The final paper of that year introduced the now famous equivalence between mass and energy in the equation E = mc2. ... In Berlin, Einstein perfected his general theory of relativity, summing up the equation e = mc2. ... He joined other scientists in a push to prevent future use of atomic weapons, proposing the establishment of a system of world government that would provide "the binding authority necessary for world security." ...

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One of its equations became the backbone of the atomic age. ... He proposed instead that observed mass, length, and time vary; according to the relative motion between the observer and the system under observation. ...

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