On Friday, March 9, 2018 at 8:59:09 PM UTC-5, Brent wrote:
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> On 3/9/2018 5:28 PM, agrays...@gmail.com <javascript:> wrote:
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> On Friday, March 9, 2018 at 12:51:29 PM UTC-5, Lawrence Crowell wrote: 
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>> On Friday, March 9, 2018 at 9:44:30 AM UTC-6, agrays...@gmail.com wrote: 
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>>> On Friday, March 9, 2018 at 12:10:13 AM UTC-5, Brent wrote: 
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>>>> On 3/8/2018 8:40 PM, agrays...@gmail.com wrote:
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>>>>
>>>> ...
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>>>> *This I find troubling. We have two fundamental physical phenomenon, 
>>>> gravity and EM, and they seem to have no intrinsic relationship between 
>>>> each other. AG *
>>>>
>>>>
>>>> They have more relationship than they did when Maxwell discovered EM.  
>>>> It was purely a field on a fixed background.  So you've been troubled 
>>>> since 
>>>> 1862.
>>>>
>>>> Under GR the EM field is a source of gravity and hence warps spacetime; 
>>>> and warped spacetime deflects EM waves.
>>>>
>>>> Brent
>>>>
>>>
>>> *Good perspective on the situation. OTOH, for Newton movement is caused 
>>> by an attractive force, whereas for Einstein it's caused by the advancement 
>>> of time. So, IMO, the mystery of movement in a gravity field persists. AG*
>>>  
>>>
>>
>> I am not exactly sure why you are stuck on the idea that the advance of 
>> time causes motion. 
>>
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> *Because in the absence of a force causing non-geodesic motion, the 
> increase in time results in a change in spatial position since in the 
> equations of motion, spatial coordinates are not independent variables; 
> they depend on time IIUC. AG*
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>
> You seem to have a confused concept of "cause".  To say time causes motion 
> is like saying being different places at different times causes motion.
>
> Brent
>

*I didn't intend "cause" to be taken so literally. I just meant that if 
time changes, and it does so for no apparent reason, the equations of 
motion imply or result in different positions in space; thus, the 
advancement of time necessarily yields different positions in space and can 
be understood as the "cause" of motion. AG *

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