May 20, 2020
Day 141 of 366
May 20th is the 141st day of the year. It is European Maritime Day, an event that seeks to raise European citizens’ awareness of the seas and their importance. It was established jointly by the European Council, European Parliament, and European Commission in 2008 as part of the EU maritime policy.
In the United States, today is “celebrated” as National Be a Millionaire Day, National Pick Strawberries Day, National Rescue Dog Day, National Quiche Lorraine Day, Emergency Medical Services for Children Day (typically observed on the Wednesday of Emergency Medical Service Week), and National Juice Slush Day (typically the third Wednesday in May).
Historical items of note:
- In 1570, cartographer Abraham Ortelius issued Theatrum Orbis Terrarum. It was the first modern atlas.
- In 1609, Shakespeare’s sonnets were first published in London (perhaps illicitly) by the publisher Thomas Thorpe.
- In 1873, Levi Strauss and Jacob Davis received a United States patent for blue jeans with copper rivets.
- In 1883, Krakatoa began to erupt. More than 36,000 people were killed when the volcano exploded three months later.
- In 1891, Thomas Edison’s prototype kinetoscope was first publicly displayed.
- In 1908, actor James Stewart was born.
- In 1911, author and DC Comics alum Gardner Fox was born.
- In 1932, Amelia Earhart took off from Newfoundland to begin the world’s first solo nonstop flight across the Atlantic Ocean by a female pilot. She landed in Ireland the next day.
- In 1936, actor Anthony Zerbe was born.
- In 1946, singer-songwriter, producer, and actress Cher was born.
- In 1959, actor Bronson Pinchot was born.
- In 1960, actor John Billingsley was born.
- In 1964, cosmic microwave background radiation was discovered by Robert Woodrow Wilson and Arno Penzias.
- In 1968, actor and producer Timothy Olyphant was born.
- In 1983, the first publications of the discovery of the HIV virus that causes AIDS were made in the journal Science by Luc Montagnier.
- In 1996, the Supreme Court of the United States ruled in Romer v. Evans against a law that would have prevented any city, town or county in the state of Colorado from taking any legislative, executive, or judicial action to protect the rights of gays and lesbians.
In 1875, the Metre Convention was signed by 17 nations, leading to the establishment of the International System of Units (SI).
The SI (abbreviated from French: Système international (d’unités)) is the modern form of the metric system. It is a coherent system of measurement starting with seven base units:
- the second (the unit of time with the symbol s)
- the metre/meter (length, m)
- the kilogram (mass, kg)
- the ampere (electric current, A)
- the kelvin (thermodynamic temperature, K)
- the mole (amount of substance, mol)
- the candela (luminous intensity, cd)
The system allows for an unlimited number of additional units, called derived units, which can always be represented as products of powers of the base units. There are twenty-two derived units that have special names and symbols, including hertz, joule, watt, ohm, volt, and so on. Both the base and derived units can use prefixes (such as kilo, mega, and centi) to measure nearly any quantity.
Prior to 2019, the base units were defined by simple readily observable terms. For instance, a kilogram was defined as, “The mass of one litre of water at the temperature of melting ice. A litre is one thousandth of a cubic metre.” Unfortunately, these measurements were also imprecise and subjective.
Since 2019, the magnitudes of all SI units have been defined by declaring exact numerical values for seven defining constants when expressed in terms of their SI units.
- The speed of light in vacuum, c
- The hyperfine transition frequency of caesium, ΔνCs
- The Planck constant, h
- The elementary charge, e
- The Boltzmann constant, k
- The Avogadro constant, NA
- The luminous efficacy, Kcd
These defining constants range from fundamental constants of nature (the speed of light in a vacuum) to the purely technical (Kcd). One consequence of the 2019 redefinition is that the distinction between the base units and derived units is in principle not needed since any unit can be constructed directly from the seven defining constants.
All of the technical jargon aside, this all makes the International System of Units incredibly precise and exacting.
In celebration of the anniversary of the International System of Units, World Metrology Day is celebrated annually on May 20th.
In 1734, the pioneer of beekeeping Anton Janša was born. In honor of his birth and to acknowledge the role of bees and other pollinators for the ecosystem, World Bee Day is celebrated on May 20th.
The Thing About Today is an effort to look at each day of 2020 with respect to its historical context.
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