3
$\begingroup$

In this recent question, there was a comment 'The "zero point" of Kelvin is natural, but the scale is not'. This led me to wonder whether setting $R = 1$ in the ideal gas law would be an attractive and more natural temperature scale.

I am aware that changing to such a scale is not practical, the investment in the Kelvin is too great.

$\endgroup$
5
$\begingroup$

In natural units Boltzmann's constant, $k$, is normally set to one, rather than $R$. They differ by a factor of Avogadro's number; a mole is an arbitrarily defined unit based on the kilogram and is not "natural".

At least in my experience of high energy physics choosing $k = 1$ is common practice; I'm sure it occurs in other branches too.

$\endgroup$
2
  • $\begingroup$ Plus one for beating me to the post by 35 seconds. $\endgroup$ – David Hammen Jun 9 '19 at 20:02
  • $\begingroup$ Regarding your edit, there are several different systems of natural units. All but one sets $k_b$ to one. The one that doesn't? Its sole concern is gravitation, so it only sets $c$ and $G$ to one. $\endgroup$ – David Hammen Jun 9 '19 at 20:06
1
$\begingroup$

Would setting the ideal gas constant to 1 yield an attractive natural temperature scale?

Not really. The universal gas constant involves two arbitrary units: energy and temperature, and also the unitless mole. Getting rid of the concept of moles results in Boltzmann's constant $k_b$. This is the value that is set to 1 rather than $R$ in all systems of natural units.

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.