>The author of the article doesn't understand elementary physics as well as you do Don't be so quick to make such judgments: There is ample scientific interes

>The author of the article doesn't understand elementary physics as well as you do Don't be so quick to make such judgments: There is ample scientific interest in the differences between inertial and gravitational mass [1]. That they seem the same is a profound question known to Einstein. He explicitly assumed they were the same in his equivalence principle [2]. So their equivalence is a postulate, not derived from deeper theories. But one day we may find it is not consistent over time. It most certainly is a deep question in physics. There are other theories of gravity, taken seriously, as possible future modifications to relativity, such as Brans-Dicke theory [3], that remove this equivalence principle, yet still agree with all observational evidence to date. Current experimental evidence puts them equivalent to under 1 part in 10^-15 [2], with more experiments still being done. [1] https://en.wikipedia.org/wiki/Mass#Inertial_vs._gravitational_mass https://en.wikipedia.org/wiki/Mass#Inertial_vs._gravitationa... [2] https://en.wikipedia.org/wiki/Equivalence_principle https://en.wikipedia.org/wiki/Equivalence_principle [3] https://en.wikipedia.org/wiki/Brans%E2%80%93Dicke_theory https://en.wikipedia.org/wiki/Brans%E2%80%93Dicke_theory