• Question: What does E=MCsquared mean, and how does this affect the way we view the world?

    Asked by dave to Chris on 16 Jun 2015.
    • Photo: Chris Armstrong

      Chris Armstrong answered on 16 Jun 2015:

      Energy = mass * speed of light squared.

      Its called the mass-energy equivilency and is the intrinsic energy an object has. Its just “stored” as mass. A way to explain this a little more clearly is fusion.

      At the end of the PP chain (fusing hydrogen to helium – happens in the sun) a helium3 ion and a hydrogen ion combine to make a helium 4 ion, an electron, a neutrio and a stack of energy. Now “energy cannot be created” is still a true statement so where did the energy come from? Well the answer is E=mc^2, the mass of he3 + h is slightly more than the mass of he4 + electron + neutrino, this change in total mass (or mass defect) corresponds to the energy emitted with this reaction.

      If you want to show off to some friends in the nerdiest way possible, you can talk about how that equation is incomplete. E=mc^2 is a special case where the total momentum of the system = zero, the more general equation includes momentum terms:

      E^2 = (m*c^2)^2 + (p*c)^2

      p = momentum

Comments