Nobody's Exactly Sure How Much A Kilogram Is Right Now 

but they're feathers......

Came here looking for this comment, wasn't disappointed.

But they're the same

They are the same. Even a pound of steel and a pound of feathers. But a pound of gold and a pound of feathers aren't. Well, an ounce of gold and an ounce of feathers aren't. Because an ounce of gold is a Troy ounce. (An old joke. When Troy pound existed, a pound of feathers was heavier.)

This comment is like going the wrong way down a one way street.

thanks, dad

_shrug_ No point denying that.

this is a very massive issue, it's been weighing down on me for a long time

I like your joke a ton!

we might not understand the gravity of the situation, yet. It will be a heavy task to take on.

It's been more than an year since the kg is based on physics laws and not an object anymore

A channel that has 1.62M subs in 2020 had a comment with just 1 like for 4 Years! RU-vid really is the level playing field one hopes for! Hey Grady! Love Your videos!! One of my favourite channels out there!!

ok

Is it done?

@Practical Engineering I hope you have a plank's constant project in the works, because that's how it's defined now

And we've been still waiting!

Underrated comment

Yup

Nice

Worse, they were so unsure about what a pound is, there are many kinds of pounds now.

+Alexander Tamayo Dont you get the joke?

Oh god that hurt my brain

And people think Fahrenheit is bad smh

This is neat. Doesn't tell us how they'll actually 𝘮𝘦𝘢𝘴𝘶𝘳𝘦 kilograms for standardisation purposes, but the definition itself is pleasingly simple and universal. Yes, I said simple. If you don't believe me, try these two on for size: "The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency ΔνCs, the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s-1." "The candela, symbol cd, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 x 1012 Hz, Kcd, to be 683 when expressed in the unit lm W-1, which is equal to cd sr W-1, or cd sr kg-1 m-2 s3, where the kilogram, metre and second are defined in terms of h, c and ΔνCs." See my point? 😉

@@sakkikoyumikishi a second is the time time it takes for me to say "one thousand and one".

@@theJuggla17 Fahrenheit is defined based on kelvin, and "since 2019 the scale has been defined by fixing the Boltzmann constant k to be exactly 1.380649×10−23 J⋅K−1."

Or steal it, chip a corner and return it. :)

In 20th of May next year the definition of a kilogram will change at it's core. Stealing that kilogram now is not such a big deal.

... as if there was no backup of that existing :D

Wow, an affidavit that that would be worth its weight in kilograms

@@krzysztofpiasek5682 warning time is near

But you kep going down and down.

+Ninja lemur he's joking

Dilip Tien oh noes, you found out!!!

1g = 1000mg duh

the best cameraman kilogram/1000

YAY! You beat me to it!

@Nunovia Gottdamnedbizzness Noether says what?

Funny thing here, the new definition of the kilogram came into effect on the day of my physics exam, and the examinations removed a question regarding the definition, because the answer didn't hold up anymore.

11.16*

@@1brianm7 16.11, like most of the world use it

meters are now defined by the speed of light

A kg is as big as you want it to be. But it’s always one kg heavy. 🙄

@@sahibjot01 r/woooosh

@@sahibjot01 r/woooosh

@@sahibjot01 jesus christ kid calm yourself down

@@sahibjot01 Like you, kiddo

Because it was a similar item meant for the same purpose.

I actually thought it was the same sphere from veritasium's video

Niall Kinsella​ Maybe it is?

tf guys, that's the similar sphere from veritasium video

awesome video, I've watched it soo many times, It's fascinating and ingenious to see the Metric system was invented in all of its glory!!

There was an attempt to standardize kilogram as a liter of water at 0°C and under atmospheric pressure, but the problem as, that pressure units are derived from are and mass, so it would refer to itself.

The mass of 1mol of water would not change based on temperature

The silicone sphere is the same thing, 100% definitive and easier to handle than water...

Isn't the definition of a kilogramme 1L of pure H2O at 4°C?

Kenji Gunawan no

Yupie. What's a km? Kanadian miles?

~2 lbs 🦅🇺🇸🦅🇺🇸🦅🇺🇸🦅🇺🇸🦅🇺🇸🦅🇺🇸🦅🇺🇸🦅🇺🇸🦅🇺🇸

This is *SATIRE* I am american, and am constitutionally allowed to make this joke.

@@Attaxalotl Not if you're from Puerto Rico, Guam, Samoa or others :(

is that block in the middle not Tom’s phone on a stand?

@@marielikes2502 what ever that is (phone or otherwise) it's definitely what took the video.

It's a video, not a photo.

@@marielikes2502 yes, but the reason why MrLagEveryP2WServer was confused was because it looks like the guy in the background is doing things on top of it.

Surely the main problem with it is that gravity isn't constant around the world, whereas the kilogram is a unit of mass and needs to be independent of such things?

Exactly, using weight to mesure mass is problematic.

+d2factotum yeah good point. And what about the equipment you use to measure it?

For the majority of the world gravity is considered to be constant as the relative height differences between different counties compared to the radius of the earth is most of the time insignificant. But for the absolute 1 kg mass it would make a difference. So how about using the watt balance at agreed radius from the centre of the earth so that gravity would be constant and the weight of a 1 kg mass would also be the same.

Wilron Gravity isn't constant even at constant radius from the centre of the Earth--local geology can make a difference. Not a large difference, but when you want something to be accurate to better than a millionth of a percent, an important difference. Also, how would you accurately measure your distance from the centre of the Earth in the first place?

Newest comment

No. The sphere that Veritasium touched was the "most spherical object" in the world which is different to this one

wtf youtube comment posted 6 minutes ago reply 9 minutes ago

Which is the same thing if not the exact same sphere.

did you jsut see the title of the video and not watch it? the whole point of the spehere was a base kilogram unit

That line hit hard at the end of The Doctor Falls

+Gavers23 Not quite! And that depends on a lot of qualities of the water…

for example if the water is slightly different to base H2O (like if chlorine is added) the weight will be changed so weight is very difficult to measure like that

+Tom Scott are you going to talk about brexit?

Wait, are you an Arandanaut?

Not ... really, no. A kilogram is a measure of weight. A liter is a measure of volume. A liter of yoghurt isn't going to weigh as much as a liter of milk (or even water)

It wouldn't matter, that is the constant, we'd still use that as our Kilogram.

They're measuring mass, not weight. You should see how volts are defined, you need an infinitely long pair of conductors.

Well, looks like it is time to go back to English units, we will just take an average of everyone's foot size and go with that.

Yes, indeed it's wrong. "The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540×10^12 hertz and that has a radiant intensity in that direction of 1⁄683 watt per steradian." That's how the candela is defined.

luxs?

That's still just disgustingly arbitrary. 1 watt per steradian would at least be seemingly logical.

Everything in these definitions has a purpose, i learned about this in my class and the 1/683 of a watt also has a purpose (although i've forgotten it by now)

+Sam Otten All unit definitions are arbetrary, because units themselves are inherently arbitrary. It's not like it matters how we measure things. We just use what we use for historical reasons.

he's just optimistic about the future

It's fantastic that i can't tell how much of this comment is satire

Also isn't velocity American Flags'waves per bullet?

look at that bullshit! they removed all the spaced lines. the bastards!

It does

+Minecraftster148790 like this

I heard that "only 1% of their userbase uses that function" or something. Because that's a good reason to make the comment section much worse for anyone actually using it for fruitful dialogue. Bollocks is what it is.

Cyril Nope. I've tried. But it still works when you reply using the "bell" notifications.

A Banana hence the "left"

watt*

but the left didn't want to leave... xD

now y'all did leave the eu

beanard In theory ...

What was is before and what year?

Oh, please get a job with Texas Instruments and make me an overpowered calculator.

+MrDeadInMyPocket That's basically what they do (there are many copies) - but how would you know if they all shifted in sync?

It's not a matter of knowing "if" they shift. Individual units will shift. Some will shift one way, some will shift in the other. The average of all remains the same. You can even have various sample groups. Perhaps three sets of 100. EDIT; Now that I'm thinking about your question. What we're talking about is really subjective vs objective, perhaps? If we all agree to call this specific measure a kilogram and that measure is drifting, the important thing is that we all agree, not the actual measure. I don't want to call what we call a kilogram arbitrary, that's why I say subjective. Can there be an objective measure of what a kilogram is and can that be a constant. Not sure. Maybe it's something we need to constantly test and maintain. I'll think on it, thanks for the video.

That's why Tom mentioned the "in sync" bit... If they all shift to the same side of the scale, you'd have no way of knowing.

Thomas Vandermeiren You might get aberrant shifts in small sample sizes. It's unlikely, and less likely the more you have. That's why I suggested multiple sets. If you think of it this way. If you have two clocks and one clock runs slow, how do you know which clock is really wrong? The more clocks you have the greater accuracy. Clocks will "Shift" their measurement, but with work you're able to maintain the proper time. Though the idea of an objective measure sounds like a good idea.

***** Exactly. The idea of a kilogram is somewhat subjective. We agree on what a kilogram is and under what conditions we measure. The subjective measure is a useful tool At this point I'm wondering if there is such a thing as an objective kilogram. So this is a kilogram, but relative to what? lol

This was the definition between 1795 and 1799. You are slightly out of date.

LARAUJO How do you know the markings on the measuring device are accurate and haven't changed since then?

Volume depends on temperature so a liter of water wouldn't weigh the same at all temperatures.

And assuming water doesn't compress or expand much due to the change in the atmospheric pressure

Water is simply less constant than this and i'd guess also more difficult to handle.

why not just say a gram is 1 cubic centimeter of some metal

How would you use a pendulum to measure mass? (Seems like there's some way that I'm not aware of, so I'm genuinely curious)

Until we start needing to measure mass on different planets, the relationship between the two is defined by a simple constant, so unless you're talking about specific values of the weight/mass of something, it doesn't matter.

Titanium1500 This is physics goddammit. Our measurements should work perfectly even on the edge of a black hole! :)

It's interchangeable in this instance. Obviously we're talking about weight, that's what we use Kilos for, but since we're establishing a set weight here it's not inaccurate to say that's it's a set mass. We're not changing gravity so the two are the same.

As the kilogram is defined as a unit of mass they are talking about a unit of mass. Weight is physically measured in Newton which is itself depending on the mass.

+Fabian Neundorf yes, because if this object has a MASS of 1Kg, the its weight is actually 9.8N on earth.

But what if he's filming this on the moon

b 28282 then it would be 1.6N I think

Nothing weights Newton. Newton is a Force, that's why it can vary

Daniel Palaci weight is the force downwards due to gravity, weight is a force. Kg is for mass. W=mg.

Yea you are right. I got confused with mass.

That was the definition between 1795 and 1799. Even then it was known to be such a bad definition that it was only kept in effect for four years. It's been 224 years since the kilogram had anything to do with water, and you can't just change the value now without breaking the entire world.

I've put a note with my thoughts on my Facebook page - the link's in the description - but ultimately it's not predictable. No-one knows what's going to happen next!

+Tom Scott Boris Johnson knows, according to himself. Then again, Boris has become as optimistic of late as that Iraqi minister in the Second Gulf War who was declaring to the world that everything was fine while bombs were audibly dropping in the background...

it was defined with water at a specific pressure and temperature... but pressure itself is derived from mass - which meant the definition was circuitous. however, this was indeed one the historical definitions of the kilogram

I also imagine in todays world once you have a liquid kilo and you make a solid kilo there would be no real reason to use the liquid kilo afterward it would only be a less reliable weight being the inside is moving?

But they're both a kaelogram....

@@wisdry But they're both a kaelogram

It's actually surprisingly large: ~21.8 micrograms. Not all Planck units are incredibly tiny.

But then isn't the Planck system still kinda arbitrary, because we chose to calibrate it using decimal system? It would be much more practical for scientists indeed, but is it, in theory, less arbitrary than what we use today?

I find "sharkee" pretty good, and he doesn't have many subscribers.

+Simon Clarkstone Really?! 72000 is quite a lot of people

Veritasium and Smarter Every Day for science-y stuff, CGP Grey for very infrequent but very high-quality, well-researched videos. Numberphile, Computerphile, Sixty Symbols, Periodic Videos, and other channels done by Brady Haran for more long-form, still sciencey/mathey/computery, much more frequent videos.

I highly recommend VSauce. He explains interesting question in a really unique way. You should watch him. As for my predecessor i can second his choice on brady haran videos.

I'd suggest Nerdwriter1. He just brilliant!

It's quite refreshing that it wasn't

+Zack Miller Don't worry, it's not weighing down by much. It's in pounds remember.

+Zack Miller *a very limp 'ba dum tss'*

+BOSK *a slightly less limp 'ba dum tss'*

Hi IUNFE, No it really won't,

I like your name.

Hodor:D

he made one when he entered Russia without Visa once he's no longer EU citizen, stuff like this will be harder

+666Tomato666 it'll still be possible.

Rocks move under this one spot

For some places that is very much correct, the California coast is exhibit A. Other places have huge areas of granite core that do not move at all. The Candian Shield for example.@@vsctutorials8355

@@vsctutorials8355 This is very much true for many places on earth, the California coast is a good example. There are some places that do not move at all. The Candian shield area is a good example. I'd think that to have a rock-solid (pun not intended) place to be made the standard for measurement, the equipment would have to be set up on an ultra-stable core place and never moved.

Pan kurczak But at least it's stays consistant in the long term. Every once in a while you do a refresh.

Yeah because the mass of a litre of water is constant right

But the mass of the water will still depend on temperature and ambient pressure

Actually it is supposed to be at 4 degrees celsius

Yep, the temperature is given as 4 degrees celsius, when water is at its densest.

The redefinition of the kilogram required a correction of 0.1 parts per milion for the Volt and 0.02 ppm for the Ohm. That had an effect on calibration labs, for sure, but it went unnoticed by 99.5% of "the electronic world".

Dark

it was about curvature not weight

+SCOFIE he did one about weight as well.

Exactly what I was thinking

it was the same object, it needs to be perfectly spherical in order to measure it accurately

+Pan kurczak Watch the video again. Dirk explained that the kilogram sphere is the most spherical thing.

This doesnt make really sense bc kgs can be translated to 1kg = 1000000mg also 1kg = 10hg or 1kg = 100dag

moomin renjun Kilo means thousand.

Matthew Campbell You'd need extremely pure water, extremely stable pressure and temperature, and extremely accurate volume measurement. Too many sources of error. The methods mentioned in this video are far easier to measure with precision.

How do you know that's one liter of water just as you don't know what's a kilogram of water

Water is simply less constant than this and i'd guess also more difficult to handle. A meter is actually defined by natural constants, and as a result a liter too.

Yes the liter is precisely defined but really if you want to make it an amount of substance, the better definition is the ball of silicon, with the number of _atoms_ made the correct definition. That could also be done for water, a certain number of water molecules to fill a liter, but it's easier I'd believe to make a precise silicon ball than a precise amount of water due to silicon being a hard and stable solid at ordinary conditions.

if you kept watching and didn't pause to comment, you would see he says right after "The British National Standard Kilogram"... Since he's on Britain, that's his Kilogram. The one all balances on Great Britain are measured against. He also says the International Prototype is on Paris... That's the magic of actually watching the video before commenting. You don't make yourself a fool.

Yes, he made a major point of saying this in the video.

ha! loser responding to a comment

Ah yes, but he did slip up in the beginning. (I actually did watch the entire video.) Let there be no confusion as to which is THE kilogram. There can only be one THE one, and that of Britain is not THE one. One musn't confuse a transfer standard for the real deal, e.g. one musn't confuse a Rubidium frequency standard for a Cesium frequency standard.

Just admit you didn't watch the full video and wanted some "AKCHUALLY" points

Not by their strictest definitions, but as far as standardized units of measure are concerned, they are interchangeable.

They are a measurement of weight

No, they're a measurement of mass; the weight of a 1kg object is different depending on the local acceleration due to gravity, which varies by more than 1 part in 10^8 between places you'd like to make accurate measurements.

"No, they're a measurement of mass;" Part of the problem with our definition of the kilogram is that currently--while it is supposed to be a measurement of mass--is that it is inextricably tied to force (weight/gravitational pull). No matter how you slice it, the only way to actually measure "the kilogram" (the one in Paris) is by placing it on a scale and measuring the force that it and the Earth exert upon each other--which is done by seeing how far the scale is depressed (how hard "the kilogram" presses on the scale, which is to say force and not mass). The kilogram is currently based on weight, but "the kilogram's" mass and weight are one and the same because of how it is measured. So yes, the kilogram is supposed to be mass instead of weight, but unfortunately, we don't have a way to do that. When the kilogram was based on water, then it was much more easily distinguishable from weight, but that had problems that were more severe.

You could drop a box with a magnet through a horizontal magnetic field and see how different its deflection is when it contains the kilogram versus when it doesn't; that's unaffected by the local strength of gravity, so long as you calibrate it by timing how long the box spends in the magnetic field. You could also swing the kilogram around on a force gauge in a circle of a particular size with a particular period. You'll have to correct for gravity, but you can work out from the angle it swings at how much of the force you're measuring is centripetal acceleration times one kilogram. And, of course, a balance scale isn't affected by the local gravity so long as gravity is the same for both pans and there's enough gravity to keep the items in the pans. Since you're generally trying to verify that your lab's reference object has the same mass as "the kilogram", that's sufficient.

And it's interchangeable across units! Divide that by a hogshead and you get the furlong! Brilliant!

Actually the metric system was invented by the french.

1 pound equals 3 feet. God bless America. Also, 16 ounces in a pound m88!

It's not 'our' metric system any more than Fahrenheit is 'our' system.

Actually the current imperial measurement system is now based on the metric system because it's much more stable. Sad but true.

I needed a laugh

The problem is: It is liquid and also easily changes its density, not to mention that it is really hard to have pure water. The new definition of a KG should be based on Avogadro's number of Silicon 28 (Silicon is often handled pretty pure and flat btw), a real variable and not a physical object like water. Water can be used in a kind of comperison since this is what the metric system is mostly based off but still, better have a constant number instead to rely on physical objects just like distance and time are already this.

MarioFanGamer But the current standard (platinum and iridium) also changes its density, right?

At what pressure? Pressure is measured in pascals which are derived from kilograms.

Ralesk they simultaneously measure local gravity using a gravimeter. Then the forces cancel, leaving mass alone.