Twin paradox

Sobabi · March 16, 2006

I have an issue understanding the twin paradox. Could someone please clear it up for me. (whats this thing about relativity not applying in no inertial frames of reference? I am prolly completely on the wrong track. Don't even really remember how time dilation works, does it matter if some thing is moving away or towards you?

Twin leaves earth on rocket at near speed of light. Twin A (in rocket) sees time slow down on earth, twin B (on earth) sees time slow down in rocket. So both see the other age at a slower rate than themselves. Now twin A appraches earth slows down and sits. He has moved into twin B's inertial frame of reference. Now to both twin A and B, twin A has aged less than twin B. Correct so far?

Now what I don't understand is: lets say the two twins are looking at each other as this is happening. What will the rocket twin observe? He sees Twin B who is younger than he is, but he slows down, lands gets out, and sees that Twin B is in fact older. So at one point from the point of reference or Twin A does this occur.

Man this stuff makes you feel stupid.

Jay-qu · March 16, 2006

It way to early in the morning and I am way to drunk :eek2: to answer relativity questions.. sorry :) I'm sure someone else will step up to the plate soon enough - goodnight.

arkain101 · March 16, 2006

It comes down to describing motion. If space has no absolute, then you at first have a hard time decifering which of a pair of reference frames is doing the motion.

Look at it this way. Lets say you had a lazer propelled rocket and you were in space but for the experiments sake we will say, nothing else is in space, anywhere you look there is no other object of which to compare. You can experience acceleration forces (which is only temporary inertia from your existing mass, atoms pushing atoms) for 10 years. Then as you shut down your engine, you become weightless again in your ship. Now you have NO idea how fast you are going and in fact you can argue you are not moving at all.

Now we add in the ship to earth thought experiment. The ship takes off, but we dont really know who is moving, they ARE seperating in distance but since space does not appear to have any absolute, the earth is moving at 30m/s while the galaxy is twisting at such and such m/s and the galaxy itself could be traveling at 25% the speed of light, but as far as I know we dont really know. So logistically you would say, its very possible the ship may take off in the wrong direction and in turn actually be slowing itself down. But, it isnt like this in relativity, we compare earth that thinks it is rest and sees the ship moving and the ship that can think its at rest and the surroundings are moving. Because the ship experiences a force, they beleive they can say that it is only the ship that can have a time dialation applied to it, even though its velocity is somewhat unknown, but may match up to a beam of light that is traveling by a ship from earths view.

I also get really confused by SR because it always seems to run into some kind of problem.. but I undestand I am no einstien.

InfiniteNow · March 16, 2006

Hello Sobabi,

I've never studied relativity with anything more than a personal interest, but I searched the term "twin paradox" within the forum, and here are my previous posts. I chose to link to them instead of retyping it again. Anyway, when you feel confused, it means you're probably doing something right. :angel:

http://hypography.com/forums/physics-mathematics/5699-relationship-between-speed-time-2.html?highlight=twin+paradox#post88955

http://hypography.com/forums/strange-claims-forum/5440-tortoise-hare-race.html?highlight=twin+paradox#post84047

http://hypography.com/forums/strange-claims-forum/5440-tortoise-hare-race.html?highlight=twin+paradox#post84258