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

Комментарии • 34 459

  • Mickey Bauer
    Mickey Bauer 11 часов назад

    I wonder if you could measure all that sexual tension in kilograms

  • RandomisedGaming
    RandomisedGaming 14 часов назад +1

    100% it's not the roundest object in the world (that's like saying we know the shape of everything on earth and we don't)

  • Angel Bulldog
    Angel Bulldog 16 часов назад

    The earth IS FLAT! Try round like a basketball.

  • Dave Thursfield
    Dave Thursfield 23 часа назад

    Very nice work.

  • Swess2908
    Swess2908 День назад

    if the earth was scaled down to the size of that thing the earth would be more smooth

  • Argenis Arteaga
    Argenis Arteaga День назад

    this man looks high af. That woman's head is the roundest object in the world.

  • end times
    end times День назад

    Uhhhh....back to the round thing please.

  • Daniel Pabst
    Daniel Pabst День назад

    Well...To get it right:
    on 1:14 she says, that, if the earth was sized like this ball, the highest mountain and the deepest valley would be 14m apart?
    I'm german, so maybe I'm missunderstanding this.
    Could anyone clearify this to me?

  • Comments Comenter
    Comments Comenter День назад

    Can just about guarantee that the weights changed due to the Kirkendall effect. Temperature was kept low in an attempt to stall diffusion, but obviously it wasn't low enough.

  • Bryan Ekers
    Bryan Ekers День назад

    I want to handle HER rounded objects.
    Just kidding, this subject is actually quite interesting.

  • Craig Usselman
    Craig Usselman 2 дня назад

    the earth is lumpy and pear shaped.

  • C pro
    C pro 2 дня назад

    wow great from being a practicable comparision the kilogram becomes a theoretically impossible to guess amount of silicon atoms, losing all its practicability.

  • Ask me channel
    Ask me channel 2 дня назад +1

    Too informative

  • Lapse
    Lapse 3 дня назад

    wow, 2013? wasnt expecting that!

  • Ashmeed Mohammed
    Ashmeed Mohammed 3 дня назад

    the roundest object in the world, next to the cutest object in the world.

  • LegalZilu Gamingislife
    LegalZilu Gamingislife 3 дня назад

    earth is flat

  • KREIG The parrot
    KREIG The parrot 4 дня назад

    I need that

  • AntsLifeUk
    AntsLifeUk 4 дня назад

    The sexual tension between them two is real

  • Drakegamez
    Drakegamez 4 дня назад

    ooooh I wanna touch a *ball*

  • macroevolve
    macroevolve 4 дня назад

    It gets to a point for most Humans, where round is a ball bearing

  • Michał Prądzyński
    Michał Prądzyński 4 дня назад

    Ball in Gravity probe B satelite measuring apparatus is EVEN MORE ROUND.

  • Nick900
    Nick900 4 дня назад

    wOOOOW I'VE NeVeR tOuChEd A bAlL bEfOrE

  • Swedish Meatball
    Swedish Meatball 4 дня назад


  • alikarim391
    alikarim391 4 дня назад

    What on earth is he talking about it’s just a round metal ball what’s so good about that

  • JupiterIsMyCountry
    JupiterIsMyCountry 4 дня назад

    Yo mama so fat her fingerprint weighs 300 micro grams

  • Max GG4
    Max GG4 5 дней назад

    Is this Silicon Ball made in Silicon Valley?

  • TIM Grills
    TIM Grills 5 дней назад

    Was this guy in the movie "The Big Short"?

  • ToxicSkull0
    ToxicSkull0 5 дней назад

    Am i the only one that wants to see the ball getting shot out of a cannon

  • NightWolf 99
    NightWolf 99 5 дней назад

    i noticed that when he turned it, it looked like his hand was moving but the sphere wasn't

  • M Led
    M Led 6 дней назад

    Suck it yourself. The end of Le Grand K is nigh since scientists have discovered an accurate universal way to measure weight that means they can do away with another pretentious French affectation that is virtually meaningless in the modern world. The Grand K is the last of the outdated units of measurement that rely on a physical object to measure a standard, rather than a system of calculation that can be replicated anywhere.
    Scientists now can work out mass using a calculation taking in Einstein's theory of relativity and Planck's constant - a vital component in the field of quantum mechanics. So, the Grand K will be relegated to history by 2020, where it will join the meter bar - also made of the platinum-iridium alloy - in the dust bin of history.

    RK LMBD 6 дней назад

    @veritasium - I notice you refrained from calling the world's roundest object PERFECTLY round. Was that deliberate? I remember reading that its impossible to create a perfect ball bearing because of gravity. As you form the ball, whichever point is lowest will ever so slightly bulge, be denser, be heavier. I think it was eventually even a space shuttle experiment, to form a ball bearing in zero gravity. My question is, if the sphere isn't perfect, how can the number of silicon atoms be accurately computed?

  • MD Zunaid Mansuri
    MD Zunaid Mansuri 6 дней назад

    Roundest object in the world is a water bubble !!!

  • John Dekker
    John Dekker 7 дней назад

    I can't stand these presenters who expend so much on trying to seem cute, just give me the science.

  • Random Shit
    Random Shit 7 дней назад

    Is he high¿

  • Andrew Tolmasoff
    Andrew Tolmasoff 7 дней назад

    This guy looks so blazed in his face close ups.

  • Mercman1010
    Mercman1010 7 дней назад

    polishing a foil ball done here first

  • karti med amine
    karti med amine 7 дней назад

    Hello , I am a big fun from morroco I respect what you do sir but there is just one problem the map you have used is in 5:09 shows morroco divided in a half and this is embarassing this south half is also morroco .. Thanks

  • Adrian Aguilar
    Adrian Aguilar 7 дней назад

    Does anyone else hear halo music in the beginning ?

  • PelaajaW
    PelaajaW 7 дней назад

    dät green screen is nice i can see it because of the weight

  • Oh Gee! Champion!
    Oh Gee! Champion! 7 дней назад

    Yeah, but, can it cocaine?

  • Person
    Person 7 дней назад +2

    0:37 when he turns his ahnd, the ball looks like it doesn't move

  • Ibrxhim
    Ibrxhim 7 дней назад

    My head is rounder than that.

  • Kid James
    Kid James 8 дней назад

    What about the Fushigi ball

  • Hysterix
    Hysterix 8 дней назад

    1:05 i mean the earth is pretty round isnt it?
    *Flat earthers triggered*

  • Juan Manuel Machuca Rodriquez
    Juan Manuel Machuca Rodriquez 8 дней назад

    I want to know if you were high on 4:20?

  • Johnny Casteel
    Johnny Casteel 8 дней назад +1

    But its still not a perfect sphere so meh.....

  • Amanapanda
    Amanapanda 8 дней назад

    You know a video is good when it starts off with the sentence "Can I Hold It?"

    • Do the Maths
      Do the Maths 6 дней назад

      Amanapanda still... better than being a idiot

  • donatas k
    donatas k 9 дней назад


  • shtik
    shtik 9 дней назад

    6:57 at this point I forgot the video was originally about a sphere.

  • lildrummaboy1000
    lildrummaboy1000 10 дней назад

    How is mol affected by kilogram since one mol is defined to be 6,22*10^23 Atoms

  • Jesus Lopez
    Jesus Lopez 11 дней назад

    Pretty sure I own a snow globe a lot rounder than that

  • Amir Hakiem
    Amir Hakiem 11 дней назад

    So bad watching your self in closeup type of shot. Better in medium closeup ..

  • v12345vtm
    v12345vtm 12 дней назад

    Boss hoggins

  • Vincent Stern
    Vincent Stern 12 дней назад

    Most boring video ever

  • Scott Johnson
    Scott Johnson 12 дней назад

    While watching this I'm trying to decide why I found it so interesting. I'll have to check out your other videos.

  • Benjamin Goodlich
    Benjamin Goodlich 12 дней назад +1

    So pointless

    I'm sorry I'm unoriginal. At least atmiting it is original

  • cbapiaz
    cbapiaz 12 дней назад

    I am always pissed that the us doesn't use the metric system...

  • Selachimorpha
    Selachimorpha 12 дней назад

    Lmfao that silicon sphere be probably round than the woman's chest

  • Golden Champ
    Golden Champ 13 дней назад

    Me: a sphere can’t be perfectly round
    Other guy: *hold my beer*

  • Gut Instinct
    Gut Instinct 14 дней назад

    What a pointless waste of time for the scientists who could be doing more important things. And wouldn't the roundest thing of Earth be a simple Soap Bubble . What would we need exactly 1kg of that needs to be so exact? certainly not my fruit and veg lol

  • my favevorites Antolin
    my favevorites Antolin 14 дней назад

    2nd most roundest thing in earth

    My butt cheek

  • Daniel Broadbridge
    Daniel Broadbridge 14 дней назад

    Ignorance has 8400 thumbs.

  • PsychoHobbit1
    PsychoHobbit1 15 дней назад

    But pounds are a measure of weight, not mass. So they should be defined in terms of Newtons.

  • Juan Oo
    Juan Oo 15 дней назад

    Those 420 eyes, man... :)

  • Pedro.G B.S
    Pedro.G B.S 15 дней назад

    This is absolutely incredible

  • Benedikt von Gahlen
    Benedikt von Gahlen 15 дней назад

    Thanks left ear

  • shiang Johnson
    shiang Johnson 15 дней назад

    i am american -__-

  • keanu tamatea
    keanu tamatea 16 дней назад

    My nut is more round

  • Nick Yelovich
    Nick Yelovich 16 дней назад

    I want to steal Big K. Who wants to participate in a massive heist?

  • Ronald Doe
    Ronald Doe 16 дней назад

    its so I don't know its beautiful and little bit scary this thing O

  • Paul Ward
    Paul Ward 16 дней назад

    so is there a follow up to this video?
    Statement near the end says we should have resolved this about 3 or 4 years ago now.

  • andrew davis
    andrew davis 16 дней назад


  • SFG Jointzz
    SFG Jointzz 17 дней назад

    what about math class....? :D

  • Evan Cook
    Evan Cook 17 дней назад

    Spoilers: the US's definition of the kilogram (the one using the Watt balance) will change October 2018.

  • J.B. Ironman
    J.B. Ironman 17 дней назад

    Freeze it. Wonder if it shrinks.

  • itsahardlifewhenyourreneverwrong
    itsahardlifewhenyourreneverwrong 17 дней назад

    Pointless.. Really

  • Seth Masters
    Seth Masters 17 дней назад

    Who else is watching this in 2018? I started laughing so hard when he said 2014

  • Márton Vrabecz
    Márton Vrabecz 17 дней назад

    The earth is flat

  • Róbert Mátrai
    Róbert Mátrai 17 дней назад

    Nothing compared to a Kardashian butt.

  • MrSeeks Seeks
    MrSeeks Seeks 17 дней назад

    Just pick it up soft cock

  • Theodrick Davis
    Theodrick Davis 17 дней назад

    Why all the stupid comments? Silicon and Aluminum are two different elements. In other words, they are not the same!

  • Nirmal c sekhar
    Nirmal c sekhar 18 дней назад

    My balls are more roundest😂

  • Jasper G
    Jasper G 18 дней назад


  • VideoKolay
    VideoKolay 18 дней назад

    hot secretary! Greetings from Greek

  • sorrow loro
    sorrow loro 18 дней назад

    World’s roundest object would have to be the world itself

    • MikeRosoftJH
      MikeRosoftJH 16 дней назад

      Nope, it's about a thousand times smoother than the Earth. (If you were to magnify the object to the size of Earth, any irregularity on it would be of the dimension on the order of meters.)

  • Ian Dropsyface
    Ian Dropsyface 18 дней назад

    The kilogram is poo ...

  • khitish rajput
    khitish rajput 18 дней назад

    2:18 that french revolutionary boobs 😂

  • Live On The Flight Deck
    Live On The Flight Deck 18 дней назад

    So incredible...I never knew!! Thank you!

  • Tom Storm
    Tom Storm 18 дней назад

    It looks so cool I want to take it home !!

  • Disco Shark
    Disco Shark 19 дней назад

    Amethyst: Aw man! I think my favorite round thing was in there!
    Garnet: I’ll get you a new round thing

  • clorox bleach
    clorox bleach 19 дней назад

    This is so pointless

  • Andreas Østerlund
    Andreas Østerlund 19 дней назад

    I would smash it with a hammer just to see her reaction😁😂😃

  • Jake
    Jake 19 дней назад

    Its a shame the presenter is so awful, the videos are interesting

  • Claudiu04
    Claudiu04 19 дней назад

    japan's foilball

  • Crayo Popp
    Crayo Popp 19 дней назад

    So polishing ball was a hobby long before the Japanese started them in 2018

  • CFG Racing Vids
    CFG Racing Vids 19 дней назад

    2018 now, was the KG redefined?

  • Chef Lambo
    Chef Lambo 20 дней назад

    my brain hurts

  • gracie vlogs
    gracie vlogs 20 дней назад

    Notch would hate this video ( Minecraft)

  • BabyRage
    BabyRage 20 дней назад

    the eath is not raundt

  • Waranz League
    Waranz League 20 дней назад

    I completely understand😒