Well I have enjoyed time and frequency measurement for many years. I have no
equipment (nor do I expect to get any) that can tell the difference between the
current second and the proposed standard. And at one point I asked if there
was a limit on the smallest time interval that could be discerned.
I do remember being impressed with the Collins gear in the 1950s, and wanting
one of those 7 foot racks of time standards made by General Radio, the one with
the big clock on top.
As the years passed I obtained more and more accurate frequency measurement
equipment, including a home made heterodyne frequency meter that outdid the
Collins radios. Then the lousy radio propagation ended my dependence on WWV
and I luckily obtained a rubidium oscillator.
But that's about as far as I want to go. My HP 8657B resolves 1 Hz at more
than 2 GHz and it can be set to within a very small error with respect to the
rubidium standard. At this point I see no reason to improve my time and
frequency measurement accuracy.
Of course it can be an end in itself, hence the name Time Nuts. So I propose
the question, how many out there have interest in this topic for academic and
psychological reasons, and how many actually have a concrete reason to be this
precise? One part per billion isn't a lot. And some systems require iron clad
synchronism such as space exploration and long range communication. But the
average tinkerer probably doesn't need it.
Bob
On Monday, May 27, 2019, 3:20:24 AM PDT, Dave B via time-nuts
<[email protected]> wrote:
Hi.
This from the recent ShortWave Radiogram broadcast, may be of interest.
~ ~ ~
(Snipped stuff about other SI units undergoing a revamp...)
Scientists now have their sights set on updating the unit of
time: the second.
Currently, the second is defined by atomic clocks made of cesium
atoms. Those atoms absorb a certain frequency of light. The
wiggling of the light's electromagnetic waves functions like the
pendulum on a grandfather clock, rhythmically keeping time. One
second is defined as 9,192,631,770 oscillations of the light.
But a new generation of atomic clocks, known as optical atomic
clocks, outdo the cesium clocks. "Their performance is a lot
better than what currently defines the second," says physicist
Andrew Ludlow of the National Institute of Standards and
Technology in Boulder, Colo. Because those optical atomic clocks
operate at a higher frequency, their "ticks" are more closely
spaced, making them about 100 times more precise than cesium
clocks.
Ideally, the length of a second should be defined using the most
precise timepieces available. A switch might happen in the late
2020s, Ludlow says.
The change to the kilogram's definition was carefully
orchestrated so that it wouldn't affect normal people: A kilogram
of flour still makes the same number of biscuits. Any change to
the second will be similarly coordinated.
So, sorry, there'll be no chance to squeeze any extra seconds
into a day.
https://www.sciencenews.org/article/kilogram-just-got-revamp-unit-time-might-be-next
~ ~ ~
So, perhaps a host of surplus cesium clocks on the market at some point?
73
Dave B G0WBX.
--
Created on and sent from a Unix like PC running and using free and open source
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