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My Version of Laws of Thermodynamics

  1. Apr 1, 2013 #1
    Hi everyone,
    Here is my version of laws of thermodynamics which I would like to share it with you and hear your feedback:

    Zeroth Law: More than being a law, it is a definition for temperature and it follows:
    Two systems are in thermal equilibrium iff (if and only if) they have the same temperature.

    First Law: Similar to the Zeroth Law, it hold a definition and a concept:
    Heat is energy and total energy of a system is conserved.

    Second Law: I call this the Dahh! Law because it says whatever is more probable happens the most, dahh! Here is the formal definition:
    For a closed system, the macrostate with the highest number of microstates is more probable to occur.

    Third Law: It can be considered as the complementary definition and concept for the Zeroth Law:
    As the number of available microstates (also entropy since 'S = k ln(w)') of a system minimizes, the inverse temperature value (i.e. β ≡ 1/T ) explodes to positive infinity.

    Comments are appreciated,
    Milad P.
  2. jcsd
  3. Apr 1, 2013 #2
    What is original in these laws that makes them yours?

    0) As WBN noted, this doesn't define a temperature.

    1) Heat is energy is not very informative and it misses the essence of the first law that makes it stronger than just a conservation law - it says how energy transfers between systems.

    2) The Dahh? You don't get to rename entropy.

    3) This is incorrect. Temperature is related to [itex]\frac{\partial S}{\partial E} [/itex], not the absolute value of entropy.
    Last edited: Apr 1, 2013
  4. Apr 1, 2013 #3


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    How is your version of the zeroth law even a definition of temperature as you claim? It doesn't define temperature in any way. It is like saying the following statement DEFINES what being homeomorphic means: two topological spaces are "essentially the same" if they are homeomorphic. That doesn't define what homeomorphic means at all; the same goes with your "version" of the zeroth law.
    Last edited: Apr 1, 2013
  5. Apr 1, 2013 #4
    My First Reply

    First of all, I like to say I missed having such discussions and I'm glad I'm on this site and there are people like you responding to my posts.

    Lest get started. The most common version of the "zeroth law states that if two systems are each in thermal equilibrium with a third system, they are also in thermal equilibrium with each other" (Wikipedia). What exactly is thermal equilibrium in this sentence? To me this is a definition of thermal equilibrium and when you combine it with the state meant that temperature is what a thermometer measures, you get to a sentence stating that for having the same temperature between two systems is the indicator of thermal equilibrium. They could have defined temperature as rate of flow of heat, etc, but they didn't define it that way, instead they used a relativistic idea (not Einstein's relativity). How come this is not a definition? Maybe we just have a disagreement on the definition of the word 'definition'!

    For the first law, for centuries our fathers could not make sense of temperature and heat. The fact that coldness is absence of heat, and head is energy is a big achievement. Please recall Jules famous experiment in 1843. I think one of the big ideas that his experiment proves is that heat is energy, or work can convert to heat.

    For the second law, I have to tell Jorriss that I am not claiming that I came up with these laws and having a little fun and calling this law the Dahh Law is OK! I believe the fact that this law is so simple and obvious and yet very powerful is very amazing to me. And all I tried to show here was that how simple this law is.

    At the end, a question for Jorriss. So you are claiming that when we minimize the energy and entropy to their lowest values, temperature does not approach zero?
    To be honest, I wanted to relate this law to derivative of entropy with respect to energy, but I couldn't, and couldn't extract this formula just by relying on other people's version of this law. However, I do not see why this was so important that they've announced it the third law. If you can share your opinion, I would appreciate it.

    Milad P.
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