随着科学技术发展以及人们在互联网上产生的海量数据，如何准确描述数据的大小成为科学家们的新课题，数量级的最大最小，该如何描述呢？
据美国全国公共广播电台（NPR）19日报道，第27届国际计量大会近日宣布，国际单位制引入4个新的用于构成十进倍数和分数单位的词头，分别扩展了最大和最小数字的计数单位，以应对科学进步和数据存储量大增的需求。
新增的4个词头分别是ronna、quetta、ronto和quecto。其中，ronna表示数字后有27个零，quetta表示数字后有30个零。ronto和quecto则用于表示极小的数字，分别表示小数点后有27个零和30个零。而新增的4个单位词头能代表目前已测量过的最大和最小数据。
The 27th General Conference on Weights and Measures last Friday introduced four new prefixes to the International System of Units, or metric system: ronna (27 zeroes after the first digit) and quetta (30 zeroes), which are now at the top of the measurement range, and ronto (27 zeroes after the decimal point) and quecto (30 zeroes), which are now at the bottom.
英国国家物理实验室度量衡学负责人理查德·布朗博士，向国际计量大会提出了增加上述单位的建议。他在接受美联社采访时表示，人们已经熟知“毫米”“毫克”等单位中的词头“毫”，而新增的4个单位词头则能代表目前已测量过的最大和最小数据。
“Most people are familiar with prefixes like milli- as in milligram. But these are prefixes for the biggest and smallest levels ever measured,” Dr Richard Brown, head of Metrology at the U.K.’s National Physical Laboratory who proposed the four new prefixes, told The Associated Press.
布朗说：“过去30年，数据领域的规模以指数级别增长，数据科学家也意识到，现在没有合适的词去形容这个级别的存储量了。”布朗补充道，新增的单位，方便科学家去描述已经知晓的事物。
“In the last 30 years, the datasphere has increased exponentially, and data scientists have realized they will no longer have words to describe the levels of storage,” he explained. Brown said the new terms also make it easier to describe things scientists already know about.
据NPR报道，此前，最大的单位为yotta，即数字后带24个零。在描述地球重量时，可以用6000 yottagrams（即yotta词头+gram克）。现在，则可以用6 ronnagrams来表示。太阳的重量可以用 2000 quettagrams来描述，不再需要以前的 2,000,000,000 yottagrams。
Yotta (24 zeroes) was the largest prefix in the metric system before the new additions. Now, the Earth's mass can be said to be about 6 ronnagrams rather than 6,000 yottagrams. The sun can be said to be about 2,000 quettagrams rather than 2,000,000,000 yottagrams.
而ronto 和quecto将用于量子科学和粒子物理学。例如电子的质量为1 rontogram，而不再用此前最小计量单位的0.001 yotcograms。
The prefixes for small numbers (ronto and quecto) will be useful for quantum science and particle physics. An electron's mass can be said to be about 1 rontogram rather than 0.001 yoctograms (the smallest prefix before the new additions).
布朗建议的这4个词头的单位，即时生效。这也是1991年以来，国际单位制首次新增内容。
The new terms take effect immediately, marking the first time since 1991 that any new additions have been made.
他表示，ronna、quetta分别简写为R和Q，而ronto和quecto则分别简写为r和q。
他说，之所以选择ronna、quetta、ronto和quecto为新增单位词头，是因为只有字母r和q尚未被用作单位词头，同时这4个单词发音听起来像希腊语发音，并满足大单位词头以a结尾、小单位词头以o结尾的惯例。
He explained how the new names were not chosen at random: The first letter of the new prefixes had to be one not used in other prefixes and units.“There were only the letters ‘r’ and ‘q’ that weren’t already taken. Following that, there’s a precedent that they sound similar to Greek letters and that big number prefixes end with an ‘a’ and smaller numbers with an ‘o,’” he added.
综合来源：新华网，NPR，美联社
