4 ms·

I guess the next redefinition will happen if and when there's detectable drift in "fundamental" constants?

reaperducer 8y ago
I guess the next redefinition will happen if and when there's detectable drift in "fundamental" constants? And until then, all the metric fanbois will constantly tell you that metric is superior to imperial because its measurements are immutable. Until suddenly they are.
- nafey 8y ago
  As opposed imperial constants? How is a foot standardized anyway? I suspect most manufactures rely on SI metrics for that.
  - tialaramex 8y ago
    There are no other standards. Metrology is expensive and doing it over again would offer no benefit whatsoever. All prior standards in widespread use were abandoned during the 20th century in favour of defining the relevant units in terms of SI units. Specifically the international yard equals 0.9144 meters and the international pound equals 0.45359237 kilograms There literally isn't another definition, in the US when you say "100 yards" the only legal meaning that has is 91.44 metres, which is whatever CGPM / BIPM says it is.
  - ska 8y ago
    Foot is defined as 0.3048 meters, you can't get away from the SI definitions.
- redial 8y ago
  I've never heard anyone claim that as the reason for its superiority. Metric is superior because it makes sense as a system.
  - khawkins 8y ago
    1/2 m = 50.00 cm, 1/2 ft = 6 in 1/3 m = 33.33 cm, 1/3 ft = 4 in 1/4 m = 25.00 cm, 1/4 ft = 3 in 1/6 m = 16.67 cm, 1/6 ft = 2 in This is why imperial makes more sense to me than metric. If we had a base-12 number system, metric would be perfect, but base-10 is terrible under division. For practical divisors like these, imperial shines. If you're doing science, metric makes more sense because units work out. But most all US science has already adopted metric.
    - OscarCunningham 8y ago
      You might be right for length, but 1st = 14lb is even less convenient than a factor of 10.
    - pbhjpbhj 8y ago
      Something is 3ft x 3/8in, what area is that? Something is 3m x 0.3cm, what area is that? If that's one internal face of a container what width will hold a pint/litre respectively?
    - redial 8y ago
      I won't disagree with you on this because you'll always feel more comfortable with something if you've been using your whole life. For example, I would never understand why you think 1/2ft = 6in is simpler when you have to know in advance that 1ft = 12in. It could be because I'm not used to it. Using the metric system you'll rarely write 1/2m, as fractions are not what a person used to metric would default to. That is why 1/6m looks so weird as no one would use it like that, but if you write it 0.5m now it's obvious we are talking about 50cm, or 500mm. BUT, In those examples you are not using the system, you are just using one unit. If the question were, for example, what is the mass of the water contained in a 1m x 1m x 1m box, then the answer is obvious which system is by far the most sane one.
      - Jach 8y ago
        > If the question were, for example, what is the mass of the water contained in a 1m x 1m x 1m box, then the answer is obvious which system is by far the most sane one. You're not disagreeing, the GP said > If you're doing science, metric makes more sense because units work out. But most all US science has already adopted metric. Your question asks for mass of a cubic meter of water, presupposing a typically scientific quantity (mass, instead of weight) and presupposing that a cubic meter (why not a cubic foot?) of water is a useful collection of water for some purpose. Fine, use metric. But imperial units as a system are made for practical everyday utility, which your example doesn't presuppose. On the other hand if we imperial users run across a situation where metric seems more useful, fortunately we can precisely convert, so it doesn't really matter. In other places of utility (such as engineering disciplines) adopting a unit agnostic approach is the best. Some fields don't use either imperial or metric units but their own domain specific things, and software can always present units in whatever preference someone has or whatever is the most useful for the moment.
- ska 8y ago
  You are confused, arguments about the benefits or lack thereof of metric are based on internal consistency, not standards and metrology. Nobody is arguing against more precise definition of standard values, which is why Imperial units these days are themselves defined in terms of SI units. So if the meter were to change, for example, so would the US foot.
mherdeg 8y ago
The kilogram was the last one -- we're out of SI base units. This was the last one not defined based on some measurable universal constant, per https://en.wikipedia.org/wiki/SI_base_unit https://en.wikipedia.org/wiki/SI_base_unit and https://en.wikipedia.org/wiki/Redefinition_of_SI_base_units https://en.wikipedia.org/wiki/Redefinition_of_SI_base_units . The meter was originally an actual physical rod (you can see the prototype on display at the fascinating French Musée des Arts et Métiers). Now it's based on the speed of light in a vacuum. The kilogram was a physical mass (and, yes, it was evaporating). Now it's finally defined in terms of the Planck constant, the second, and the meter. The second was originally 1/86400th of Earth's day. Now it's based on the radiation of cesium-133 (I don't really understand how this is measured). The ampere was originally defined based on depositing milligrams of silver from a solution of silver nitrate; it's now based on newtons and meters. The kelvin was originally defined based on water; it's still defined based on water. The mole hasn't really changed much? It's based on the number of atoms in a kilogram of carbon. The candela was originally based on a literal standard amount of light emitted by candles made from dead whales; now it's based on radiation from light sources of a specific frequency and an intensity based on the watt (which relies on kilograms, meters, and seconds).
- fengb 8y ago
  Mole was just redefined as exactly 6.02214076e23 — the number of Si-28 atoms in a perfect 1 kg sphere. This was an intentionally check against the kibble balance measurement. More info from an older Veritasium video: https://www.youtube.com/watch?v=ZMByI4s-D-Y https://www.youtube.com/watch?v=ZMByI4s-D-Y
  - mherdeg 8y ago
    Yeah, I had totally missed that a change was in the works to redefine Avogardo's number as an exact number with no uncertainty. Pretty cool.

I guess the next redefinition will happen if and when there's detectable drift in "fundamental" constants? And until then, all the metric fanbois will constantly tell you that metric is superior to imperial because its measurements are immutable. Until suddenly they are.

nafey 8y ago
As opposed imperial constants? How is a foot standardized anyway? I suspect most manufactures rely on SI metrics for that.
- tialaramex 8y ago
  There are no other standards. Metrology is expensive and doing it over again would offer no benefit whatsoever. All prior standards in widespread use were abandoned during the 20th century in favour of defining the relevant units in terms of SI units. Specifically the international yard equals 0.9144 meters and the international pound equals 0.45359237 kilograms There literally isn't another definition, in the US when you say "100 yards" the only legal meaning that has is 91.44 metres, which is whatever CGPM / BIPM says it is.
- ska 8y ago
  Foot is defined as 0.3048 meters, you can't get away from the SI definitions.
redial 8y ago
I've never heard anyone claim that as the reason for its superiority. Metric is superior because it makes sense as a system.
- khawkins 8y ago
  1/2 m = 50.00 cm, 1/2 ft = 6 in 1/3 m = 33.33 cm, 1/3 ft = 4 in 1/4 m = 25.00 cm, 1/4 ft = 3 in 1/6 m = 16.67 cm, 1/6 ft = 2 in This is why imperial makes more sense to me than metric. If we had a base-12 number system, metric would be perfect, but base-10 is terrible under division. For practical divisors like these, imperial shines. If you're doing science, metric makes more sense because units work out. But most all US science has already adopted metric.
  - OscarCunningham 8y ago
    You might be right for length, but 1st = 14lb is even less convenient than a factor of 10.
  - pbhjpbhj 8y ago
    Something is 3ft x 3/8in, what area is that? Something is 3m x 0.3cm, what area is that? If that's one internal face of a container what width will hold a pint/litre respectively?
  - redial 8y ago
    I won't disagree with you on this because you'll always feel more comfortable with something if you've been using your whole life. For example, I would never understand why you think 1/2ft = 6in is simpler when you have to know in advance that 1ft = 12in. It could be because I'm not used to it. Using the metric system you'll rarely write 1/2m, as fractions are not what a person used to metric would default to. That is why 1/6m looks so weird as no one would use it like that, but if you write it 0.5m now it's obvious we are talking about 50cm, or 500mm. BUT, In those examples you are not using the system, you are just using one unit. If the question were, for example, what is the mass of the water contained in a 1m x 1m x 1m box, then the answer is obvious which system is by far the most sane one.
    - Jach 8y ago
      > If the question were, for example, what is the mass of the water contained in a 1m x 1m x 1m box, then the answer is obvious which system is by far the most sane one. You're not disagreeing, the GP said > If you're doing science, metric makes more sense because units work out. But most all US science has already adopted metric. Your question asks for mass of a cubic meter of water, presupposing a typically scientific quantity (mass, instead of weight) and presupposing that a cubic meter (why not a cubic foot?) of water is a useful collection of water for some purpose. Fine, use metric. But imperial units as a system are made for practical everyday utility, which your example doesn't presuppose. On the other hand if we imperial users run across a situation where metric seems more useful, fortunately we can precisely convert, so it doesn't really matter. In other places of utility (such as engineering disciplines) adopting a unit agnostic approach is the best. Some fields don't use either imperial or metric units but their own domain specific things, and software can always present units in whatever preference someone has or whatever is the most useful for the moment.
ska 8y ago
You are confused, arguments about the benefits or lack thereof of metric are based on internal consistency, not standards and metrology. Nobody is arguing against more precise definition of standard values, which is why Imperial units these days are themselves defined in terms of SI units. So if the meter were to change, for example, so would the US foot.

mherdeg 8y ago

The kilogram was the last one -- we're out of SI base units. This was the last one not defined based on some measurable universal constant, per https://en.wikipedia.org/wiki/SI_base_unit https://en.wikipedia.org/wiki/SI_base_unit and https://en.wikipedia.org/wiki/Redefinition_of_SI_base_units https://en.wikipedia.org/wiki/Redefinition_of_SI_base_units . The meter was originally an actual physical rod (you can see the prototype on display at the fascinating French Musée des Arts et Métiers). Now it's based on the speed of light in a vacuum. The kilogram was a physical mass (and, yes, it was evaporating). Now it's finally defined in terms of the Planck constant, the second, and the meter. The second was originally 1/86400th of Earth's day. Now it's based on the radiation of cesium-133 (I don't really understand how this is measured). The ampere was originally defined based on depositing milligrams of silver from a solution of silver nitrate; it's now based on newtons and meters. The kelvin was originally defined based on water; it's still defined based on water. The mole hasn't really changed much? It's based on the number of atoms in a kilogram of carbon. The candela was originally based on a literal standard amount of light emitted by candles made from dead whales; now it's based on radiation from light sources of a specific frequency and an intensity based on the watt (which relies on kilograms, meters, and seconds).

fengb 8y ago
Mole was just redefined as exactly 6.02214076e23 — the number of Si-28 atoms in a perfect 1 kg sphere. This was an intentionally check against the kibble balance measurement. More info from an older Veritasium video: https://www.youtube.com/watch?v=ZMByI4s-D-Y https://www.youtube.com/watch?v=ZMByI4s-D-Y
- mherdeg 8y ago
  Yeah, I had totally missed that a change was in the works to redefine Avogardo's number as an exact number with no uncertainty. Pretty cool.