This is the first time in more than three decades that the international system, established in 1960 and commonly known as the metric system, has introduced new prefixes.

If everyone knows the kilo, which expresses, for example, a number of meters or grams in thousands, with three zeros after the unit, only scientists use the zetta or the yotta, which express a quantity with 21 or 24 zeros respectively.

They were introduced in 1991 when the chemical community needed to express quantities of molecules on this scale.

But even yotta cannot satisfy the need to express ever larger dimensions through the explosion of digital technologies.says Richard Brown, head of metrology, the science of measurement, at Britain’s National Physical Laboratory.

” We are very close to the limit of expressing data in yottabytes, the highest prefix available. »

This change affects not only the infinitely large, but also the infinitely small as we study Quantum science, particle physics, where you measure very, very small thingsadds Richard Brown.

The new prefixes ronna (R) and quetta (Q) express magnitudes with 27 and 30 zeros after the unit, respectively. Symmetrically, the ronto (r) and the quecto (q) express quantities whose unit is the 27th or 30th after the decimal point.

With these prefixes the earth weighs about 6 ronagramsa 6 followed by 27 zeros, notes Dr. Brown.

Conversely, something weighing 6 rontograms would correspond to a decimal number with the 6 in the 27th place to the right of the decimal point.

These changes were approved on Friday at the Palace of Versailles (west of Paris) by scientists gathered at the quadrennial CGPM.

The British scientist wanted to create new prefixes by paying attention to the appearance of whimsical data storage designations such as brontobytes or hellabytes.

But the SI requirement to use single-letter prefixes had to be met. The only letters that cannot be used for other units or symbols are R and Qhe says.

A convention also dictates that prefixes of large magnitudes end in the letter Hasand those of very small amounts by a Oh.

According to the metrology specialist, Ronna and ronto, quetta and quecto should meet the requirements of measuring very large numbers for at least the next 20 to 25 years.