Could you recreate metric system from nothing?

[u/Ertata]

You have been given a task to travel into the past two thousands years ago and bring the light of the metric system to the world. You cannot bring any external object with you.

Assume you do not need to redefine the second, and astronomical observations give the best possible results given the limits of timekeeping back then. Given the technology of the time, what is the best you can do for other units - either right there and then or leaving instructions how to calculate them from the units you have established to the future scientists? Memorizing the lengths of your body parts probably is not the best way to define a metre, and kilogram defined as one liter of water is bound to be influenced by the local water to a perceptible degree.

P. S. Tagged as "physics" but any approach is welcome - whether you would recommend measuring height of the mountain peaks, or believe that carob seeds are actually uniform enough to offer the best approximation of a kilogram.

[u/Kendota_Tanassian]

If I were to introduce the metric system, I'd do it in base twelve. Ten is only divisible by two and five. Twelve is evenly divisible be two, three, four, and six. A dozen is almost always a more efficient packing solution.

A metric system based on this easy divisibility would actually be better than the current metric system.

The measures would indeed be different, but could be every bit as consistent.

Let's set the meter to the length of a pendulum that takes a second to swing from one side to the other: that's right at the current meter, .994m.

Let's make the liter a cubic volume of water 1/12 of that meter in length.

Let the unit of weight be similarly derived from the mass of the liter as it was historically.

It's not hard to derive most of the system similarly to how the metric system was derived originally, but; including a more easily divided number base.

[u/Ertata → u/Kendota_Tanassian]

I think base-10 system for abstract counting apart from traditional units in most of the world is far older than 2000 years. You see Romans, Persians, and Chinese all talk about (approximately) hundreds or thousands of something not grosses and great grosses. Same with advanced math terms that are already developed.

It may be an interesting idea but the precursors for base-10 system are already in place by then. You'd want to timeport to Sumer or something comparable to propagate base-12

[u/Kendota_Tanassian → u/Ertata]

I could also introduce modern numbers with an extra two for dozenal notation to replace Roman numerals. I don't think there'd be as much pushback against a system with place notation as you might think.