Not mentioning that the clock traveled in a passenger seat (even with
the seat belt fastened). The vision of a big box with cables and a good
sized clock ticking (it was a Patek Philippe movement in early HP
Cesiums) frightened some passengers and the person accompanying the
clock had to give a lot of explanations. The use of the word "atomic"
worsened things somewhat.
(Memories from Apollo flights good times)
Regards,
Ignacio, EB4APL
El 23/03/2017 a las 12:33, Bob Camp escribió:
Hi
Back before GPS and similar systems, hauling Cs standards on commercial
aircraft was
a bit more common than it is today. One of the critical tricks of the trade was
knowing where
each power outlet was on a specific plane and how close it was to this or that
seat. The next
trick was knowing how to talk the crew into letting you plug the gizmo in the
seat next to yours
into that outlet. Sometimes the magic worked and other times you had to depend
on your
battery pack. Needless to say, getting through the over ocean travel process
with a dead
standard was not good news.
Bob
On Mar 22, 2017, at 10:59 PM, Bob Bownes <bow...@gmail.com> wrote:
It's not getting one past the airport authorities that's the issue. It's
getting one that's powered up past them. ;)
Written from about 10,000'. :)
On Mar 22, 2017, at 20:15, Tom Van Baak <t...@leapsecond.com> wrote:
Chris Albertson wrote:
Why drive up a mountain?
"Because it's there" ;-) And because there's a paved road, and it's free, and
there's a place to stay overnight, and the mountain doesn't move. Plus a car makes a good
portable time lab; you can share the experience with family or students or visiting time
nuts; and a number of technical reasons.
But most importantly: you can remain at altitude as long as you want -- in
order to accumulate just enough nanoseconds of time dilation to meet your
experiment's S/N goal -- without running into (or much worse, going beyond) the
flicker floor of your clocks.
There are several different ways to measure time dilation with atomic clocks.
Some notes here:
http://leapsecond.com/pages/atomic-tom/
Take the clock with you inside the pressurized cabin of a commercial airliner
Yes, and this has been done many times. The first (1971) and most famous of all
traveling clock relativity experiments is:
https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
For vintage hp flying clock articles see:
https://www.febo.com/pipermail/time-nuts/2013-January/073743.html
Two modern examples are described here:
"Time flies"
http://www.npl.co.uk/news/time-flies
"Demonstrating Relativity by Flying Atomic Clocks"
http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf
/tvb
----- Original Message -----
From: Chris Albertson
To: Tom Van Baak ; Discussion of precise time and frequency measurement
Sent: Tuesday, March 21, 2017 7:12 PM
Subject: Re: [time-nuts] Time Dilation tinkering
"flight" there is the word. Why drive up a mountain? Take the clock with
you inside the pressurized cabin of a commercial airliner next time you are on one of
those 10 hour trans=pacific flights. You be taller then any mountain and it is actually
cheaper then a weather balloon.
Can you get a Rb clock past the TSA x-ray machine. Maybe if you ask first.
There must be a way to hand cary specialized equipment.
On Tue, Mar 21, 2017 at 7:03 PM, Tom Van Baak <t...@leapsecond.com> wrote:
But attached is one of the first plots where I put a SA.32m in a home-brew
vacuum chamber and pulled down to a few inches of Hg for a few hours to
simulate the low pressure of a flight up to 50 or 90,000 ft. For a high
altitude relativity experiment -- where you'd like your clock to remain stable
to parts in e-13 and not accumulate too many stray ns -- it's not a good sign
when your clock changes by 2e-11 (that's more than 1 ns per minute) just
because of ambient pressure changes.
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