World's Roundest Object!

  • Опубликовано: 25 мар 2013
  • The world's roundest object helps solve the longest running problem in measurement -- how to define the kilogram.
    Support Veritasium on Patreon:
    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
  • Длительность: 11:44
  • 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 • 32 443

  • FusionPointInc
    FusionPointInc 7 часов назад

    My balls are rounder than that.

  • Night Howl
    Night Howl 10 часов назад

    1:05 you didn't just say that.
    Earth isn't that round.
    Remember those asteroids in movies and cartoons? That's what Earth really looks like. Lots of bumps.

  • Love Life
    Love Life 13 часов назад

    The earth is a level plain. Its definately not a globe.

  • scot E. king
    scot E. king 22 часа назад

    The earth is pretty round? Unsubscribed

  • Pilgrim Dust
    Pilgrim Dust 23 часа назад

    And.... 1 kilogram is 2.1441789E+25 atoms of Si! :D

  • Enchanted Gamer9
    Enchanted Gamer9 День назад

    Dude back away from the camera

  • Oh Lol
    Oh Lol День назад

    So its basically an overpriced rounder and bigger marble?

  • Onsen23
    Onsen23 День назад

    this is why i love to masterbete than education

  • The Guinea Pig ENVADED
    The Guinea Pig ENVADED День назад

    was it turning?

    • The Guinea Pig ENVADED
      The Guinea Pig ENVADED 18 часов назад

      william hay
      I when he first picked it up I didn’t see it turn except the reflection

    • william hay
      william hay 18 часов назад

      The Guinea Pig ENVADED yes imagine you holding a mirror and your spinning it'll pretty much follow you around

  • tera gammons
    tera gammons День назад

    Ur mom is the worlds roundest object.

  • Drew Wilson
    Drew Wilson День назад

    Never knew there was so much math in shapes

  • Mediocre As Hell
    Mediocre As Hell День назад


  • Óscar Escobar
    Óscar Escobar День назад

    Great video

  • Kat Mack
    Kat Mack 2 дня назад

    True level!!

  • CapitanoGUC
    CapitanoGUC 2 дня назад

    Would give a nice bowling ball :-)

  • Tomeuhh
    Tomeuhh 2 дня назад +1

    Les français représentent🤷🏻‍♂️

  • Gautam Verma
    Gautam Verma 2 дня назад

    She is sexy.

  • Avarol Official
    Avarol Official 2 дня назад

    he reminds me of jugghead from riverdale

  • Christian Kim
    Christian Kim 2 дня назад

    I means it's a sphere...

  • Ken Carter
    Ken Carter 3 дня назад

    By 2014? This is 2018!!!

  • PlanetaryBrother Yayy
    PlanetaryBrother Yayy 3 дня назад

    its the roundest object in the universe

  • IronNote
    IronNote 3 дня назад

    That platinum cylinder has been kilogramming like a boss since 1799.

  • TheGerry236
    TheGerry236 3 дня назад

    The world most roundest object in earth
    Accept earth and other planets

  • Phalgun KP
    Phalgun KP 3 дня назад

    Unfortunately in 2014 the definition of kilogramme wasn't changed !! But a change has been 'proposed' which might come into effect this year -2018

  • Mac Lakatos
    Mac Lakatos 3 дня назад


  • prabal nepal
    prabal nepal 3 дня назад

    i think this guy is high 🤔🤔🤔

  • Torpedo Fails
    Torpedo Fails 3 дня назад +1

    that sphere be thicc

    ARTEMIS HAYDEN 3 дня назад

    Dance macabre. I see what you did there with the graves.

  • ClawedMetal 7064
    ClawedMetal 7064 3 дня назад

    My mind is no longer

  • MemeWolf
    MemeWolf 3 дня назад

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  • Facundo Hormaechea
    Facundo Hormaechea 3 дня назад


  • C. Schoenfeld
    C. Schoenfeld 4 дня назад

    Um, doesn't defining the kilogram as n number of silicon 28 atoms pretty much just bring us back to square one, where the number of atoms was calculated by measuring the volume of a 1kg sphere of silicon? Why not just calculate the number of H2O atoms of ultra-pure water and go with that?

  • 3nglish Elusive
    3nglish Elusive 4 дня назад

    I would bang that nerdy girl silly.

    MOHAMMAD ABDULLAH 4 дня назад


  • Xiere Teefv
    Xiere Teefv 4 дня назад

    I bet touching it wasn't that amazing

  • PackRat
    PackRat 4 дня назад

    "Can i pick it up"
    "sure AS long as your....."
    *SMASHES it

  • Daphne Riversong
    Daphne Riversong 4 дня назад

    Was I the only person internally cringing at his French pronunciations? Not to offend him, or anyone, though

  • Brooke
    Brooke 4 дня назад

    wow a sphere so cool.

  • EwokMyWeeWok
    EwokMyWeeWok 4 дня назад

    History is fake bro why lie

  • Red TheGamingStarts
    Red TheGamingStarts 4 дня назад +1

    how did i get here,all i remember is whaching some drone videos

  • La Red
    La Red 4 дня назад

    Soooo the Earth 🌏 must not be too round at all??

    • La Red
      La Red 4 дня назад

      Plus that I don't buy this LOL..... What about an atom? Microscopic things? Something has to be more round somewhere LOL

  • Catharina Tjahjono
    Catharina Tjahjono 4 дня назад

    It looks like its spining in his handbecause when he turns it the other way it still looks the same from the angle 😂

  • Eric Smith
    Eric Smith 4 дня назад

    What is the song at 1:37

  • Moxon
    Moxon 4 дня назад

    Roundest? are you flat earth people?

  • Eric K
    Eric K 5 дней назад

    I can't believe I just watched that whole 11:43 long video.

  • TF24LIFE [P2P]
    TF24LIFE [P2P] 5 дней назад

    1:10-1:15 I don’t get what they are saying, what does mountain and valley got to do with the roundest object, she said “about 14 metres apart” like WHAT? what does that mean, that’s just weird, maybe comparisons

  • Katy Yang
    Katy Yang 5 дней назад +1

    I want to roll it.

  • fuzzypanther45
    fuzzypanther45 5 дней назад

    fun fact: when someone head is cut off their faces are still making emotions the medulla i think its called (the center of all live and "power" of your brain) is still connected to the part of your brain that makes emotions in the face.

  • Greenball Science
    Greenball Science 5 дней назад

    How many digits of pi did you use.

  • Greenball Science
    Greenball Science 5 дней назад

    I thought the gram was a base unit.

  • Galacticpulse Gaming
    Galacticpulse Gaming 5 дней назад

    "How much does that worth?"
    -"It's priceless"
    * disappointments on his face *

  • Cameron Cassar
    Cameron Cassar 5 дней назад

    I feel asleep

  • Caleb Lackie
    Caleb Lackie 5 дней назад +1

    adidas jabulani is rounder

  • Giannis Dravis
    Giannis Dravis 5 дней назад

    How can you perfectly calculate something when there's π involved?

  • Ryan Thomson
    Ryan Thomson 6 дней назад

    How to define a kilo gram: 1000g

  • Tom van Loon
    Tom van Loon 6 дней назад

    Didn't you make it less round and heavier than a kg by touching it?

  • Browns Fan
    Browns Fan 6 дней назад

    Can i pick it up? Yeah just be car- TOUCHDOWN

  • Rhamel Spaulding
    Rhamel Spaulding 6 дней назад

    is it me or is he high af

  • Courtney
    Courtney 6 дней назад

    Earth is not a she, it is a he, and he has a bulge.. just s yall know lol

  • Exp General
    Exp General 6 дней назад

    Did he just saw the earth is pretty round, knowing that we have hills, mountains, and etc

  • horus2369
    horus2369 6 дней назад

    I'm interested in what a watt balance is

  • Outdoors With Pat
    Outdoors With Pat 7 дней назад

    "You can't have a unit that changes it's value" Mhm Bitcoin?

  • François D
    François D 7 дней назад

    At what height the kilogram was weighted. Was it at sea level ?
    Was the kilo weighted against a liter of water or the the water weighted against a kilo, and how they knew that a liter of water weighted a kilo since they had to define the kilo against a liter of water.
    It is like the chicken and the egg.

  • mr kikass45
    mr kikass45 7 дней назад

    Response to suck it: I do not care about stupid pounds or kilograms. we went to the moon. Suck it.

  • Jonathan Nickerson
    Jonathan Nickerson 7 дней назад

    This is bullsh*t

  • Devin Savage
    Devin Savage 7 дней назад

    And i thought it was just going to be like a satisfying video

  • RandomShit
    RandomShit 8 дней назад

    true level b1tc

  • Cyberchip 047
    Cyberchip 047 8 дней назад

    I really wish he dropped it😊

  • iii 3xki
    iii 3xki 8 дней назад

    Stupid asshole, the earth isn't exactly "round"

  • originalbot
    originalbot 8 дней назад +1

    you are talking too close to the sphere, modifying its weight. thank you for ruining humanity's future,..

    • François D
      François D 7 дней назад

      The volume will be modified, not the mass... humanity's future is safe lol

  • ViruqMC
    ViruqMC 9 дней назад

    Looks like a fushigi ball to me

  • The Openminded Skeptic
    The Openminded Skeptic 9 дней назад

    Legalized it they haved. :D

  • xXBig_BananaXx
    xXBig_BananaXx 9 дней назад

    How rounder does round get, like really?

  • General Incredible
    General Incredible 9 дней назад

    My Play Doh ball is rounder

  • Barberman
    Barberman 9 дней назад

    Deepest ocean Mariana Trench? or real ocean like pacific ocean?

  • 4nc13nt
    4nc13nt 9 дней назад

    The people in the market temper with the kilogramm everyday..

  • seanktb
    seanktb 9 дней назад

    I wonder how much that thing weighs

  • David Tower
    David Tower 9 дней назад

    Tried watching but just cannot get past how nauseatingly close the camera is to this guy's face. Hmm, five pimples, two blackheads, a scar and sixty five nose hairs.

  • memeymarshall
    memeymarshall 9 дней назад

    1:05 I wonder how many people shouted at their screens saying "ThE EaRtH IsN'T rOunD it'S fLaT"

  • zombiepixlez gamer
    zombiepixlez gamer 9 дней назад

    "the earth is pretty round isnt it?" dumbo the earth is an oblate sphere it isnt perfectly round aside from tall mountains theres the fact that at the equater the earth stretches to be wider due to the speed in which the earth travels.

  • Joshua Tee
    Joshua Tee 10 дней назад

    Its ROUNDerful

  • Clorox Bleach :D
    Clorox Bleach :D 10 дней назад

    who else knew that the music playing in the backround is from roblox on flood escape?

  • Halil CANDAN
    Halil CANDAN 10 дней назад

    Its very interesting. You cause to love science. Thanks

  • Hadi Sulman
    Hadi Sulman 10 дней назад

    After watching him explain grave, I think that I have the right to say


  • yehet ohorat
    yehet ohorat 10 дней назад

    It looks like his hand is only thing that rotates, not the sphere. Mindblowing 😂

  • James Darnley
    James Darnley 10 дней назад

    "By 2014" it's 2018 and this still isn't done😂😂😂😷

  • Gavin Bolanos
    Gavin Bolanos 10 дней назад +1

    Im from 2018

  • Franz Liszt
    Franz Liszt 11 дней назад +8

    That "danse macabre" in the background c:

    • Chuck Norris
      Chuck Norris 10 дней назад +1

      Franz Liszt aaayyy i love ur music

  • ssj Kyto
    ssj Kyto 11 дней назад

    I'm just tempted to touch it now

  • lewis pick
    lewis pick 11 дней назад

    he sounds like sheldon off the big bank theory

  • HomesickProductions
    HomesickProductions 11 дней назад

    *the roundest? Well, you've not seen her assets yet*

  • memorylife
    memorylife 11 дней назад

    The song which came befor he holded it crazyblox is the actual guy who made it for game flood escspe in roblox

  • BRNT!
    BRNT! 11 дней назад

    I swear hes stoned look at his eyes

  • Prateek Panwar
    Prateek Panwar 11 дней назад

    1kg of filtered sand worth 1m euros. I can be millionaire

  • TimOn Tube
    TimOn Tube 11 дней назад

    Dirk from Veristablium is leading a charmed existence

  • Haider Abbas
    Haider Abbas 11 дней назад

    Counting atoms and all y don't u use just water at 4 ° as definition of kilogram because it is actually what it is

  • EvanThe Legend
    EvanThe Legend 12 дней назад


  • AIbinoPo1arBear
    AIbinoPo1arBear 12 дней назад

    Paint it like a pokeball and give it to me

  • Robotoon
    Robotoon 12 дней назад

    *drops it*

  • Jonathan Hiner
    Jonathan Hiner 12 дней назад

    Cuz it is