The Lagrangian and the second derivative?

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filip97
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Why Lagrangian not depend of higher derivatives of generalised coordinates ?
 
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Sometimes it depends, eg in general relativity or in elastomechanics. In most cases it does not, but there is no deeper explanation for that.

EDIT: AFAIK in QFT it would lead to inconsistencies, but I don't remember details.
 
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