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First principle?

  1. Sep 4, 2006 #1
    I often se mention of first principle.
    Deriver something from first principle ect.

    But what on earth does that mean:confused: I dont know if it maby we dont use any equvivalent to first principle in the swedish language or if I just happen to have missed it so far during my education. But I havent figured out what it means.:grumpy:

    to deduce something from first principle. Does it mean something like deducing something only by using the most fundamental hypothesis or axioms?
  2. jcsd
  3. Sep 4, 2006 #2


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    It is sometime also called ab initio. What it means is that you start off from the most fundamental form for the derivation, as opposed to coming up with an expression via phenomenology. For example, if you can derive a phenomena starting from the Hamiltonian, then that would be a First Principle derivation.

    In superconductivity, for example, the London equation would be an example of phenomenology, while the BCS theory would be something from First Principle.

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