Quetta, Ronna, ronto, quecto, and a Partridge in a Pear Tree.

Four new prefixes for the metric system have been approved by the Metric Bishops. We now have Quetta, Ronna, ronto, and quecto. They are 1027 1030 10-27 10-30. No doubt that true believers of the metric clergy are already incenced that I used my own elements of style to capitalize Quetta and Ronna, and left ronto and quecto lower case. Why would it not make sense to use capitalization to designate magnifying and reducing prefixes in prose? I have no idea, but it’s apparently as questionable as an Oxford Comma in some circles—yes, I like the Oxford Comma. That said, apparently, according to Wikipedia, we now need eight words to describe this essential set of additions to the metric system. Quetta is nonillion (short scale) and quintillion (long scale). Ronna is octillion and quadrilliard, ronto is octillionth and quintilionth, and quecto (with one c not two as that’s a big deal), has nonillonth and quintillionth. I’m taken to task for capitalization that would help the reader realize if ronna is bigger than ronto?

Well, they’ve done it, added four more prefixes without depreciating the prefix cluster around unity, that is: hecto, deca (the one with two letters da), deci, and centi. What is the reason these were needed? According to one article in the press, a reason given was:

“The change was largely driven by the growing requirements of data science and digital storage, which is already using prefixes at the top of the existing range (yottabytes and zettabytes, for expressing huge quantities of digital information),” said a release from the UK’s National Physics Laboratory, which was involved in the new prefix adoptions. “These can be used with any SI unit, for example in the future we can be expected to talk about ronnametres and quettagrams.”

Of course, data storage generally involves factors of two, so the metric prefixes don’t work in an exact manner. This is how the kibi, mebi, tebi, pebi, and exbi came about. They are binary prefixes meant for computers, so the use of powers of ten does not confuse. It appears to me that the rational for the four new prefixes is that computer people need a new metaphor for the size of their storage, but only that, as it is not a technically descriptive of a power of two.

I have previously discussed my view of expanding the metric prefixes past yocto and Yotta in my earlier essay On Beyond Yotta. The prefix Yotta can describe the dimensions of the observable universe, but mass is where things really become astronomical. In my earlier essay:

Dr. Asimov states that about 4.2 Tg (Teragrams) of mass is converted to energy every second inside of the sun. He uses pre-metric terms to describe this value as “4 600 000 tons of mass per second.” Unfortunately so does Wikipedia: “the Sun fuses about 620 million metric tons of hydrogen each second.” As I understand it 1 million is  106  and a “metric ton” is a Megagram or 106 grams for 4.2 x 1012 grams per second or 4.2 Tg per second. That’s a lot of grams. Dr. Asimov inquires: “Is it possible  for the Sun to support this steady drain of mass at the rate of millions of tons per second? Yes, it certainly is, for the loss is infinitesimally small compared with the total vast mass of the sun.”  The currently accepted mass of the sun is, approximately 2 x 1030 kg. This means it’s 2 x 1033  grams, and the proper metric prefix would be?—oh, well, there isn’t exactly a metric prefix for this value. The last magnifying metric prefix is Yotta, which allows the mass to be written as 2 000 000 000 Yg (Yottagrams). Which by current convention it appears there are about three extra metric prefixes needed to express the mass of the sun with a 2, and a minimum of two extra prefixes to use 2000 as a magnitude.

In my second edition of The Dimensions of the Cosmos, I have a table which demonstrates how quickly mass increases for astronomical bodies.

The use of Yottagrams for our planetary system is two metric triads beyond what makes sense with Naughtin’s Laws when we describe Jupiter’s mass, but Mercury and Mars are both whole numbers. This seems preferable to writing them in Ronnagrams. The list for our planets would become:

Planet Mass
Mercury 0.330 Rg
Mars 0.642 Rg
Venus 4.69 Rg
Earth 5.97 Rg
Uranus 86.81 Rg
Neptune 102.41 Rg
Saturn 568.34 Rg
Jupiter 1 898.60 Rg
Sun 198 900.00 Rg

I don’t see this as a superior way to present this data compared with Yg, other than it shows clearly how much less mass Mars has compared with the Earth and Venus, but really not better than using Yottagrams with integers. But “Richard Brown, the head of the laboratory, told AFP that Earth weighs about 6 ronnagrams, and Jupiter is about 2 quettagrams.” Thanks for switching metric prefixes so they are not directly comparable. The addition of two new sets of prefixes does not seem to help describe our planets better than before.

In my earlier essay I wrote:

Asimov also makes this surprising statement:

Release of energy is always at the expense of disappearance of mass, but in ordinary chemical reactions, energy is released in such low quantities that the mass-loss is insignificant. As I have just said, 670,000 gallons of gasoline must be burned to bring about the loss of 1 gram (1/27 of an ounce). Nuclear reactions produce energies of much greater quantities, and here the loss of mass becomes large enough to be significant.

What I’ve been able find in my research on this subject is both minimal and contentious. It is mostly stated that the amount of mass lost in chemical reactions is “unmeasurable.” The few who venture to put numbers to paper (including a textbook example) end up with magnitudes on the order of 10-33 grams. One example computation has 70 x 10-33 grams as the amount of mass lost in the given chemical reaction. This would be 0.000 000 070 yg (yoctograms) and would indicate a possible need for at least two more metric prefixes. It appears that, at least in theoretical discussions, it might be useful to have two more metric prefixes on the dividing side of the prefixes.

Well now we have two more prefixes, so we can write the mass changes as 0.070 quectograms. This does not seem to be a considerable improvement either. The place where these prefixes could come in handy is for subatomic mass energy equivalents. A single electron is 910 quectograms, or 910 qg. In The Dimensions of the Cosmos I have a table which relates the mass of the electron clouds of atoms to their equivalent energy:

We can rewrite the table from The Dimensions of the Cosmos as perhaps:

SubstanceMass in quectograms Energy in Femtojoules
Single Electron 910 qg82 fJ
Beryllium (4) 4 000 qg328 fJ
Sodium (11) 10 000 qg901 fJ
Bromine (35) 32 000 qg2867 fJ
Uranium (92) 84 000 qg7535 fJ

We are now able to write the entire table with integers if we wish. In this case, the two new reducing prefixes are definitely of utility. We now have two extra sets of prefixes, that seem mostly driven by computer metaphor at the magnification end, so I don’t plan on expanding The Dimensions of the Cosmos anytime soon.

Sorry for the typo spelling error on Quetta in an earlier draft.

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.

The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.

The third book is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.

3 thoughts on “Quetta, Ronna, ronto, quecto, and a Partridge in a Pear Tree.

  1. Maven, my brain explodes every time I try to read one of your awsome articles!

  2. You have written quetta as quecca in the title and twice in the body!

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