[time-nuts] GENIUS by Stephen Hawking (PBS TV), with 5071A cesium clocks

Bob Camp kb8tq at n1k.org
Fri May 20 13:01:30 EDT 2016


Hi

A GPS receiver is simply picking up the time information from the orbital system. The satellites 
do not change height when you move around, thus their reported time does not change either. 
Coming up with 20 ns from GPS involves a lot of post processing, that’s not going to play very
well on prime time TV. There’s just to much handwaving. Moving real clocks is much more convincing. 

Bob

> On May 20, 2016, at 11:24 AM, Peter Reilley <preilley_454 at comcast.net> wrote:
> 
> I have a question.   I, of small brain, am wondering: if the time difference between the
> top of the mountain and the bottom of the mountain is 20 nS over 24 hours could you
> repeat the same experiment using GPS?    The time difference of 20 nS is measurable
> using GPS.
> 
> The GPS clock must run faster on the mountain top than the GPS at the mountain
> base and yet the two remain synchronized to the satellite reference.   Therefore
> the GPS 1 PPS signal (measurable to a few nS) must be wrong in in one of the local
> frame references.
> 
> My brain hurts.
> 
> Pete.
> 
> 
> On 5/20/2016 10:16 AM, Bob Camp wrote:
>> Hi
>> 
>> Ok, so *that* link got me to the episode. Very impressive stuff. Well done !!!
>> 
>> Bob
>> 
>> 
>>> On May 20, 2016, at 2:04 AM, Tom Van Baak <tvb at LeapSecond.com> wrote:
>>> 
>>> For those of you who missed the live TV broadcast, I'm told PBS has a live stream:
>>> http://www.pbs.org/video/2365757267/
>>> 
>>> The cesium clock parts are in the last 15 minutes of the show.
>>> I also added more photos/plots to:
>>> http://leapsecond.com/great2016a/photos.htm
>>> 
>>> /tvb
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