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One can verify that, in the non-relativistic limit, the relativistic values converge to the classical ones.

One can verify that, in the non-relativistic limit, the relativistic values converge to the classical ones.

It is this requirement, and some "''gedanken'' experiments" involving conversion between potential and kinetic energy, that lead to E=mc².<ref name="wvarticles"/>  These experiments involve some kind of object that isn't moving (though there might be internal motion that doesn't figure in the experiment) and therefore has no kinetic energy and only potential energy, turning into some things that have kinetic energy.  The requirements of strict conservation of total momentum and total energy prove the equation.

It is this requirement, and some "''gedanken experiments''"<ref>https://www.britannica.com/science/Gedankenexperiment</ref> involving conversion between potential and kinetic energy, that lead to E=mc².<ref name="wvarticles"/>  These experiments involve some kind of object that isn't moving (though there might be internal motion that doesn't figure in the experiment) and therefore has no kinetic energy and only potential energy, turning into some things that have kinetic energy.  The requirements of strict conservation of total momentum and total energy prove the equation.

Einstein's famous derivation<ref name="einstein1905b">[http://www.fourmilab.ch/etexts/einstein/E_mc2/www/ "Does the Inertia of a Body Depend its Energy Content?" Albert Einstein, Sept 1905]</ref> involved light instead of tangible objects, but the result is the same.

Einstein's famous derivation<ref name="einstein1905b">[http://www.fourmilab.ch/etexts/einstein/E_mc2/www/ "Does the Inertia of a Body Depend its Energy Content?" Albert Einstein, Sept 1905]</ref> involved light instead of tangible objects, but the result is the same.