The central part of the argument is that over time the center of gravity moves lower thus making it easier to balance the egg if you believe you can balance the egg than if you give up earlier because you don't.

That the hypothesis for the mechanism for this lowered center of gravity has a flaw resulting from bad data (relative densities of yolk and white) does not invalidate it as an explanation for different success rates of believers and disbelievers, and I would expect it to get fixed in new editions.

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"God bless thee, my son; I will give thee the greatest jewel I have ...
"The end of our foundation is the knowledge of causes, and secret motions of things; and the enlarging of the bounds of human empire, to the effecting of all things possible."Trying to make sense of computers, The Error Log.