[delta_p_delta_x]

> In the US that is, not in metric counties that use the SI system by default.

India which metricated in the late 1950s is still a big (ab)user of poor SI symbolism. A lot of the 'cms', 'gms', 'cc', 'kgs', etc come from Indian writers and Indian publications (case in point: the article in this thread).

> The other notable system that's still in use is the cgs (centimetre–gram–second) system.

> 'cgs units' are still used in some areas notably physics as they can make calculations easier, there they're called Gaussian-cgs units.

I'm not sure they're used all that much—I was under the impression most CGS units fell out of favour as MKS and eventually SI took over. I was an RA at my physics department for a while and we used SI as much as we could. Some specialisations use a certain form of natural units (like geometrised units in general relativity), but by and large SI dominated.

[hilbert42]

Right, there are offenders everywhere but the chief offender is the US by far (many don't have a clue about SI let alone metric, ask an American what 20°C is in Fahrenheit and they've no idea).

The UK is also troublesome in that whilst supposedly a metric country Imperial is still commonplace. For example, there's widespread use of antiquated units like the 'stone' (14 pounds)†, even BBC medical programs still regularly use the term.

Re Gaussian/cgs, in physics it's still widely used especially in field theory/Maxwell, SR (Special Relatively), etc. because in charge calculations and such involving permeability, permittivity, speed of light certain terms can be restated as 1 instead of their actual SI values.

Personally, I understand why this is done but from my perspective it's confusing if not misleading for reasons well outside this discussion (but who am I to argue with those more learned than me?). This Wiki provides justification of sorts (see Unit of charge): https://en.m.wikipedia.org/wiki/Gaussian_units.

† In Australia where I am, only people of my generation who've been around for decades would even know what a 'stone' was. Anyone born after say the mid 1970s would likely think you're talking about a rock. Trouble is, we see BBC/UK programs here. Fact is the UK is oblivious to the problem or it'd first correct its exports.

[spauldo]

Why would your average American need to know what 20°C is in Fahrenheit? Very few people use Celsius here. All our appliances use Fahrenheit, weather reports use Fahrenheit, our recipes use Fahrenheit, and for science and physics we use Kelvin.