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: 19821364
Runtime: 11:44
Comments: 28712

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Author Manuel Arce ( ago)
But can it run Crisis?

Author Da One ( ago)
I got so scared at 1:31

Author HIGH SQUAD ( ago)
"how could you say that it is the roundest thing in the world? I mean the earth is round" wow, I didn't know you were that stupid

Author hetepatat ( ago)
So dissapointed that this isn't just an elaborate "Yo momma!" joke.

Author Rodrigo H. Avaria S. ( ago)
what about pi? how many decimal are they using? can it be an exact definition if they use an arbitrary number of decimals of an irrational number?

Author thunder2.0 ( ago)
but what's inside

Author Jonas Lona ( ago)
Why did I got recommended this? You know what's round? a circle.

Author Achilleas Valioulis ( ago)
so basically he got excited for touching a ball.

Author cole3688 ( ago)
hydraulic presse's next upload

Author Kids Invent Stuff ( ago)
It does look pretty round.

Author Lightning LJ ( ago)
you know there are two dudes who play catch with that thing when nobody else is around

Author 10k Subs With No Videos??? ( ago)
Today's my birthday


Author Sherwin ( ago)
my ball bag is the roundest object

Author A M ( ago)
ehmergherd eet feels ebselotly oncredehble! yeah, feels round...

Author ShinyRedHead ( ago)
When you hear "well you see," in a video you know it's about to be boring...

Author Blake Norris ( ago)
Wow... A metal ball... awesome... sorry where am I? Oh yeah boredom don't worry

Author Daniel Bykov ( ago)
I came here to see a sphere not the history of kilograms

Author Nate Willaert ( ago)
my balls are rounder

Author PTNLemay ( ago)
Seems to me like we should have stuck with 1 liter of water. Granted, we would have had to redefine the modern gram to match water, but... it seems so much easier than all of these others ideas.

Author mrmillsap ( ago)
"Newton's Jewels"
The internet has ruined me.

Author Trey Trivigno ( ago)
its 2017

Author Denson Camp ( ago)
One fushigi to rule them all

Author Alucard ( ago)
This is 2017 telling you, get some sleep

Author Steve Koala ( ago)
anyone else notice how ever since he said grave the background was a graveyard?

Author Barrymon ( ago)
Worlds roundest object. Its a ball...

Author It's Me ( ago)
only at 5;05 i realized the importance of this

Author Seth s ( ago)
"If this were the earth, then the highest mountain and the lowest valley would be"
"about 14 meters apart"

... wait... what?? That tiny sphere is MUCH smaller than a single meter. What is she smoking?

Author Michael Sedgley ( ago)
The roundest thing is the earth.

Author Joshua Graham ( ago)
but why does this matter? we all know what a kilogram is. so why does tgey have to be an object of a kilogram... god in so confused. whats with all the security locked up etc

Author Stick figure ( ago)
Why do you need gloves?
(It might sound a bit stupid.)

Author Norwegian Fan ( ago)

Author Mac S ( ago)
My balls are rounder

Author Harsesis Hok'tar ( ago)
@ 4:55 is that the tii (today in ios) podcast intro music?

Author Naz Smith ( ago)
Pfft, I live in America. Go pounds!

Author redstone craft guy ( ago)
Not as round as a black hole

Author Jerritto Knight ( ago)
sombody is going to put it in a press

Author Robert S. ( ago)
World's roundest object? Like anyone can really know that, Napoleon...

Author Marz ( ago)
i would drop it

Author Zulo ( ago)
All the OCD people out there be like... I WANNA HOLD IT!!!!

Author Hobbes Ehlert ( ago)
what is the music at the begging it really common

Author Oliver Robinson ( ago)
music: Danse Macabre

Author malcolm wallace ( ago)
learn your French sir its the big k

Author william qiu ( ago)
AvoirdupoiDs with the D means "haves weight"

Author BaconBrothers ( ago)
Why are people spending their money on making spheres

Author my daughter is kissing a stranger ( ago)
So how did we went from the worlds roundest object to kilograms

Author Drake Drake ( ago)
Um the earth is flat my boy...

Author GhostMasterZzGaming ( ago)
1000 degree knife challenge inbound

Author WeeabooXD ( ago)
shockingly round yourself ass wipe

Author Luis GGgaming ( ago)
Now just add the "Hey, VSauce, Michael here." at the start of the video and bam.

Author HK Zero ( ago)
Priceless ball on a tripod on top of a box barely big enough for it. Who likes to live on the edge?

Author First Name Surname ( ago)
Whats inside

Author XbossgameingHD ( ago)
It is the roundest object on earth.But not in the world/Universe, it's a nutron star.

Author Svilpa ( ago)
what if you were to made a silicon mold around that thing.. ?

Author Maya Brahma ( ago)

Author Psycho Players ( ago)
u look kinda like lolyou

Author John Roberts ( ago)
Trump is going 2 nuke all of you and your kilograms lol

Author Dashmesh Singh ( ago)
Now someone will mess up the Big K just to watch the world burn.

Oh wait....

Author Harambe Flavoured Bleach ( ago)
I have no idea what he was talking about

Author chinh trinh ( ago)
Oh no my man hours!

Author Motiwor Rahman ( ago)
if I broke that and I had to pay for that...I'd be killing my self by the second I would have to deal with the painfull money I'd have to pay

Author Don't Suscribe ( ago)

Author Daniel Edwards ( ago)
fushigi ball?

Author Emery Knotts ( ago)
Roundest object in the world my ass! I can draw circles blindfolded rounder than that shit😂😂

Author TheCNGmusic ( ago)
False. The roundest object is your mom.

Author Liam Richardson ( ago)
And there probably some alien civilization thinking they have the roundest object ever made.

Author Jesus Sarabia ( ago)

Author Zach Moore ( ago)
Versus 1000 degree knife

Author Auzzy The Great ( ago)
So, the world's roundest object is a ball or aluminum. Why is the video 3/4 about what a kilogram is?

Author Ethan Corbin ( ago)
When a piece of metal is more talented than you

Author Kim Bierley ( ago)

Author shadowstyle68 ( ago)
but pi is irrational so this will never be exact, theyd have to use a cube

Author Tushar Bhudia ( ago)
Smart guy

Author 123rykam ( ago)
early as 2014, but it aint... because its 2017! :D

Author Justin Morales ( ago)
Don't drop it. Throw it across the room

Author Joker ( ago)
its round

Author XxItsHim ( ago)
"Can I hold it?"

Author UniqueTrash ( ago)
1000 degree knife vs worlds roundest sphere

Author FulfMubLana ( ago)
Nothing could possibly be rounder than Karl Pilkington's head

Author lonelyPorterCH ( ago)
but, why do you need such athing that weights exactly one kilogram at all?

Author Gaurav Bagul ( ago)
Thank you for the information

Author Justin Chirila ( ago)

Author Oni ( ago)
waste of money

Author Ice Flake ( ago)
Give this to the Hydraulic Press Channel.

Author mako ( ago)
This is like homebrand vsauce

Author subscribe me ( ago)
kids in Africa could have eaten that sphere.

Author FirmsMcGee ( ago)

Author Scotty J ( ago)
1KG = 1 bag of sugar

Author Renav Solanki ( ago)
Guys what is the definition of a kilogram now in 2017?

i'm too lazy

Author 123 456 ( ago)
1000 degree knife versus worlds roundest object.

Author KoWe Kingdom ( ago)
Well actually something cannot be "more round", it is round or not

Author Rockstarness ( ago)
i just closed my eyes and watched through some of the video, and when she said "its slippery, be careful," i had a heart attack and almost died laughing XD

Author Mateo Toons ( ago)
sponsored by fushigi.

Author DEaD[-_×]RiSE ( ago)
her bra is dark green

Author Kuuda ( ago)
Crush it please.

Author Fianna Monaghan ( ago)
Imagine if he just dropped it


Author Frost Soul 7755 ( ago)
soooooooooo this is where all the taxes go interesting ........

Author sape ( ago)
"i promise i'll be careful"
*w h a m*

Author Endermanso ( ago)
What is the color of the sphere??

Author Kofi Mills ( ago)
I like her confidence.

Author Daniel D ( ago)

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