Which of these makes more sense on a quantum level and why;

Energy and mass are interchangeable.
or
Energy and mass are equivalent.

Question

Which of these makes more sense on a quantum level and why;

Energy and mass are interchangeable.
 or
Energy and mass are equivalent.

anonymous · Answer

Energy and mass interchangeable makes more sense,
Let's consider helium atom, it consists of 2 protons, 2 neutrons.
If you add the masses of  2 protons and 2 neutrons it turns out that it's greater than the mass of He given in the periodic table, the amount of mass difference becomes nuclear energy that holds 2 protons and 2 neutrons together. i.e. some amount of mass changes to energy. $$E=mc ^{2}$$

unklerhaukus · Answer

mass is a form of energy