Interview with Lars Brink: String Physicist

Dear Lars: I hope you are willing to give a little interview with me as an amateur physicist. I tried with Ulf Danielsson but got no response.

CJ: Is the equivalence of intertial and heavy/gravitational mass a matter of definition, which I believe with inertial mass the only mass there is, or is it a deep fact of physics revealed by Einstein? Is the constancy of the speed of light likewise a matter of definition, which I believe, or is it a deep physical fact revealed by Einstein?

LB: I will return with answers after my vacation is over.