I really like the book, its the first physics textbook that I liked actually. But I've found a minor error.(adsbygoogle = window.adsbygoogle || []).push({});

On page 8 (chapter 1 The Wave Function) it says that if you sum deviations from average of a random variable you'd get zerobecause" Δj is as often negative as positive", here's the formula:

[tex] \Delta j=j-<j> [/tex]

But I think that's not the reason you will get zero, it need not deviate the same number of times in both direction from the average, but in that case number of deviations on one side will be canceled by the magnitude of deviations on the opposite side, I think Griffith mixed median with an average.

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# Funny thing I've found in David Griffiths QM textbook

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