Standards for Measurement
Ever wonder what really defines a meter? Or a second? Or a twip? From Charlie Emrich in the September 2007 issue of Wired comes this list of standards.
- Meter
- Standardized in 1983
- Measures length
- Defined by the distance light travels in a vacuum in 1/299,792/458 second
- Second
- Standardized in 1967
- Measures time
- Defined by the time it takes for a cesium-133 atom to cycle 9,192,631,770 times between two specific quantum states
- Ampere
- Standardized in 1948
- Measures electrical current
- Defined by the current required to create a force of 2×10E-7 newtons per meter between two parallel wires
- Kelvin
- Standardized in 1954
- Measures temperature
- Defined by 1/273.16 the temperature of the triple point of water - when it’s simultaneously gas, liquid and solid
- Mole
- Standardized in 1971
- Measure amount of stuff
- Defined by the number of atoms in 12 grams of carbon 12 (6.022×10E23)
- Candela
- Standardized in 1979
- Measures brightness
- Defined by the intensity of a 1/683-watt yellow-green light spread over a square meter, seen from a meter away
Now for some more interesting, obscure units of measure.
- Gou
- 180 milliliters - better known as a rice cup for an electric cooker
- Pack Year
- cigarette consumption based on one pack a day for a year
- Nibble
- typically four bit of binary code, or half a byte
- Score
- 20 of something
- Hand
- 4 inches of horse height
- Twip
- 1/20 of a typesetting point
- Thrave
- 24 sheaves of wheat
- Shake
- 10 nanoseconds
- Mickey
- ratio of computer mouse movement to onscreen cursor movement
- Jansky
- strength of radio signals from space
- Butt
- two hogsheads, or about 126 gallons, of booze
- Smoot
- a measure of length developed by some MIT students, equal to 5′ 7" - the height of one Oliver R Smoot
