Summing up

There are two twins A and , 20 years old
A remains on the earth
B leaves with his stracraft, travelling at 90 % of the light speed

B is back on the earth, 20 years later, according to the A calender

A is now 40 years old
According to the special relativity
B is only 20 + 8.71 = 28.71 years old

Therefore A will likely die first

You say (If I understood ) :
Nope B is also 40 years old because also the acceleration and deceleration must be also taken in consideration
In other words , in your opinion, there is a sort of compensation

It is right that you should consider also the acceleration for an accurate calculation of B age but the result is :

Actually B would be even younger than 28.7 years

If you have a look at the B calendar, the one hang on the starcraft , you will see that 8.71 years ( or less) have elapsed from the departure (The B time)

It seems unbelievable but it is the plain truth

The decay time ( the life spam ) of atomic particles in particle accelerator
comply with the theory
If this is true for a single particle there is no reason to doubt that it must be true also for a human being

I think you didn't understand.


special relativity has nothing to do with the outcome of the experiment.


no there is no compensation from acceleration. In contrast, acceleration is what makes B age slower in first place.


Nope, different effect. This is plain old special relativity (which has no effect on the twin paradox problem => it IS a paradox if you only look at special relativity. That's what we've discussed all the time).

You should seriously read through the twin paradox article on wikipedia.

because you didnt read and he said that both are 20 when they start.

thus one is 40 the other ne is 28 something.

and why is that? because time is relative to the gravitational force of its suroundings. end of story.

Ah sorry for that ^^. I changed my post. His explanation is still not valid, though. Yours is neither, but yeah, lets skip that discussion. I'm tired of it...

it is valid though. time is relative. thats as valid as it gets...

Are you joking , I suppose ?
The relativism of time and space has been introduced with the special relativity
The super famous equation :

dT = dT'/SQRT( 1- (v/c)^2))

It has been announced in the year 1905
The general relativity 1915 further expanded the principle of equivalence
assimilating inertial and gravitational forces

The surrounding mass / energy further curve the space /time but the relativism of time / space by itself does not depend only on the presence of mass / energy

"You must study a little bit more , young lad "

Albert(o) Einstein

Alberto:


... Uh, no, I didn't. Never did, I'm afraid!

I've tried to explain to you what the problem was, and then posted the solution to it. So with your new post, we've both settled on the same result. No more conflict. Isn't that nice?

~ ~ ~
Joey:


No, it isn't.
It's just a lot harder to derive than simply using t' = t/\gamma and x' = \gamma*x .

But it still ISN'T a paradox. Special relativity says: In inertial frames, THESE formulas work. But Twin B isn't moving in an inertial frame, and thus, those formulas won't work.

~ ~ ~
Spike:


Have you read my first post in this topic? You should. It might interest you.

If it's too long to your liking, here's the relevant part quoted for your convenience.




In other words: The twin paradox is not because of masses. it works teh same way if you remove earth from the equation and have A stay somewhere in vacuum, while B travels away and comes back (all in vacuum, with no masses anywhere). Their age difference is due to special relativity and NOT because of masses.

Masses DO curve spacetime and thus can make clocks go faster/slower as well, but that is an effect described by general relativity, and one that is not relevant here. It could be added to this scenario, but you don't have to to get the twin-paradox.

I'll skip these discussions from now on. I really don't need that.
@Error: Good luck.

I did not realize that,in principle, we were telling the same stuff

About above claim I am not that sure

Lets see

The special relativity plays of course a key role, in the twin paradox (Which is not pardox ) as well as in the particle accelerator experiments

However it is not exhaustive
Since the pilot comes back to the earth , the paradox entails an acceleration
The special relativity on the contrary assume a constant speed

The natural question is

What does it happen during the acceleration ?

In my opinion the explanation must be found in the Einstein's principle of equivalence , replacing the old Galileo's principle , i.e

Inertial forces == gravitational forces

The acceleration , regardless of the direction, is therefore equivalent to the presence of a mass ,which causes a further dilation of time, thus confirming the hyphotesi that the twin paradox is not a pardox but the plain truth

Dont get offended ...please
Read your posts instead
You have alwayes a "top down " attitude
" It is wrong...full stop " without even spending a words of explanation
Not only in this occasion

It is not the way to behave in a forum where nobody knows each other so nobody should play the role of the professor

btw
My sentence "You must study a little bit more, young lad ..." was simply a little bit ironic
It is the answer given by Einstein in a seminar to a young guy who was arguing with him
Since my name is Alberto was just joking