All metrology articles
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News
Warnings that US national standards facilities are in ‘alarming physical condition’
Leaks, power outages and repeated equipment repairs mean Nist needs as much as $6.6bn in upgrades, National Academies analysis says
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News
SI units get new prefixes for huge and tiny numbers
Ronna, quetta, ronto and quecto are the first new prefixes for the metric system in 30 years
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Opinion
Callendar’s platinum thermometer
Solving the hot topic of accurate and reproducible temperature measurement
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Research
A new way to measure pressure is born from efforts to redefine temperature
20 years after the idea was first dreamt up, scientists can now realise the SI unit Pascal by measuring helium’s electrical properties
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News
King of kilograms is no more as metric system gets a makeover
Metre convention countries have agreed to redefine four of the seven SI base units and link them to immutable natural constants
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Opinion
What’s in a number?
Redefining the mole is more than just bean-counting – it helps people reconnect with chemistry
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News
Textbooks need an update after mole's definition changed
Although little will change in practice, Iupac’s new definition of a mole has gained support from (almost) all sides
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News
Game over for the original kilogram
The big K has performed admirably for over a century but all the data is in to redefine the kilogram using natural constants
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Research
Purest silicon sphere ever created will redefine the kilogram
Largest impurity is copper taking the place of one silicon atom in every three billion
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News
Union worries that jobs will be lost at NPL
Cuts could hit 9% of scientists at the UK’s National Physical Laboratory as research strategy shifts
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Research
Refining Avogadro’s number on way to new kilo
Most precise value yet reduces uncertainty down to 20 atoms in a billion
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Research
Neutron–proton mass imbalance put on the quantum scales
Mass difference between nucleons calculated to the highest level of precision yet
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Research
Supermarket scales for the microscopic world
New technique can weigh red blood cells, pollen grains and cancer cells