After reading a lot of posts lately, I believe I recall someone mentioning that physicists no longer look at the relativistic effect of mass-"dialation" but rather velocity. Im not 100% sure I understand this so firstly, please explan a little. The way I understood it was that the more relativist speeds you reached, others viewed you as gaining more mass. Feel free to use heavy math, it always seems to help me understand when I can see the math behind it. Now my question about this is also: Do mass-full observers witness a change in gravitational spacetime distortion when a relativistic mass-full object passes by (more than they would if the object moved slowly?). A way to impossibly measure this: have two masses arranged in space such that they are connected in a line by a rope/mechanism that will expand but not contract. That way the masses don't fall into eachother, but can stil lbe pulled around by different means. A relativistic mass of the same amount (rest) passes by within close enough range where it can feel the effects noticeably. >>>>>>-----O------>>>>> O | | | O Would, since it is moving fast, and relativistically its "heavier", the other two masses notice these effects physically. Would there be a greater pull than one would expect non-relativistically. Of course it would be in the system for only a short amount of time, and the time it takes for spacetime distortions to have effect is c. (i assume) [As an afterthough, the whole reason why I made two mases is I couldn't think of another way to measure a spacial field gradient than to measure the differences in changes of momentum (differences in potential). When theres no other objects you cant measure agains anything. Is this question making sense? It's nothing too crazy but I'm tryign to be clear. I know length contraction or time dialation is all how you choose to think about the problem, and from where you're watching. What about mass and the effects of gravity?