The kg is dead, long live the kg Electromagnetic Levitation Quadcopter 1 day ago   09:58

The kilogram, mole, kelvin, and ampere will be redefined by physical constants. For a limited time, get 3 months of Audible for just $6.95 a month: or text VERITASIUM to 500500

Will this be the last video I make about SI units? Quite possibly. There's something about being so precise and defining the systems within which science works. When we can more accurately and routinely measure a kilogram, a mole, a kelvin and an ampere, then we can make better observations, we can better detect anomalies and improve our theories. That is why this is so important to me.

Special thanks to Patreon supporters:
Donal Botkin, Michael Krugman, Ron Neal, Nathan Hansen, James M Nicholson, Terrance Shepherd, Stan Presolski

Special thanks to NIST:

Additional graphics by Ignat Berbeci

Music from "Experimental1"

Comments 6387 Comments

Saravanakumar Muthusamy
and this is the day, the change enforced.
Hey Derek, happy World Metrology Day as we say goodbye to "Le Grank K!"
saroj baral
Then what is the new definition??
Anuraag Rapaka
does measuring mass with that balance in 4:56 , have a difference when measured in different places on earth and also differ in vacuum??
John Weber
Fallen kingdom was better
Amrit Mehta
I'm trying to imagine the 14 people in the world who will go like
"OMG the volt value changed by one part in 10 million! MY LIFE IS RUINED!"
Police Officer
Don't mind me, I'm just learning what it is I have to vote for tomorrow.
Game of life update:
Minor bug fixes
Alex Madsen
why is the Headlline and description in Danish?!

We redefined kg

"stays the same"
It's happening!!
The Physicist Cuber
-2 DAYS (UTC+1 time zone)
John Cabacungan
Long live the kilogram
loys zimmermann
One must hope that constants are... constants. And not, let say, changing with time, as the universe expand.
we want arabic caption pleaaaase
Great, I have to go recalibrate my two Fluke 5730A calibrators
Helix Studios
Anyone else notice the TES: Redguard reference in the title?
Tit Elmund
Wait, that doesn't make sense. Which frequency do you use for the equation m=hf/c2? We were told that E=hf can only be used to determine the energy of light waves.
mmh fdsf
why they dont measure cylinder in paris and give planck number to it
Chris Marzarella
Can you give the dumb as F, dirty-downed, I have only 3% of my brain in actual use? Also, how does this apply to a powerlifting federation that uses kg numbers? Does that mean all the weights they use and records made are inaccurate?
Jakob butzbach
the background music... checked facebook 20 times. sounds like messages were running in!
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Electromagnetic Levitation Quadcopter The kg is dead, long live the kg 1 day ago   06:19

Spinning magnets near copper sheets create levitation!
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Special thanks to Hyperloop One for showing me around.

Thanks to Patreon supporters:
Nathan Hansen, Donal Botkin, Tony Fadell, Saeed Alghamdi, Zach Mueller, Ron Neal, Perry cl, Bryan Baker
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Filmed by Raquel Nuno, Edited by Trevor Carlee

Obviously this "quadcopter" is a demonstration device, showing how moving magnets over a conducting surface can generate levitation. It has not been optimized to minimize losses or be an efficient mode of transport. I still think it's pretty cool. I'm used to seeing light things levitated by induced currents but not a 100+ lb machine.

For more on Hyperloop One: