Is Planck's Constant Irrational?

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Discussion Overview

The discussion revolves around the nature of Planck's constant, specifically whether it is rational or irrational. Participants explore the implications of measurement, definitions, and the context of physical constants, touching on theoretical and conceptual aspects of mathematics and physics.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • Some participants question the classification of Planck's constant as rational or irrational, noting that it depends on the units used and the precision of measurement.
  • One participant argues that in atomic units, Planck's constant can be defined as 1, suggesting it could be rational, while others counter that it is equal to 2π, which is irrational.
  • There is a discussion about the uncertainty in measurements, with some stating that since the exact value of Planck's constant is not known, its rationality cannot be determined.
  • Several participants challenge the assertion that "no physical quantity can be irrational," citing examples like \(\sqrt{2}\) and discussing the philosophical implications of mathematical objects in nature.
  • Some participants propose that defining a constant to have a specific value does not necessarily make it rational, as the definition may not reflect the true nature of the constant.
  • There is a mention of Avogadro's number, with differing opinions on its rationality based on its definition and the nature of the units involved.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the rationality of Planck's constant and the implications of measurement uncertainty. The discussion remains unresolved, with no consensus on the nature of Planck's constant or the broader implications for physical quantities.

Contextual Notes

Limitations include the dependence on definitions, measurement precision, and the philosophical nature of mathematical objects versus physical quantities. The discussion highlights the complexities involved in categorizing constants in physics.

  • #31
LeonhardEuler said:
If you add atoms one by one, you will probably come to a point where you have slightly less than 12g, and if you add one more atom you will have slightly more.

That's exactly what I was thinking. Atoms' masses are so small so we have no practical way of measuring so precisely, but I don't see a reason to believe that a whole number of 12C happens to weigh exactly 12 g. It could be that the closest one can get is barely under or barely over exactly 12 grams by half the mass of a neutron or any other small, positive number. And since it's nigh impossible to get two 12-gram samples of 12C with exactly the same percentage of isotopes, Avogadro's number will vary from sample to sample, which I hadn't thought of before...
 
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  • #32
If one defines units of measure on phyisical observations (as the speed of light), then yes it is possible to exactly know what the constant equals (since one is using the constant as the new "yard stick")

And I can see Avogardo's number being defined some day to be so many atoms of standard C12 atoms (or some other standardizable atom) - and define the kilogram to be so many of those. This completely changes the conversation though.

Of course, there is always the issue as to whether all neutrons weigh the same etc.

But we digress. Some constants are rational, some aren't.

--Elucidus
 

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