World's Roundest Object!

  • Added:  4 years ago
  • 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
  • Video CategoriesEducation
  • Runtime: 11:44
  • Tags for this video:  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  

Comments: 30 207

  • Soraya Haidari
    Soraya Haidari 20 hours ago

    Seems like he got punched on his right eye

  • Mr Zeta
    Mr Zeta 1 day ago

    What's this doing in my recommendations 4 years after its release?

  • Evan Tozzi
    Evan Tozzi 1 day ago

    1:38 what's the music

  • Wireless Baguette
    Wireless Baguette 1 day ago

    G.R.R. Martin must be working with them on the kilogram, seeing as it's 2017 and we still don't have the new definition.

  • Hansraj Gaikwad
    Hansraj Gaikwad 1 day ago +1

    I want to know more about walkbalance

  • New Born DJ
    New Born DJ 1 day ago

    cant you just 3d print a ball?

  • Zanthar
    Zanthar 2 days ago

    kilo veren dye

  • D'Ascoyne
    D'Ascoyne 2 days ago +1

    Karl Pilkington's head is rounder.

  • kanszo
    kanszo 2 days ago

    btw your eyes are a little bit red :)

  • Kibbly Kibbs
    Kibbly Kibbs 2 days ago

    Mabey if i was Michael Scofield i could

  • Smapty
    Smapty 2 days ago

    Now can we get our gravity reading on earth to be "constant" also, that would be nice.

  • microsoftwindows
    microsoftwindows 2 days ago

    Wait so why make the sphere then?

  • Salient Salem
    Salient Salem 3 days ago

    u on drugs maann

  • Theangry Italian
    Theangry Italian 3 days ago

    I just discovered this channel...the transistions are so similar to vsauce

  • jø sunflowerkid
    jø sunflowerkid 3 days ago


  • jø sunflowerkid
    jø sunflowerkid 3 days ago


  • Gabriele Bernard
    Gabriele Bernard 3 days ago

    2017 still depending on an object

  • SecludedMemory
    SecludedMemory 3 days ago

    I want one. I'd do absolutely nothing scientific with it. Just hold it and caress it, in a super villain-esque manner.

  • gurami abramishvili
    gurami abramishvili 3 days ago

    except roundest objects in the world are black holes.

  • Hans
    Hans 3 days ago

    She is sooo sweet :D

  • Shotyme 81
    Shotyme 81 4 days ago

    this would be very interestin if I was nerdy

  • IamAndreo
    IamAndreo 4 days ago

    I was like; "wait for it, wait for it", while the guy was holding the sphere.

  • gammkrab
    gammkrab 5 days ago

    The name "Veritasium" is a combination of the Latin word for truth, Veritas, and the suffix common to many elements, -ium. This creates "Veritasium", an element of truth,

    Well played

  • Das Boot
    Das Boot 5 days ago

    I wonder what the diameter of her breast are, I could easily find out. But I would have to suck them and fondle them to get the right measurement.

  • borntobeborn1
    borntobeborn1 5 days ago

    9:31 well thats just fuckn akward

  • BenTheBoss24
    BenTheBoss24 6 days ago

    Just listen to the first 20 seconds with out looking 😂😂😂😂😂

  • Nyan Kitty
    Nyan Kitty 6 days ago

    I'm from the future. Nothing changes until 2017

  • Heath ledger
    Heath ledger 6 days ago

    My balls are much rounder

  • assaf roden
    assaf roden 6 days ago

    he looks like col suprouse

  • Piyush Singh
    Piyush Singh 6 days ago

    You should make a video on Watt Balance. I'm waiting for it.

  • Никита Вертиков

    -Alright, Morty, don't drop it.
    -I'm not an idiot Rick, I'm not gonna dro...

  • The unusual
    The unusual 7 days ago

    What if the men balls were as round as the silicon sphere ?

  • Zav Uzumaki
    Zav Uzumaki 7 days ago

    So you’re saying that someone’s boobs aren’t rounder than that

  • Tjør Hulshof
    Tjør Hulshof 7 days ago

    But, does it blend?

  • Felipe Souza
    Felipe Souza 7 days ago

    I came to the future to say that we still working on kg measure, mate!

  • Baby The Magic Cat
    Baby The Magic Cat 8 days ago

    when you were turning it at the beginning of the video it looked like it was just staying still and your hands were slipping around it

  • Clint McCaleb
    Clint McCaleb 8 days ago

    Heard you on Adam Carolla, came home, checked it out. Loved it. Subscribed.

    Good call on going on Adam's show.

  • xja85mac
    xja85mac 8 days ago

    6:40 it's a troy pound actually!

  • V
    V 8 days ago

    but yet Americans use pounds.. not kilogram. lol

  • Nathan Staples
    Nathan Staples 9 days ago

    Shouldn't the answer to the title here be George Michael's BUTT!!!??? #SNL80s

  • Octopuss
    Octopuss 9 days ago

    🌚 this molester moon is much rounder

  • Xander Hebert
    Xander Hebert 10 days ago

    That reflection tho

  • PotatoGodz Playz
    PotatoGodz Playz 10 days ago

    but to calculate the volume of a circle u need pie, whichis infinite, so u can never get the exact volume

  • Pedro Valdes
    Pedro Valdes 10 days ago +1

    Next up the shiniest, roundest, blackest object in the world; BHDs Head.

  • shashwat johri
    shashwat johri 10 days ago +1

    i thought the title was about her..

  • Patryk Janowski
    Patryk Janowski 10 days ago

    The world's roundest object is my girlfriend's ass, bitch. Don't you dare doubt it.

  • shortbuspileup
    shortbuspileup 11 days ago

    That sphere makes me want to watch Phantasm.

  • Umesh Leelasena
    Umesh Leelasena 11 days ago

    A comment from 2017. the kilogram isn't defined yet ;) 9:56

  • Jesus Da lawd
    Jesus Da lawd 11 days ago

    No matter where you close your eyes you cant image someyhing not innapropriate

  • Random Human
    Random Human 12 days ago

    I know a rounder stomach

  • Luis Merchan
    Luis Merchan 12 days ago

    6:30 OwO

  • Alpha Q
    Alpha Q 12 days ago

    He missed out th uk and canada

  • Paul Simeon
    Paul Simeon 12 days ago

    Gravity Probe B claims to have the two roundest objects in the world. Stanford has the Guinness World Record certificate on display.

  • Guillermogamer1
    Guillermogamer1 12 days ago

    Did you think of the water... WHEN YOU WASH IT!

  • Arjun Rajput
    Arjun Rajput 12 days ago

    That's because I roughened my testicles.

  • 155heyman
    155heyman 12 days ago

    avoirdupois pound = havingsomeweight pound

  • Quinson Hon
    Quinson Hon 13 days ago

    "They may redefine the kilogram as early as 2014"

    4 years later

    "In 2018, we will redefine the kilogram"

  • jckatz
    jckatz 13 days ago

    I guess 2014 isn't going to happen

  • Dixlexxik
    Dixlexxik 13 days ago

    I think he was tired ... he seem like someone missing sleep ...

  • Trotskisty
    Trotskisty 13 days ago

    Wrong revolution.

  • JaviShoot
    JaviShoot 13 days ago

    That painting is not the 1789 french revolution.

  • scout gλming 2017
    scout gλming 2017 13 days ago

    I like how you trying to be Vsauce but like more funny

  • allysa therese
    allysa therese 13 days ago

    next step: how to turn a sphere inside out

  • Michal Nemecek
    Michal Nemecek 14 days ago

    is the kilogram still defined by a physical object?

  • Elder John Johnson Of 'murica

    If it's the roundest thing and it's priceless than its free

  • Agatka Grzyb
    Agatka Grzyb 14 days ago

    dat shiny
    i want shiny
    giv shiny or i kil u

  • Abhijit More
    Abhijit More 14 days ago

    Why do i think that they had sex after the scene right on that table...??? 🤔🤔

  • uvuvwevwevwe onyetenyevwe ugwemubwem ossas

    His french accent is so weird.

  • Saitama OK
    Saitama OK 15 days ago +1

    Roundest thing? Challenge accepted. (Sees marble) Ok, were equal now

  • Kris Piasek
    Kris Piasek 16 days ago

    Soooo, it is not roundest object, it is world itself.

  • Zombie Killa
    Zombie Killa 16 days ago

    only amis still use foots and toes to measure things, neandethaler

  • Richard
    Richard 17 days ago

    piss off thirty second cunt wanker ad

  • pafnutiytheartist
    pafnutiytheartist 17 days ago +1

    What's up with ihis project? I have seen no news on Avogadro project in years.

  • Quantrindic
    Quantrindic 17 days ago

    You need to get you some visine

  • bzunyi
    bzunyi 17 days ago

    Around 6:00
    What if not the masses of the cylinders changed but the gravity?

  • ianslai
    ianslai 18 days ago

    And we're getting close in 2017! A new definition was just submitted at the end of June based on Planck's constant.

  • Laughuntilyoucry Cryuntilyoulaugh

    Science, history, science and history this.

  • مصطفى العراقي

    مذهل ..

  • morgan wolf
    morgan wolf 19 days ago

    waou french power !

  • Stijn Meenderink
    Stijn Meenderink 19 days ago

    If i were him i would throw it on the floor

  • Stiderspace
    Stiderspace 19 days ago

    so is it already a constant or ?

  • Trevor Williams
    Trevor Williams 20 days ago

    you ever seen karl pilkington?

  • Shaibo Das
    Shaibo Das 21 day ago

    The guy who said "Start the video and listen with your eyes closed" should be pinned to the top.. Damn

  • Sammy
    Sammy 21 day ago

    6:50 :(

  • Kandela Brown
    Kandela Brown 21 day ago

    Her head is about as round as that silicon.

  • Zayed Deryn
    Zayed Deryn 21 day ago

    1:05 triggered FE

  • Diego Vera
    Diego Vera 22 days ago

    Casually makes most of the video with a cementery in the background

  • brambo5000
    brambo5000 22 days ago

    sphere has the least big surface area

  • Antoine Dut
    Antoine Dut 22 days ago

    je suis français et je m'appelle antoine looooooooooooooooooooooo yo this video is pretty cool man

  • skuzzle butt
    skuzzle butt 23 days ago

    This video is mostly useless yammering about nothing. And I think the whole Avoirdupois pound to metric is wrong since you are taking two separate units of measurement and trying to use them together. What I think should be used is the Troy system though it's only used in Precious metals and gemstones measurement.

  • Creator Sun Kinda active now

    The real question is: Where's the front?

  • Geeky Grant
    Geeky Grant 24 days ago

    Why did the EU blow millions on the worlds roundest object?

    Same reason why the UK is leaving the EU, pointlessness spending of money X-D

  • Clorox Bleach Meadow Scent

    Why do men wanna touch round things so bad?

    • None None
      None None 16 days ago

      Hannah Baker Well you can find it in 13 reasons why.

    • Your Crush
      Your Crush 24 days ago


  • Total War Master
    Total War Master 25 days ago

    So its basicly a very flashy, pricey fushigi ball?

  • Alfred Nobel
    Alfred Nobel 25 days ago

    Dude.... u look high AF, i dont blame u tho all this science is way cooler and more interesting high :)

  • RelexSoldier
    RelexSoldier 27 days ago +1

    I don't know about that, I mean my balls are pretty round.

    • RelexSoldier
      RelexSoldier 26 days ago

      pewize You better get them checked then.

    • pewize
      pewize 26 days ago

      idk, mine are quite oval

  • Max Lake
    Max Lake 27 days ago

    wtf! the final answer is the same as the first .... the water at 4 degrees. who measures the ruler with which you make the sphere? this is stupid. good thing about water. everyone has access to it. this is elitest nonsense designed to keep science from the people as no one could check to see if the elites are coin shaving. perfect for mr george soros.

  • Koulatko
    Koulatko 27 days ago

    wouldn't it be simpler if they used a cube?

    BIG GUY 28 days ago

    Close your eyes and listen to the first 22 seconds of the video

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