in twin paradox if the spaceship is considered stationary & earth moving the opp result is got.how can it be??

Answer 1

Motion is relative. From the point of view of the spaceship, the earth is moving, and from the point of view the earth, the spacehip is moving.
However, in order for the spaceship to reach a velocity close to that of light, it must accelerate.
THAT is the difference. You can always feel acceleration. The stationary Earth feels no such acceleration, even if the spaceship, once in constant motion, considers it to be moving.

Answer 2

The theory says nothing about acceleration. If the spaceship never fired its engine but simply had always been flying and always continued flying, then as it passed Earth it would indeed be impossible to tell which one was moving and which one was not. Each observer would say that the other one was moving and experiencing slow time. But if the spaceship started on Earth and accelerated away, or if it arrived at nigh speed and decelerated to a stop, then it would be clear from the acceleration that the spaceship was the one moving and not the Earth. Then the paradox disappears.

Answer 3

The key is that the spaceship has to turn around and come back home (to see her twin). Until she turns around, each twin sees the other as being the one moving. But no one can deny that the twin on the spaceship is the one who turned around (use the distant stars as a reference point). That turning is the acceleration that "fixes" the paradox.

Answer 4

Yah. Acceleration is the key. Special Relativity spawned the twin paradox, but it does not exist in the more general theory of General Relativity. Acceleration is in that one (and that is why it is a lot more complex. Special R can be derived with quadratic algebra and the assumption that the speed of light is the same for all reference frames) and if you start the ship stationary on earth, it is the traveling twin that ages more slowly, and he sees the one left behind aging more quickly.

Answer 5

pure magic