Not really a problem but was reading a review of a book on amazon and came across this:(adsbygoogle = window.adsbygoogle || []).push({});

.) It is mathematically sloppy. Dirac introduces the Bra and Ket notation (for which he is responsible, by the way) without mentioning the dual space, and sometimes even reasons wrongly; i.e., he writes "let us postulate that for each ket, there exists a corresponding bra" - this is not a postulate. This is ALWAYS true for finite dimensional vector spaces,and NEVER true for infinite dimensional vector spaces, and can be proven mathematically. In short, there is little attention given to the mathematics behind QM.

Is the bit in bold right? Isn't <psi| normally infinite dimensions or am I confused?

Thanks

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# Homework Help: Bra kets

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