[Home]  [Headlines]  [Latest Articles]  [Latest Comments]  [Post]  [Sign-in]  [Mail]  [Setup]  [Help] 

Status: Not Logged In; Sign In

Consequences of Mild, Moderate & Severe Plagiarism Plagiarism: 5 Potential Legal Consequences When Philadelphia’s Foul-Mouthed Cop-Turned-Mayor Invented White Identity Politics Trump Wanted to Pardon Assange and Snowden. Blocked by RINOs. What The Pentagon Is Planning Against Trump Will Make Your Blood Run Cold Once Revealed How Trump won the Amish vote in Pennsylvania FEC Filings Show Kamala Harris Team Blew Funds On Hollywood Stars, Private Jets Israel’s Third Lebanon War is underway: What you need to know LEAK: First Behind-The-Scenes Photos Of Kamala After Getting DESTROYED By Trump | Guzzling Wine!🍷 Scott Ritter Says: Netanyahu's PAINFUL Stumble Pushes Tel Aviv Into Its WORST NIGHTMARE These Are Trump's X-Men | Dr. Jordan B. Peterson Houthis (Yemen) Breached THAAD. Israel Given a Dud Defense!! Yuma County Arizona Doubles Its Outstanding Votes Overnight They're Stealing the Race from Kari Lake Trump to withdraw U.S. troops from northern Syria Trump and RFK created websites for the people to voice their opinion on people the government is hiring Woke Georgia DA Deborah Gonzalez pummeled in re-election bid after refusing Laken Riley murder case Trump has a choice: Obliterate Palestine or end the war Rod Blagojevich: Kamala’s Corruption, & the Real Cause of the Democrat Party’s Spiral Into Insanity Israel's Defense Shattered by Hezbollah's New Iranian Super Missiles | Prof. Mohammad Marandi Trump Wins Arizona in Clean Sweep of Swing States in US Election TikTok Harlots Pledge in Droves: No More Pussy For MAGA Fascists! Colonel Douglas Macgregor:: Honoring Veteran's Day Low-Wage Nations? Trump to pull US out of Paris climate agreement NYT Pixar And Disney Animator Bolhem Bouchiba Sentenced To 25 Years In Prison Six C-17s, C-130s deploy US military assets to Northeastern Syria SNL cast members unveil new "hot jacked" Trump character in MAGA-friendly cold open Here's Why These Geopolitical And Financial Chokepoints Need Your Attention... Former Army Chief Moshe Ya'alon Calls for Civil Disobedience to Protest Netanyahu Government The Deep State against Trump

Science/Tech
See other Science/Tech Articles

Title: Manic Metric Monday: Scientists Rethink the Kilogram--
Source: [None]
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: 440
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)

Post Comment   Private Reply   Ignore Thread  

Begin Trace Mode for Comment # 26.

#6. To: gengis gandhi, Original_Intent, all (#0)

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.

wudidiz  posted on  2011-01-25   21:06:19 ET  Reply   Untrace   Trace   Private Reply  

Isn't a kilogram the weight of a litre of water?

No. I have never even heard that before.

RickyJ  posted on  2011-01-25   21:49:56 ET  Reply   Untrace   Trace   Private Reply  

Isn't a kilogram the weight of a litre of water?

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.

wudidiz  posted on  2011-01-25   22:06:20 ET  Reply   Untrace   Trace   Private Reply  

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.

RickyJ  posted on  2011-01-25   22:12:46 ET  Reply   Untrace   Trace   Private Reply  

But the kilogram is not based on the liter, the liter is based on the kilogram, and the kilogram is based on that bar.

No.

A litre is the cubic equivalent of 1 cm cubed X 1000

the metric system is not based on the bar.

wudidiz  posted on  2011-01-25   22:17:18 ET  Reply   Untrace   Trace   Private Reply  

No.

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.

RickyJ  posted on  2011-01-25   22:34:24 ET  Reply   Untrace   Trace   Private Reply  

#27. To: RickyJ (#26)

Metric System History & Explanation

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.

 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

wudidiz  posted on  2011-01-25 22:44:35 ET  Reply   Untrace   Trace   Private Reply  

No.

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.

wudidiz  posted on  2011-01-25 23:01:31 ET  Reply   Untrace   Trace   Private Reply  

Top • Page Up • Full Thread • Page Down • Bottom/Latest

[Home]  [Headlines]  [Latest Articles]  [Latest Comments]  [Post]  [Sign-in]  [Mail]  [Setup]  [Help]