1. How did Einstein derive his most famous equation: $$E=mc^2$$

  2. Is the above equation a special case of $$E^2=m^2c^4+p^2c^2$$

  3. Its derivation?

  4. What is the difference between them?

  • $\begingroup$ do you mean Einstein's original derivation or any derivation will do? $\endgroup$
    – Nikos M.
    Oct 29, 2014 at 11:12
  • 3
    $\begingroup$ the original 1905 paper of Einstein on the electrodynamics of moving bodies already contains a form of this relation $\endgroup$
    – Nikos M.
    Oct 29, 2014 at 11:13
  • 2
    $\begingroup$ this is a second paper of Einstein on the relation between inertia and energy and contains a further form of the relation $\endgroup$
    – Nikos M.
    Oct 29, 2014 at 11:15
  • $\begingroup$ @Nikos M it would be helpful if you can furnish me with Einstein's original derivation, as long as it does not involve too much calculus(I am fine with basic calculus); although I will be indebted to you for any logically consistent proof $\endgroup$ Oct 29, 2014 at 11:18
  • 1
    $\begingroup$ @Nikos M.: Note that age is not always decisive when deciding which is a duplicate of which. $\endgroup$
    – Qmechanic
    Oct 29, 2014 at 13:11


Browse other questions tagged or ask your own question.