Originally Posted by **kiwiheretic** Isn't Schrodinger's equation postulated rather than derived? |

That's correct. There are derivations of it in a certain sense of the term but they are only meant to be a rough outline of a derivation and not a real derivation because a real derivation is based on simpler postulates for which the Schrodinger equation "derivation" has none. It's really just a postulate.

Originally Posted by **kiwiheretic** Besides, if psi is physical then what are its units? Does anyone even know? |

The meaning of psi is that the norm of the normalized wavefunction is the probability density. Being a probability density it's not unitless. The units depend on the system and can be found by dimensional analysis just like topquark noted.

Originally Posted by **kiwiheretic** I think Schrodinger once described it as some kind of energy density relation but wouldn't that imply it should be something like Joules per cubic metre or something? |

I know of nowhere where he said that because its not true.

Originally Posted by **kiwiheretic** Yet after all these years it continues to even defy definition!! |

That's not true at all. The Shrodinger equation and the wave function psi are both well defined.

Originally Posted by **kiwiheretic** What new revelations has psi unveiled about the internal structure of subatomic particles? Any? Or has it just been used to curve fit experimental data? |

Neither.