Kelvin - not the basic, but the derived unit of measurement?

[Piotrovskiy Yury]

TL;DR

Kelvin - not the basic, but the derived unit of measurement.

1. Kelvin - not the basic, but the derived unit of measurement?

Modern physics believes that kelvin is the basic unit of measurement of SI (one of seven).
At the same time, in all encyclopedias and textbooks it is written:

T= Θ/k = Θ /1,380649x10е-23

Θ - is the energy of the molecule in joules.
k - is the Boltzmann constant = 1,380649e-23 J / K
T - is the absolute temperature in kelvin.

From the formula it follows that the absolute temperature of kelvin is derived through the joules of kinetic energy of the molecule.
And this means that Kelvin is not the basic unit, but a derived unit.

Another proof that kelvin is not the basic, but a derivative, is a site-converter

Convert kelvin [K] <-> joule [J]

https://www.translatorscafe.com/unit-converter/EN/...

2. In accordance with the fact that kelvin is not the basic unit, it is proposed to legalize, along with the use of the Celsius scale and others, the mandatory parallel use of the energy scale in joules.

That is, in addition to “historically established practice”, habits, inertia of thinking, temperature measurement in degrees, not joules, is unjustified.

In addition, the measurement of temperature in degrees (Celsius, Kelvin, Fahrenheit, etc.) hides, disguises the essence of temperature as a physical phenomenon, complicates its understanding and contributes to the physical illiteracy of the people.

THERMOMETERS WITH JOULE - SCALE:

 

[Herman Trivilino]

Modern physics believes that kelvin is the basic unit of measurement of SI (one of seven).

The choice is a matter of convenience.

From the formula it follows that the absolute temperature of kelvin is derived through the joules of kinetic energy of the molecule.
And this means that Kelvin is not the basic unit, but a derived unit.

You can always make your own choice of what you consider to be fundamental. The choice is a matter of convenience.

 

[scottdave]

A website unit converter does not prove anything. The Joule is still a derived SI unit, even if defined in terms of another unit.
Note that Ampere is a base unit even though it is Coulombs/sec.
I believe the reason was because it was easier to measure amps than Coulombs.

 

[Piotrovskiy Yury]

You're right. The Joule is still a derived SI unit, but the joule is 1 J = 1 kg m² / s².
So kelvin is equal to 1 kg m² / s².
That is, kelvin is reduced to kg, m, s

 

[Vanadium 50]

So kelvin is equal to 1 kg m² / s².

That's simply not correct.

 

[Dale]

Modern physics believes that kelvin is the basic unit of measurement of SI (one of seven).

It is not a matter of belief, it is a matter of definition. The BIPM committee has defined the K as a base unit. They could have defined another, but they chose to define K.

the absolute temperature of kelvin is derived through the joules of kinetic energy of the molecule

This is not correct in general. It is only true for ideal gasses, but other molecules posses vibrational modes which are as much potential energy as kinetic energy.

That said, yes, the SI could have defined the J as a base unit and the K as a derived unit, but they didn’t. They defined it the other way.

 

[Piotrovskiy Yury]

That's simply not correct.

OK. What exactly is “just not correct”?

1. T = Q / k correct?

2. Q = J = kg x m² / s² correct?

 

[Piotrovskiy Yury]

It is not a matter of belief, it is a matter of definition. The BIPM committee has defined the K as a base unit. They could have defined another, but they chose to define K.This is not correct in general. It is only true for ideal gasses, but other molecules posses vibrational modes which are as much potential energy as kinetic energy.

That said, yes, the SI could have defined the J as a base unit and the K as a derived unit, but they didn’t. They defined it the other way.

I agree. Yesterday it was determined this way, but in a year it will be determined differently.

 

[Dale]

I agree. Yesterday it was determined this way, but in a year it will be determined differently.

Certainly in a year it *could* be determined differently. I doubt that it *will* be determined differently. The BIPM is a group that is pretty concerned with historical continuity.

 

[vanhees71]

The SI has been made over right in May this year by fixing all the fundamental constants like $\hbar$, $c$, $e$, and also $k_{\text{B}}$. It's hard to imagine that there will be major changes in the basic definitions of the SI in the foreseeable future. The only thing which might be still changed is the definition of the second which is still defined via the hyperfine structure transition of Cs. Maybe within a decade there'll be more accurate possibilities be achieved leading to an even more accurate and more robust definition of the second (like the nuclear transition of Thorium).

 

[Dale]

The only thing which might be still changed is the definition of the second which is still defined via the hyperfine structure transition of Cs. Maybe within a decade there'll be more accurate possibilities be achieved leading to an even more accurate and more robust definition of the second (like the nuclear transition of Thorium).

I agree, I think that sort of change is the most likely in the next couple of decades.

 

[Vanadium 50]

What exactly is “just not correct”?

The 1.

 

[Piotrovskiy Yury]

The 1.

It is not correct?

1. T= Θ/k = Θ /1,380649x10е-23

Θ - is the energy of the molecule in joules.
k - is the Boltzmann constant = 1,380649e-23 J / K
T - is the absolute temperature in kelvin.

 

[weirdoguy]

No, it's not. Besides, what's your point?