Who Decides How Long a Second Is?
Who Decides How Long a Second Is 2023? A second is a measure of time. It equals 1/66,400th of an Earth rotation on its axis.
A second is a fundamental unit of time defined by the International System of Units since 1967. It is measured in relation to atomic clocks.
The International System of Units (SI)
The International System of Units (SI) is a globally accepted measurement system used in science, technology, industry and everyday commerce. The SI is composed of seven base units which correspond to physical quantities like length, mass and temperature.
The seven base units are the second, symbol s; metre, symbol m; kilogram, kilogramm; ampere (coulomb); kelvin (kilokelvin); mole (mole); candela (candelah). These seven units are chosen because they are widely used to represent fundamental quantities such as time, length, and temperature.
Each of the seven base units has a derived unit related to it, such as the joule for energy or centimetre for length. Derived units are defined using their associated base units as their foundation and can be converted back to SI units by adding an appropriate conversion factor that is a power of ten.
In 1967, the SI adopted a standard that redefined a second as the amount of time it would take for an unperturbed ground-state hyperfine transition frequency of caesium atom to change from one hyperfine level to the other. This was done in order to keep both units as precise as possible while Earth’s rotation slows, leading to longer average solar days.
However, it was recognized that this would not be sufficient for future applications and a new definition was made in 2019. This new definition defines the second as the time needed to vibrate 9,192,631,770 Cesium atoms – an extremely accurate and stable way of measuring the SI second than using the average solar day to measure how long it takes for Earth to rotate once.
As the International System of Units (SI) develops and new technologies are developed, prefixes are created and unit definitions modified through agreement among all participating nations. This has been going on for many years and is intended to continue. When completed, SI will provide a more precise system for measuring time and other basic quantities.
The National Institute of Standards and Technology (NIST)
Have you ever stopped to consider who determines the length of a second? That would likely be NIST. Situated in Gaithersburg, Maryland, this agency of the United States government works to promote innovation and industrial competitiveness through measurement standards.
NIST creates and updates measurement standards for a variety of industries, such as aerospace, energy, information technology, and medical research. Furthermore, NIST promotes public-private adoption of cutting-edge measurement technologies and procedures in science and technology fields.
One of the greatest challenges NIST faces is maintaining accurate time. To do this, they need to calibrate atomic clocks regularly.
Atomic clocks rely on microwave radiation to measure a cesium atom’s frequency, or number of cycles per second. As such, they have become increasingly accurate and stable over the years.
In the 1950s, NIST began construction of an atomic clock that would serve as a national standard of frequency. However, it took them nearly three decades to complete this endeavor.
Today, NIST utilizes atomic clocks to maintain U.S. time and contribute to Universal Coordinated Time (UTC), the world’s official clock.
NIST uses “primary standards” to measure the second, such as F1 and F2. Both atomic fountain clocks were created in 2014 using a cloud of cesium atoms trapped inside a cylinder that are elevated using lasers.
Over the years, both F1 and F2 clocks have been refined, making them more reliable and precise. In 2014, NIST-F2 launched a version that is approximately three times as accurate as its predecessor; it will not gain or lose a second in 300 million years or 1/300,000,000th of a second per year.
NIST atomic clocks are not used to accurately tell time in the real world, but rather they serve to calibrate other commercially available clocks. NIST also offers a range of time and synchronization measurement services for various customers. These include remote measurements made at their site using GPS-enabled equipment instead of one-time calibrations.
The International Astronomical Union (IAU)
The International Astronomical Union (IAU) is an organization dedicated to the advancement of astronomy. Established in 1919, its membership includes professionals and amateur astronomers from around the globe.
The International Astronomical Union (IAU) is one of the premier scientific organizations. It coordinates numerous astronomical projects worldwide and acts as the international authority for assigning official names and designations to celestial bodies and their surface features. Furthermore, IAU plays an essential role in creating new global-scale infrastructures by building consensus on their design and construction.
Throughout its first century, the IAU focused on several key initiatives such as science diplomacy and organizing scientific symposia. These events provided scientists from around the globe a forum to present their work and network, often leading to new ideas or collaborations.
Technology advancements enabled many of these meetings to move online. This enabled a much larger number of researchers to participate at low costs, making them accessible even to people living in areas without access to electricity or Internet.
Some astronomers argued the IAU’s new format was unproductive and prone to social problems, while others saw it as an opportunity for open discussions about astronomy. They saw it as a chance to lift people’s spirits during difficult times for everyone in their daily lives.
The IAU is organized into Divisions, Commissions and Working Groups that oversee various areas of astronomy. These include 9 Science Divisions, 38 specialized Commissions and 47 Working Groups that encompass the full scope of astronomy.
In addition to these initiatives, the IAU supports several educational and outreach activities. For instance, they organize the UNESCO International Year of Astronomy and plan to establish an Office of Astronomy for Education that will train young people how to utilize telescope data.
The IAU also takes action to promote gender equality within its ranks, making significant efforts to increase female representation within astronomy.
The World Meteorological Organization (WMO)
The World Meteorological Organization (WMO) is a United Nations agency responsible for international cooperation and coordination on meteorology, climatology, hydrology and geophysics. With 193 Member States and territories having ratified or acceded to its Convention, WMO serves as an advocate for meteorologists worldwide.
The primary mission of the WMO is to coordinate global weather observations, data exchange and forecasting. To do this, they promote international standards and assist with their implementation. Moreover, they offer advice to national meteorological and hydrological services as well as other organizations involved with weather, climate change and water resources.
Established in 1950, the World Meteorological Organization has a proud legacy of international cooperation in meteorology and related fields. This has resulted in improved weather observations, data exchange, and forecasting capabilities worldwide.
Today, the WMO coordinates a global network of Earth systems observations, research and global, regional and national data-processing for numerical weather prediction. This ensures all members of the WMO can provide accurate, timely weather forecasts and services to their citizens.
In addition to coordinating the global system of weather observations, data exchange, and forecasting, the WMO offers technical support, training and education. Furthermore, it contributes to developing international treaties and agreements on topics such as weather, climate change, and water.
To reach its objectives, the World Monetary Organization collaborates with a range of agencies such as the United Nations, other governments and nongovernmental organizations. For instance, they partner with UN Environment Programme to monitor air pollution.
The World Meteorological Organization (WMO) offers a number of programs to promote research in areas such as ozone depletion, atmospheric sciences, oceanography and the cryosphere. Furthermore, it coordinates an initiative to study climate change’s effects on human health and economic development.
The WMO provides support to the aviation industry by ensuring airlines have access to accurate weather forecasts and other vital information to enable safe operations. It has a Commission for Aeronautical Meteorology as well as an Education and Training Office which educates pilots and other air traffic professionals about weather conditions and aviation safety procedures. https://www.youtube.com/embed/OKms5a0nGO4