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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.
Does anyone here want to inform CmdrTaco that boobs shouldn't be perfectly spherical, and in fact, it's preferable if they're not?
This guy's the limit!
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
Of course, I'm no experimental physicist, but if I were to guess, I might suggest the fact that the binding energy (and thus the mass) might change with force-field fluctuations in the vicinity, but I think that problem should be solvable by defining the proper environment for measuring.
Does anyone know?
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.
http://science.slashdot.org/article.pl?sid=07/09/13/2234236
http://science.slashdot.org/article.pl?sid=07/06/15/0541230
Government cannot make man richer, but it can make him poorer. - Ludwig von Mises
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.
Burma Shave
Get thee glass eyes, and, like a scurvy politician, seem to see things thou dost not.--King Lear
Crystal growth is often spherical. And very controlled crystal growth is a method to get a very uniform object without (many) defects.
Does this also pin down the value of pi? I mean, they know exactly how many silicon atoms are on the surface of the sphere, and they know exactly how many atoms there are from the center to the surface.
hmm.
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. :)
The roundescht object in the world isch your mother, Trebek.
Colin Dean Go a year without DRM
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
They should have visited this guy's website
http://www.kyokyo-u.ac.jp/youkyou/4/english4.htm?
making spherical mud balls. I've had this bookmarked in del.icio.us for a long time
from TFA "To shape the spheres, the Australian Center for Precision Optics pulled optical engineer Achim Leistner out of retirement. Leistner, who has been creating precision spheres for decades, considers these final two to be his masterpieces"
Great. What happens when this guy kicks the bucket?
I'll see your hokum and raise you a boondoggle.
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).
number of atoms = (volume * density) / mass of silicon atom
With the volume of a perfect sphere simply being
Pi*r^3 (I think)
It's also much much easier to test for the perfection of a sphere over any other geometric shape. All you do is spin it with slight axis rotation while a laser is pointed at it, and measure the distance.
Defective Logic
Its shrinking. Losing incredibly small pieces over long periods of times. No object can realistically stay -exactly- the same forever.
Easy. At some point in time some people decided to base the US system on the metric system. There was a time of course when the US system was standalone, but then came a situation when these people had to refine this system and they made the choice to base it on the metric one.
Adventure, Romance, MAD SCIENCE!
Quote:
In the United States, the (avoirdupois) pound as a unit of mass has been officially defined in terms of the kilogram since the Mendenhall Order of 1893.
...has created the most perfect spheres ever made...
...roughly 9cm...
That precise eh?
For the specification they are trying to achieve, even a little chip from a corner would be a tremendous error. It's a lot tougher to damage a sphere that way. Of course you can damage both from dropping them.
I too think eventually this physical weight will be replaced by a known voltage/wattage on a scale to counteract a force, although for practicality purposes, having a physical object is probably much easier to use in daily situations.
..........FULL STOP.
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.
If all women had scientifically 'perfect' breasts then those perfect breasts would get pretty boring
Where has your penis gone? Breasts getting boring? What kind of silly, nonsensical, jibber-jabber is that?
Breasts NEVER get boring! I love my wife's breasts as much today as the day I married here!
Actually, come to think of it, it'd be pretty awesome for all women to have the same sized breasts. That's a whole level of insecurity that men wouldn't have to deal with any longer.
Give a man a fire and he'll be warm for a day. But light a man on fire and he'll be warm for the rest of his life.
Just define the KG in terms of pounds at 1 G. Do Americans have to solve all of France's problems for them?
I often don't like the choices people make, but I like the fact that people make choices. That's why I'm a conservative.
The answer is none.
None more round.
I think the reason why they made it a sphere is because a sphere is defined by one parameter only, its diameter. To make a perfect sphere all you need is to make sure it has exactly the same curvature everywhere. Now, let's see what it takes to make a perfect cube:
1) each of its six faces must be perfectly plane
2) each of its twelve edges must have exactly the same length
3) each of its twelve angles must be exactly ninety degrees
Just to illustrate how difficult this is, I once read this anecdote about Wernher von Braun: when going through his mechanical engineering course in Germany, one of the professors gave each student an irregular lump of iron. The assignment would be to create a cube, as perfect as possible, from that lump. The size of the resulting cube didn't matter but, naturally, if it was a very small cube it meant the student had a tough job getting it right.
I hope someone with more knowledge than I do answers, but I'll try to give my best answer, from the understanding I've gleaned so far from my Engineering Physics courses at the University I'm attending. . .
I think, at an atomic level, atoms don't actually touch. When they get close enough, I think the internal atomic forces cause them to repel each other based upon field-forces (field forces are things like magnetism, or gravity, where no contact is required for things to act upon each other), or, for some elements, start sharing electrons and form lattices/grids of evenly spaced atoms (and, again, the grid spacing is determined by a balancing of repelling and attracting field forces, I think). This is definitely an area of physics I want to learn more about, and like I said, I hope someone who truly knows the answer will comment, but that's my best answer.
It's 1024 grams, right? Easy definition.
(NSFW)
http://images.fok.nl/upload/050701_30560_howtodrawboobsfok.jpg
Funny how they refer to it being a "roughly 9cm" sphere. All that effort to just say "screw it, call it 9cm and let's get out of here."
The world is made by those who show up for the job.
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
Problem being that if the balls were touching - well, it would be gay. Consequently, the answer is unimportant.
The pound is the kilogram's bitch. When the kg says bend over, the lb presents it's tight little ass for a pounding.
The pound is no more equivalent to the kilogram than Disney dollars are equivalent to US dollars.
What if Tetris was invented by Nazis?
This answer is mostly correct, but it should be noted that the primary force that keeps atoms apart is the electromagnetic force. At large distances an atom appears neutral being made up of an equal number of positive and negative charges. However since the negative charges (i.e. electrons) are on the outside and the positive charges are on the inside (i.e. protons), when atoms get close to each other the repulsive force between the negative charges is over a shorter distance and is thus stronger than the canceling out attractive force between the positive and negative charges. (Disclaimer: This ignores quantum effects which paint a slightly different picture.)
Two silicon atoms that are in the same sphere will be sharing a metallic (?) bond which means they will be sharing electrons. Silicons atoms in different spheres won't be sharing electrons.
Finally, I suspect that the two spheres will deform slightly where they touch so more than one atom will be "touching". It would look about like if you were push two rubber balls together, except the physics might be totally different (I am not a rubber expert).