Re: A silly fact about an atomic clock that relativist never want you to know.

On Jul 14, 10:54 pm, "Spaceman" <space...@xxxxxxxxxxxxxxxxxxxxxxxxxx>
wrote:
Jerry wrote:
It doesn't matter Whether you speak of an "old fashioned" cesium
beam clock or a fountain clock, the cesium atoms being monitored
are ALWAYS in freefall.

In the case of a conventional cesium beam clock, you can think of
the cesium atoms as being "thrown" across the Ramsey cavity
(microwave cavity) and, as they traverse the microwave cavity
away from the the magnetic fields of the A- and B-magnets, they
follow a VERY shallow parabolic trajectory.

Take a look at the illustration in the following link:
http://www.aero.org/publications/crosslink/winter2000/02_sidebar1.html

Note that the freely falling cesium atoms as they cross the
Ramsey cavity do not experience more than a very tiny
gravitational potential change.

------------------------------------------

In the case of a fountain clock, the atoms are gently lobbed
up and down through the microwave cavity. They move MUCH more
slowly than the cesium atoms crossing the Ramsey cavity of a
conventional cesium beam clock, and as a result the cesium atoms
can be much more accurately tuned.

Take a look at the illustration in the following link:
http://tf.nist.gov/cesium/fountain.htm

The microwave cavity in a fountain clock is only a few cm in
length, so the gravitational potential changes that the cesium
atoms experience as they fall through the cavity are relatively
insignificant.

No attempt is made to monitor the cesium atoms throughout their
ENTIRE trajectory. As you rightly point out, there would be a
significant difference in the measured resonant frequencies at
the bottom and the top of the trajectory, and the clock designers
are a lot smarter than to attempt such a foolish notion.

Basically, the microwaves in the cavity are generated by a highly
stable oscillator, and once every second, this oscillator is
re-tuned as the puff of cesium atoms crosses the microwave cavity.

resonant frequency of an imbalanced spin.
Do you know that actually changes with accelerations?
Do you know that is what is "being counted"
I am bummed that not one person has any classical mechanics
smarts here at all.
Ooops.. of course they don't this is the relativity group!
LOL

Not so long ago, you were grateful because I was the only person
who understood the confusion you were having distinguishing
between the difficulty of -achieving- ultrahigh vacuums with the
pressure difference that exists between the inside and outside of
a vacuum chamber.
http://groups.google.com/group/sci.physics/msg/004d1c5cf3787549

I spent considerable time carefully crafting an answer that
focused on the single point that you seemed to be obsessed with,
(freefall vs. gravitational potential changes), leaving out tons
of detail that I figured would only confuse you at this point
(for example, laser cooling... what does the puffball of cesium
atoms lasting for a whole second imply about the temperature of
atoms in the puffball, and what does that imply about doppler
shift and the sharpness of the spectral lines) and what happens?

It's obvious that you didn't spend more than ten seconds reading
my answer, and certainly you didn't follow up on any of the
links nor looked at the diagrams, nor gave my answer any thought
at all.

You're not worth wasting my time on. Goodbye.

Jerry
.

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