On Sat, Feb 22, 2014 at 11:51 AM, David Roberson <dlrober...@aol.com> wrote:
> Harry, I am currently supporting the idea that acceleration is the main > reason for the clock differences because it would not appear reasonble to > expect a difference in clock readings if both observers continued to move > at constant velocities. Ok, so let's propose that 2 very long parallel space trains exist, both were built and neither has begun moving, except they were built in different reference frames by beings that existed naturally in this state of motion/stillness, the relative speed between the train is 99.9% of *C*. Each occupant of each train can look at the clocks and occupants in the other train, according to SR each would expect to see that in the tiny window of time they have to inspect the rate of time in each cabin, then the rate of time in the other train would appear slowed, this is odd as they would both need to agree despite the fact that high speed real time communication between the cabins would be possible. Anyway the real paradox is this, each sees that almost no time has passed for the occupants of the opposite train, if both trains accelerate evenly to come to a relative stop SR would declare a tie, and demand that in the instant it takes to equalize speeds that each would see time in the other train to accelerate dramatically to have it experience all the missing time. If one matches the other however it is asymmetrical and the accelerated train should be found to have less time having passed. And of course visa versa. In case you missed it let me point that out again, our 'twins' can look at each other face to face (at velocity), both see the other an younger, but then how they equalize speeds will effect the age each twin is when they meet! They could both be middle age if they meet in the middle, or either one could be young and the other old depending on who changes speed to come to a relative stop! And if a passenger on one of these trains was from another reference frame, they would age differently. Objections can be raised for say twins existing in different reference frames, and there are issues with synchronization, but these issues are solvable with slight variations such as a slightly curved path than lead to the trains actually being in counter-rotating loops. If a slight curve changed time dilation dramatically from what it would be straight line then time dilation would never exist since all paths are curved in practice as we are orbiting stars, galaxies etc... John > They need to eventually come to rest at the same location to make an > accurate comparison. Some might argue that a signal could be sent between > then, but I prefer to have a solid legitimate measurement that can not be > faked. > > My visualization of the system is fairly simple to follow. Initially, > both brothers are at rest and can synchronize their watches. In this > state, we can assign the location as 0,0,0,0. The 3 space dimensions are > zeroed out as well as the clocks synchronized to read zero time. > > From this initial state everything concerning their velocity, position and > of course instantaneous acceleration can be totally determined by one > measurement, which is acceleration. This parameter can be measured > relatively easily and also is not influenced by any relative motion of the > remainder of the universe. In other words, the spaceman on the ship knows > exactly what his acceleration is at every point in time. > > Now, the first integral of acceleration is velocity. The magnitude of the > instantaneous velocity as well as its direction can be accurately > calculated by the space guy. Next, he can perform a second integration of > the acceleration to obtain an accurate reading of his position with respect > to the initial coordinate system reference point where his brother is > located. This collection of data representing his instantaneous velocity > and position can then be used to calculate any time dilation or distance > contraction effects that he expects to measure. > > If the spaceman controls his acceleration carefully, he can pass very > close to his brother at a high velocity. If no additional acceleration is > applied, then we would expect the balanced time dilation effect that we > have been considering a paradox. But keep in mind that there had to be > quite a bit of behind the scenes acceleration applied in order to get to > this condition. So far I have not pursued an exact calculation of this > type of case and therefore can not speak with authority that the numbers > add up. Others claim that they have done this and you might wish to locate > some of their proofs. If I recall, there was an article in Scientific > American a few years ago where they claimed to have done that. > > Dave > > > > -----Original Message----- > From: H Veeder <hveeder...@gmail.com> > To: vortex-l <vortex-l@eskimo.com> > Sent: Fri, Feb 21, 2014 2:05 pm > Subject: Re: [Vo]:Time Dilation impossibility > > > > > On Wed, Feb 19, 2014 at 9:50 PM, Eric Walker <eric.wal...@gmail.com>wrote: > >> On Wed, Feb 19, 2014 at 3:25 PM, H Veeder <hveeder...@gmail.com> 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 > > >
