World's Roundest Object!

  • Опубликовано:  4 года назад
  • 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
  • КатегорииОбразование
  • Длительность: 11:44
  • Тэги для этого Видео:  veritasium  science  physics  Perfect  sphere  kilogram  avogadro  avogadro project  redefining the kilogram  kilo  metric system  silicon  silicon sphere  silicon-28  silicon 28  watt balance  bipm  history of the kilogram  grave  units  SI units  definition  gram  mass  quantity  weight  weights  kilograms  csiro  kilogram of the archives  kilogramme  definition of the kilogram  unit  perfect sphere  roundest object  world's roundest object  kilogram definition  

Комментарии: 30 070

  • MDShadowMan FTW
    MDShadowMan FTW 17 часов назад

    I would be too scared to pick it up

  • The boss of YouTube Charlie
    The boss of YouTube Charlie 22 часа назад


  • VectorTime
    VectorTime 1 день назад

    "Worlds roundest object"
    "You can't have one unit more noble than the other so he got his head chopped off"
    How did we get here?

  • Михаил Юрьевич
    Михаил Юрьевич 1 день назад


  • Pixiestix
    Pixiestix 1 день назад

    I thought that after a while he just started to ramble, but in the end it all came full CIRCLE
    Ha get it

  • ShockSyndrom
    ShockSyndrom 2 дня назад


  • John Ward
    John Ward 3 дня назад

    These two should date.

    CELIA PERKINS 4 дня назад

    What would they do if he threw it and broke it?

  • Michael Goddard
    Michael Goddard 5 дней назад

    any updates on the if this new system is making progress to becoming reality?

  • The.#1 T
    The.#1 T 5 дней назад

    Close your eyes and watch the start

  • jay Garcia
    jay Garcia 5 дней назад


  • Dragon Son
    Dragon Son 6 дней назад

    his green screen reflected off the top of his metal cilinder

  • brettcone
    brettcone 6 дней назад

    so basically all these expensive fancy kg standards are pointless bc their weights will always change over time

  • Lord Taco
    Lord Taco 6 дней назад

    "And to make *matters* worse". I see what you did there.

  • snoozed.
    snoozed. 7 дней назад

    so its basically a fushigi ball

  • Agustín Carfora
    Agustín Carfora 7 дней назад


  • Dead Star
    Dead Star 7 дней назад

    can we get an update video on this subject?

  • hotmojo1
    hotmojo1 8 дней назад

    She sets off my Spock sensors.

  • Willie Diaz
    Willie Diaz 8 дней назад


  • jinggo78
    jinggo78 8 дней назад

    I guess I'm not nerdy enough but... why does it matter that the kilogram is based on a real object when you could just say a kilogram is a kilogram regardless what objects exist in the world. I'm also not quite understanding why the mass changes. Cool sphere that they made down to the atomic level of accuracy but I just don't understand what the point is. It's like saying the number zero is represented by a fruit loop that never goes soggy.

  • MorpheusZues
    MorpheusZues 8 дней назад

    get her number, bro.

  • blü balls
    blü balls 9 дней назад

    i have something rounder than that. you cannot dispute.

  • K. E
    K. E 9 дней назад

    lol this guy, "the earth is pretty round isn't it?"

  • Jamless Yaoi
    Jamless Yaoi 9 дней назад

    I thought my balls are the roundest object in the world...

  • Mr. Ocean
    Mr. Ocean 9 дней назад

    well, honesty, I'm tired of this shits, world ,,,,,,,,,. if its round it's round, you can get more than that.

  • mkd1r
    mkd1r 9 дней назад

    Wasnt 2014 3 years ago?

  • jack steel
    jack steel 10 дней назад

    "you cant have a unit that changes value", like money?

  • EM3rIC4_88
    EM3rIC4_88 10 дней назад

    2:19, her titties were rounder than the sphere.

  • Sub Vae
    Sub Vae 10 дней назад

    you don't wear masks,your postilions are changing the weight of it...😄

  • Angela Renee
    Angela Renee 10 дней назад

    perhaps the mass changed because time was not mirrored the same in each place. if time bubbled like the foam across boiling water similar to how the continents may move, then maybe.

  • Mykola Yefimenko
    Mykola Yefimenko 11 дней назад

    whats up with his eyes?
    the most stoned object ?

  • Manavendra Sen ツ
    Manavendra Sen ツ 11 дней назад

    It's 2017 and 1kg is 1kg

  • Nick Loz
    Nick Loz 11 дней назад

    The only chemistry here is between the host and the scientist

  • ghostrecon755
    ghostrecon755 11 дней назад

    Start the video and close your eyes but have the speed at 0.5 XD

  • Silvus Sol
    Silvus Sol 11 дней назад

    This reminds me of that movie "Sphere". I'm just waiting for your reflection to start going upward until it disappears.

  • Flame Flower383
    Flame Flower383 12 дней назад

    your face in the thumbnail

  • Omar
    Omar 12 дней назад

    the worlds roundest object is my grandmas balls

  • Mulepick
    Mulepick 13 дней назад

    In 2018 the kg will be expressed by Planck's constant and the reference kg can go to a museum.

  • tom thumb
    tom thumb 13 дней назад

    my left testicle is rounder

  • Mip Mup
    Mip Mup 14 дней назад

    Earth isnt round ffs

  • KoalaLumpUhr
    KoalaLumpUhr 14 дней назад

    Send a magician there, who exchanges it with a fake globe and drops it on the ground - but please record the faces of the physicians ;)

  • Arsenio Ortiz
    Arsenio Ortiz 14 дней назад

    When none of your youtubers upload anything so you look at random stuff like this but this turns out to be more entertaining than you thought

  • Carson Canady
    Carson Canady 14 дней назад

    it was a ball

  • MattStormage
    MattStormage 14 дней назад

    2017 and Le Grand K still stands strong

  • Leroy J
    Leroy J 14 дней назад

    that dude has a face that just asks: PUNCH ME

  • ProtoPrints
    ProtoPrints 14 дней назад

    is this guy always high?

  • Kevin Cahya Setiawan
    Kevin Cahya Setiawan 15 дней назад

    Anyone thinks that Na was Neil Amstrong?

  • Chilled Pixel
    Chilled Pixel 15 дней назад

    I have it when you want to tap on a time in the comments and miss by 0.03 micrometers and YouTube says: "OH YOU TAPPED REPLY OK YOU HAVE TO REPLY NOW!!!! I SAID REPLY!!! OH YOU DINT WANT TO OK WELL HERES ANOTHER POPUP ASKING YOU IF YOU REALLY WANT TO MAKE A DECISION BY YOURSELF!!!"

  • fearfullpeople
    fearfullpeople 15 дней назад

    Prince Rupert's sphere!Zero G plane?Space station?Skydiving chamber?You can do it!

  • lebron mosua
    lebron mosua 15 дней назад

    more more

  • Xbox Highlights
    Xbox Highlights 16 дней назад


  • ordinaryfuturefoxgang
    ordinaryfuturefoxgang 16 дней назад

    Jolie olie is rounder

  • The Default Guy
    The Default Guy 16 дней назад

    Worlds most expensive Fushigi Ball

  • Moonman
    Moonman 16 дней назад

    This is one of those things that makes you wonder why is it so expensive.If I had that I would give it to the kids to play with it.

  • Kunj Bhoria Sonepat
    Kunj Bhoria Sonepat 17 дней назад

    hold my and i have two, down here

  • silver lorance
    silver lorance 17 дней назад

    Man ur the best scientific youtube channel

  • Gamma Ray
    Gamma Ray 17 дней назад

    Excellent episode, this subject has boggled my mind for many year, great amount of information

  • Sean Baxter
    Sean Baxter 17 дней назад

    It looks so weird when he holds it because it doesn't look like it's rotating.

  • Alex Crosslin
    Alex Crosslin 17 дней назад


  • Joe Shmoe
    Joe Shmoe 18 дней назад

    Since E=MCsquared, adding energy to the sphere will change its mass. Energy can be added to the sphere simply by moving it. So basically the sphere has a different mass moving along with our planet than it would at some other location.

  • dank bro
    dank bro 18 дней назад

    imagine if he dropped it the instant he held it

  • GRaToMiC
    GRaToMiC 18 дней назад

    my balls are rounder

  • imac1957
    imac1957 18 дней назад

    The two methods would be COMPLEMENTARY not COMPLIMENTARY

  • Astrophel Vlad
    Astrophel Vlad 18 дней назад

    doesn't micro dust and other stuff get on the sphere cause it surrounded by air and these people are talking which can shoot tiny particles out of their mouths onto the sphere.. they were concerned about fingerprint weigh.. in that case.. they must be worried about this too.. well he said the 'kilogramme' no longer depends on an object.. so.. this thought is rubbish?

  • JK JK
    JK JK 18 дней назад

    So, so cool. We will tell weight what a kilogram is. Not let weight tell us. Awesome.

  • James Dinius
    James Dinius 18 дней назад

    Forget English units. Go metric. And yes, I'm from the US.

  • Coelhos e Limões
    Coelhos e Limões 18 дней назад

    uh, i thought it was your mom!

  • Haiying Zeng
    Haiying Zeng 18 дней назад

    I'm from 2017 and I'm sorry to say that according to, the kilogram is still defined by the Platinum-Iridium cylinder kept in Sèvres, France.

  • Your body is 75% water and i'm thirsty

    Damn, I haven't seen something so perfect since the android saga.

  • blackmore56
    blackmore56 18 дней назад

    That's Waverley Cemetery in Sydney.

  • Krinner
    Krinner 18 дней назад

    1:05 the flat earth society has members all around the globe

  • ROUSH4203
    ROUSH4203 19 дней назад

    Yeah but can it run crysis

  • tyler jonhson
    tyler jonhson 19 дней назад

    this would make a great fushigi ball

    UNDEAD SPART4N 19 дней назад

    It's just a fushigi!

  • Jake And Company
    Jake And Company 19 дней назад

    this total miner music is lit

  • John thomas-jones
    John thomas-jones 20 дней назад

    I must disagree... Karl Pilkington's head is rounder

  • Donald Trump
    Donald Trump 20 дней назад

    idiot, the world's roundest object is world

  • Sly Rocko
    Sly Rocko 20 дней назад

    (2.15*10^25)/Na = 35.something mol
    35.something * 28 = 1000g
    Math checks out

  • George Bryson
    George Bryson 20 дней назад

    Was your dad a G.I.? You're so exotic-looking, hostman. Your ambiguous ethnic blend perfectly represents the melting pot of the American dream....

  • TheChilled MC
    TheChilled MC 20 дней назад

    Nope mate is 2017 and the definition hasn't changed as far as i know.

  • Prateek Singhal
    Prateek Singhal 21 день назад

    I want that thing on my table.

  • Arthur Pristupa
    Arthur Pristupa 21 день назад

    He lost me after grave.

  • Will Blackler
    Will Blackler 22 дня назад

    The redefinition of the kilogram is scheduled for 2018!

  • Alex Ne-k
    Alex Ne-k 22 дня назад

    you are so damm stupid. earth is not a round idiot.

  • William Lazaris
    William Lazaris 22 дня назад

    Is that waveily cemetery??

  • Iluminaty _3
    Iluminaty _3 22 дня назад

    what's the song in the video

  • Mintfriction
    Mintfriction 22 дня назад

    1 milion euros for 1kg of silicone? Wtf

  • Balog Szilárd
    Balog Szilárd 22 дня назад

    Saint-Saens's Danse Macabre just really creates the mood :D

  • Yara Alnaemi
    Yara Alnaemi 23 дня назад

    Only if he dropped the metal Ball ...

  • ShahJahan Khan
    ShahJahan Khan 23 дня назад

    She is the happiest scientist I've ever seen.

  • Fenridir
    Fenridir 23 дня назад

    Idubbbz brought me here.

  • Andrew Cobb
    Andrew Cobb 23 дня назад

    How do they determine what size the sphere will be? If it is meant to be exactly 1Kg, isn't that still based on the weight of 1Kg? Also, it would be really risky as you would need to directly predict the dimentions so that you do not end up with a final product that is too small -- but that being said, you could still easily calculate how many atoms are in it?

  • ChistoBot 9000
    ChistoBot 9000 23 дня назад


  • Trey Dixon
    Trey Dixon 23 дня назад

    It's spherical!


  • Creeper Crook
    Creeper Crook 23 дня назад

    *The laughing was just to much for my brain...*

  • Agile Cock
    Agile Cock 23 дня назад

    Damnit i feel sooo dumb. Avogadro's constant??? thank goodness for Google ; )

  • Sam Hyman
    Sam Hyman 23 дня назад


  • Jesse Givan
    Jesse Givan 23 дня назад

    Wow. That sphere is so cool! If you would spin it really fast, and held it in the same place, you couldn't tell it was spinning!

  • hangytangy WOT!!!
    hangytangy WOT!!! 23 дня назад

    5:36 to make matters worse