But it does matter how long you coast between accelerating away from Earth and the braking maneuver in which you accelerate back toward Earth. If you don't coast at all there is only a small effect. If you wait a long time, 10yrs, there is a big effect - which is easily seen in terms of the difference in length of the world lines in Minkowski space.

Brent

On 1/3/2014 8:13 AM, Edgar L. Owen wrote:
Jason,

Come on Jason. Of course not. You have to have EQUAL amounts of acceleration to produce the same effect. But doesn't matter where in space it is.

Edgar



On Friday, January 3, 2014 10:24:26 AM UTC-5, Jason wrote:




    On Fri, Jan 3, 2014 at 10:19 AM, Edgar L. Owen <edga...@att.net 
<javascript:>> wrote:

        Jason,

        If the acceleration is the same, the slowing of clock time will be the 
same...
        Doesn't matter where it is. Or equivalently (by the principle of 
equivalence) it
        could be standing 'still' in a strong gravitational field.

        Edgar



    Okay but this is certainly not what happens.  If you spent 4 minutes 
accelerating
    and came back, there would not be a 4 year age difference when Pam returned.

    Jason




        On Friday, January 3, 2014 10:06:08 AM UTC-5, Jason wrote:




            On Fri, Jan 3, 2014 at 9:21 AM, Edgar L. Owen <edga...@att.net> 
wrote:

                Lliz, Brent and Jason,

                Actually Liz is correct here, by GR it is the acceleration. 
That is the
                physical cause of the clock time differences of the twins.


            In my experiment, lets say the acceleration lats for a total of 4 
minutes:
            one minute to accelerate up to 0.8 c, one minute to slow down at 
Proxima
            Centauri, one minute to accelerate back up to 0.8 c toward Earth, 
and a
            final minute to accelerate down to back at Earth.

            If the accelerations alone account for the clock discrepancies, 
then there
            would be no need to go to Proxima Centauri at all.  Pam could spend 
4
            minutes whizzing around the solar system and get in all the same 
accelerations.

            Is this what you are saying?

            Jason

                It is true the effects can also be analyzed just by spacetime 
paths as
                others have suggested, but it is actually the acceleration (or
                equivalent gravitational field which is in effect an 
acceleration) which
                actually physically produces the clock time differences when 
the twins
                meet up again.

                Edgar


                On Friday, January 3, 2014 1:27:55 AM UTC-5, Liz R wrote:

                    On 3 January 2014 17:30, meekerdb <meek...@verizon.net> 
wrote:

                        On 1/2/2014 8:00 PM, LizR wrote:
                        On 3 January 2014 15:52, Jason Resch 
<jason...@gmail.com> wrote:

                            On Thu, Jan 2, 2014 at 9:31 PM, LizR 
<liz...@gmail.com> wrote:

                                Jason,

                                You may be missing the fact that the 
acceleration of
                                the space traveller is what causes the twin 
paradox.


                            I would say it is not so much the acceleration that
                            explains the paradox, but the fact that no matter 
how you
                            rotate the paths, you always see a kink in the path 
Pam takes.


                        May I venture to suggest this is the same thing :-)

                        That's not exactly wrong - but it tends to make it 
confusing.
                        It's like saying a road from A to B is longer than
                        as-the-crow-flies because of its curves.  Yeah, that's 
true; but
                        if you want to calculate how much longer you see that 
the rate
                        of excess distance is proportional to the first 
integral of the
                        curvature and so the total excess is the second 
integral of the
                        curvature - which is just the distance.  So it boils 
down to
                        unstraight lines are longer than straight lines.  All 
the
                        specific details of acceleration get integrated out so 
it's easy
                        to see that a broken line (infinite accelerations) is 
just
                        longer.  Or in spacetime, unstraight worldlines are 
shorter than
                        straight ones.  To phrase it in terms of acceleration 
misleads
                        people into thinking about the stressful effects of 
acceleration
                        and how that could affect a clock,...

                    I bow to your superior knowledge. I wasn't thinking about 
the aging
                    effects of acceleration (as in the Heinlein story where 
they have to
                    fly to Pluto at 3G) but just the fact that the course 
changes are
                    the only way the twin paradox can be enacted - that is to 
say, it's
                    what breaks the symmetry that otherwise exists between one 
ref
                    frame's measurements and another's.

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