I've been thinking of something for quite a while I'd would really appricate some opinions of the matter. I was wondering if the mass density of an object changes when it approaches the speed of light, just like charge density changes and causes the lorentz force. Could this change in mass density effect an objects gravitational field in anyway? I tried to formulate an equation that would equate the gravitational field emitted by an object (like a star) with the rate of its spin, but saddly I don't posess the mathematical skills necisssary to accomplish such a task. If anyone has any relavent thoughts I'd appricate your input.