The kelvin scale - how could it have been defined?

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    Kelvin Scale
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Discussion Overview

The discussion revolves around the definition of the Kelvin scale, particularly the rationale behind using the triple point of water alongside absolute zero. Participants explore the necessity of having two reference points for defining a linear temperature scale and the implications of using different points for accuracy.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions why the Kelvin scale requires the triple point of water if absolute zero is already defined as its null point.
  • Another participant asserts that two reference points are necessary to define a linear scale, contrasting the Celsius scale's use of freezing and boiling points of water with the Kelvin scale's reliance on absolute zero and the triple point.
  • A different participant suggests that if the size of a degree Kelvin is equivalent to a degree Celsius, then only one base temperature might be needed.
  • One participant argues that using the triple point of water may provide better accuracy than relying on the Celsius scale's two points, which depend on the accuracy of pressure unit definitions.
  • A later reply references a decision made in the 1960s regarding the definition of the Kelvin scale.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of two reference points for defining the Kelvin scale, indicating that multiple competing perspectives remain unresolved.

Contextual Notes

There are assumptions regarding the equivalence of degree sizes and the accuracy of temperature definitions that are not fully explored, as well as dependencies on the definitions of pressure units.

spaghetti3451
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Hey,

I know that the kelvin scale uses the absolute zero as its null point. If so, I wonder why the scale needs to be defined using the triple point of water. I mean, the absolute zero serves the purpose of defining the kelvin scale already, doesn't it?
 
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You must have two points to define linear scale, not just one.
Celsius used freezing and boiling points of water. Kelvin found one, being fundamental, but still needs the second.
 
I was under the impression that the size of a degree Kelvin was defined to be the same as a degree celsius. If that is true then you would only need a single "base" temperature.
 
Those two approaches are equivalent, with respect to accuracy.

We may obtain better accuracy using just one point (tripple point of water) than using inherited after Celsius distance between two points (melting and boiling of water at the 1bar pressure), which depend in turn on accuracy of our definition of pressure unit.
 

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