• Question: Why is the zeroth law of thermodynamics called the zeroth law of thermodynamics and not the fourth law?

    Asked by stormwhite to Arttu, Ceri, James_M, Monica, Philip on 20 Jun 2011.
    • Photo: Arttu Rajantie

      Arttu Rajantie answered on 20 Jun 2011:

      I am not sure, but I think that, first of all, it was introduced later, so the other option would have been to call it the fourth law, as you suggest. But it is in some sense more fundamental because it defines the concept of temperature which is used in the third law, and therefore it should come before it.

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