Additional Solar System Gravitational Anomalies
Round 1
Reviewer 1 Report
I reviewed "Additional Solar System Gravitational Anomalies" by Les Coleman. This article focuses on uncertainty in experimental determinations of the gravitational constant, G, and known anomalies regarding bodies within the solar system as well as experiments. The article notes a general variation of G with mass and suggests reformulation of Newton’s Law of gravity. While the article is well written and includes some interesting data, I can't recommend publication at this time in current form.
General comments: The writing/language is very good. I note a few things below under specific comments, but only a few.
My bigger issue comes from the article's objective, which seems to be suggesting a reformulation if Newton's Law. I don't think the data in the article justify such a reformulation and that the article should not propose it. It could be a good review article that notes a better fitting mathematical relationship in an informal sense - but there are many issues I think that are not covered in the article that preclude any suggestion that a formal reformulation is in order. I will note however, that the article does not attempt to explain apparent NGA in objects (in general) or the G variance with mass. This is a plus, but to me, also points to one problem the article faces. Any formal correction should be more than simply observational unless that correction implies there is a missing constant - and I don't think the data to show that are here. Lastly, I think if MOND is going to be invoked, it needs to be introduced and discussed. Actually, I don;t think it should be in the article - but a more introduced approach might make it useful.
It is possible I am misunderstanding the manuscript's point, but of so, many others will as well.
Page 1, Introduction Line 37
"In a typical example, 1I/2017 U1 ‘Oumuamua,..." This is not a typical example. It is however a clear example.
Page 2, Regarding Eq. 1
I know it is G - but units are still in order once values are invoked - at least the first time. Also, what is "t=2.06"? I am not sure the need for it so I am not sure what it is.
Regarding Figure 1 - units on the Y axis
Page 3 Line 80
"These involve the same team and equipment, with the only difference being the target mass, which should eliminate systematic errors." It does not eliminate other errors though - and with only two data points it is hard to determine what that error might be.
Page 3 Table 1 needs a title/label
Page 5 table 2 seems cut off.
Figure 2 - axis labels and units. I realize the title and description will lead the reader to it (and a guess on units), but it is easier to read on the actual axis.
Page 9. If the author is going to invoke MOND, the article needs to introduce it.
Author Response
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Author Response.docx
Reviewer 2 Report
Please find my comments and opinions attached.
Comments for author File: 
Comments.pdf
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
The claim here -- the need for a modification of a fundamental law of physics, i.e. Newtonian gravity -- is based on inspection of data culled from various publications. This paper fails to make a supportable scientific case due to insufficient attention to (a) possible alternative explanations of the so-called "anomalies" and (b) random and systematic errors that affect any attempt to derive scientific conclusions from empirical data.
A publishable paper could conceivably come from serious and objective consideration of these issues. To be scientifically credible, the conclusions of such a greatly augmented study, if any, would have to be stated with caveats and reference to limits of validity, statistical and other uncertainties. E.g. statements " ... anomalies reflect variation in solar gravitational mass ..." suggest a prejudgment that ignores issues (a) and (b) above.
More specifics:
None of the Figures include error bars, needed for the reader to assess the significance of the putative relations presented.
The kinematic analysis referenced in the equations in Section 2.2 leaves out effects such as perturbations due to other planets, solar wind and solar radiation effects, and non-circular orbits. The latter can be accounted for, but was this done correctly in the papers publishing these data?
Inexplicably Figure 4 is taken as evidence for a partial contribution due to gravitational anomalies. Most of the points fall at zero (although gross over-plotting of the symbols obscures the details), and the other points seem to scatter randomly (where are the error bars?)
Section 2.5 seems to be weak justification for a bit of "cherry picking" -- that is, ignoring data that does not support one's desired conclusion.
If one believes the derived formulas in Section 3, one is faced with questions about G's behavior as m --> 0 and m --> infinity. A explicit and clear discussion of the limits of validity of the proposed modification of Newtonian gravity is missing.
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
I previously reviewed this article and recommended reject I believe. However, I also gave a number of comments that could improve it. While I still have some uncertainty with the article, the author did address my comments in good faith. The manuscript is a bit less overstated. There is speculation, but it is obviously when it is there. I still believe it is more of a review manuscript, but there is some analysis in it. I do not see any misstated facts so I think it is acceptable. A remaining question is if it is appropriate for Symmetry - and I think the editor will make that call.
Author Response
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Author Response File: Author Response.docx
Reviewer 2 Report
The amendments and changes are fine, and the paper clearly looks better now. The text around line 269 is I think not quite appropriate, unless you explicitly show that your data varies with time (statistically), so I suggest changing that.
I think the paper is OK as it stands, as it comprises an interesting review of previous research, and gives an interpretation of it.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
Some improvements have been made, but on on the whole major issues from the early draft have not been satisfactorily addressed.
Serious attention to the observational errors is crucial. Regarding the response:
"Figures 1-4 plot single observations."
I don't know what this means; they show multiple values. And in any case there is no reason why error bars cannot be included.
In fact, a glance at the errors reported in the table suggests that on the scale of these plots the error bars would be quite large and would cast doubt on the linear relation.
"Figure 5 plots calculated , and error bars have been shown; these are ±1σ values"
I can see two error bars in one panel; the plot is so poor that perhaps others are not visible. In general the difference between two panels in the figures is not explained, in the caption and for the most part elsewhere. In particular the comet plot seems to show the same thing in both panels, possibly in a largely unsuccessful attempt to alleviate the point over-plotting problem. And it is still not at all clear why this scatter plot, with lots of outliers, can be seriously taken as evidence for anything.
There are three vague references to the equivalence principle. As far as I can see the content of the paper has nothing to do with the equivalence principle.
I still could not find any discussion of the range of validity of the logarithmic formulas, such as the limit of m --> 0 or large. Fitting a log relation forces a relation [ effective mass = M ( 1 _+ c log M ) ] that is physically very peculiar. No rationale for logarithmic rather than linear relations is given.
"Econometric equations" is not defined.
The leap -- crucial to the claim of the paper -- from anomalous acceleration data to differences in the value of G pervades this paper; I believe at the very least there should be an honest appraisal of the validity of this, the largest astrophysical weak point of the paper. The largest analysis weak point is the ignoring of the importance of observational errors, random and systematic.
Speculations and results of exploratory data analysis are fine, but there must be some reasonably credible support -- which I feel is not offered by this paper.
Author Response
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Author Response File: Author Response.docx
