twin paradox?

Answer 1

There is a paradox and no-one who answered before me clearly exposed it.

Imagine two twins, A and B in space. A is stationary, B is moving at 0.866c with respect to A. Now everyone says A is aging at twice the rate of B.

But in fact, from the point of vue of B, B is stationary and it is A which is moving at 0.866c... so B will think that A is aging faster.

So which is it? They cannot both age faster. Now I still don't understand the answer to that. It implicates the fact that B has to stop and reverse course to come back to A and compare clocks. And this implies a change of reference at the turnaround point, which implies and accelerated frame of reference and then it falls under general relativity which I still don't grasp fully.

Someone asked about the curvature of space and this is interesting. If space is closed, then B doesn't have to turnaround, it can simply carry on for a very (very very) long time before coming back to its origin, where A is standing still. But come to think of it, space can be closed only through the action of gravity, so B would feel the minute effect of this gravity throughout the whole trip, and again it would fall under general relativity.

Answer 2

There is none.

Twin A traveling near the speed of light (v ~ c) would be observed by Twin B on Earth as aging very very slowly. Twin A would see Twin B, back on Earth, aging very very rapidly. There is nothing paradoxical about this. These effects follow the validated Lorentz Transform, a major component of Einstein's relativity.

When Twin A got back to Earth, she would have aged only a little compared to what Twin B would age. In fact, Twin B might have died, along with all her contemporaries, because centuries might have passed on Earth, while only a year or two passed on Twin A's craft. (How much time passes on Earth depends on how long Twin A flies near light speed and how near light speed she flies.)

Flying near the speed of light is improbable. Flying at the speed of light is impossible. When v ~ c, the amount of energy to accelerate a craft further approaches infinity...more energy than is available in our known universe. When v = c, the energy required IS infinity, more than the energy available anywhere, inside or outside our known universe.

Answer 3

This is not a question. If you have heard the term and don't know how to Google it, you will not understand any description of it. It involves special relativity and the time dilation effect of near-light-speed travel. If one twin stays on Earth, say, and the other goes off at near light speed and returns, the returning twin will find his twin who stayed older than he is, or even dead of old age.

Answer 4

Yeah, they proved this by sending a clock into space, and leaving one on earth (they were both synchronized). When the one came back from space, it experienced a smaller time change than the one that stayed on earth. This proved yet another one of Einstein's theories.

Answer 5

Whats the question?