Topic: Time (Page 2)
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๐ Tomorrow is the shortest day of the year: 23 hours, 59 minutes, 38.7 secs
Solar time is a calculation of the passage of time based on the position of the Sun in the sky. The fundamental unit of solar time is the day. Two types of solar time are apparent solar time (sundial time) and mean solar time (clock time).
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- "Tomorrow is the shortest day of the year: 23 hours, 59 minutes, 38.7 secs" | 2013-09-15 | 119 Upvotes 40 Comments
๐ Corpus Clock (Grasshopper Clock)
The Corpus Clock, also known as the Grasshopper clock, is a large sculptural clock at street level on the outside of the Taylor Library at Corpus Christi College, Cambridge University, in the United Kingdom, at the junction of Bene't Street and Trumpington Street, looking out over King's Parade. It was conceived and funded by John C. Taylor, an old member of the college.
It was officially unveiled to the public on 19 September 2008 by Cambridge physicist Stephen Hawking. The clock was named one of Time's Best Inventions of 2008.
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- "Corpus Clock (Grasshopper Clock)" | 2021-06-02 | 112 Upvotes 32 Comments
๐ Golden hat
Golden hats (or Gold hats) (German: Goldhรผte, singular: Goldhut) are a very specific and rare type of archaeological artifact from Bronze Age Europe. So far, four such objects ("cone-shaped gold hats of the Schifferstadt type") are known. The objects are made of thin sheet gold and were attached externally to long conical and brimmed headdresses which were probably made of some organic material and served to stabilise the external gold leaf. The following Golden Hats are known as of 2012:
- Golden Hat of Schifferstadt, found in 1835 at Schifferstadt near Speyer, c. 1400โ1300 BC.
- Avanton Gold Cone, incomplete, found at Avanton near Poitiers in 1844, c. 1000โ900 BC.
- Golden Cone of Ezelsdorf-Buch, found near Ezelsdorf near Nuremberg in 1953, c. 1000โ900 BC; the tallest known specimen at c. 90ย cm.
- Berlin Gold Hat, found probably in Swabia or Switzerland, c. 1000โ800 BC; acquired by the Museum fรผr Vor- und Frรผhgeschichte, Berlin, in 1996.
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- "Golden hat" | 2015-04-20 | 87 Upvotes 28 Comments
๐ Symmetry454
The Symmetry454 calendar (Sym454) is a proposal for calendar reform created by Irv Bromberg of the University of Toronto, Canada. It is a perennial solar calendar that conserves the traditional month pattern and 7-day week, has symmetrical equal quarters in 82% of the years in its 293-year cycle, and starts every month on Monday.
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- "Symmetry454" | 2019-12-15 | 71 Upvotes 33 Comments
๐ DCF77
DCF77 is a German longwave time signal and standard-frequency radio station. It started service as a standard-frequency station on 1 January 1959. In June 1973 date and time information was added. Its primary and backup transmitter are located at 50ยฐ0โฒ56โณN 9ยฐ00โฒ39โณE in Mainflingen, about 25ย km south-east of Frankfurt am Main, Germany. The transmitter generates a nominal power of 50ย kW, of which about 30 to 35ย kW can be radiated via a T-antenna.
DCF77 is controlled by the Physikalisch-Technische Bundesanstalt (PTB), Germany's national physics laboratory and transmits in continuous operation (24 hours). It is operated by Media Broadcast GmbH (previously a subsidiary of Deutsche Telekom AG), on behalf of the PTB. With Media Broadcast GmbH, a temporal transmission availability of at least 99.7% per year or under 26.28 hours of annual downtime has been agreed upon. Most service interruptions are short-term disconnections of under two minutes. Longer lasting transmission service interruptions are generally caused by strong winds, freezing rain or snow-induced T-antenna movement. This manifests itself in electrical detuning of the antenna resonance circuit and hence a measurable phase modulation of the received signal. When the maladjustment is too large, the transmitter is taken out of service temporarily. In the year 2002, almost 99.95% availability, or just over 4.38 hours of downtime, was realized. The timestamp sent is either in Coordinated Universal Time (UTC)+1 or UTC+2 depending on daylight saving time.
The highly accurate 77.5ย kHz (approximately 3868.3ย m wavelength) carrier signal is generated from local atomic clocks that are linked with the German master clocks at the PTB in Braunschweig. The DCF77 time signal is used for the dissemination of the German national legal time to the public.
Radio clocks and watches have been very popular in Europe since the late 1980s and, in mainland Europe, most of them use the DCF77 signal to set their time automatically. Further industrial time-keeping systems at railway stations, in the field of telecommunication and information technology, and at radio and TV stations are radio-controlled by DCF77 as well as tariff change-over clocks of energy supply companies and clocks in traffic-light facilities.
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- "DCF77" | 2021-06-30 | 67 Upvotes 37 Comments
๐ Decimal Time
Decimal time is the representation of the time of day using units which are decimally related. This term is often used specifically to refer to the French Republican calendar time system used in France from 1794 to 1800, during the French Revolution, which divided the day into 10 decimal hours, each decimal hour into 100 decimal minutes and each decimal minute into 100 decimal seconds (100000 decimal seconds per day), as opposed to the more familiar standard time, which divides the day into 24 hours, each hour into 60 minutes and each minute into 60 seconds (86400 SI seconds per day).
The main advantage of a decimal time system is that, since the base used to divide the time is the same as the one used to represent it, the representation of hours, minutes and seconds can be handled as a unified value. Therefore, it becomes simpler to interpret a timestamp and to perform conversions. For instance, 1h23m45s is 1 decimal hour, 23 decimal minutes, and 45 decimal seconds, or 1.2345 decimal hours, or 123.45 decimal minutes or 12345 decimal seconds; 3 hours is 300 minutes or 30,000 seconds. This property also makes it straightforward to represent a timestamp as a fractional day, so that 2024-01-15.54321 can be interpreted as five decimal hours and 43 decimal minutes and 21 decimal seconds after the start of that day, or a fraction of 0.54321 (54.321%) through that day (which is shortly after traditional 13:00). It also adjusts well to digital time representation using epochs, in that the internal time representation can be used directly both for computation and for user-facing display.
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- "Decimal Time" | 2024-01-13 | 42 Upvotes 47 Comments
๐ Phantom Time Hypothesis
The phantom time hypothesis is a historical conspiracy theory asserted by Heribert Illig. First published in 1991, it hypothesizes a conspiracy by the Holy Roman Emperor Otto III, Pope Sylvester II, and possibly the Byzantine Emperor Constantine VII, to fabricate the Anno Domini dating system retrospectively, in order to place them at the special year of AD 1000, and to rewrite history to legitimize Otto's claim to the Holy Roman Empire. Illig believed that this was achieved through the alteration, misrepresentation and forgery of documentary and physical evidence. According to this scenario, the entire Carolingian period, including the figure of Charlemagne, is a fabrication, with a "phantom time" of 297 years (AD 614โ911) added to the Early Middle Ages.
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- "Phantom Time Hypothesis" | 2016-02-02 | 54 Upvotes 31 Comments
๐ Segal's Law
Segal's law is an adage that states:
A man with a watch knows what time it is. A man with two watches is never sure.
At surface level, the adage emphasizes the consistency that arises when information comes from a single source and points out the potential pitfalls of having too much conflicting information. However, the underlying message is to question the apparent certainty of anyone who only has one source of information. The man with one watch has no way to identify error or uncertainty.
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- "Segal's Law" | 2024-04-23 | 43 Upvotes 41 Comments
๐ Before Present
Before Present (BP) years is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred in the past. Because the "present" time changes, standard practice is to use 1 January 1950 as the commencement date (epoch) of the age scale, reflecting the origin of practical radiocarbon dating in the 1950s. The abbreviation "BP" has been interpreted retrospectively as "Before Physics"; that refers to the time before nuclear weapons testing artificially altered the proportion of the carbon isotopes in the atmosphere, making dating after that time likely to be unreliable.
In a convention that is not always observed, many sources restrict the use of BP dates to those produced with radiocarbon dating; the alternative notation RCYBP is explicitly Radio Carbon Years Before Present.
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- "Before Present" | 2018-07-20 | 56 Upvotes 27 Comments
๐ ShorttโSynchronome free pendulum clock
The ShorttโSynchronome free pendulum clock was a complex precision electromechanical pendulum clock invented in 1921 by British railway engineer William Hamilton Shortt in collaboration with horologist Frank Hope-Jones, and manufactured by the Synchronome Co., Ltd. of London, UK. They were the most accurate pendulum clocks ever commercially produced, and became the highest standard for timekeeping between the 1920s and the 1940s, after which mechanical clocks were superseded by quartz time standards. They were used worldwide in astronomical observatories, naval observatories, in scientific research, and as a primary standard for national time dissemination services. The Shortt was the first clock to be a more accurate timekeeper than the Earth itself; it was used in 1926 to detect tiny seasonal changes in the Earth's rotation rate. Shortt clocks achieved accuracy of around a second per year, although a recent measurement indicated they were even more accurate. About 100 were produced between 1922 and 1956.
Shortt clocks kept time with two pendulums, a master pendulum swinging in a vacuum tank and a slave pendulum in a separate clock, which was synchronized to the master by an electric circuit and electromagnets. The slave pendulum was attached to the timekeeping mechanisms of the clock, leaving the master pendulum virtually free of external disturbances.
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- "ShorttโSynchronome free pendulum clock" | 2020-09-17 | 62 Upvotes 18 Comments