydrogen, in electrically neutral state as of 2011[8] 3.6 ks: one (h), time for the minute hand of a clock to cycle once around the face, approximately 1/24 of one mean solar 7.2 ks (2 h): typical length of feature films 86.399 ks (23 h 59 min 59 s): one day with a removed on UTC time scale. Such has not yet occurred. 86.4 ks (24 h): one day of by standard. More exactly, the mean solar day is 86.400 002 ks due to tidal braking, and increasing at the rate of approximately 2 ms/century; to correct for this time standards like UTC use leap seconds with the interval described as "a day" on them being most often 86.4 ks exactly by definition but occasionally minutes, hours, days one second more or less so that every day contains a whole number 3 10 1 kilosecond ks (1 ks is 16 min 40 s) of seconds while preserving alignment with astronomical time. The hour hand of an analogue clock will typically cycle twice around the dial in this period as most analogue clocks are 12 hour, less common are analogue 24-hour clocks in which it cycles around once. 86.401 ks (24 h 0 min 1 s): one day with an added leap second on UTC time scale. Note that while this is strictly 24 hours and 1 second in conventional units, a digital clock of suitable capability level will most often display the leap second as 23:59:60 and not 24:00:00 before rolling over to 00:00:00 the next day, as though the last "minute" of the day were crammed with 61 seconds and not 60, and similarly the last "hour" 3601 s instead of 3600. 88.775 ks (24 h 39 min 35 s): one sol of Mars 604.8 ks (7 d): one week of the Gregorian calendar

1.641 6 Ms (19 d): length of a "month" of the Baha'i calendar 2.36 Ms (27.32 d): length of the true month, the orbital period of the 2.419 2 Ms (28 d): length of February, the shortest month of the Gregorian calendar 2.592 Ms (30 d): 30 days, a common interval used in legal weeks to years agreements and contracts as a proxy for a month 1 (1 Ms is 11 d 13 h 46 min 2.678 4 Ms (31 d): - length of the longest months of the Gregorian 6 Ms 10 megasecond 40 s) calendar 23 Ms (270 d): approximate length of typical human gestational period 31.557 6 Ms (365.25 d): length of the Julian year, also called the annum, symbol a. 31.558 15 Ms (365 d 6 h 9 min 10 s): length of the true year, the orbital period of the Earth

https://en.wikipedia.org/wiki/Orders_of_magnitude_(time) 3/7 03/08/2018 Orders of magnitude (time) - Wikipedia

Unit Multiple Symbol Common units Comparative examples & common units (s) 1.5 Gs: approximate time as of the beginning of year 2018, that is, the number of seconds since 1970-01-01T00:00:00Z ignoring leap seconds. 2.5 Gs (79 a): typical human life expectancy in the developed world , , millennia 3.16 Gs (100 a): one century 1 109 Gs (1 Gs is over 31 years and 31.6 Gs (1000 a, 1 ka): one , also called a kilo-annum (ka) gigasecond 287 days) 63.7 Gs: approximate time since the beginning of the era as of 2018 - 2,018 years, and traditionally the time since the birth of Jesus Christ 363 Gs (11.5 ka): time since the beginning of the

3.1 Ts (100 ka): approximate length of a glacial period of the current Quaternary glaciation epoch 31.6 Ts (1000 ka, 1 Ma): one mega-annum (Ma), or one million years millennia to geological 79 Ts (2.5 Ma): approximate time since earliest hominids of genus 1 epochs 1012 Ts Australopithecus terasecond (1 Ts is over 31,600 years) 130 Ts (4 Ma): the typical lifetime of a biological species on Earth 137 Ts (4.32 Ma): the length of the mythic unit of mahayuga, the Great Age, in Hindu mythology.

2 Ps: approximate time since the -Paleogene extinction event, believed to be caused by the impact of a large asteroid into Chicxulub in modern-day Mexico. This extinction was one of the largest in Earth's history and marked the demise of most dinosaurs, with the only known exception being the ancestors of today's birds. 7.9 Ps (250 Ma): approximate time since the Permian-Triassic extinction event, the actually largest known mass extinction in Earth history which wiped out 95% of all extant species and believed to have been caused by the consequences of massive long-term volcanic eruptions in the area of the Siberian Traps. Also, the approximate time to the supercontinent of Pangaea. Also, the length of one galactic year or cosmic year, the time required for the Sun to complete one orbit around the Milky Way Galaxy. 16 Ps (510 Ma): approximate time since the explosion, a massive evolutionary diversification of life which led to the appearance of most existing multicellular organisms and the replacement of the previous Ediacaran biota. 22 Ps (704 Ma): approximate half-life of the uranium isotope 235U. 31.6 Ps (1000 Ma, 1 Ga): one giga-annum (Ga), one billion years, the 1 geological eras, history of 15 Ps 10 petasecond Earth and the Universe largest fixed time unit used in the standard geological time scale, approximately the order of magnitude of an eon, the largest division of geological time. +1 Ga: The estimated remaining habitable lifetime of Earth, according to some models. At this point in time the stellar evolution of the Sun will have increased its luminosity to the point that enough energy will be reaching the Earth to cause the evaporation of the oceans and their loss into space (due to the uv flux from the Sun at the top of the atmosphere dissociating the molecules), making it impossible for any life to continue. 136 Ps (4.32 Ga): The length of the legendary unit kalpa in Hindu mythology, or one day (but not including the following night) of the life of Brahma. 143 Ps (4.5 Ga): The age of the Earth by our best estimates. Also the approximate half-life of the uranium isotope 238U. 315 Ps (10 Ga): approximate lifetime of a main-sequence star similar to our Sun. 435 Ps (13.8 Ga): The approximate age of the Universe

https://en.wikipedia.org/wiki/Orders_of_magnitude_(time) 4/7 03/08/2018 Orders of magnitude (time) - Wikipedia

Unit Multiple Symbol Common units Comparative examples & common units (s) All of this length and beyond are currently theoretical as they surpass the elapsed lifetime of the known universe. 1.08 Es (+34 Ga): time to the Big Rip according to some models, but this is not favored by existing data. This is one possible scenario for the ultimate fate of the Universe. Under this scenario, dark energy 1018 1 exasecond Es future cosmological time increases in strength and power in a feedback loop that eventually results in the tearing apart of all matter down to subatomic scale due to the rapidly increasing negative pressure thereupon 300 - 600 Es (10 000 - 20 000 Ga): The estimate lifetime of low-mass stars (red dwarfs)

3 Zs (+100 000 Ga): The remaining time until the end of Stelliferous Era of the universe under the heat death scenario for the ultimate fate of the Universe which is the most commonly-accepted model in the current scientific community. This is marked by the cooling-off of the 1 last low-mass dwarf star to a black dwarf. After this time has elapsed, 1021 Zs zettasecond the Degenerate Era begins. 9.85 Zs (311 000 Ga): The entire lifetime of Brahma in Hindu mythology.

600 Ys (9 × 1018 a): The radioactive half-life of bismuth-209 by alpha decay, one of the slowest-observed radioactive decay processes. 1.310 019 × 1012 Ys (4.134 105 × 1028 years) – The time period equivalent to the value of 13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.0.0.0.0 in the Mesoamerican Long Count, a date discovered on a stela at the Coba Maya site, believed by archaeologist Linda Schele to be the absolute value for the length of one cycle of the universe[9][10] 2.6 × 1017 Ys (8.2 × 1033 years) – the smallest possible value for proton half-life consistent with experiment[11]

1029 Ys (3.2×1045 years) – the largest possible value for the proton half-life, assuming that the Big Bang was inflationary and that the same process that made baryons predominate over antibaryons in the early Universe also makes protons decay[12] 6 × 1053 Ys (2×1066 years) – approximate lifespan of a black hole with the mass of the Sun[13] 5.4×1093 Ys (1.7×10106 years) – approximate lifespan of a 1024 1 supermassive black hole with a mass of 20 trillion solar masses[13] and yottasecond Ys and on onward and beyond Ys ( years) – Scale of an estimated Poincaré recurrence time for the quantum state of a hypothetical box containing an isolated black hole of stellar mass[14] This time assumes a statistical model subject to Poincaré recurrence. A much simplified way of thinking about this time is that in a model in which history repeats itself arbitrarily many times due to properties of statistical mechanics, this is the time scale when it will first be somewhat similar (for a reasonable choice of "similar") to its current state again. Ys ( years) – Scale of an estimated Poincaré recurrence time for the quantum state of a hypothetical box containing a black hole with the mass of the .[14]

Ys ( years) – Scale of an estimated Poincaré recurrence time for the quantum state of a hypothetical box containing a black hole with the estimated mass of the entire Universe, observable or not, assuming Linde's chaotic inflationary model with an inflaton whose mass is 10−6 Planck masses.[14]

https://en.wikipedia.org/wiki/Orders_of_magnitude_(time) 5/7 03/08/2018 Orders of magnitude (time) - Wikipedia See also

Orders of magnitude (frequency) Annum Geologic timescale Logarithmic Planck units Second SI unit Temporal resolution

Footnotes

Notes

References

1. "CODATA Value: Planck time" (http://physics.nist.gov/cgi-bin/cuu/Value?plkt). The NIST Reference on Constants, Units, and Uncertainty. NIST. Retrieved October 1, 2011. 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. "12 attoseconds is the world record for shortest controllable time" (http://www.physorg.com/news192909576.html). 4. Li, Wen; et al. (November 23, 2010). "Visualizing rearrangement in space and timeduring the transition from a molecule to atoms" (http://www.pnas.org/content/107/47/20219.abstract). PNAS. 107 (47): 20219–20222. Bibcode:2010PNAS..10720219L (http://ad sabs.harvard.edu/abs/2010PNAS..10720219L). doi:10.1073/pnas.1014723107 (https://doi.org/10.1073/pnas.1014723107). PMC 2996685 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2996685) . PMID 21059945 (https://www.ncbi.nlm.nih.gov/pubmed/2105 9945). Retrieved 12 July 2015. 5. http://www.noteaccess.com/APPROACHES/ArtEd/ChildDev/1cNeurons.htm 6. Eric H. Chudler. "Brain Facts and Figures: Sensory Apparatus: Vision" (http://faculty.washington.edu/chudler/facts.html). Retrieved October 10, 2011. 7. https://www.minimatters.com/youtube-best-video-length/ 8. "Confinement of antihydrogen for 1,000 seconds" (https://www.webcitation.org/5zFRxLTE5?url=http://www.nature.com/nphys/journal/vao p/ncurrent/full/nphys2025.html). Nature Physics. 7: 558–564. 5 June 2011. arXiv:1104.4982 (https://arxiv.org/abs/1104.4982) . Bibcode:2011NatPh...7..558A (http://adsabs.harvard.edu/abs/2011NatPh...7..558A). doi:10.1038/nphys2025 (https://doi.org/10.1038/nph ys2025). Archived from the original (http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys2025.html) on 6 June 2011. Retrieved 12 May 2012. 9. Falk, Dan (2013). In search of time the science of a curious dimension. New York: St. Martin's Press. ISBN 1429987863. 10. G. Jeffrey MacDonald "Does predict 2012 apocalypse?" (https://www.usatoday.com/tech/science/2007-03-27-maya-2012 _n.htm) USA Today 3/27/2007. + + 0 + + 0 11. Nishino, H. et al. (Super-K Collaboration) (2009). "Search for Proton Decay via p → e π and p → μ π in a Large Water Cherenkov Detector". Physical Review Letters. 102 (14): 141801. arXiv:0903.0676 (https://arxiv.org/abs/0903.0676) . Bibcode:2009PhRvL.102n1801N (http://adsabs.harvard.edu/abs/2009PhRvL.102n1801N). doi:10.1103/PhysRevLett.102.141801 (http s://doi.org/10.1103/PhysRevLett.102.141801). PMID 19392425 (https://www.ncbi.nlm.nih.gov/pubmed/19392425). 12. A Dying Universe: the Long-term Fate and Evolution of Astrophysical Objects, Adams, Fred C. and Laughlin, Gregory, Reviews of Modern Physics 69, #2 (April 1997), pp. 337–372. Bibcode: 1997RvMP...69..337A (http://adsabs.harvard.edu/abs/1997RvMP...69..337A). doi:10.1103/RevModPhys.69.337 (https://doi.org/10.1103/RevModPhys.69.337). 13. Particle emission rates from a black hole: Massless particles from an uncharged, nonrotating hole, Don N. Page, Physical Review D 13 (1976), pp. 198–206. doi:10.1103/PhysRevD.13.198 (https://doi.org/10.1103/PhysRevD.13.198). See in particular equation (27). 14. Page, Don N. (1995). "Information Loss in Black Holes and/or Conscious Beings?". In Fulling, S.A. Heat Kernel Techniques and Quantum Gravity. Discourses in Mathematics and its Applications. Texas A&M University. p. 461. arXiv:hep-th/9411193 (https://arxiv.org/ abs/hep-th/9411193) . Bibcode:1994hep.th...11193P (http://adsabs.harvard.edu/abs/1994hep.th...11193P). ISBN 978-0-9630728-3-2.

External links

Exploring Time (http://exploringtime.org/?page=segments) from Planck time to the lifespan of the universe

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