An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
The following resources may be used by media outlets when reporting on the SI redefinition. Videos should be credited to NIST. Photos should include the appropriate credit.
Scientists Vote on Metric Makeover
After decades of groundbreaking laboratory work, the world’s scientific and technical community has redefined four of the seven base units for the International System of Units (SI). A vote to adopt the change took place on November 16, 2018, at Versailles, France. The affirmative vote means the kilogram (mass), kelvin (temperature), ampere (electric current) and mole (amount of substance) are now determined by fundamental constants of nature instead of by physical objects. This historic change is the largest single shift in international measurement since the Treaty of the Meter was signed in 1875. Scientists expect this change will spur technological innovation and lower the cost of many high-tech manufacturing processes.
Scientists to Vote on Metric Makeover - English Full
Scientists to Vote on Metric Makeover - Portuguese
In Portuguese.
The video above was produced by the National Institute of Standards and Technology.
Writer/Director: José Ricardo García · Producers: Leon Gerskovic, Robin Materese · Executive Producers: Kevin Kimball, Gail Porter · Scientific Adviser: Ben Stein · Animation by Fugu GFX (fugu-gfx.squarespace.com) · Director of Animation: Ariel Martian · Producer of Animation: Jodie Baltazar · Art Director/Illustrator/Animator: Ariel Martian · 3D Artist: Talon Nightshade · Animatics Editor: Jodie Baltazar · Illustrator: Songgu Kwon · Post Production Sound Services by Studio Unknown · Re-recording Mixer: Kevin Hill, CAS · Sound Designer/ Sound Effects Editor: Cazz Cerkez · Dialogue Editor: Kevin Hill · Audio Post Coordinator: Jaime Horrigan · Audio Post Office Manager/Voice Casting: Mandisa Henry · Original Music by: Cazz Cerkez
NIST's platinum-iridium kilogram K92 (front) with stainless-steel kilogram masses in the background.
Credit:
J.L. Lee/NIST
Michael Moldover and an acoustic resonator he and his colleagues developed for making some of the world's most accurate measurements of the Boltzmann constant. Read more about Mike's work in this blog post.
Credit:
NIST
The NIST-4 watt balance has measured Planck's constant to within 34 parts per billion, demonstrating that the high-tech scale is accurate enough to assist with 2018's planned redefinition of the kilogram.
Credit:
J. L. Lee / NIST
NIST's Eddie Mulhern holding K92, one of the agency's kilogram masses.
Credit:
J.L. Lee/NIST
This wallet card displays the fundamental constants and other physical values that will define a revised international system of units.
Credit:
Stoughton/NIST
Single-electron transport (SET) chip that could be used to count electrons in a redefined ampere.
Looking to interview someone from NIST about the SI Redefinition? Contact jennifer.huergo [at] nist.gov (subject: SI%20Redefinition%20Interview%20Request) (Jennifer Huergo) (301-975-6343) or bstein [at] nist.gov (subject: SI%20Redefinition%20Interview%20Request) (Ben Stein) (301-975-2763).
