World's Roundest Object!

The world's roundest object helps solve the longest running problem in measurement -- how to define the kilogram.
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A kilogram isn't what it used to be. Literally. The original name for it was the 'grave', proposed in 1793 but it fell victim to the French Revolution like its creator, Lavoisier. So begins the tale of the most unusual SI unit. The kilogram is the only base unit with a prefix in its name, and the only one still defined by a physical artifact, the international prototype kilogram or IPK.

But the problem with this definition has long been apparent. The IPK doesn't seem to maintain its mass compared to 40 similar cylinders minted at the same time. The goal is therefore to eliminate the kilogram's dependence on a physical object. Two main approaches are being considered to achieve this end: the Avogadro Project and the Watt Balance.

The Avogadro project aims to redefine Avogadro's constant (currently defined by the kilogram -- the number of atoms in 12 g of carbon-12) and reverse the relationship so that the kilogram is precisely specified by Avogadro's constant. This method required creating the most perfect sphere on Earth. It is made out of a single crystal of silicon 28 atoms. By carefully measuring the diameter, the volume can be precisely specified. Since the atom spacing of silicon is well known, the number of atoms in a sphere can be accurately calculated. This allows for a very precise determination of Avogadro's constant.

Special thanks to Katie Green, Dr. David Farrant, the CSIRO, and the National Measurment Institute for their help. Thanks also to Nessy Hill for filming and reviewing earlier drafts of this video.

There is debate as to whether this is truly the roundest object ever created. The Gravity Probe-B rotors are also spherical with very low tolerances such that they may in fact be rounder.

Music by Kevin McLeod ( Decision, Danse Macabre, Scissors

Views: 20202166
Runtime: 11:44
Comments: 29406

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Author NELSON X ( ago)
I got a boner the moment he touched it.

Author JoeAceJR ( ago)
If two of these spheres touch each other, how big is the touching area?

Author lookoutforchris ( ago)
The US has been on the metric system since the 1970s. All science, medicine, government, industry, and commerce used it. Traditional units are still used in cooking and construction and for everyday use. This is the same situation as the U.K. Stop spreading the falsehood that US does not use the metric system.

Author montgomery mchargue ( ago)
bro its circuler reasoning

Author eXcommunicate1979 ( ago)
Man, the sexual tension in this video is palpable.

Author lisa sch. ( ago)
i feel like im on that side of youtube that only physicians and chemistry students understand. for me this thing is just a Metall ball :D but the commentarea is full of smart questions, so i feel pretty dumb right here

Author Road Brew ( ago)
She's got a nice rack.

Author Awesome Sause ( ago)
well its 2017 and it has not changed...

Author Karam Mohamed ( ago)
0:32 it looks like his hand is rotating around the ball

Author Hector Castillo ( ago)
whats the name of the violin song

Author Dustin Bess ( ago)
any update video planned?

Author Mockey Moose ( ago)
My balls are pretty round

Author Fifteen Archieve ( ago)
depending on the environment on a planet, width how those atoms would change. and manipulate it's structure. and the sample was created in france had a handle(unit). what element on the periodic table would have weight.

Author Arya Wira ( ago)
customer: how much this mass of 2.15x10^25 silicon-28 atoms of beef price?
butcher: wait, what???

Author Kevin Tourdeau Mad ( ago)
she is flirting with mamma wanting young flesh

Author Swess2908 ( ago)
so you're telling me it's not my balls?

Author Reenal Chand ( ago)
6.51 mic drop

Author Berger A. ( ago)
Couldent we use the momentum or force of light that has the color #FFFFFFFF in a Vacume

Author Neil Does Game ( ago)
nice green screen and info for the wold roundest object bro keep it up

Author I Changed My Name ( ago)
2:18 *Boobies ( ͡° ͜ʖ ͡°)*

Author DailyMotion Official TM ( ago)
If this is the worlds roundest object then why it is called as sphere instead of circle????

Author Rishabh Goyal ( ago)
A soap bubble is rounder

Author /encode ( ago)
is the host from the UK? his accent is really throwing me off. It's only noticeable when he says certain words.

Author Nostalgiamadpspmad ( ago)
If two sets of these touch, would it be gay?

Author GamerBot ( ago)
lmao, THE GRAVE got me... XD

Author spacey1809 ( ago)

Author Théo michel ( ago)
how did it go ?

Author Rajendra Lama ( ago)
oh my oh my she is blushing and I love her!!!

Author Hallel Goldenberg ( ago)

Author Carlos Muñoz ( ago)
I want the same but made of chocolate and nutella, bye

Author Smooth ( ago)
Question- what would happen if the ball was on a flat floor? Would it just roll endlessly, or would it just sit flat?

Author Cool Drue ( ago)
You are so handsome. I like your teeth.

Author Hemanth Chitneni ( ago)
I must say she looks hot, because she is smart.

Author PopularMinecraft Films ( ago)
my girlfriend's butt is rounder

Author Dominic Swider ( ago)
*whatsinside* hey guys we are gonna be cutting open the world's roundest object!

Author Rodrigo Vazquez ( ago)
Was the kg redefined?

Author ronak dev ( ago)
world's roundest object would be the 0 I get on my tests.

Author El Plub ( ago)
How did I get to this... I just need to sleep

Author Brian Bond ( ago)
I don't care, I don't use metric, and things are still working

Author Michael gyle Deguzman ( ago)

Author Kyle Hodgeman ( ago)
Idk if it's ever been discussed before on this channel, but the definition of a second is even more convoluted in my opinion then the kg

Author ukstevey ( ago)
why not just hold it above a large cushioned surface

Author verz ( ago)
my penis is the only thing in the entire universe with the mass of my penis, because it is my penis

Author iGadget ( ago)
He looks quite baked...

Author TheCaucasianAsian ( ago)
Welcome to the hydraulic press channel

Author Justin Groenenveld ( ago)

Author tetrak ( ago)
i came here on accident but wow very interesting. excellent explanation that i think any layman would understand. great vid

Author EtArcadiaego ( ago)
look at me im a renaissance man

Author Andy Wadsworth ( ago)
doesn't altitude have an effect on density for the litre/kilo bit? love the vids keep em coming, andy....

Author tot tota ( ago)
She was thirsty af. She wanted the D

Author ChEng Ergo ( ago)
the first 20 seconds is riddled with sexual innuendos lol

Author Kylee Abramson ( ago)
This is my favorite video on youtube I watch it every year

Author Anurag Kumar ( ago)
The lady was so much into our guy.

Author Z sheesh ( ago)
bending does nothing

Author Manish Savkare ( ago)
I'm confused. Is he talking about mass or weight of the sphere?

Author Jorginetta Ultime ( ago)
Maybe washing them changed their mass slightly

Author BakedPotatoYT ( ago)

Author Billy Danuarta ( ago)
my balls is the rounded object in the world

Author nacho playmer ( ago)
looks like a normal ikea ball to me

Author SmartK8 ( ago)
How did they found out by how much the kilogram prototypes changed if the reference kilogram also changed?

Author Kim Gustafson ( ago)
-I thought this comment was stupid so I crossed it out-

Author INFINITY!! MIKE!! ( ago)
When he was holding it I just wish he would just smash the ball

Author Volx Stormknight ( ago)
2:16 French think boobs fight wars .....horny bastards XD

Author Ibn Huzair ( ago)
Drunken Face!

Author Señor Chicken ( ago)
2:17 tiiiiitssssss :D

Author Bhagwan Singh ( ago)

Author Bhagwan Singh ( ago)

Author Danku_Meme 1337 ( ago)
so its a ball?

Author Pavel Galimov ( ago)
We use mathematics to explain what happens around us. But wasn't mathematics made up by humans since it is not always perfect?

Author Brian Egendorf ( ago)
Wow...its a modern marble..

Author ronnie graham ( ago)
the presenter better have a good collection of bell jars, what a load of shite

Author YouKnow ( ago)
What about the mono-layer of water that that forms on most surfaces exposed to the atmosphere. and does not Si oxidize a mono layer of SiO2 or SiO on it surface ???

Author Conal O'Neill ( ago)
It looks like your hands are moving around the ball, not the other way around.

Author big baller c ( ago)
she wants his dick

Author Getting Better at Music ( ago)
A sphere is not the most practical object for this particular purpose.. as long as we haven't reached the final digit of PI, it never will be. So.. still puzzled why they chose a sphere.

Author P-for d ( ago)
can anyone tell me what happen to my eyes? -_-

Author Bob the Shish Kebab ( ago)
But I got a quession for yeh. What's heavier, a kilogram o' steel, or a kilogram o' feathas?

Author Michał Prądzyński ( ago)
Is it really more round then ball in Gravity Probe B gyroscope?

Author Renovaware Gaming ( ago)
The earth isn't perfectly round,

Author curiousbird ( ago)
I wish that we kept the name grave, think of the puns?

Author Somethings Gonna Happen ( ago)
you cant tell witch one is moving your hand only or both (bad english i know)

Author Superior Improvers ( ago)
Is she related with Brandi Love`?

Author Carl Swagan ( ago)
He's so pretty...

Author OccultD3m0n ( ago)
So interesting! It feels and looks like a sphere...

Author Christian Carvajal ( ago)
it looks like he thinks its about to melt his hand when he struggles to touch iy

Author Jake ( ago)
Imagine making a ball bearing out of these...

Author Jayesh Warade ( ago)
wonderful video

Author Big Cazza ( ago)
waste of silicon, could have made me a hole bunch of titan xp gpus

Author ø itz Ash ø ( ago)

Me : Oh SH.....

Author PewnedBywat ( ago)
touching metal balls feels incredible ???

Author liquidalloy ( ago)
@0:35 when he spins it in his hand and seeing how perfect the reflections on it are looks so fake but it's not. Incredible.

Author Zachary Jesenovec ( ago)
Well actully, the earth is not very round. Because of terrain, it is extremely unround.

Author chop suey ( ago)
anyone make a ball joke yet? like how the guy was so excited to touch a ball?

Author D/D/D Oblivion King Abyss Ragnarok ( ago)
Eintoen Lab oisiei. lel. An to ain e Labuasie would be close to how its pronounced. Just my 2 cents.

Author the squishe squad ( ago)
Well it's 2017 and I'm still waiting

Author Puresox333 ( ago)
Since when was nostril cam a good idea ?!

Author Asterope ( ago)
WRONG, yo mumma's ASS is the roundest object in the world!

Author Anim Soultron ( ago)
think you wrong nigga
we all know the gamesphere is the most spherical object on earth

Author Nihar Naidu ( ago)
dude whats wrong with yer eye

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