[ntpwg] draft minutes from Vancouver NTP WG meeting

[Rob Seaman]

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.

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.

Rob Seaman
National Optical Astronomy Observatory