# Re: Another stab at the universal present moment - a gedanken..

```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

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<javascript:>
> > 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
>>>> 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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