Changes

For most types of physical interactions, the masses of the initial reactants and of the final products match so closely that it is essentially impossible to measure any difference.  But for nuclear reactions, the difference is measurable.  That difference is related to the energy absorbed or released, described by the equation E=mc².  (The equation applies to '''all''' interactions; the fact that nuclear interactions are the only ones for which the mass difference is measurable has led people to believe, wrongly, that E=mc² applies only to nuclear interactions.)

For most types of physical interactions, the masses of the initial reactants and of the final products match so closely that it is essentially impossible to measure any difference.  But for nuclear reactions, the difference is measurable.  That difference is related to the energy absorbed or released, described by the equation E=mc².  (The equation applies to '''all''' interactions; the fact that nuclear interactions are the only ones for which the mass difference is measurable has led people to believe, wrongly, that E=mc² applies only to nuclear interactions.)

The [[Theory of Relativity]] played no role in this work, but later tried to retrofit the theory to the data in order to explain the explain the observed mass changes.  Here is the most famous example of the mass change.

The [[Theory of Relativity]] played no role in this work, but proponents later tried to retrofit the theory to the data in order to explain the explain the observed mass changes.  Here is the most famous example of the mass change.

Nuclear fission, which is the basis for nuclear energy, was discovered in experiments by [[Otto Hahn]] and [[Fritz Strassman]], and analyzed by [[Lise Meitner]], in 1938.

Nuclear fission, which is the basis for nuclear energy, was discovered in experiments by [[Otto Hahn]] and [[Fritz Strassman]], and analyzed by [[Lise Meitner]], in 1938.