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Sameness: When are two things the same?

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    What (do you think) is sameness? What (do you think) is differentness?

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    Sameness is a predicate shared by two bodies that exhibit the same properties. Two objects can be slightly the same, but for most bodies complete sameness is impossible, due to an impossibility of having the same spacial co-ordinates. But i have to go into physics to explain that, so ill stop now.
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    Wittgenstein talks about 'family resemblances'. This is the best way to understand our use of 'the same' in the world we inhabit.

    If we start looking for some essential or transcendental 'sameness' we end up with something like Platonic forms.
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    (Original post by The_Duck)
    Sameness is a predicate shared by two bodies that exhibit the same properties. Two objects can be slightly the same, but for most bodies complete sameness is impossible, due to an impossibility of having the same spacial co-ordinates. But i have to go into physics to explain that, so ill stop now.
    If you go into quantum mechanics then that's not a problem: all particles of the same kind are fundamentally equal, and they can even exist in the same state if they're bosons...
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    (Original post by viriol)
    If you go into quantum mechanics then that's not a problem: all particles of the same kind are fundamentally equal, and they can even exist in the same state if they're bosons...
    Has anyone seen one of these?

    They are theoretical entities and 'the same' by virtue of theory.
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    (Original post by snozzle)
    Has anyone seen one of these?

    They are theoretical entities and 'the same' by virtue of theory.
    They are 'the same' to the extent that, in particular bosons, are identical with respect to every property - including position if one so wanted.
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    (Original post by snozzle)
    Has anyone seen one of these?

    They are theoretical entities and 'the same' by virtue of theory.
    Bose-Einstein condensates are a theoretical implication of this which have been created in laboratory. Bosons are just integer spin particles (like photons, helium-4, carbon-12, etc). Not only is there no experience you can perform to distinguish them, there is evidence that they "lose individuality" when mixed with identical particles. This "loss of individuality" is corroborated by verifiable probability calculations.
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    (Original post by snozzle)
    Has anyone seen one of these?

    They are theoretical entities and 'the same' by virtue of theory.
    Well light is constructed of bosons, so we have some good evidence :P
    The point is that bosons can occupy the same energy levels, so their position co-ordinates can be identical. This does not happen with fermions, due to the strong nuclear force.

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Updated: November 26, 2012
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