Discussion»Statements»Rosie's Corner» Sometimes you "test" things to make sure they are working correctly. You CALIBRATE them. Except how do you know the calibrater is right?
My first job in the Navy was calibrating electronic instrumentation. All of the standards we used were at least ten times more accurate than the equipment we calibrated. Our standards were then check with higher standards that can be traced back to the National Institute of Standards. The highest standards are absolute as we define them.
Does the highest standard instruments ever get calibrated? At some point there is no higher "authority" so to speak. How do you know when to stop seeking it? There is a beginning/starting point. How does the accuracy of that ever get checked? Sorry E. My brain is in a loop on this for some reason. Sigh. Thank you for your reply and Happy Tuesday to thee and thine. !:)
No, they don't. For example, the kilogram. it is a cylinder of platinum-iridium stored in an inert gas under 2 bell jars. It is one kilogram because we say it is; there is nothing to compare it to. It is the same with all of the others, such as length, volt, second etc.
All units still need defining, including those you list.
The ISO might not physically hold the standard objects but they have defined those which are, and how they are defined, in the Systeme Internationale it developed. I turned to my Physics text-book:
The International Prototype kilogramme is as you say, a piece of metal, and is kept in Paris. After all, the Metric System was invented in France - hence the spellings.
Otherwise, the Metre is based on the distance travelled by light in a vacuum in one second.
The Second is based on the behaviour of the atom of Caesium 133.
I suspect they had to find natural phenomena that matched the long-established metre and second closely enough to then be used in turn as the definitions!
There are only 4 other basic SI units, apart from the angle units Radian and Steradian. Those rest are the ampere, kelvin, mole and candela. My book does not state their definitions. All other units are compounds derived from just those 7 - even the Volt, as it is a unit of force.
I find it interesting that the metre is defined by 2 other constants, c and the second, rather than it be a fundamental unit. BTW, on myfirst ship I was in charge of a caesium beam oscilator, used to calibrate the rubidium oscillators on the submarines. I tried to keep it less than 1 billionth of a second accuracy. It was fun. (I am such a nerd.)
AARRGGHH! "It is one kilogram because we say it is; there is nothing to compare it to. It is the same with all of the others, such as length, volt, second...???? Okay can you run that by me again? My brain does not stretch that far. Something is so because we say it is so. No evidence fact proof needed? We have spoke is enough? I dunno. I'm missing something. That can't be the way it is...can it? Thank you for your reply E. Double AARRGGHH. :(
I've worked in organisations that like Element's, needed to have their test and measuring equipment calibrated against national standards. It is a bit of a chain process though, in order to give that traceability.
Nowadays the ultimate definitions of measurement units are maintained by the International Standards Organisation, of which virtually all countries in the world are either full members or associates - I forget the proper terms for those.
So can you always be positive that the standard measures against which things are checked for "correctness" are always accurate? Thank you for your reply Durdle. Is there a department of weights and measures in every country? When you want a pound of of something in the market you bag it and weigh it on those hanging scales. I always wonder how often those scales are checked and if they agree with what the cashier scale reads? :) Does the butcher put his thumb on the scale? Aarrgghh!
You can be confident of the national / international standards; and of the national agencies responsible for weights and measures.
I think most countries have such departments; and ultimately they work to appropriate levels of precision based on internationally-agreed units. The USA is now almost the only country, and is the only major one, not using Metric measures for everyday trading. Nevertheless, whether Imperial or Metric your local weights and measures need still conform to the ANSI standards whose reference units will be those accepted internationally. That does recognise that America changed the "sizes" of some units into their own versions; but if and when the USA does go all-Metric it would not be allowed to invent its own "sizes" of metres, etc.
So for example if I buy 10 gallons of petrol in Los Angeles they will be 10 US Gallons not 10 UK Gallons; but if bought the fuel in New York I would be confident it is still 10 US Gallons within a very small tolerance. Anyway you can't buy UK Gallons now, not in the UK anyway, where all fuel is sold in Litres.
You should be confident that the scales or other measuring equipment used in shops is reasonably accurate; and they ought to be tested at appropriate intervals, perhaps yearly or every two years depending on type, use and appropriate trading laws. The display you read should be the same as that seen by the cashier, or at least be a second one reading identically.
I remember the old type of shop scales that had a tall mechanical display whose pointer moved between two sheets of glass each with the graduations, one facing the customer, the other facing the seller. We can be sure that the graduations were identical, so if the pointer on our side read 5lbs 5oz, it read 5lbs 5oz on the counter side. That would not have detected cheating though!
The con artists and scammers are always looking for ways to get an edge...screw the public. We look to our authorities to make sure it doesn't happen but any more we don't know since so many of THEM are colluding conspiring benefitting. Am I despondent? No. Do I trust any of the things/people/institutions I used to? No. What happened to me is happening to everyone all of the time. You cannot trust anyone for anything. Knowing that you gamble...place your bets. Maybe YOUR bet will be placed on someone who actually is HONORABLE FAIR JUST TRUTHFUL. Of course the odds are against that but well what could it hurt to hope you are that exception? Each day a new chance shows up...a chance that your gamble will pay off. Right? Thank you for your reply Durdle! :) The dumb cluck duck never gambles. He rigs everything in advance to make sure he won't lose.
This post was edited by RosieG at October 25, 2020 2:47 PM MDT
Element 99 