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Title: Manic Metric Monday: Scientists Rethink the Kilogram--
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URL Source: http://newsfeed.time.com/2011/01/24 ... nk-the-kilogram/#ixzz1C4McrMyy
Published: Jan 25, 2011
Author: Nick Carbone
Post Date: 2011-01-25 13:34:01 by gengis gandhi
Keywords: None
Views: 441
Comments: 31
Manic Metric Monday: Scientists Rethink the Kilogram By: Nick Carbone (1 day ago) Topics: kilogram, Mass, measures, metric system, royal society, Science, weights kilo2 Monday kicks off an urgent meeting between some of the greatest minds in science, a debate that could result in a rethinking of the most elemental scientific measurements. Will the kilogram ever be the same? The researchers are gathering at the Royal Society in London to discuss adjusting the fundamental mass of the kilogram. The kilogram is the only unit in the International System of Units (SI) whose measurement is based on a physical object. And anyone who's ever stepped on a scale knows how unkind Father Time can be to a person's weight. Turns out the keepers of the kilo are facing the same problem. (More on TIME.com: See the top 10 amazing scientific discoveries of 2010.) Currently, the kilogram is based on the mass of a platinum-iridium bar stored in a vault in a Parisian suburb. Aside from sounding like it should be the target of a heist in the next crime thriller, scientists estimate the bar's mass may have actually changed by 50 micrograms over the years, which they note is “the mass of a small grain of sand 0.4 mm in diameter.” (More on TIME.com: See a brief history of the periodic table.) The best and the brightest in science will meet to work out a constant on which the kilogram can be based. They anticipate it will be tied to the value of the Planck constant, h, which reflects the size of the smallest particles of physical matter in quantum physics. But don't jump on the scale just yet - there's no set date to officially recalibrate the kilo's mass. (via Royal Society)
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#1. To: gengis gandhi (#0)
(Edited)
In fifty years no one there had the sense to dust the official set of scales at all.
I don't get it. Are they saying the platinum or iridium atoms have gone somewhere else? Have they handled it so much that it's knocked some atoms off the bar?
i just figured its more weirdness. if measurements all get screwy, we're gonna have real fun. 'space and time makin love' Montrose, Space Station No. 5
Thou hast power only to act not over the result thereof. Act thou therefore without prospect of the result and without succcumbing to inaction. The mind acts like an enemy for those who do not control it...Perform your obligatory duty, because action is indeed better than inaction...Sever the ignorant doubt in your heart with the sword of self-knowledge. Observe your discipline. Arise. The Bhagavad Gita
What it suggests is that mass is not a constant. The implications reach further than the Kilogram, but are suggestive of fundamental principles of the physical universe which are not yet known or understood within the envelope of traditional physics.
"“Believe nothing merely because you have been told it. Do not believe what your teacher tells you merely out of respect for the teacher. But whatsoever, after due examination and analysis, you find to be kind, conducive to the good, the benefit, the welfare of all beings - that doctrine believe and cling to, and take it as your guide.” ~ Gautama Siddhartha — The Buddha
It's a lousy article really. Doesn't tell us anything meaningful except we are all getting heavier as compared to the Supreme Ingot in France. Either it is getting lighter for some reason or there is an unaccounted difference in measurement that has appeared over the years as a result of the instuments or because the mass of the earth is not constant (which seems unlikely but is not impossible).
This doesn't make any sense. Isn't a kilogram the weight of a litre of water? I doubt they use a physical object to base a measurement so important on. Seriously. What do they base a gram on then? I'm calling bs on this one.
grams are based on either graham crackers or billy graham... next question.
Thou hast power only to act not over the result thereof. Act thou therefore without prospect of the result and without succcumbing to inaction. The mind acts like an enemy for those who do not control it...Perform your obligatory duty, because action is indeed better than inaction...Sever the ignorant doubt in your heart with the sword of self-knowledge. Observe your discipline. Arise. The Bhagavad Gita
Like gramma hash?
The mass of the Earth is not constant. Meteorites add mass and escaping gasses decrease it. The net total is a very slight increase over time I think. They must mean the mass of the bar is getting lighter, not heavier. If they know the mass has gotten lighter I don't see what the problem is, they still know what a kilogram is suppose to weigh or they wouldn't have known it has gotten lighter. It very well could be that with better scales the more accurate weight of the bar is being revealed for the first time. As long as the scales are properly calibrated to what we say a kilogram is now, there shouldn't be a problem even if they lost that bar. I think the mass of kilogram should be based on the atomic weight of hydrogen times X(whatever number necessary to be as close as possible to today's definition of a kilogram) to be as accurate as possible. The atomic weight of hydrogen will always be a constant, at least as far as we presently know.
God is always good!
No. I have never even heard that before.
God is always good!
It is based on the kilogram. It is exactly 1/1000th of a kilogram.
God is always good!
The mass of most objects are not constant. This is not new information but has been known for many centuries. But to be precise with measurements as we can be, basing a mass on the smallest know mass, an electron, we can be more confident about knowing the mass of an object with the proper tools to measure them of course.
God is always good!
That would be my guess.
God is always good!
I learned that the first time I made popsicles in my parents freezer.
"I am not one of those weak-spirited, sappy Americans who want to be liked by all the people around them. I don’t care if people hate my guts; I assume most of them do. The important question is whether they are in a position to do anything about it." - William S Burroughs
No. I have never even heard that before. I learned about 35 years ago when they first changed to metric in Canada that one litre of water weighs one kilogram.
It is based on the kilogram. It is exactly 1/1000th of a kilogram. It was more a rhetorical question. I already knew the answer. One could easily argue that a kilogram weighs 1000 grams instead.
A cubic centimeter of water weighs exactly one gram. Metric's funny that way.
a piece of gold in a suburb in Paris lmfao Good Lord grammma hash
I didn't know this before but you are right, 1 liter of water does have the mass of 1 kilogram. But the kilogram is not based on the liter, the liter is based on the kilogram, and the kilogram is based on that bar.
God is always good!
Seems negligible. But then the article doesn't impart much actual science and chooses to focus on why we, the Fat People Of The Earth, seem to keep getting heavier which is just stupid. This is very dumbed down science reporting. Below the level of even something like the old Omni magazine.
No. A litre is the cubic equivalent of 1 cm cubed X 1000 the metric system is not based on the bar.
Here is a picture of the object used to determine what the mass of a kilogram is. God is always good!
Ricky my friend it's a beautiful picture, but as a representative of the Canadian Ministry of Truth, I am here to inform you that you have been misinformed. The metric system is not based on the bar, it's based on the metre which is a fraction of the earth's circumference. That is, a metre = 1/10,000,000 of the earth's circumference.
a centimetre = 1/100th of a metre a litre = 1000 cubic centimetres a kilogram = 1 litre of water a gram = 1/1000th of a kilogram bar schmar
The metric system is not based on the bar, the bar's weight is measured in metric. It's supposed to weigh one kilogram. Apparently it doesn't even do that properly.
A litre is the cubic equivalent of 1 cm cubed X 1000 the metric system is not based on the bar. OK, I am wrong, sorry about that. But the kilogram is based on that bar. And it seems most of the metric system is based on the length of a meter, which is now defined as the distance traveled by light in an absolute vacuum during 1/299,792,458 of a second. Which means they better have constant definition of a second or we are screwed.
God is always good!
History and Definition of the Meter The word 'meter' is from the Greek word 'metron', which means 'a measure'. At the time the metric system was being defined, there were two competing approaches to the definition of the length of the meter. The initial suggestion was that it be the length of 'a pendulum having a half-period of one second'. The alternative approach was to set it to one ten-millionth of 'the length of the earth's meridian along a quadrant'. Specifically, one ten-millionth of the distance from the North Pole to the equator, along the meridian running near Dunkirk in France. The French Academy of Science, which was tasked with developing the metric system, decided on the latter approach in 1991 (on the basis that the former approach does not give a consistent measure, as slight variations in the earth's gravity from one place to another would result in different values). This distance was calculated (with a slight error, as the flattening of the earth due to its rotation was not taken into account), and a brass bar of metal was cast to this length. This metal bar was then used as the standard. Since then, although the length has remained constant, several changes have been made to the definition in order to increase the precision of the measurement. First this involved replacing the brass bar by a platinum bar (and subsequently a platinum-iridium bar) and specifying the conditions (e.g. temperature) under which the bar is stored. Later, for even greater precision, the definition was changed to reflect constant physical phenomenon rather than a metal rod. The following table summarises the major changes. The definition used since 1983 is accurate to within 2.5*10-11. Year Definition of the Meter 1793 1 / 10 000 000 of the distance from the pole to the equator. 1795 Provisional meter bar constructed in brass. 1799 Definitive prototype meter bars constructed in platinum. 1889 International prototype meter bar in platinum-iridium, cross-section X. 1906 1 000 000 / 0.643 846 96 wavelengths in air of the red line of the cadmium spectrum. 1960 1 650 763.73 wavelengths in vacuum of the radiation corresponding to the transition between levels 2p10 and 5d5 of the krypton-86 atom. 1983 Length travelled by light in vacuum during 1 / 299 792 458 of a second. History and Definition of Gram and Kilogram A gram was initially defined as a cubic centimeter of water at its temperature of maximum density (4°C). Likewise, a kilogram was defined as a cubic decimeter of water (a cube 0.1 meters on each side), which is a thousand cubic centimeters or a thousand grams. This mass (weight) has been reproduced in a metal weight (platinum-iridium), which is now used as the standard. In other words, a kilogram is no longer officially defined in terms of the mass of a volume of water, but rather in terms of the mass of the corresponding official metal weight. Accordingly, a gram is now defined as one-thousandth of this metal weight, rather than in terms of a cubic centimeter of water. Current Official Definitions Measure Definition meter The length of the path travelled by light in a vacuum during 1/299 792 458 of a second (see above discussion). kilogram The unit of mass equal to that of the international prototype of the kilogram (see above discussion). It is the only metric base unit defined in terms of an object; the other six are defined in terms of physical phenomenon. second The duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom. ampere The constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and place 1 meter apart in vacuum, would produce between these two conductors a force equal to 2 * 10-7 newton per meter of length. It is named after the French physicist Andre Ampere. kelvin The unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. It is named after the Scottish mathematician and physicist Lord Kelvin. mole The amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12. candela The luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 * 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian. Notable Measures Quantity In metric Imperial or USA Freezing point of water 0°C 32°F Boiling point of water 100°C 212°F Healthy temperature of a person 37°C 98.6°F Density of water 1 kg/l 10 pounds/Imperial gallon 8.35 pounds/USA gallon Speed of light 300 000 km/s 186 000 miles/s Speed of sound 330 m/s 1090 feet/s Circumference of Earth 40 000 km 25 000 miles Distance between earth and sun 150 000 000 km 93 000 000 miles Distance between earth and moon 385 000 km 240 000 miles Altitude of geostationary orbit 35 800 km 22 300 miles Earth's gravity 10 m/s2 32 feet/s2 Actually it is possible both the speed of light and the current definition of a second are not really constants which in time will totally screw the metric system up.
God is always good!
A litre is the cubic equivalent of 1 cm cubed X 1000 the metric system is not based on the bar. OK, I am wrong, sorry about that. But the kilogram is based on that bar. And it seems most of the metric system is based on the length of a meter, which is now defined as the distance traveled by light in an absolute vacuum during 1/299,792,458 of a second. Which means they better have constant definition of a second or we are screwed. Cool :) I disagree the kilogram is based on the bar, for reasons I stated. Nevertheless, I agree it must be extremely difficult to keep this or any other system of measurement 100% accurate.
It did use to be based on the mass of 1 liter of water, but they changed it for whatever reason I don't know. I guess to be more accurate they choose the bar, but now realize they need something more accurate to base it on, which in all likelihood will be a multiple of the smallest know mass, which will be subatomic particles.
God is always good!
even better
Thou hast power only to act not over the result thereof. Act thou therefore without prospect of the result and without succcumbing to inaction. The mind acts like an enemy for those who do not control it...Perform your obligatory duty, because action is indeed better than inaction...Sever the ignorant doubt in your heart with the sword of self-knowledge. Observe your discipline. Arise. The Bhagavad Gita
Currently, the kilogram is based on the mass of a platinum-iridium bar stored in a vault in a Parisian suburb. Aside from sounding like it should be the target of a heist in the next crime thriller, scientists estimate the bar's mass may have actually changed by 50 micrograms over the years, which they note is “the mass of a small grain of sand 0.4 mm in diameter.”
#2. To: gengis gandhi (#0)
Currently, the kilogram is based on the mass of a platinum-iridium bar stored in a vault in a Parisian suburb. Aside from sounding like it should be the target of a heist in the next crime thriller, scientists estimate the bar's mass may have actually changed by 50 micrograms over the years, which they note is “the mass of a small grain of sand 0.4 mm in diameter.”
#3. To: TooConservative (#2)
#4. To: gengis gandhi, TooConservative (#3)
#5. To: Original_Intent (#4)
#6. To: gengis gandhi, Original_Intent, all (#0)
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#7. To: wudidiz (#6)
#8. To: gengis gandhi (#7)
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#9. To: TooConservative (#5)
#10. To: wudidiz (#6)
Isn't a kilogram the weight of a litre of water?
#11. To: wudidiz (#6)
What do they base a gram on then?
#12. To: Original_Intent (#4)
What it suggests is that mass is not a constant.
#13. To: TooConservative (#2)
Have they handled it so much that it's knocked some atoms off the bar?
#14. To: Original_Intent (#4)
(Edited)
mass is not a constant.
#15. To: RickyJ (#10)
Isn't a kilogram the weight of a litre of water?
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#16. To: RickyJ (#11)
What do they base a gram on then?
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#17. To: RickyJ, All (#16)
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#18. To: All (#17)
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#19. To: wudidiz (#15)
#20. To: RickyJ (#9)
The mass of the Earth is not constant. Meteorites add mass and escaping gasses decrease it. The net total is a very slight increase over time I think.
#21. To: RickyJ (#19)
But the kilogram is not based on the liter, the liter is based on the kilogram, and the kilogram is based on that bar.
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#22. To: wudidiz (#18)
#23. To: RickyJ (#22)
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#24. To: All (#23)
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#25. To: All (#24)
bar schmar
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#26. To: wudidiz (#21)
(Edited)
No.
#27. To: RickyJ (#26)
Metric System History & Explanation
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#28. To: wudidiz (#27)
#29. To: RickyJ (#26)
No.
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#30. To: wudidiz (#29)
(Edited)
I disagree the kilogram is based on the bar, for reasons I stated.
#31. To: wudidiz (#8)
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