Good news… it’s finally happened!

A wise man once said:

Utilisez le Système International d’Unités ou mourez, foutreurs des meres!

https://www.bipm.org/utils/common/pdf/SI-statement.pdf

Even in this anti-expert age, there are some experts who can get their $#!+ together and reach consensus.

https://www.bipm.org/en/publications/si-brochure/

The International System of Units, the SI, is the system of units in which

• the unperturbed ground state hyperfine transition frequency of the caesium 133 atom ∆ν_Cs is 9 192 631 770 Hz,
• the speed of light in vacuum c is 299 792 458 m/s,
• the Planck constant h is 6.626 070 15 × 10⁻³⁴ J s,
• the elementary charge e is 1.602 176 6 34 × 10⁻¹⁹ C,
• the Boltzmann constant k is 1.380 649 × 10⁻²³ J/K,
• the Avogadro constant N_A is 6.022 140 76 × 10²³ mol⁻¹,
• the luminous efficacy of monochromatic radiation of frequency 540 × 10¹² Hz, K_cd, is 683 lm/W.

https://www.bipm.org/en/measurement-units/

Congratulations, all.

In my opinion:

1)
the new definitions more or less remove the need for Avogadro’s number, or related concepts such as the mole.

2)

Kcd has no place in this list, as it pertains to average human perception and hence a) at the risk of stating the obv, is entirely antrhopocentric and b) glosses over the fact that different humans have different response curves. It has no more place in this list than, say, the scoville or the phon.

SCIENCE said:

Good news… it’s finally happened!

A wise man once said:

Utilisez le Système International d’Unités ou mourez, foutreurs des meres!

https://www.bipm.org/utils/common/pdf/SI-statement.pdf

Even in this anti-expert age, there are some experts who can get their $#!+ together and reach consensus.

https://www.bipm.org/en/publications/si-brochure/

The International System of Units, the SI, is the system of units in which

• the unperturbed ground state hyperfine transition frequency of the caesium 133 atom ∆ν_Cs is 9 192 631 770 Hz,
• the speed of light in vacuum c is 299 792 458 m/s,
• the Planck constant h is 6.626 070 15 × 10⁻³⁴ J s,
• the elementary charge e is 1.602 176 6 34 × 10⁻¹⁹ C,
• the Boltzmann constant k is 1.380 649 × 10⁻²³ J/K,
• the Avogadro constant N_A is 6.022 140 76 × 10²³ mol⁻¹,
• the luminous efficacy of monochromatic radiation of frequency 540 × 10¹² Hz, K_cd, is 683 lm/W.

https://www.bipm.org/en/measurement-units/

Congratulations, all.

Beautifully summarised. So the Planck constant is used to define the kilogram, who would have thunk it?

I had occasion recently to need a unit that wasn’t related to any of those, for some obscure purpose. ie. a unit outside the scope of the SI. If I remember why, I’ll let you know. Perhaps …

The Gray and the Sievert are both SI units and both given in units J/kg. But they are different.

Am I making sense here?

What would the SI unit be for Sieverts per Gray?

SCIENCE said:

Good news… it’s finally happened!

A wise man once said:

Utilisez le Système International d’Unités ou mourez, foutreurs des meres!

https://www.bipm.org/utils/common/pdf/SI-statement.pdf

Even in this anti-expert age, there are some experts who can get their $#!+ together and reach consensus.

https://www.bipm.org/en/publications/si-brochure/

The International System of Units, the SI, is the system of units in which

• the unperturbed ground state hyperfine transition frequency of the caesium 133 atom ∆ν_Cs is 9 192 631 770 Hz,
• the speed of light in vacuum c is 299 792 458 m/s,
• the Planck constant h is 6.626 070 15 × 10⁻³⁴ J s,
• the elementary charge e is 1.602 176 6 34 × 10⁻¹⁹ C,
• the Boltzmann constant k is 1.380 649 × 10⁻²³ J/K,
• the Avogadro constant N_A is 6.022 140 76 × 10²³ mol⁻¹,
• the luminous efficacy of monochromatic radiation of frequency 540 × 10¹² Hz, K_cd, is 683 lm/W.

https://www.bipm.org/en/measurement-units/

Congratulations, all.

No worries.

dv said:

In my opinion:

1)
the new definitions more or less remove the need for Avogadro’s number, or related concepts such as the mole.

2)

Kcd has no place in this list, as it pertains to average human perception and hence a) at the risk of stating the obv, is entirely antrhopocentric and b) glosses over the fact that different humans have different response curves. It has no more place in this list than, say, the scoville or the phon.

Couldn’t we keep Avogadro’s number, and drop something else?

It just seems like a nice intuitive and basic sort of unit to me :)

The Rev Dodgson said:

dv said:

In my opinion:

1)
the new definitions more or less remove the need for Avogadro’s number, or related concepts such as the mole.

2)

Kcd has no place in this list, as it pertains to average human perception and hence a) at the risk of stating the obv, is entirely antrhopocentric and b) glosses over the fact that different humans have different response curves. It has no more place in this list than, say, the scoville or the phon.

Couldn’t we keep Avogadro’s number, and drop something else?

It just seems like a nice intuitive and basic sort of unit to me :)

It’s just a number…

dv said:

The Rev Dodgson said:

dv said:

In my opinion:

1)
the new definitions more or less remove the need for Avogadro’s number, or related concepts such as the mole.

2)

Kcd has no place in this list, as it pertains to average human perception and hence a) at the risk of stating the obv, is entirely antrhopocentric and b) glosses over the fact that different humans have different response curves. It has no more place in this list than, say, the scoville or the phon.

Couldn’t we keep Avogadro’s number, and drop something else?

It just seems like a nice intuitive and basic sort of unit to me :)

It’s just a number…

It’s the measurement for it smashed on toast isn’t it.

My favourite unit of measures is the Couric

dv said:

The Rev Dodgson said:

dv said:

In my opinion:

1)
the new definitions more or less remove the need for Avogadro’s number, or related concepts such as the mole.

2)

Kcd has no place in this list, as it pertains to average human perception and hence a) at the risk of stating the obv, is entirely antrhopocentric and b) glosses over the fact that different humans have different response curves. It has no more place in this list than, say, the scoville or the phon.

Couldn’t we keep Avogadro’s number, and drop something else?

It just seems like a nice intuitive and basic sort of unit to me :)

It’s just a number…

A nice intuitive and basic sort of number, nonetheless.

The Rev Dodgson said:

dv said:

The Rev Dodgson said:

Couldn’t we keep Avogadro’s number, and drop something else?

It just seems like a nice intuitive and basic sort of unit to me :)

It’s just a number…

A nice intuitive and basic sort of number, nonetheless.

Right and there are few useful numbers like that, but it is not a fundamental physical unit like the meter or the second.

“…the meter…”

oh dear.

dv said:

The Rev Dodgson said:

dv said:

It’s just a number…

A nice intuitive and basic sort of number, nonetheless.

Right and there are few useful numbers like that, but it is not a fundamental physical unit like the meter or the second.

OK, furry nuff.

To be honest, I’d have to do a fair bit of reading to remind myself how they all work anyway.

ChrispenEvan said:

“…the meter…”

oh dear.

It was a measured response.

sibeen said:

ChrispenEvan said:

“…the meter…”

oh dear.

It was a measured response.

maybe, but if you give DV an inch he’ll take a mile.

ChrispenEvan said:

sibeen said:

ChrispenEvan said:

“…the meter…”

oh dear.

It was a measured response.

maybe, but if you give DV an inch he’ll take a mile.

He’s worse than that.

He’ll take a kilometer if given a centimetre.

Cymek said:

dv said:

The Rev Dodgson said:

Couldn’t we keep Avogadro’s number, and drop something else?

It just seems like a nice intuitive and basic sort of unit to me :)

It’s just a number…

It’s the measurement for it smashed on toast isn’t it.

My favourite unit of measures is the Couric

The what?

Ah, https://en.m.wikipedia.org/wiki/More_Crap#Plot

But what had Katie Couric ever done to deserve such an honour?

SCIENCE said:

Good news… it’s finally happened!

A wise man once said:

Utilisez le Système International d’Unités ou mourez, foutreurs des meres!

https://www.bipm.org/utils/common/pdf/SI-statement.pdf

Even in this anti-expert age, there are some experts who can get their $#!+ together and reach consensus.

https://www.bipm.org/en/publications/si-brochure/

The International System of Units, the SI, is the system of units in which

• the unperturbed ground state hyperfine transition frequency of the caesium 133 atom ∆ν_Cs is 9 192 631 770 Hz,
• the speed of light in vacuum c is 299 792 458 m/s,
• the Planck constant h is 6.626 070 15 × 10⁻³⁴ J s,
• the elementary charge e is 1.602 176 6 34 × 10⁻¹⁹ C,
• the Boltzmann constant k is 1.380 649 × 10⁻²³ J/K,
• the Avogadro constant N_A is 6.022 140 76 × 10²³ mol⁻¹,
• the luminous efficacy of monochromatic radiation of frequency 540 × 10¹² Hz, K_cd, is 683 lm/W.

https://www.bipm.org/en/measurement-units/

Congratulations, all.

How is the Dalton ~ amu ~ unified amu affected by the SI changes?