Is that imperial lightyear or survey lightyear?
It makes sense when you think about it, defining a unit of mass pretty easy, all you need to do take a lump of metal and say ‘from now on this one kg/pound/slug/whatever’.
But force? How would you define a unit of force without referring to a unit of mass?
Here in Europe we also use inches for tv’s. I really don’t remember when this started exactly, but at some point they switched from cm to inches.
This has got to be one of the signs of the apocalypse.
We’ll be switching to cubits next…
Yes. in 1971, British currency became sane - 100 ‘New Pence’ to a pound. In 1981, the ‘New’ prefix was dropped, when they weren’t really new any more.
Yeah, but, I don’t think we are. That is, in many ways we are, but a machine shop in the US is typically somewhere between 100% English and dual versions of every tool that has a size (drills, taps, reamers, collets, punches, and the like). I hear that in Europe the machine shops have only one version of sized items, and never have to make adapters or stock twice as many fasteners. Way simpler! I also often buy instruments that are in some way optimized for English units (for example a transducer goes from 0 to 10 volts with 0 to 10 psi pressure input). Pressure gages, flowmeters, force gages, and similar things are generally made in two separate product lines, English and SI. And it is still pretty typical for a hardware store to have a big selection of “normal” fasteners like 1/4-20 nuts, and then a limited selection of nuts that are “special”, such as acorn nuts, and nylon locking nuts, and jam nuts, and castellated nuts, and metric nuts, like being metric is obscure.
They left that one out of the sacred text that is “Ghostbusters”, but it sounds legit
While that’s true, there are two things to consider: (1) legacy applications, and (2) commercial advantage. In the case of (1), Canada, for example has been metric since the 70’s, but yet they still have so much legacy use that they’ll never really shake the metric system. The machine shops that I’ve been to there still have to support both metrics anyway. For (2), I’m often a commercial consumer of machine shop services (my company is nearly 100% SI), and I don’t really care what the machine shop does internally as long as they’re able to compete, i.e., give me what I need on time and on budget.
Remember how I said my company was “nearly” 100% SI? Yeah, our tooling is all metric, and our products are all metric, but a lot of our gages are still US (yeah, even in Canada and Mexico). We’re getting a lot better, but even I have some resistance to leaving behind psi and pounds-force. And that’s not because I can’t deal in newtons, but for my entire career I’ve known that I need x pounds for y thickness, for example.
I had forgotten about things like “number 8 wood screws”, which use neither U.S. customary units nor metric (S.I.) units.
They’re kinda like dress sizes, I guess. Although there’s a hell of a lot more standardization in wood-screw sizes than there is in dress sizes.
Newspapers do, from time to time:
I need that Simpsons “That’s the Joke” picture. 
NZ has been metric since the early 70s – when I was a kid – and I use metric for everything… well except some people’s heights… and see nothing wrong with being 6’ 4" and 118 kg… well, nothing wrong other than being overweight. 
My son, on the other hand, is currently about 140 cm… I must be finally getting the hang of this metric thing.
All well and good for you, but it’s a pain for the machine shop. Besides, the only resources they can bring to bear on all that extra hassle and expense are the prices they charge and the service they provide.
To some degree the choice of units is arbitrary, especially if you don’t use any math that relies on the coherence of unit systems (that property that makes many equations require no constant parameters, like F=m•a, in coherent systems like the SI).
What isn’t arbitrary, and what is arguably the only wrong way to go about doing it, is to maintain multiple unit systems. It COSTS.
Yeah, maybe it costs, but there are worse costs. Maybe the machine shop can decide they’re not going to do any SI work, and make things cheaper for them. The new cost is the loss of all of the SI work. Or maybe they want to be pioneering, and make a purely emotional, non-logical decision to be exclusively an SI shop. That will have a huge cost in the loss of US units work. It’s an economic decision, pure and simple. Their competition has to make the same decisions. The fact that there is competition will limit the costs associated with both systems. Not until the incentives for going 100% SI are greater than costs will anyone switch.
There simply aren’t enough incentives for a switch. It won’t do anyone any good that hasn’t discovered the incentives already for himself, and has already switched. Saying “let’s post speed limits in kilometers” doesn’t serve anyone except for sign makers and post hole diggers.
In Sweden we use cubic metres when buying heating oilf for our houses.
As far as I know we have never used centimetres. It’s always been inches.
UPDATE:
I’ve uploaded a higher-quality version of this video to YouTube, with easier-to-read text in the graphics and balanced audio. It’s here:
As a result, I have DELETED the original video link I posed in the OP. Please use the new link to watch this video instead.
In Switzerland they still use inches for garden hoses and plumbing pipes from times immemorial :rolleyes:
Funny SNL skit about it: https://www.youtube.com/watch?v=JYqfVE-fykk
Referring all the way back to the OP - Troy pounds are a thing in the silver collecting world. A Troy pound bar is worth about $1800 now.
I don’t see how kelvin fixes that. You could just as well say “574 K minus 573 K is 1 K. But that’s liquid helium temperature, and we were talking about something hot!”. Kelvin definitely matters when you’re multiplying or dividing temperatures, but when you’re subtracting them, the Celsius (or Fahrenheit) offset goes away anyway.
Meanwhile, for all that people talk about the powers-of-ten thing, that’s only like #4 on the list of why metric is better than the “customary system”. The complaint in the OP’s video, that so many different units have the same name, is #1. And it’s not a problem until it is, which does happen sometimes, and then it’s a huge problem.
Celsius is vastly overrated compared to Fahrenheit. Also square/cubic foot is better than square/cubic meter. Other than that the metric system is superior.