Topic: Time
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π Timeline of the far future
While the future can never be predicted with absolute certainty, present understanding in various scientific fields allows for the prediction of some far-future events, if only in the broadest outline. These fields include astrophysics, which has revealed how planets and stars form, interact, and die; particle physics, which has revealed how matter behaves at the smallest scales; evolutionary biology, which predicts how life will evolve over time; and plate tectonics, which shows how continents shift over millennia.
All projections of the future of Earth, the Solar System, and the universe must account for the second law of thermodynamics, which states that entropy, or a loss of the energy available to do work, must rise over time. Stars will eventually exhaust their supply of hydrogen fuel and burn out. Close encounters between astronomical objects gravitationally fling planets from their star systems, and star systems from galaxies.
Physicists expect that matter itself will eventually come under the influence of radioactive decay, as even the most stable materials break apart into subatomic particles. Current data suggest that the universe has a flat geometry (or very close to flat), and thus will not collapse in on itself after a finite time, and the infinite future allows for the occurrence of a number of massively improbable events, such as the formation of Boltzmann brains.
The timelines displayed here cover events from the beginning of the 11th millennium to the furthest reaches of future time. A number of alternative future events are listed to account for questions still unresolved, such as whether humans will become extinct, whether protons decay, and whether the Earth survives when the Sun expands to become a red giant.
Discussed on
- "Timeline of the Far Future" | 2024-01-14 | 16 Upvotes 1 Comments
- "Timeline of the Far Future" | 2020-05-17 | 168 Upvotes 112 Comments
- "Timeline of the far future" | 2018-07-18 | 696 Upvotes 258 Comments
- "Timeline of the far future" | 2012-05-06 | 294 Upvotes 88 Comments
π Day of the Programmer
The Day of the Programmer is an international professional day that is celebrated on the 256th (hexadecimal 100th, or the 28th) day of each year (September 13 during common years and on September 12 in leap years). It is officially recognized in Russia.
The number 256 (28) was chosen because it is the number of distinct values that can be represented with a byte, a value well known to programmers. 256 is also the highest power of two that is less than 365, the number of days in a common year.
Discussed on
- "Happy Programmers' Day to all devs in HN" | 2020-09-12 | 51 Upvotes 15 Comments
- "Day of the Programmer" | 2016-09-12 | 10 Upvotes 2 Comments
- "Happy Programmers' Day" | 2013-09-13 | 245 Upvotes 65 Comments
- "Programmer's Day - 13 September" | 2013-09-09 | 20 Upvotes 11 Comments
- "Programmers' Day" | 2011-09-13 | 417 Upvotes 84 Comments
- "Today is Programmer's Day" | 2010-09-13 | 240 Upvotes 38 Comments
π Year 2038 Problem
The Year 2038 problem (also called Y2038 or Y2k38 or Unix Y2K) relates to representing time in many digital systems as the number of seconds passed since 00:00:00 UTC on 1 January 1970 and storing it as a signed 32-bit integer. Such implementations cannot encode times after 03:14:07 UTC on 19 January 2038. Similar to the Y2K problem, the Year 2038 problem is caused by insufficient capacity used to represent time.
Discussed on
- "Year 2038 problem of Unix time" | 2024-10-09 | 14 Upvotes 4 Comments
- "Year 2038 Problem" | 2022-11-27 | 27 Upvotes 3 Comments
- "Year 2038 Problem" | 2022-08-23 | 24 Upvotes 2 Comments
- "Year 2038 problem" | 2018-11-12 | 22 Upvotes 9 Comments
- "Year 2038 problem" | 2018-08-25 | 15 Upvotes 4 Comments
- "The Year 2038 Problem" | 2017-07-04 | 12 Upvotes 3 Comments
- "Year 2038 problem" | 2014-05-19 | 45 Upvotes 27 Comments
- "Year 2038 problem" | 2013-05-02 | 194 Upvotes 108 Comments
π Swatch Internet Time
Swatch Internet Time (or .beat time) is a decimal time concept introduced in 1998 by the Swatch corporation as part of their marketing campaign for their line of "Beat" watches.
Instead of hours and minutes, the mean solar day is divided into 1000 parts called ".beats". Each .beat is equal to one decimal minute in the French Revolutionary decimal time system and lasts 1 minute and 26.4 seconds (86.4 seconds) in standard time. Times are notated as a 3-digit number out of 1000 after midnight. So, for example @248 would indicate a time 248 .beats after midnight representing β248β1000 of a day, just over 5 hours and 57 minutes.
There are no time zones in Swatch Internet Time; instead, the new time scale of Biel Meantime (BMT) is used, based on Swatch's headquarters in Biel, Switzerland and equivalent to Central European Time, West Africa Time, and UTC+01. Unlike civil time in Switzerland and many other countries, Swatch Internet Time does not observe daylight saving time.
Discussed on
- "Swatch Internet Time" | 2024-04-14 | 61 Upvotes 39 Comments
- "Swatch Internet Time (1998)" | 2018-02-05 | 86 Upvotes 78 Comments
- "Swatch Internet Time" | 2014-01-12 | 103 Upvotes 96 Comments
- "Ask HN: Why did this idea of Internet Time not work?" | 2009-03-17 | 7 Upvotes 28 Comments
π Kairos
Kairos (Ancient Greek: ΞΊΞ±ΞΉΟΟΟ) is an Ancient Greek word meaning the right, critical, or opportune moment. The ancient Greeks had two words for time: chronos (ΟΟΟΞ½ΞΏΟ) and kairos. The former refers to chronological or sequential time, while the latter signifies a proper or opportune time for action. While chronos is quantitative, kairos has a qualitative, permanent nature. Kairos also means weather in Modern Greek. The plural, ΞΊΞ±ΞΉΟΞΏΞ― (kairoi (Ancient and Modern Greek)) means the times. Kairos is a term, idea, and practice that has been applied in several fields including classical rhetoric, modern rhetoric, digital media, Christian theology, and science.
Discussed on
- "Kairos" | 2021-10-10 | 235 Upvotes 69 Comments
π Digital sundial
A digital sundial is a clock that indicates the current time with numerals formed by the sunlight striking it. Like a classical sundial, the device contains no moving parts. It uses no electricity nor other manufactured sources of energy. The digital display changes as the sun advances in its daily course.
Discussed on
- "Digital sundial" | 2014-07-16 | 232 Upvotes 47 Comments
π ISO week date
The ISO week date system is effectively a leap week calendar system that is part of the ISO 8601 date and time standard issued by the International Organization for Standardization (ISO) since 1988 (last revised in 2004) and, before that, it was defined in ISO (R) 2015 since 1971. It is used (mainly) in government and business for fiscal years, as well as in timekeeping. This was previously known as "Industrial date coding". The system specifies a week year atop the Gregorian calendar by defining a notation for ordinal weeks of the year.
The Gregorian leap cycle, which has 97 leap days spread across 400 years, contains a whole number of weeks (20871). In every cycle there are 71 years with an additional 53rd week (corresponding to the Gregorian years that contain 53 Thursdays). An average year is exactly 52.1775 weeks long; months (β1β12 year) average at exactly 4.348125 weeks.
An ISO week-numbering year (also called ISO year informally) has 52 or 53 full weeks. That is 364 or 371 days instead of the usual 365 or 366 days. The extra week is sometimes referred to as a leap week, although ISO 8601 does not use this term.
Weeks start with Monday. Each week's year is the Gregorian year in which the Thursday falls. The first week of the year, hence, always contains 4 January. ISO week year numbering therefore slightly deviates from the Gregorian for some days close to 1 January.
A precise date is specified by the ISO week-numbering year in the format YYYY, a week number in the format ww prefixed by the letter 'W', and the weekday number, a digit d from 1 through 7, beginning with Monday and ending with Sunday. For example, the Gregorian date Monday 23 December 2019 corresponds to Monday in the 52nd week of 2019, and is written 2019-W52-1 (in extended form) or 2019W521 (in compact form). The ISO year is slightly offset to the Gregorian year; for example, Monday 30 December 2019 in the Gregorian calendar is the first day of week 1 of 2020 in the ISO calendar, and is written as 2020-W01-1 or 2020W011.
Discussed on
- "ISO week date" | 2019-12-26 | 141 Upvotes 84 Comments
π Long Hundred
The long hundred, also known as the great hundred or twelfty, is the number that was referred to as "hundred" in Germanic languages prior to the 15th century, which is now known as 120, one hundred and twenty, or six score. The number was simply described as hundred and translated into Latin in Germanic-speaking countries as centum (Roman numeral C), but the qualifier "long" is now added because present English uses the word "hundred" exclusively to refer to the number of five score (100) instead.
The long hundred was 120 but the long thousand was reckoned decimally as 10 long hundreds (1200).
Discussed on
- "Long Hundred" | 2021-02-08 | 97 Upvotes 106 Comments
π Doomsday rule
The Doomsday rule is an algorithm of determination of the day of the week for a given date. It provides a perpetual calendar because the Gregorian calendar moves in cycles of 400 years. The algorithm for mental calculation was devised by John Conway in 1973, drawing inspiration from Lewis Carroll's perpetual calendar algorithm. It takes advantage of each year having a certain day of the week, called the doomsday, upon which certain easy-to-remember dates fall; for example, 4/4, 6/6, 8/8, 10/10, 12/12, and the last day of February all occur on the same day of the week in any year. Applying the Doomsday algorithm involves three steps: Determination of the anchor day for the century, calculation of the doomsday for the year from the anchor day, and selection of the closest date out of those that always fall on the doomsday, e.g., 4/4 and 6/6, and count of the number of days (modulo 7) between that date and the date in question to arrive at the day of the week. The technique applies to both the Gregorian calendar and the Julian calendar, although their doomsdays are usually different days of the week.
The algorithm is simple enough that it can be computed mentally. Conway can usually give the correct answer in under two seconds. To improve his speed, he practices his calendrical calculations on his computer, which is programmed to quiz him with random dates every time he logs on.
Discussed on
- "Doomsday rule" | 2016-03-26 | 31 Upvotes 2 Comments
- "Doomsday rule: calculate the day for any date" | 2014-08-10 | 125 Upvotes 30 Comments
- "Doomsday rule" | 2013-12-11 | 10 Upvotes 2 Comments
π Antikythera Mechanism
The Antikythera mechanism (, ) is an ancient hand powered Greek analogue computer which has also been described as the first example of such device used to predict astronomical positions and eclipses for calendar and astrological purposes decades in advance. It could also be used to track the four-year cycle of athletic games which was similar to an Olympiad, the cycle of the ancient Olympic Games.
This artefact was retrieved from the sea in 1901, and identified on 17 May 1902 as containing a gear by archaeologist Valerios Stais, among wreckage retrieved from a shipwreck off the coast of the Greek island Antikythera. The instrument is believed to have been designed and constructed by Greek scientists and has been variously dated to about 87Β BC, or between 150 and 100Β BC, or to 205Β BC, or to within a generation before the shipwreck, which has been dated to approximately 70β60Β BC.
The device, housed in the remains of a 34Β cm ΓΒ 18Β cm ΓΒ 9Β cm (13.4Β in ΓΒ 7.1Β in ΓΒ 3.5Β in) wooden box, was found as one lump, later separated into three main fragments which are now divided into 82 separate fragments after conservation efforts. Four of these fragments contain gears, while inscriptions are found on many others. The largest gear is approximately 14 centimetres (5.5Β in) in diameter and originally had 223 teeth.
It is a complex clockwork mechanism composed of at least 30 meshing bronze gears. A team led by Mike Edmunds and Tony Freeth at Cardiff University used modern computer x-ray tomography and high resolution surface scanning to image inside fragments of the crust-encased mechanism and read the faintest inscriptions that once covered the outer casing of the machine.
Detailed imaging of the mechanism suggests that it had 37 gear wheels enabling it to follow the movements of the Moon and the Sun through the zodiac, to predict eclipses and even to model the irregular orbit of the Moon, where the Moon's velocity is higher in its perigee than in its apogee. This motion was studied in the 2nd century BC by astronomer Hipparchus of Rhodes, and it is speculated that he may have been consulted in the machine's construction.
The knowledge of this technology was lost at some point in antiquity. Similar technological works later appeared in the medieval Byzantine and Islamic worlds, but works with similar complexity did not appear again until the development of mechanical astronomical clocks in Europe in the fourteenth century. All known fragments of the Antikythera mechanism are now kept at the National Archaeological Museum in Athens, along with a number of artistic reconstructions and replicas of the mechanism to demonstrate how it may have looked and worked.
Discussed on
- "The Antikythera Mechanism" | 2023-12-05 | 16 Upvotes 7 Comments
- "The Antikythera Mechanism" | 2021-07-22 | 23 Upvotes 3 Comments
- "Antikythera Mechanism" | 2019-07-27 | 83 Upvotes 35 Comments