ronnagram

The unit of measurement ronnagram was created in 2022, when four new SI prefixes were added. Why weren’t they needed before? Well, the diameter of the observable universe is about 0.88 ronnameters. The size of the entire internet is about 0.0001 ronnabytes. At least the mass of the earth is 5.97 ronnagrams, phew!

Here’s the full table of SI prefix etymologies, another example of what a carefully groomed system might look like after 230 years of only ever adding, never modifying. More detail below.

10^1	deci-	decimus	L. tenth	deca-	δέκα (déka)	G. ten
10^2	centi-	centum	L. hundred	hecto-	ἑκατόν (hekatón)	G. hundred
10^3	milli-	mille	L. thousand	kilo-	χίλιοι (khílioi)	G. thousand
10^6	micro-	μικρός (mikrós)	G. small	mega-	μέγας (mégas)	G. great
10^9	nano-	νᾶνος (nânos)	G. dwarf	giga-	γίγας (gígas)	G. giant
10^12	pico-	pico	Sp. little bit	tera-	τέρας (téras)	G. monster
10^15	femto-	femten	Da. fifteen	peta-	πέντε (pénte)	G. five
10^18	atto-	atten	Da. eighteen	exa-	ἕξ (héx)	G. six
10^21	zepto-	ἑπτά (heptá)	G. seven	zetta-	ἑπτά (heptá)	G. seven
10^24	yocto-	ὀκτώ (oktṓ)	G. eight	yotta-	ὀκτώ (oktṓ)	G. eight
10^27	ronto-	ἐννέα (ennéa)	G. nine	ronna-	ἐννέα (ennéa)	G. nine
10^30	quecto-	decem	L. ten	quetta-	decem	L. ten

A year after the French Revolution, in 1790, the Académie des sciences (French Academy of Sciences) tasked a panel of scientists to come up with a unified national system of weights and measures. The traditional systems they wanted to supplant had definitions that varied between towns, making even internal trade difficult. Also the revolutionaries were on a bit of a crusade to replace everything from the ancien régime with new, rational systems, such as decimal time[1]. By 1795, their proposal was accepted, including the original metric prefixes: deca-, hecto-, kilo-, and myria-, based on the Greek words for ten, hundred, thousand, and ten-thousand; and deci-, centi-, and milli-, based on the Latin words for tenth, hundred, and thousand.

Over the next 170 years of the system’s spread and adaptation, myria- fell out of use in favor of new prefixes based on multiples of 1000. They seem to each have come from regional vernacular before becoming codified and standarized with the creation of the SI in 1960. Mega- is from the Greek for great, giga- for giant, and tera- for monster. Micro- is from the Greek for small, nano- for dwarf, and pico- is, uh, from Spanish “pico” meaning “little bit”.

In the modern era, SI prefix expansion is much more documented and formalized, immortalized in resolutions made at the General Conference on Weights and Measures (CGPM). In 1964, the need to measure atomic lengths and extremely precise periods of time led to the addition of femto- (10^-15) from the Danish for fifteen, and atto- (10^-18) for eighteen.

The lopsided prefixes stood until the 1975 adoption of new prefixes for use with world energy usage and radiation, peta- (10^3^5) from the Greek for five, and exa- (10^3^6) for six.

By 1991, there was a clear need for smaller units for working with single molecules and spectral analysis. Vowing never to repeat its past mistakes, the CGPM introduced matching larger prefixes despite there being no known applications at the time. They opted to give them consistent abbreviations by prepending letters to the traditional Greek roots. So zepto- (10^3^-7) is z + seven, yocto- (10^3^-8) is y + eight, zetta- (10^3^7) is Z + seven, and yotta- (10^3^8) is Y + eight.

Finally, we arrive at the 2022 resolution, which recognized that the only remaining unused letters were Q and R. So ronto- (10^3^-9) is r + nine, quecto- (10^3^-10) is q + Latin for ten, ronna- (10^3^9) is R + nine, and quetta- (10^3^10) is Q + Latin for ten. Ironically, these changes were driven by the larger units. People had started using vernacular coinages for prefixes above 10^24 like bronto- and hella-, and the CGPM vowed never to repeat its past mistakes by superseding them with official, designed prefixes.

[1] Each day would be divided into 10 hours of 100 minutes, each composed of 100 seconds. This isn’t an obviously terrible idea. However, the government gave up trying to enforce the use of the new clocks just six years later.