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What is a kilogram?

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The International System of Units, abbreviated SI, is the modern form of the metric system and is generally a system devised around the convenience of the number ten. It is the world's most widely used system of measurement, both in everyday commerce and in science. Because the SI is not static, units are created and definitions are modified through international agreement among many nations as the technology of measurement progresses, and as the precision of measurements improves.


The meter is already defined by the speed of light, but scientists are under way to tie all seven units to fundamental physical constants. The KILOGRAM, abbreviated [kg], is the only base unit that still relies on an artifact. This artifact.




By definition, the International Prototype ‘K’, a 39mm-cylinder of 90% platinum and 10% is one kilogram. Even though it seems to have lost weight in comparison to its copies. It is kept hidden inside a vault in the basement of the Bureau International des Poids et Mesures BIPM in Sèvres near Paris, France. Only once every year is prototype K ever seen.





The three persons guarding the keys to the vault join to open it for eyeball inspection of ‘K’ during a little ceremony: the BIPM's director, the head of the French National Archive, and the president of the CIPM. They cover the teeth of the ancient skeleton keys for fear they might be reproduced from the photo. Metrologists worldwide seek to get rid of 'K' and search for a new definition which ties the Kilogram to a fundamental constant of nature.







In an effort to redefine the kilogram by tying it to a fundamental constant, the mass of a single atom, PTB metrologist Dr. Arnold Nicolaus and colleagues have designed the Avogadro sphere. The single crystal silicon ball of 1 kg is polished to 50 nm accuracy and measured by laser interferometry in order to determine via the Avogadro constant the number of atoms it consists of. Checking for dust.







Metrologists at the BIPM in Sèvres near Paris, France, seek to redefine the kilogram by tying it to the Planck constant. Once it is finished, their watt balance will essentially compare the gravitational force on a mass – here represented by five copper weights – with the magnetic force on a coil in a magnetic field. The final setup will be placed inside a vacuum chamber.







With this experiment, PTB metrologists sought to redefine the kilogram by tying it to the atomic mass unit. The setup creates metal mass artifacts by accumulating bismuth ions inside a collector and counting them by measuring the electrical current required to neutralize the ions. Because the required measurement precision can’t be reached in due time, however, the experiment will be discontinued.






[mol] ‘The MOLE is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.







The chemical industry requires the mole to ensure that substances mix at the ideal ratio for a reaction to be efficient. The PTB supplies elemental solutions which act as transfer standards for calibration of industrial applications. An optical emission spectrometer compares the content of a specific element in an unknown solution with a primary reference solution of known mass content.







Elemental analysis for dissemination of the mole at the PTB. Thermal ionisation mass spectrometry allows measuring the amount of a specific element. The samples are thermally ionized in the ion source (at front). The ions are then accelerated, sorted by a magnet and measured by detectors. In back: heat-cleaning of used sample holders in a vacuum chamber for further use.







The chemical industry requires the mole to ensure that substances mix at the ideal ratio for a reaction to be efficient.The PTB (Physikalisch-Technische Bundesanstalt) in Braunschweig, Germany, supplies elemental solutions of known mass content to act as transfer standards for calibration of industrial applications.






[m] ‘The METER is the length ofthe path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.’







Realization of the metre in a PTB quantum optics lab. A laser wavelength standard with a stabilized, frequency doubled Neodym:YAGLaser produces light of a specific frequency for interferometric length measurement. The three glass cylinders contain gaseous iodine which, analogous to a tuning fork, provides the reference frequency to which the laser is tuned.






‘The SECOND is 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 caesium 133 atom.’







Realization of the second with 3 Caesium atomic clocks at the PTB in Braunschweig, Germany. These three instruments define UTC (PTB ) as basis of civil time in Germany. They are also part of a worldwide network of atomic clocks in some 50 institutions defining UTC, Coordinated Universal Time. Copper lining on the walls shields the instruments against electromagnetic interference.







The PTB’s caesium fountain atomic clock will be 10x more accurate than standard caesium atomic clocks currently defining time worldwide. At the center of the instrument, caesium atoms are trapped andcooled by 6 laser beams in a vacuum to be accelerated vertically and to fall back down again. During their flight an internal oscillation is excited to achieve a pacemaker of great accuracy.








Prototype optical atomic clock in a PTB quantum optics laboratory. The instrument will be at least 100x as accurate as present-day ceasium atomic clocks and may one day serve as a better primary standard of frequency. The oscillation of a selected atomic transition of 10 million strontium atoms trapped inside a spherical vacuum chamber is used as a pacemaker of unrivalled accuracy.






[cd] ‘The CANDELA is 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.’







Realization of the candela on the PTB’s unique 40-meter photometric bench with a Toshiba transfer standard lamp. Under specific conditions, the lamp generates a luminous intensity of exactly 1 cd. It is used for realization, preservation and dissemination of the candela. A photometer measures the illuminance at various distances.







Photometry at the PTB with an integrating sphere 2.5 m in diameter. A light source is completely enclosed by the aluminum shell. The light is scattered through diffuse reflection off the matte white coating on the interior and measured with a photometer. Thus light sources can be characterized by comparison with standard transfer lamps of known properties.








The PTB’s unique robot-goniophotometer measures light sources to be used as transfer standards for calibration of industrial applications. Its three multi-jointed arms adjust the light fixture – here an array of blue LEDs – in space and orbit two photodetectors around it to measure its luminous intensity and color in all directions and at various distances.






[A] ‘The AMPERE is that constant current which, if maintained in two straight parallel conductors of

infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would produce between these conductors a force equal to 2·10–7 newton per meter of length.’







As of 2011, the SET chip developed at the PTB may well be the key to a novel definition of the ampere which links it to a fundamental physical constant, the charge of an electron. The chip transports and counts electrons. This quantum effect – called ‘single electron tunneling’ – only occurs at low temperatures, therefore the chip needs to be cooled down to 20 mK with a cryostat – at right – and liquid helium.








Production of SET chips with an electron beam lithography system at the PTB’s clean room centre. En route towards a redifinition of the ampere by tying it to the charge of an electron, PTB scientists are engaged in elaboration of SET chips – single-electron tunneling – which transport and count electrons. The screen shows the submicrometer layout of a single electron pump.








Production of SET chips at the PTB’s clean room centre. The chip’s capacity to transport and count electrons – a quantum effect called ‘single electron tunneling’ – could make it the foundation of a novel definition of the ampere as of 2011, linking the base unit to the charge of an electron. The screen shows the 1 x 1 mm central area of one chip.

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[K] ‘The KELVIN, unit of thermo-dynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.’







Realization of the kelvin with a triple point cell at a PTB lab in Berlin. The cell contains pure water and is used for calibration of thermometers and temperature standards which can be inserted into the central tube. At exactly 273.16 K (0.01°C), the three phases ice, water and vapor coexist in a stable equilibrium. This delineates one of a number of defined temperature points our temperature scale relies on.







Realization of the kelvin with MK2, a ‘dilution refrigerator with copper demagnetization stage’ at a PTB lab in Berlin. For calibration, the cryostat cools thermometers – inside the compartment at center – down to 0.000065 K close to absolute zero, thus setting a cornerstone of our temperature scale. During operation, the stage rests inside a superconducting coil and a thermally insulating vessel and is helium pre-cooled.







An array of tungsten strip lamps in a spectral radiance measuring set-up at a PTB lab in Berlin helps metrologists establish a range of high temperature reference points needed for calibrating thermometers and the dissemination of the kelvin. With increasing temperature, color and intensity of the radiation emitted by the glowing filaments change: the hotter, the whiter.

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Good thread. I used to read all about this type of shit for years. I stopped and shit because no matter how many times I read bullshit like this and get it, a couple months later I totally forget. Fuck science.

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Ever hear the story of Joseph Dombey? In 1794 he was sent as a scientist from France to the US and brought on his journey a set of weights and measure to introduce to them to the political and scientific bodies here in the states.


His ship was attacked by pirates instead and he never made it, if he had the US would probably be on the Metric System.


I can not really do this story justice there is a good chapter on it in Measuring America by Andro Linklater. I could not find too much in a quick google search to post.

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A kilo is the standard amount of hashish that people swallow to smuggle from Morocco to Europe. In thumb size pieces. Ouch.

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theres a movie (called maria i believe) where a girl smuggles blow across the border with a friend to help out her familys finances


one of the latex balloons break inside her friends stomach & shes dies, then she gets sliced open in a motel tub by the recievers


sad shit

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