Einstein Relatively Easy

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As we have seen in our previous article, Einstein published for the first time in 1905 a demonstration to try set the equivalence of inertia and energy, or mass and energy.

However, it is only in 1912 in the Manuscript of Special Relativity, that the famous formula E=mc2 appears in its well known form.


In this draft, however, the equation, which demonstrates that mass is a form of energy, appears in a somewhat different form. Originally, Einstein used the variable "L" for energy (the "L" stood for Lagrangian, a general form of energy); later, he crossed out the "L" and changed it to "E." The letter q stands for the velocity of the moving body.


In the below english translated extract corresponding to the above original manuscrit, we recognize the formula E=mc2, with m=γm0 (rest mass) as seen in our article Introduction to Four-momentum vector and E = mc2

Then Einstein makes the supposition that the body is moving with a velocity q<<c, and expands in a Taylors series

We recognize the equation we have exposed in our article Introduction to Four-momentum vector and E = mc2



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"Five or six weeks elapsed between the conception of the idea for the special theory of relativity and the completion of the relevant publication" Einstein to Carl Seeling on March 11, 1952

"Every boy in the streets of Göttingen understands more about four-dimensional geometry than Einstein. Yet, in spite of that, Einstein did the work and not the mathematicians."
David Hilbert

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