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

```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
>>>>>> 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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