Question

What was the evidence that lead to the development of the principle of mass-energy equivalence?

a. During nuclear fission and fusion reactions, mass is not conserved, but energy is released
b. Stars were observed to be radiating colors beyond the visible spectrum
c. During the photoelectric effect, the energy that was released by the material only comes from released electrons
d. During the process of radiation, energy is not conserved even though there is mass present

Answer 1

a. During nuclear fission and fusion reactions, mass is not conserved, but energy is released. This observation, along with others such as the discovery of radioactivity and the theory of relativity, led to the development of the principle of mass-energy equivalence expressed by the famous equation E=mc².