Kilogram conflict resolved at last

[OrbitalDawn]

After a fraught few years, experiments to redefine the unit have reached agreement.

For decades, metrologists have strived to retire ‘Le Grand K’ — the platinum and iridium cylinder that for 126 years has defined the kilogram from a high-security vault outside Paris. Now it looks as if they at last have the data needed to replace the cylinder with a definition based on mathematical constants.

The breakthrough comes in time for the kilo*gram to be included in a broader redefinition of units — including the ampere, mole and kelvin — scheduled for 2018. And this week, the International Committee for Weights and Measures (CIPM) will meet in Paris to thrash out the next steps.

“It is an exciting time,” says David Newell, a physicist at the US National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland. “It is the culmination of intense, prolonged efforts worldwide.”

The kilogram is the only SI unit still based on a physical object. Although experiments that could define it in terms of fundamental constants were described in the 1970s, only in the past year have teams using two completely different methods achieved results that are both precise enough, and in sufficient agreement, to topple the physical definition.

Redefinition will not make the kilogram more precise, but it will make it more stable. A physical object can lose or gain atoms over time, or be destroyed, but constants remain the same. And a definition based on constants would, at least in theory, allow the exact kilogram measure to be available to someone anywhere on the planet, rather than just those who can access the safe in France, says Richard Davis, former head of the mass division of the International Bureau of Weights and Measures (BIPM) in Sèvres, France, which hosts the metal kilogram.

 

[StellenboschStudent]

It is an exciting time

I just cannot keep it in!

 

[Pitbull]

I always thought Kilogram was determined by fresh water quantity.

1ml = 1g

1000ml = 1Kg.

Just not sure if Litre or Kg came first in that scenario. That's interesting, ty Orbital.

 

[ScottulusMaximus]

I always thought Kilogram was determined by fresh water quantity.

1ml = 1g

1000ml = 1Kg.

Just not sure if Litre or Kg came first in that scenario. That's interesting, ty Orbital.

1mL of water isn't always 1g, it changes with temperature.

 

[Hamish McPanji]

I would not give a £ what the US physicist says, let alone 2 pence

 

[StellenboschStudent]

I always thought Kilogram was determined by fresh water quantity.

1ml = 1g

1000ml = 1Kg.

Just not sure if Litre or Kg came first in that scenario. That's interesting, ty Orbital.

That depends on the liquid. 1000ml of normal tap water isn't equal to 1kg, a bit more, due to all the impurities.
With DI-water, it is true (I think), more or less.

1L is quantified as the volume inside 10cm x 10cm x 10cm.

 

[Pitbull]

1mL of water isn't always 1g, it changes with temperature.

I recall reading about it a few years ago that they actually used water to determine weight of things for building in some age of engineering. I never knew they had something stored somewhere as a standard measure .

 

[LazyLion]

So do I still need to go on a diet, or what?

 

[Drifter]

That's it. I am a fulfilled man.

 

[ToxicBunny]

I recall reading about it a few years ago that they actually used water to determine weight of things for building in some age of engineering. I never knew they had something stored somewhere as a standard measure .

Here it is....

 

[Garson007]

Time for a new set of units, all defined by constants. Will be interesting to see my weight loss in Plancks. xD

 

[ScottulusMaximus]

I recall reading about it a few years ago that they actually used water to determine weight of things for building in some age of engineering. I never knew they had something stored somewhere as a standard measure .

Have a watch of BBC Precision: The Measure Of All Things, documentaries on how we measure everything, here's the second episode for Mass:

[video=youtube;GqTB7mLpiQY]https://www.youtube.com/watch?v=GqTB7mLpiQY[/video]

There's 3 episodes, "Heat, Light and Electricity", "Mass and Moles" and "Time and Distance"

 

[Pitbull]

Have a watch of BBC Precision: The Measure Of All Things, documentaries on how we measure everything, here's the second episode for Mass:

[video=youtube;GqTB7mLpiQY]https://www.youtube.com/watch?v=GqTB7mLpiQY[/video]

There's 3 episodes, "Heat, Light and Electricity", "Mass and Moles" and "Time and Distance"

Thanks will watch these tonight from home.

 

[envo]

but constants remain the same

No ****. It's in the definition of the word

 

[Ho3n3r]

No ****. It's in the definition of the word

It was put in so that the 'Mericans can also understand.

 

[satanboy]

I am mildly moist.

 

[LazyLion]

I am mildly moist.

It's that Cape Town weather. Get an umbrella.

 

[ToxicBunny]

Have a watch of BBC Precision: The Measure Of All Things, documentaries on how we measure everything, here's the second episode for Mass:

[video=youtube;GqTB7mLpiQY]https://www.youtube.com/watch?v=GqTB7mLpiQY[/video]

There's 3 episodes, "Heat, Light and Electricity", "Mass and Moles" and "Time and Distance"

Those were fantastic, must actually watch them again.