[theThinker (OP)]

The Planck constant is defined strictly through the relation E = hν. 

Not any more.
"The SI units are defined in such a way that, when the Planck constant is expressed in SI units, it has the exact value

h = 6.62607015×10−34 J⋅Hz−1"

From
https://en.wikipedia.org/wiki/Planck_constant

You confuse the physical concept of the Planck constant with the operational definition of the constant in a system of units - here the SI unit. We may set the Planck constant to any value we choose. 

[theThinker (OP)]

I have one conjecture. The Kibble balance or the Watt balance may only be used to calibrate a standard one kilogram in a new SI unit definition. But such balance may not be acceptable as a weighing scale to measure mass in general. It cannot qualify as an acceptable weighing scale in the manner a lab analytical balance or a scale balance may. So you cannot use it to measure the mass of a sample of material in your experiment, say of 312.23 g.   

[Bored chemist]

So you cannot use it to measure the mass of a sample of material in your experiment, say of 312.23 g. 

You could, but it wouldn't be sensible.

[Bored chemist]

The two are two different physical dimensions in physics.

Nobody said that they were not.
Energy and frequency also don't have dimensions of mass, but you are happy enough to use them to define Planck's constant

[theThinker (OP)]

So you cannot use it to measure the mass of a sample of material in your experiment, say of 312.23 g.

You could, but it wouldn't be sensible.

I only say the watt balance cannot be acceptable as a general balance to measure mass. On the other hand, the spring balance may be acceptable.

[theThinker (OP)]

The two are two different physical dimensions in physics.

Nobody said that they were not.
Energy and frequency also don't have dimensions of mass, but you are happy enough to use them to define Planck's constant

E has the dimension of energy; hν too has the dimension of energy.

[Bored chemist]

The two are two different physical dimensions in physics.

Nobody said that they were not.
Energy and frequency also don't have dimensions of mass, but you are happy enough to use them to define Planck's constant

E has the dimension of energy; hν too has the dimension of energy.

And mc^2 has units of energy too.

[theThinker (OP)]

The two are two different physical dimensions in physics.

Nobody said that they were not.
Energy and frequency also don't have dimensions of mass, but you are happy enough to use them to define Planck's constant

E has the dimension of energy; hν too has the dimension of energy.

And mc^2 has units of energy too.

In E=hν, the LHS E is that of the photon;  ν is the frequency of the same photon.

In E= mc², you may combine it with the above provided m is the mass of the photon and LHS E is also the energy of the photon; but a photon only has energy, never mass.

Your algebra is correct, but your physics is wrong.

[Kryptid]

but a photon only has energy, never mass.

Due to mass-energy equivalence, photons do have a mass that is dependent on their energy. What they lack is an invariant (rest) mass.

[Bored chemist]

Your algebra is correct, but your physics is wrong.

The algebra and physics I'm using are the ones which earned Louis de Broglie his Nobel prize.

https://en.wikipedia.org/wiki/Louis_de_Broglie#Duality_of_the_laws_of_nature

[alancalverd]

I have one conjecture. The Kibble balance or the Watt balance may only be used to calibrate a standard one kilogram in a new SI unit definition. But such balance may not be acceptable as a weighing scale to measure mass in general. It cannot qualify as an acceptable weighing scale in the manner a lab analytical balance or a scale balance may. So you cannot use it to measure the mass of a sample of material in your experiment, say of 312.23 g.   

Which is exactly wrong. It measures any mass in terms of the SI unit of mass. A laboratory balance merely compares two masses and tells you which is the heavier.

Apart, that is, from a Cahn Electrobalance which is a sort of proto-mini-Kibble, using electromagnetic force to offset the gravitational force on the unknown mass. The difference is that it doesn't self-calibrate the current and voltage. 

[theThinker (OP)]

but a photon only has energy, never mass.

Due to mass-energy equivalence, photons do have a mass that is dependent on their energy. What they lack is an invariant (rest) mass.

@BoredChemist is talking about mass used for the watt balance. Do you use your watt balance to weigh rest mass or mass at speed 299792458 m/s?

I vote against your argument.

[Bored chemist]

A laboratory balance merely compares two masses and tells you which is the heavier.

For about the last 50 years balances in labs haven't looked like this

balance 1.JPG (30.92 kB . 424x388 - viewed 623 times)

They now typically look like this


balance 2.JPG (16.28 kB . 264x330 - viewed 610 times)

Arguably, it's a pity; but they are much easier to use.

[Bored chemist]

Do you use your watt balance to weigh rest mass

A fundamental aspect of the Kibble balance is that the mass moves.

[theThinker (OP)]

I have one conjecture. The Kibble balance or the Watt balance may only be used to calibrate a standard one kilogram in a new SI unit definition. But such balance may not be acceptable as a weighing scale to measure mass in general. It cannot qualify as an acceptable weighing scale in the manner a lab analytical balance or a scale balance may. So you cannot use it to measure the mass of a sample of material in your experiment, say of 312.23 g.   

Which is exactly wrong. It measures any mass in terms of the SI unit of mass. A laboratory balance merely compares two masses and tells you which is the heavier.

It's why I use the word "conjecture". It's for those in this forum to figure out why if they show any interest.

The puzzle is: The spring balance is acceptable, but not the watt balance. But please do not ask for the Nobel prize for this.

[alancalverd]

@BoredChemist is talking about mass used for the watt balance. Do you use your watt balance to weigh rest mass or mass at speed 299792458 m/s?

I vote against your argument.

It measures mass at whatever speed you happen to be travelling,as long as there is a nearby large mass that doesn't change much. At the poles, you would be travelling around the sun at about 30 km/second. You may as well vote Liberal for all the good it will do.

[alancalverd]

The spring balance is acceptable, but not the watt balance.

To whom? A non-metrologist may prefer the simplicity of a spring balance, but a metrologist would recognise its absurdity.

[Bored chemist]

It's why I use the word "conjecture". It's for those in this forum to figure out why if they show any interest.

I think I have figured out why you use the word "conjecture".
It's because you know that your idea is unsupported by evidence and thus can not be described as a theory.

[Bored chemist]

The spring balance is acceptable, but not the watt balance.

They are both acceptable.
They have different fields of application.
A Kibble balance has to be maintained in a vacuum chamber to address the issues of air density and currents.

If you want to weigh a fish before you toss it back in the river you would use a spring balance, rather than a Kibble balance.

Most cooks are quite content to use spring balances- the modern digital ones are good to better than 0.1% so they are also useful as a rough balance in a laboratory.