Thank you for your explanation. I have not had any formal physics education so I tend to miss the technical aspects of these scenarios. But I think I understand what you are saying, basically the properties of an object with regards to its mass are an effect of the objects own intrinsic mass...
Assume there is a neutron star, it has a mass that is just short of what is required for it to collapse into a black hole. Now suppose there is an observer orbiting the neutron star. Assume that the neutron star and the observer are traveling at a very high velocity with respect to a second...