The popular thought experiment states, that if of two identical twins one is left on earth an the other is embarked on a space ship and sent into open space at near-c velocity, time for the traveling one will pass slower than for the one left on earth, due to the speed. On the other hand, time passes faster for objects outside the influence of gravity. What would be the extremes of those situations? Say the spaceship in the above example has the same mass as Earth, or a greater mass, e.g. the Sun, and the extreme case, a supermassive space ship, how would that affect the thought experiment? Furthermore, I would ask for some clarification regarding reference points: consider the original thought experiment (mass of space ship is negligible compared to the mass of the Earth), but shift the reference point to the cockpit of the space ship, i.e. to the pilot it would seem that the Earth is moving with great velocity, therefore, he would conclude that time on Earth would pass slower than for him, amplified additionally by the fact of the greater gravitational influence for the twin on Earth. In other words, what provides the absolute outcome of the experiment (regardless of reference points)? Thanks a lot PS: I assume of course time validation based on identical, precise clocks placed on the Earth and on the space ship and the, somewhat subjective, statements "time passes slower/faster [for x]" refer to the difference these clocks would show after the performed experiment.