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Roundest Object In the World Created
holy_calamity writes "An international research group has created the most perfect spheres ever made, in a bid to pin down a definition of the kilogram. It should be possible to count exactly the number of atoms in one of the roughly 9cm silicon spheres to define the unit. Currently the kilogram is defined only by a 120-year-old lump of platinum in Paris, but its mass is changing relative to copies held elsewhere. Other SI units have more systematic definitions."
Did anyone else read "An international research group has created the most perfect spheres ever made" and think boobs?
"Quote me as saying I was mis-quoted." -Groucho Marx
No mere human will never be able to accomplish what God did with Jennifer Lopez's ass.
SJW: Someone who has run out of real oppression, and has to fake it.
No one will be able to claim that a game of pool, snooker or soccer was won because the ball wasn't round enough...
Summation 2
Does anyone here want to inform CmdrTaco that boobs shouldn't be perfectly spherical, and in fact, it's preferable if they're not?
It's not his fault. He watched a lot of Baywatch. He doesn't know any better.
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find their privates are on the Internet.
The picture in the article shows the sphere being handled in what obviously isn't a cleanroom. Won't that mess up its surface?
"I bless every day that I continue to live, for every day is pure profit."
In a press release today, Sir Mix-A-Lot is quoted as saying that, by viewing this object, "You get sprung", as well as "[wanting to] pull up tough" because of the perfect shape of the object.
He was later quoted as saying that "I like'em round and big, And when I'm throwin a gig, I just can't help myself". Clearly, he is an aficionado for perfectly round objects.
* my captcha was "beating", which is what I deserve for the 90's reference.
In other news... these same scientists are hosting the BEST GAME OF PONG EVER this weekend!
"Insanity in individuals is something rare - but in groups, parties, nations and epochs, it is the rule."
So the metric system, which is touted as being so much more accurate than the measurements we here in the U.S. know and love is has a measurement that is based on a disappearing lump of metal? The only logical conclusion one can draw from this disclosure is that the metric system is magic, and should be burned at the stake.
That's precisely what they are trying to do.
Onda Technology Institute
That is what they are doing. They are defining the kilogram as X silocon atoms.
You can define a kilogram in the number of atoms of X element, but you still need a physical object to calibrate your scales against. In this case, I believe they did it by number of silicon atoms. TFA says they went and milled a silicon sphere (purified to only Silicon-28) weighing as close to the current standard as they can get it. Next they're going to measure it (X-rays and the such) to find the density, spacing, and the such and end up getting a number of silicon atoms. This number will now BE the kilogram, and these spheres are going to be the new physical standards. They are suppose to be an improvement in that is it theoretically possible to recreate these spheres should anything happen to them (as we know the amount silicon needed), while it is not possible to recreate the current standards.
My other summary was a bit off, got the process a little backwards.
So I'm not getting fatter, it's the kilogram that's getting slender!
"First we create a perfect sphere, then we count the number of atoms exactly - and we get a kilogram standard!"
"Alright... so how big do we make this sphere?"
"Oh you know.. roughly 9 cm, give or take."
why not just define a kg as 1 Liter of pure H2O at 4deg C?....it is that way anyway.
Your balls may always rotate
Deiseil or widdershins
What matters is their smoothness
Reflects what's on your chins.
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Get thee glass eyes, and, like a scurvy politician, seem to see things thou dost not.--King Lear
A kilogram is defined as exactly 2.20462262 pounds of pure water at pressure of 100 kPa (1 bar) and a temperature of 273.15 K. :)
Well, it's sorta like this: a standard is only useful if you have some effective way to reproduce it or measure with it.
1. time. You can essentially just make a MASER, which means basically a cavity which resonates at that frequency. The nice part is that it can be tuned, and even continuously tuned, by just measuring the amplitude of the signal. When you've reached the maximum power, the thing is tuned to that frequency.
2. length. It's measured by Interferometry, so you have a meaningful way to transform a wavelength into any given distance.
At any rate, the transition for these two only happened when someone build a device which could actually measure one second or one metre that way.
3. mass. Well, that's the tricky one. Saying that you define a kilogram as one bazillion silicium atoms is useless unless you can somehow actually produce a lump with that many atoms. As long as we can't actually be sure how many atoms are in there, it would be a useless standard.
These guys claim to have been able to do just that: say with a high degree of confidence that, yep, their spheres contain exactly that many atoms. If they're right, then we're finally ready to move the kilo to that standard.
A polar bear is a cartesian bear after a coordinate transform.
I think that Gravity Probe B has the most perfect spheres and they are much smaller that the Kilogram sphere.
Kilogram Silicon Spheres
"If you were to blow up our spheres to the size of the Earth, you would see a small ripple in the smoothness of about 12 to 15 mm, and a variation of only 3 to 5 metres in the roundness"
Gravity Probe B Spheres
http://www.nasa.gov/mission_pages/gpb/index.html
"If these ping pong-sized balls of fused quartz and silicon were the size of the Earth, the elevation of the entire surface would vary by no more than 12 feet"
We are Dead Stars looking back Up at the Sky
Is this really the reason why it's a sphere? Crystals don't PRECISELY grow into a sphere do they? Won't they still need to shave or polish it to get it to the exact radius? And then they'll need to calculate the number of atoms using Pi, an irrational number!
Why don't they make it a cube and find a length that is close enough (cubed) to give them the approx. right number of atoms and then make THAT the standard? They'll then have an EXACT number of atoms making up each length. It should be easier to cut or shave off the requisite number of atoms to maintain it, a (perfectly) flat surface seems much easier to maintain than a 3D curved surface. In fact if they make it just a little too small they could probably even ADD to the cube in single atomic layers using vapor deposition!
Obviously brighter minds than mine have thought this through more thoroughly, so really, I'm curious: why is it a sphere?
By the way, maybe this is a good use for the ISS, to keep the 1kg reference MASS somewhere it won't be distorted by gravity, not kept at any particular country for measurement and you can keep it in a high quality vacuum for free! (A little expensive to get to though).
You can't calibrate a scale by telling it your theoretical model - at some point there actually has to be a physical thing.
Not a dupe - a follow-up.
The first article mentions only the weight loss of the original kilogram, the second article follows up on that mentioning a perfect sphere is going to be made. The current article follows up on that, announcing the actual creation of this sphere.
Now the fourth article in this series should be the announcement of the number of silicon-28 atoms needed to create exactly one kilogram.
On the other hand, isn't the exact mass of atoms known? Then it should be easy to say "this number of atoms is exactly one kilogram". The creation of the sphere being an exercise left to the reader.
That's exactly what the TFA says. They've created two spheres made out of pure crystalline silicon (so now they've lined them up). The sphere is nearly perfect (its about 95mm in diameter, has small scale variations of 0.3nm, and deviations from perfect cruve of 60-70nm). Now they're going to independently measure 60 000 points of the surface of the sphere to map out all of the surface variations, and then they're going to measure spacing using X-ray crystallography.
Also, nitpicking but... one kilogram = 10^15 picograms, always.
Pi describes an idealized construction. Physical manifestations are imperfect to the extent that they don't match pi, not the other way around.
Nerd rage is the funniest rage.
It's not totally worthless, as the kilogram is the basis for just about all other SI units. It is the only unit that is not defined according to other units, or in relation to a natural property. Thus, its definition is arbitrary, and everybody must agree as to what a kilogram is before the unit has any value as a standard. There's a very nice explanation of the kilogram as a fundamental unit here:
http://en.wikipedia.org/wiki/Kilogram#Importance_of_the_kilogram
I hate printers.
...has created the most perfect spheres ever made...
...roughly 9cm...
That precise eh?
why not use, say, electrons, as in 1kg=weight of 1.1xxxe30 electrons (at rest)?
They tried that, but when they charged their terafarad capacitor with 1e30 electrons so that they could calibrate their scale, somebody accidentally grounded it and the massive arc of current blew the roof off of the lab.
That's actually the reasoning behind the Watt Balance another potential method for defining the kilogram.
Keep in mind that the Joule is a composite SI unit, and is itself dependent on the mass of the kilogram. Unless you can calibrate the energy measurements (exactly what they are trying to do) you end up with a circular definition.
The answer is none.
None more round.
It's 1024 grams, right? Easy definition.
I am a physicist at the UK's National Physical Laboratory and I am involved in the redefinition of another unit - the unit of temperature. The work concerning the redefinition of the kilogram is >much more philosophically fraught and technically difficult. I understand many of the rather skeptical comments expressed here The current situation is unsatisfactory because the mass of the kilogram is changing, albeit by a small amount - a few micrograms in 1 kg - i.e. a few parts in 10^9. The aim of the work is to replace this artefact with (essentially) a procedure. Effort onne (using the silicon sphere) is essentially trying to build a link between a macroscopic mass, and the microscopic masses which we expect to be fixed. The other effort not mentioned here is called the watt balance which is a machine which can exhibit the same inertial mass as a kilogram - or any other weight. At the moment the two watt balances disagree with each other and they both disagree with the silicon sphere result. There is still a lot of work to do on both approaches. Incidentally, the reason is it is a sphere rather than a cube is because of edges. Edges are amazingly fragile, hence the sphere. ALl the best M