On Mon, Jan 6, 2014 at 9:03 AM, Edgar L. Owen <edgaro...@att.net> wrote:

> Jason,
>
> What clock measures your coordinate time? Apparently none.
>

Any clock in my rest frame measures my coordinate time.


> It's beginning to sound just like another name for Present time.
>
> What's the difference?
>

In relativity, "present" is not globally defined, but it seems to be in
your theory. Note coordinate time has no meaning either, without defining a
frame of reference.

Jason


>
> Edgar
>
>
>
> On Monday, January 6, 2014 9:47:36 AM UTC-5, Jason wrote:
>>
>>
>>
>> On Jan 6, 2014, at 6:55 AM, "Edgar L. Owen" <edga...@att.net> wrote:
>>
>> Brent,
>>
>> No it's not "an observation that the two twins are together at
>> particular spacetime coordinates" because the spacetime t coordinates are
>> different.
>>
>>
>> Their proper times are different, but not their coordinate times.
>>
>> A clock time is only a representation of how much speed (and accordingly
>> distance) had to be given up to travel through space. It is not an actual
>> coordinate in space time, for that you use coordinate time. All things
>> travel equal distances through space time in equal coordinate times, but
>> not all things travel equal distances through proper time (clock time) in
>> equal coordinate times.  It is when the coordinate times are equal that two
>> things can interact.
>>
>>
>>
>> Since the spacetime t coordinates are different WHEN are they together?
>>
>>
>> Their coordinate times are equal.
>>
>>
>> Certainly not in a simultaneous clock time as proved by their differing
>> clocks.
>>
>>
>> Right, their proper times are different.
>>
>>
>> When are they together Brent? Obviously in a present moment which is a
>> kind of time that clearly is not the same as clock time.
>>
>>
>> They are together when their spatial coordinates: x,y,z and coordinate
>> time t are the same. You are right this t is not the same as proper time.
>>
>> Your conclusion that there must be a global present for this to work is
>>  unneccessary.
>>
>> Jason
>>
>>
>> Edgar
>>
>>
>>
>> On Monday, January 6, 2014 12:18:16 AM UTC-5, Brent wrote:
>>>
>>> On 1/5/2014 12:00 PM, Edgar L. Owen wrote:
>>> > Brent,
>>> >
>>> > No, the present moment is NOT just a "label". It's an empirically
>>> verifiable observation
>>> > (measurement). And not only that both twins agree on that measurement,
>>> namely that they
>>> > have different clock times in the same shared present moment.
>>> >
>>> > There is simply no way around that....
>>> >
>>> > Edgar
>>>
>>> Of course it's an observation.  It's an observation that the two twins
>>> are together at
>>> particular spacetime coordinates.  I have no problem with you calling
>>> that a present
>>> moment (although everyone else calls it an event).  The problem is not
>>> that you can't
>>> define a global time at which they meet, it's that you can't define a
>>> *unique* global
>>> time.  There are infinitely many choices of coordinate time and they
>>> will all agree that
>>> the twins meet at the same coordinate time - but they will not agree as
>>> to which other
>>> distant events in the universe are at the same time as the meeting.
>>>
>>> Brent
>>>
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