[time-nuts] Einstein Special on PBS

Tim Shoppa tshoppa at gmail.com
Fri Nov 27 09:18:35 EST 2015


Would've been more fun to see Tom and his kids going to the top of Mt
Ranier in 2005 with the ensemble :-). http://leapsecond.com/great2005/

They mentioned some "6 miles per day" offset due to GPS relativity effects.
I think this is the sum of both special relativity (time dilation) and
general relativity (gravitational) effects. The GR correction is 45
microseconds a day fast; the SR correction is 7 microseconds slow. 38
microseconds seconds is 11 kilometers which is indeed 6 or 7 miles. While
time drifts 38 microseconds a day, I'm not sure that GPS coordinates would
drift that fast - aren't most of the corrections in the same direction?

Seeing Kip Thorne describe black holes was a blast - he refused to use the
word mass when describing them, just like when I took a course from him in
1990. When my advisor taught the same course, I pleaded with him, "please
use coordinates!". (Kip Thorne loves coordinate-free notation,
unfortunately my brain does not work that way!!! I would've failed the
course if it was only GR; fortunately it also had plasma physics in the
same quarter, and I was an ace at that due to some undergraduate work.)

Tim N3QE

On Fri, Nov 27, 2015 at 12:05 AM, Arthur Dent <golgarfrincham at gmail.com>
wrote:

> In the special it looks like they used two HP5071A standards, an
> SRS620 counter, and a scope. They first made sure the stds were
> in sync then took one to the building at the top of the ski lift
> on New Hampshire's Mount Sunapee at 2726' elevation for 4 days
> where it would be running a little faster because it would be
> slightly further from the center of the spinning earth. After
> bringing the 5071A back from the top of the mountain they checked
> the difference in the start of square waves displayed on the scope
> and detected the 5071A at altitude was now 20ns ahead of the
> 5071A kept at sea level, as predicted, if I understood everything
> correctly. They explained that the clocks in the GPS satellites
> traveling at a much higher speed had to correct for the speed
> difference which also verified Einstein's theory.
>
> My wife and I were on the top of Mt. Sunapee this summer where we
> enjoyed the views but didn't run any experiments. ;-)
>
> -Arthur
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