Orders of Magnitude (Time) - Wikipedia
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03/08/2018 Orders of magnitude (time) - Wikipedia Orders of magnitude (time) An order of magnitude of time is (usually) a decimal prefix or decimal order-of-magnitude quantity together with a base unit of time, like a microsecond or a million years. In some cases, the order of magnitude may be implied (usually 1), like a "second" or "year". In other cases, the quantity name implies the base unit, like "century". In most cases, the base unit is seconds 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 calendar 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 universe, about 13.8 billion years - the time since the Big Bang 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), hours (3600 s or 3.6 ks), days (86 400 s), weeks, months, and years (of which there are a number 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 Gregorian calendar. 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 Julian calendar which had one leap year 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 −44 [1] theoretically measurable time ≈ 5.39 × 10 s 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 Planck units. 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 photon) 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 femtosecond fs One quadrillionth of one second 140 fs: Electrons 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 picosecond ps One trillionth 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 nanosecond ns One billionth 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 millionth 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 millisecond 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 hundredth 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. https://en.wikipedia.org/wiki/Orders_of_magnitude_(time) 2/7 03/08/2018 Orders of magnitude (time) - Wikipedia 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 antimatter, specifically antihydrogen, in electrically neutral state as of 2011[8] 3.6 ks: one hour (h), time for the minute hand of a clock to cycle once around the face, approximately 1/24 of one mean solar day 7.2 ks (2 h): typical length of feature films 86.399 ks (23 h 59 min 59 s): one day with a removed leap second on UTC time scale. Such has not yet occurred. 86.4 ks (24 h): one day of Earth 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 Moon 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 UNIX time as of the beginning of year 2018, that is, the number of seconds since 1970-01-01T00:00:00Z ignoring leap seconds.