Noon is neither AM nor PM

However, it seems to me that we don't need the metric police to invade every informal discussion we have involving measurement with a zealot-like zeal as it would be counterproductive and would do more harm than good by unnecessarily alienating people, thus it would take longer to adopt metric measurements.

Here's just one of thousands instances one could give: it would be stupid to always enforce the common and long-held lumber measurement of 2x4 inches—in US ventricular, aka 4x2 inches in Britain and Commonwealth countries—to its nearest metric equivalents of 100x50 mm (the now common metric equivalent), as just about everyone knows what "just use a bit of 2x4 [4x2] to fix the problem" means. During conversion from imperial to metric, the way around the problem is twofold: sawmills etc. would sell slings (truck-sized bundles) marked as '100x50x3600 mm' and sub-marked in smaller lettering 'approx 2x4x142 inches', as well as to make ready-reckoner conversion charts available everywhere.

When Australia converted to metric in the early 1970s it mandated by law that everyday-type sales of rules etc. be in metric only, so one couldn't buy a school rule that was marked in both inches and centimeters etc. and this was a problem when trying to check things that were already built to imperial measurements. It seems to me this went too far but nevertheless it was very effective in getting everyone thinking metric, as these days most of Australia is converted (thinks in metric).

This law was relaxed some years after the conversion had finished and one could buy dual standard school rules once again. As I said elsewhere in another post (see link in above post), that this conversion has now gone too far backwards. As mentioned, as the result of the Chinese having ramped up production of goods specifically for the US market, Australia is now seeing a large influx of imperial-size goods as overflow 'left over' from US-market production runs. This has caused unnecessary (and unhelpful) duplication of close-sized goods in both imperial and metric. Thus, it's not uncommon to go into a large hardware store and see shelves of nuts and bolts duplicated in both imperial and metric (6mm => 1/4" and so on).

If or when the US converts to metric, it seems to me that these lessons need to be learned from conversion in other countries. With the fact that the US is a special case, in that the imperial system is so strongly ingrained in the culture. It's clear the conversion in the US will have to be very carefully administered to avoid a backlash. [This, of course, is not new; when France first introduced the metric system, it was proposed that time be metrified (10 hours per day, etc.) and even today some metric clocks still exist from that time, but that was too much for many and it was never implemented (you'll note the same goes for angular/circular measurement, 90° per quadrant and 360° per circle still remains).]

Incidentally, by sheer happenstance, earlier today in connection with another matter altogether, I was reading the preface in one of my old mathematics textbooks, that being Calculus by Stanley I Grossman, first edition 1977 [43 years ago] and I came across an interesting comment that's pertinent to this discussion. I quote:

"… Moreover, I have included "real-world" data whenever possible, to make the examples more meaningful. For example, students are asked to find the escape velocity from Mars, the effective installment rate of a large purchase, and the optimal branching angle between two blood vessels. Finally, as most of the world uses the metric system and even the United States is reluctantly following suit, the m...