The findings of henri becquerel and the curies to discredit what notion held for a very long time? that matter can never be created or destroyed. matter is made up of any smaller parts. matter is radioactive and decays over time. that matter is invisible and indestructible.

Matter is radioactive and decays over time

Henri Becquerel discovered that uranium salts spontaneously emit a penetrating radiation that can be registered on a photographic plate.

hope this helps

The answer is: That matter is indivisible and indestructible

Through his experiment, Henri Becquerel found that matters can be stored within another object, (He took potassium uranyl sulfate and put it under the sun and then put the substance within photographic plates that he cover with black paper, ) . Curie found that over time matters would decay and eventually gone.

You can say that the law of the conservation of energy states that energy cannot be created or destroyed only transferred. therefore the energy your friend said is used up is just simply transferred into other forms of energy