Author Topic: Just what is metrology?  (Read 3547 times)

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Offline Ben321

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Just what is metrology?
« on: February 27, 2017, 07:19:16 am »
Does it have any connection to meteorology (weather science)? I know there is (or at least used to be) a company called Metrologic which made equipment (namely lasers) intended for the field of science known known as metrology. Yet I have not been able yet to figure out what metrology is. What exactly is metrology?
 

Online ataradov

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Re: Just what is metrology?
« Reply #1 on: February 27, 2017, 07:41:12 am »
Alex
 

Offline DimitriP

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Re: Just what is metrology?
« Reply #2 on: February 27, 2017, 10:58:48 am »
what is google and exactly how do you spell it ?  ;D
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Offline tggzzz

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Re: Just what is metrology?
« Reply #3 on: February 27, 2017, 11:35:33 am »
what is google and exactly how do you spell it ?  ;D

Here's a surprisingly good site for correcting misspellings. :)
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Offline jpanhalt

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Re: Just what is metrology?
« Reply #4 on: February 27, 2017, 11:40:12 am »
There is a related term, "metrics" (plural) that is often, perhaps usually used in business to describe measures of performance.   It is equivalent to "measures."  Mercer Consulting popularized it in the 1990's.  From http://dictionary.cambridge.org/us/dictionary/english/metrics: "The study includes market metrics such as market and segment size estimates."

John
 

Offline Henrik_V

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Re: Just what is metrology?
« Reply #5 on: February 27, 2017, 03:06:14 pm »
Well, when it comes to stock exchange metrics and forecasts... you get close to meteorology  ;)
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Online mimmus78

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Re: Just what is metrology?
« Reply #6 on: February 27, 2017, 07:47:44 pm »
This is the official version ...

Metrology in reality is the practice of repairing measurement instruments with the purpose to have them adjusted to read the highest number of zeros on a VFD display.

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Offline CatalinaWOW

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Re: Just what is metrology?
« Reply #7 on: February 27, 2017, 08:55:49 pm »
Metrology means many things to many people.

When I first encountered it, it appeared to mean the study of doing the most deniable damage to a piece of equipment in the longest possible time, while not standing behind the accuracy of the instrument.  Since the place I worked then did all their metrology in house there was no contact with other possible definitions.

While google gets some excellent definitions, it doesn't really cover the one I encounter most, which is the maintenance, repair and calibration of test equipment.  Which is an honorable and useful realm of activity.
« Last Edit: February 28, 2017, 12:20:45 am by CatalinaWOW »
 

Offline IconicPCB

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Re: Just what is metrology?
« Reply #8 on: February 27, 2017, 09:41:17 pm »
Try  mensuration
 

Offline MrBungle

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Re: Just what is metrology?
« Reply #9 on: February 28, 2017, 02:57:01 am »
 

Online Assafl

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Re: Just what is metrology?
« Reply #10 on: February 28, 2017, 07:29:09 am »
Metrology is when popcorn doesn't make you happier staring at a display.
 

Offline Andrey_irk

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Re: Just what is metrology?
« Reply #11 on: March 01, 2017, 11:25:47 am »
As was mentioned before, usually it's all about maintenance and calibration of measurement (and test) equipment, but not only.
Every time when you want to measure something a lot of questions arise, like how to measure? what accuracy I'll get? It's metrologist's field of work. Every factory (at least, in Russia) has a metrologist or, more often, a department of metrology. These people make sure that all the measurements made there are correct. This is very important, because sometimes even people's lives depend on it.
 

Offline capsicum

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Re: Just what is metrology?
« Reply #12 on: March 07, 2017, 08:31:10 am »
It is literally the science of measurement, it has practical products that are often used for instrument calibration. Metrology proper is an academic field much like any other hard science, and just as chemists created the foundation on which chemical engineers and swimming pool boys perform their jobs, metrologists create new methods of measurement and the foundation for routine calibration labs.

In other words, they seek to answer the question, "How do you measure the trueness of the world's most accurate[correct] or most precise[resolution] tool?"
Both relative [comparative, is A or B better?] and for a known uncertainty on a fixed scale. [Z odds of it being within X deviation of Y]
Uncertainty grows as you use one instrument to calibrate another and that instrument is used to calibrate yet another... in a chain away from a fixed standard. As each calibration has a range [say +-1 unit] the exact position within said range is unknown [+0.006 or -0.9?] and those unknowns are tracked and combined and traceable [as is any good scientific data] This is the mundane accounting portion.
The real action involves the theory behind unit definitions (ie, exactly what is temperature measuring, should degrees be a linear portion of that thing? Can a time standard be defined using only the other base measurements or must we rely on a natural physical element?) and in developing better standards (replace the king's foot with a new platinum-alloy bar kept in a climate controlled room, and that in turn was replaced by the wavelength of a specific frequency of light in a vacuum)
 

Offline CatalinaWOW

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Re: Just what is metrology?
« Reply #13 on: March 07, 2017, 04:20:29 pm »
The real action involves the theory behind unit definitions (ie, exactly what is temperature measuring, should degrees be a linear portion of that thing? Can a time standard be defined using only the other base measurements or must we rely on a natural physical element?) and in developing better standards (replace the king's foot with a new platinum-alloy bar kept in a climate controlled room, and that in turn was replaced by the wavelength of a specific frequency of light in a vacuum)

Two very different concepts here.  Definition of standards is a practical solution to the traceability problem.  If you define the length standard by light in a vacuum (and pick that frequency so that it can be easily and accurately duplicated elsewhere) you reduce the number of transfers in a calibration sequence, and potentially have a standard with less inherent variability.

Defining time or other fundamental unit in terms of other units is more of a fundamental physics question.  Which units really are fundamental, and which are merely derivatives of how the universe works.  Of course this may not matter for traceability.  Even if time is not a fundamental unit, it might turn out that better results could be achieved using a time standard.
 

Offline capsicum

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Re: Just what is metrology?
« Reply #14 on: March 19, 2017, 05:21:54 pm »
For routine checks that is a fair statement, for practical daily measurement a traceable calibrated item does not need to have fundamental units on its scale. But simply taking measurements is the practice of metrology in the same manor that a child riding a bicycle is practicing physics and biology.   

Two very different concepts here.  Definition of standards is a practical solution to the traceability problem.  If you define the length standard by light in a vacuum (and pick that frequency so that it can be easily and accurately duplicated elsewhere) you reduce the number of transfers in a calibration sequence, and potentially have a standard with less inherent variability.

Defining time or other fundamental unit in terms of other units is more of a fundamental physics question.  Which units really are fundamental, and which are merely derivatives of how the universe works.  Of course this may not matter for traceability.  Even if time is not a fundamental unit, it might turn out that better results could be achieved using a time standard.
Metrology is a branch of physics.
At the highest precisions those are just two sides of the same coin, the traceability issue is one of relative variation [from the standard] while the fundamental unit issue is about the long term trueness of the standard. ie if all masses are based of the Kg standard which is currently just a lump of metal declared/defined to be the final word, you cannot be certain that the lump has not been slowly altered. Is it good enough for practical trade? Yes. Just the same, using 3.14159 rather than pi in a formula, or even producing a sin table from carefully measured triangles, could be sufficient for nearly all practical daily calculations and engineering, but practical as it may be it is not proper mathematics and neither is accepted as part of a proof or definition.
 

Offline capsicum

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Re: Just what is metrology?
« Reply #15 on: March 19, 2017, 05:28:19 pm »
Does it have any connection to meteorology (weather science)? I know there is (or at least used to be) a company called Metrologic which made equipment (namely lasers) intended for the field of science known known as metrology. Yet I have not been able yet to figure out what metrology is. What exactly is metrology?

Meteorology is from the word meteor, it is no more related to meterology than any other field of science.( they all must take measurements)
Metrology is from the words measure or metric(which is older than the SI "Metric" system).
 

Offline CatalinaWOW

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Re: Just what is metrology?
« Reply #16 on: March 19, 2017, 07:27:10 pm »

Metrology is a branch of physics.
At the highest precisions those are just two sides of the same coin, the traceability issue is one of relative variation [from the standard] while the fundamental unit issue is about the long term trueness of the standard. ie if all masses are based of the Kg standard which is currently just a lump of metal declared/defined to be the final word, you cannot be certain that the lump has not been slowly altered. Is it good enough for practical trade? Yes. Just the same, using 3.14159 rather than pi in a formula, or even producing a sin table from carefully measured triangles, could be sufficient for nearly all practical daily calculations and engineering, but practical as it may be it is not proper mathematics and neither is accepted as part of a proof or definition.

I agree that definition in terms of things like a wavelength of light you are aiding consistency (and hence traceability) over time.  At least as we currently understand physics.  But the definitions are still arbitrary.  Another civilization could pick other length and mass standards.  Particularly extraterrestrial civilizations which might find other atomic transitions easier to access and possibly more repeatable than the one we have chosen.  The relations between them would still obey the same physics, though the equations would have different scale factors.  That is a completely different fundamental layer of truth than the ratio of diameter to radius in a circle.  Which other than some arbitrariness in representation by approximation in different number bases is truly fundamental.
 

Offline capsicum

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Re: Just what is metrology?
« Reply #17 on: March 22, 2017, 08:23:36 pm »
When I was referring to definitions i did not intend the specification of a unit size scale. What I intended was the definition of what is actually being measured; length, mass, temperature, energy, amperage, etc.. In other words, defining what is temperature fundamentally, rather than the conversion between Rankin and Kelvin units. The unit is just the common reference, but to be a reference it must be as absolute as can be with current knowledge and a convertion between them can be just as absolute as the definition of Pi.

BTW [tangent to topic] Pi being irrational is irrational in all integer numeral systems, not only deci.
 


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