How much does the Earth weigh? Six ronnagrams. Here are the new prefixes for the largest and smallest units of measurement

For the first time in thirty years, the list of prefixes used in the SI has been officially expanded. The two new prefixes for large numbers are “ronna” and “quetta,” and for small numbers are “ronto” and “quecto.” Scientists introduced them to make it easier for us to handle the largest and smallest numbers.

How much data does humanity generate each year? The prestigious journal Nature reports that by the time we reach our thirties of this century, we will have crossed the one-yottabyte mark. That is, 2 to the 80th power bytes, or approximately a million trillion megabytes (MB).

Avoiding the use of ones with such a long number of zeros has been possible since 1991, when jotta (10^24) and zetta (10^21) were added to the list of prefixes used in the SI system. This happened at the request of chemists, who found it easier to handle moles (that is, a measure of the amount of matter) this way. One mole is just over 6*10^23.

For more than two decades, the new prefixes, denoting gigantically large and gigantically small numbers, were sufficient. However, they are no longer so. Scientists, engineers and programmers working with huge amounts of data have been suggesting for some time that new prefixes would be useful. The idea is to make it convenient to use even larger — and even smaller — numbers.

Small and large prefixes

They were adopted on Friday, November 18, at the 27th General Conference on Weights and Measures. This meeting of scientists from around the world, which usually takes place every four years, this time took place in Versailles.

What prefixes have joined the SI system? As of three days ago, a one with twenty-seven zeros is “ronna” (10^27). On the other hand, a number one thousand times larger — that is, a one and thirty zeros — is “quetta” (10^30). Their counterparts on the other side of the scale are “ronto” (10^–27) and “quecto” (10^–30).

What can these prefixes be useful for? Instead of writing that the Earth weighs 5.9*1024 kg, you can now say that about 6 ronnagrams. In contrast, the weight of Jupiter is 2 quettagrams. An electron, on the other hand, weighs about a rontogram.

Data science requirements

The initiator of the change is Richard Brown, a metrologist at Britain’s Terrington-based National Physical Laboratory. Brown had been advocating the introduction of new prefixes for five years. That’s because he noticed that in data analysis — that is, working with huge amounts of information — the current ones are barely sufficient.

“When it comes to measuring data in yottabytes, i.e., using the largest prefix at the moment, we are already reaching the limit,” Brown told AFP. — Expanding the list of prefixes also makes sense at the bottom of the scale. Additional prefixes will come in handy in quantum physics and particle physics. These are the scientific fields that measure really small things,” he added.

How to choose new prefixes?

Brown admitted that he came up with the idea to expand the list of prefixes when he noticed that informal terms were beginning to circulate. Google was hinting to its users, for example, that a thousand yottabytes was a hellabyte. The prefix “bronto” was also beginning to take hold.

These kinds of proposals — if they became widespread — could, however, create quite a mess in the International System of Units (or SI). —”These ideas frightened me because they were completely unofficial,” Brown said.

In theory, there is nothing wrong with this. Already, prefixes that functioned unofficially were becoming formal prefixes incorporated into the SI. The problem was hidden in the abbreviations. Prefixes are abbreviated to one letter, meanwhile both h and b were already taken. H is the symbol for hecto, or hundred, and also the unit of inductance (henr). The b, on the other hand, stands for byte.

When Richard Brown reviewed the alphabet, he found that there was little choice. Of the free letters, not used to denote either measures of physical quantities or units, only r and q remained. So the new prefixes had to start with just these.

Will there be further prefixes?

According to Brown, the changes made will satisfy our demand for symbols for large numbers for at least two decades. However, in 25–30 years, science may have advanced so much that we will be describing certain things — quantities of data, but perhaps also phenomena from the world of quanta — using ones with more than 30 zeros (or 30 decimal places). What then?

One could, of course, go for symbols from alphabets other than Latin. However, Richard Brown has a different idea. According to him, we can start building complex prefixes, consisting of two symbols. 10^33 would then be called kiloQuetta (kQ).

“However, I think we still have a very long time before we have to start worrying about this at all,” the scientist told Nature magazine.

Source: Nature

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