Clock drift. Not strictly a Linux question.

[Roger Oberholtzer]

On Friday 16 February 2007 16:59:15 Tony Alfrey wrote:
> Roger Oberholtzer wrote:
> > It's Friday. Time for a weekend-think-about-it question.
> >
> > I think I am doing my maths correct. I am checking a PC's clock against a
> > high-end Trimble receiver (> $2000), using the pulse per second signal.
> > Unless I am doing something wrong, I seem to see a 0.02 % linear (over
> > the time I have looked) drift in the PC's clock (via gettimeofday())
> > compared to the pulse from the GPS.
>
> Silly boy, this is clearly a general relativity problem.  The pulse
> you're getting from the GPS is from a geosynchronous satellite, at a
> radius of some 25,000 miles, whereas your box is in Sweden (I seem to
> remember?), where the Earth's crust is particularly thin and so you are
> close to the mantle.  Therefore, the gravitational field at the location
> of your box is considerably higher than at the geosynchronous satellite.
>   And from general relativity, we know that clocks run slower in higher
> gravitational fields.
>
> This is also why Swedes age slower than the rest of us.

Sweden it is. But if we are so close to the mantle, why is it so damned cold? 
But I will try this explaination at the next tech meeting. Care to be named 
as a reference :)

-- 
Roger Oberholtzer
OPQ Systems AB