Sujet : Re: Scalar waves
De : nospam (at) *nospam* de-ster.demon.nl (J. J. Lodder)
Groupes : sci.physics.relativityDate : 08. May 2024, 13:52:33
Autres entêtes
Organisation : De Ster
Message-ID : <1qt8m73.1ep05d01xz185yN%nospam@de-ster.demon.nl>
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Mikko <
mikko.levanto@iki.fi> wrote:
On 2024-05-07 07:43:50 +0000, Thomas Heger said:
Am Montag000006, 06.05.2024 um 13:52 schrieb J. J. Lodder:
Mikko <mikko.levanto@iki.fi> wrote:
On 2024-05-06 09:36:27 +0000, J. J. Lodder said:
A measurement is not a measurement unless it can be traced
to a primary standard.
So your multimeter measures 204.5 mA when it says so
because the manufacturer of it says so.
Your manufacturer can guarantee that,
because he has calibrated the thing
against his standard ampere meter.
He knows that his standard meter measures amps
because he takes it to his national standards lab,
where they calibrate it for him.
And ultimately (if you live in a small country)
your national lab takes their standards to NIST, or BIPM,
where they do have a primary standard.
Possibly. Or the manufacturer or certifier or the national
laboratory may have a reference that they compare directly
to the definition.
Certainly. Whatever,
the point is and remains that a measurement isn't a measurement
unless it can be traced to an SI standard.
In many cases this is even required by law.
Whatever is doing the calibrating must be a state-approved agency.
Well, no!
You can use any other consistent system of units, if you don't like
SI-units.
In a measurement only one unit is used so there is no requirement on system.
Right. Only final results of measurements should be converted.
Our American frieds may have problems with this,
so they may crash a Mars lander every now and then.
And aforteriori, there is never any need for any 'dimension'
in anny measurement proces.
The main use of 'dimensions' is to have something
to teach to the kiddies, to set exam questions about.
Real scientists don't need them to know what to do.
But actually I was talking about dimensions and how those are defined.
You need not use a defined system of dimensions. You may define your own
dimension system. For example, you can define a system whith different
dimensions for horizontal and vertical distances.
Indeed, 'pilots units' from one of my postings of long long ago.
Pilots measure vertical distances in feet,
and horizontal distances in (nautical) miles.
So their glide angle is in feet per mile. [1]
Whether or not you define a systems of dimensions
to go with those units is, just like you say, optional.
Jan
[1] Real piots do have a very good idea of what the value of it is.
It really helps when you are going to park your Airbus,
in the Hudson river.