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    SI: new prefixes for "largest" and "smallest" numbers

    The Internet generates so much data that words to describe its scale are almost impossible to find. Photo credit: Erik Isakson Photographs

    New prefixes for the world's largest and smallest numbers are likely to be determined at the International Congress of Weights and Measures (CGPM), to be held in Versailles, France, on November 18. Currently, the prefix suggestions for the largest numbers are ronna and queta, and the prefix suggestions for the smallest numbers are ronto and quecto.

    The International System of Units (SI) is the world's most commonly used standard of measurement and measurement unit agreed upon by most scientists and is the basis of every measurement.

    In addition to defining basic units such as the kilogram and the meter, the SI also dictates how large and small numbers are named. The naming scheme was last extended in 1991. For very large numbers, when the number is followed by 21 or 24 "0"s, the prefixes are zetta (1021) and yotta (1024); for very small numbers, the prefixes are zepto (10-21) and yocto ( 10-24). Such prefixes were rarely used at the time, but as the Internet generated and stored ever-increasing amounts of data, they came into play. It is estimated that by 2025, the sum of world data will reach 175 zetta bytes.

    "There's been a lot of speculation in the media about what a larger prefix than the yotta byte would be," says Richard Brown of the UK's National Physical Laboratory (the UK's national center for measurement benchmark research). Ground is used to describe 1027 bytes, and Google's unit converter has long converted the 1027-byte prefix to hella bytes.

    But Brown pointed out that SI already uses the letters "b" and "h" as prefixes, and the above-mentioned informal prefixes do not conform to SI's naming rules. Therefore, there is an urgent need to identify standard prefixes in case these informal prefixes become too deeply bound to the scientific literature.

    Brown helped draft a prefix proposal that CGPM member countries could object to at the General Assembly. If there is no objection, the new prefixes for numbers with 27 and 30 "0"s after the number will be ronna (1027) and queta (1030) for large numbers, ronto (10-27) and quecto (10- 30). But even if they are identified as international units, it may take a while for scientists to get used to them in their work.

    Also, some scientists are skeptical that the new prefix will be useful. "We tend to define our own units, which are more useful for actually studying things," says University of Nottingham astronomer Mike Merrifield.

    Brown believes that ronto and quecto may be used in the field of radio astronomy, for example to measure the weak cosmic microwave background radiation. For this, Merrifield said, astronomers already have a unit that they use often — the non-SI Jansky.

    But in Brown's view, using these standard units conveys the message better.

    These prefix names may seem arbitrary, but in fact they strictly follow SI. "R" and "q" are the only remaining letters of the English alphabet that are not used by other SI prefixes. In addition, the middle part of the new prefix word is roughly translated from Latin for "multiplied by how many 1000", while the prefix name ending in "a" or "o" follows the prefix that means "big" is always The habit of ending in an "o" with a prefix ending in "a" meaning "little".

    As for when a larger or smaller prefix will appear, Brown thinks it will be at least another 25 years.

    (Original title ""Maximum" and "Smallest" new prefixes are coming")

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