Absolutely Harry! Another thing is that if acceleration changes anything, then you end up in a even weirder paradox.
Let's propose that when travelling at near C the twin that accelerated picks up a hitch-hiker alien that has always been in this reference frame. Then when the twins are passing each other, they can each communicate in real time, they can each see the other's frames time rate. Now if as the twins are checking out each others time rate (communicating perpendicular to direction of travel as they are passing each other) they each accelerate/decelerate equally until they occupy the same reference frame. Now SR would argue that since the experience of the twin that accelerated initially is asymmetrical to the experience of the other twin who didn't that we should expect to see that the expectations of the non-accelerating twin would win out. But because the experience of the hitch-hiking alien and the non accelerating twins are symmetrical, then we have a draw! This would mean that as the non accelerating twin sees the other twin as they are moving, he would see the watch belonging to the alien to tick at a normal rate, but the watch of his brother to tick more slowly! OR he would see the watch of both the alien and his bro tick more slowly than his, but when the 2 ships come to a relative stop he would need to see in an instant all that time the alien missed out on would need to be seen to occur at a greatly accelerated rate while the brother would be unaffected! John On Sat, Feb 22, 2014 at 8:05 AM, H Veeder <[email protected]> wrote: > > > > On Wed, Feb 19, 2014 at 9:50 PM, Eric Walker <[email protected]>wrote: > >> On Wed, Feb 19, 2014 at 3:25 PM, H Veeder <[email protected]> wrote: >> >> Imagine two friends with synchronized watches. One friend boards a train >>> and zips away for a time at near c and then gets off and walks back to his >>> friend >>> so that they can compare the time on their watches. Which watch is ahead? >>> >>> Using the principles of SR I can come up with contradictory answers. >>> >> >> I'm curious what the two scenarios are. >> >> Eric >> >> > > Each friend should see the other's watch tick more slowly according to > special relativity. Therefore when they meet up again, both watches should > record the same elapsed time, but what happened to the time-dilation effect > on the passage time? SR ends in contradiction when watches are compared > after the travelling. > > Dave mentions that acceleration might play role in resolving the > contradiction. I have heard that reason too, but it strikes me as hand > waving. Even if acceleration has to be factored in, the ratio of time spent > accelerating to the time spent travelling at uniform speed near c can be > assumed to be arbrarily small so that the acceleration becomes irrelevant. > > Harry > > >
