Re: REJ: Re: Black Holes, Neutron Stars, Fusion, Electromagnetism and

[noel turntive]

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I'll try again to repost the reply..but it will be hard because I
had to respond to the moderator repeating his own unsubstantiated
claims that Cassini *had* tested for refraction.


Here is one of your repeated (false) claims Cassini did test for refraction that you are not letting me refute....
> | The complete fractional frequency shift is the sum of three parts:
> | the non-dispersive part $y_{nd}(t)$ (which includes the gravitational
> | signal) and the time dependent plasma contributions $y_\wedge(t)$ and
> | $y_\vee(t)$, proportional to the columnar electron content along the
> | beam in the up- and the downlink, respectively. With three independent
> | observables, the three quantities $y_\wedge(t)$, $y_\vee(t)$ and
> | $y_{nd}(t)$ are separately determined.
> Note particularly that last clause: "the three quantities $y_\wedge(t)$,
> $y_\vee(t)$ and $y_{nd}(t)$ are separately determined".
> -- jt]]


(For starters you supply no pg# and paper source. I cannot find
that quote in the slack.edu bertotti paper.).

Nor does your quote refer to any comparison between the 3 "parts"
for *frequency shift*. Please tell me. If you think your above quote
proves that Cassini tested two seperate frequency bands for
refraction...exactly what part of that above quote actually confirms
this?

And please tell me why you think section 3.1 of the bertotti paper,
that I only cited in the last post you rejected, does not combine
the two seperate frequencies observed by cassini into one because
of intense variability in the corona density.

You will find it hard to answer because section 3.1 says exactly
that both frequencies were combined because of intense variability
in corona density. Which means of course...that no comparison is
possible between the time delay of the two frequencies

[[Mod. note --
1. My quote was from the supplemental materials for the Bertotti et al
paper, figure caption for figure S1 (note Nature calls this the figure
"legend"). You can find this linked from the nature.com website
https://www.nature.com/articles/nature01997#Sec3
Look for the section "Supplementary Information".

2. Radio propagation through a plasma is known to be frequency-dependent.
The passage I quoted states explicitly that observed
(frequency-dependent) frequency shift (for the round-trip Earth to
Cassini and back to Earth) is the sum of a frequency-independent
(a.k.a "non-dispersive") part and two frequency-dependent parts
(one for the Earth-to-Cassini uplink, one for the Cassini-back-to-Earth
downlink), and that the multifrequency data was sufficient to -- and
the authors did -- calculate all three of these parts.

For testing general relativity the frequency-independent part is what's
wanted. But the quoted passage also explicitly says that the other two
parts "proportional to the columnar electron content along the beam"
were also calculated, and I think these are the refractive-index
measurements you're asking for. The goal of the Bertotti et al
multi-frequency analysis technique was to obtain a time series of the
frequency-independent quanitty $y_{nd}(t)$, which could then be input
into further analyses to test GR. The construction of $y_{nd}(t)$ was
designed to try to ancel out the effects of the solar plasma, and
figures S1 and S2 show that that was in large measure successfully
accomplished. Since the subject of this paper was the GR test using
the plasma-effects-cancelled-out quantity $y_{nd}(t)$, it's not too
surprising that the authors didn't explicitly show plots of the plasma
delays (what they refer to $y_\wedge(t)$ and $y_\vee(t)$).
-- jt]]