Astroparticle Physics Forum COSMOVIA

VIA lecture by Prof. Norbert Klein "Can MOND explain the data scattering of "big G" ?" was given on 22.02.2019.
Its record is in VIA library
http://viavca.in2p3.fr/norbert_klein.html
and its presentation is attached
The following questions were put during it
Houri Ziaeepour: Why only spiral galaxies used in this plot ?
Houri Ziaeepour: Some people say that the minimum acceleration a0 in ellipticals depend on the galaxy set.
Bernard: Did you try fitting for both a_0 and beta together?
Houri Ziaeepour: I am confused. You said that MOND in general is ruled out. Thus how do you interpret your conclusion about g experiments ?
Bernard: Well, you have precision measurements to go by.
Houri Ziaeepour: It does not work at cosmological scales. As you said in galaxy clusters
ant: Did you read: Absence of a fundamental acceleration scale in galaxies Davi C. Rodrigues   1,2*, Valerio Marra   1,2*, Antonino del Popolo3,4,5 and Zahra Davari6? MOND is ruled out at more than 10 sigma!!!!!
Bernard: for double fitting (a_0 and B beta together).
Houri Ziaeepour: The additional term you added to analysis may simply be a systematic not considered in the previous analysis. The MOND correction
Houri Ziaeepour: But it can have another origin rather than MOND
ant: So, according to you some MONDs are ruled out, other not. Which ones?
Jonathon Baird: It could also be extra parameters fitting a model to data... Do you remember the evidence off the top of your head?
Houri Ziaeepour: The estimation of electromagnetic acceleration is very difficult
ant: Did you receive feedback from MOND community?
Houri Ziaeepour: I am not experimentalist but it is very difficult to take into account all non-gravitational forces.
Jonathon Baird: Basically when you add parameters to your model you are able to fit a model better purely by virture of more parameters in your model. the statistical evidence will tell you how confident you should be with an extra parameter in your model.
Bernard: no sensitivity is too low for LIGO
Houri Ziaeepour: sure. We always need better experiments.
Bernard: Just work out the amplitude: its way too low.


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Dear All,

many thanks for very good questions, some of them I tried to answer during my lecture. I am not the best person to answer questions related to the astrophysical relevance of MOND (clusters, faint galaxies, etc. ). I am aware that MOND cannot explain everything, but dark matter can't either.

You may consider my approach to include electromagnetic forces in the analysis as an engineering type approach, which is justified by that fact that it gives a reasonable result. Houri, which do you think it is difficult or problematic ? I have not received any feedback from the MOND community, although Milgrom is aware of my paper. As long as it is not published (still under review with Springer Gen. Rel. and Grav.) I guess the MOND community may not wish to comment.

It is worth to try fits with more parameters, as soon as more data would be available . More data depends on dedicated experiments, which would require funding. In comparison to Axion search and Wimp discovery the required funding is rather small. I hope there will be some funding available after publication. I hope that there will be some more comments by the "big G" community, they may have unpublished data which are in agreement or contradiction with my analysis. These people are extremely reluctant to share any data which are not published.

About using LIGO: I agree that one cannot measure any changes in the spacetime metric from a periodic motion at a=a_0, but an oscillating mass of a few kg placed close enough to one of the LIGO mirrors would excite the suspended mirror pendulum due its gravitational force, which would lead to a periodic interferometer signal. It is a bit of a misuse of this experiment (they impose all measures to minimise pendulum movements), but I cannot see why it should not work.

Regards,


Norbert