[ntpwg] draft minutes from Vancouver NTP WG meeting

[Danny Mayer]

Rob Seaman wrote:
> On Dec 24, 2007, at 8:39 PM, Danny Mayer wrote:
> 
>> I forgot to comment on this one. The packet follows the geodesic  
>> which is a 4-dimensional path so you cannot just locate the 3-d  
>> coordinates of each endpoint and calculate the distance between them.
> 
> 
> Even if the Newtonian approximation doesn't apply, there is a physical  
> model that can be run through the Runge-Kutta mill to deliver an  
> estimate of the light travel time to whatever precision needed.
> 

I admit to not having looked at RK for quite a few years!

> More fundamental is that even Einstein had to punt on the central  
> conceit of NTP.  It may seem logical that the timestamp "midway"  
> between event A and event B is (A+B)/2, but this is the "standard  
> synchrony" of relativity - that is, an inductive assumption, not a  
> deductive conclusion.
> 

Agreed. I'm not really sure what the midpoint really means in such a
case never mind what the timestamp would be for it. That boggles the mind.

Danny

> Rob Seaman
> National Optical Astronomy Observatory
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