Does Milgrom\'s Acceleration Law Imply That the Equivalence Principle Is Wrong? by David Brown

David Brown

Essay Abstract

Theoretical physics is amazingly successful, but the cosmological puzzle of dark matter has not been satisfactorily explained. If there is something wrong with the foundations of theoretical physics then dark matter is a good starting point for challenging the foundations.

Author Bio

David Brown has an M.A. In mathematics from Princeton University and was for a number of years a computer programmer.

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[deleted]

Hi David,

I just read your short essay. While I personally believe that the implications of Milgrom's results should be considered seriously, it is unfortunately a fact that the overwhelming majority of astrophysicists and astronomers dismiss them out of hand without even trying to understand them. Given the brevity of your essay, there would have been room to present the arguments which rebut common dismissive claims about MOND, such as those involving the bullett cluster observations, and an opportunity to educate the skeptics seems lost.

Also, in addition to the hypotheses you list in your paper, an additional one may be that at extremely large scales, nature could simply be different in some as yet to be understood way as compared to our everyday scale, just as it appears to be at extremely small scales.

Nonetheless, I appreciate your contribution to this contest and hope that it will get many people to think about the issues you raise.

Armin

Joe Fisher

Surely, dark matter cannot be anything else other than the residue of long extinguished stars. The stars cannot possibly be distributed chronologically, or in any logical sequence at all. Each star is located at a different intervening distance apart from every other star. I think you will find that each indication of dark matter has to appear to be at a different intervening distance apart from all the other locations of dark matter. It is possible that each star came into existence at a different moment of time and in a different location than every other star did. It is more likely that the stars are eternal and that they have always been pretty much where they can be noticed presently. I think each star simply continuously heats up and expands then cools off and shrinks thus constantly altering its gravitational intensity and this has always been so.

[deleted]

Dear David,

Congratulations on a fundamental line of thought with your essay. I agree that the spiral galaxy rotation curves are the key to understanding a new physics.

[deleted]

Years ago I wondered, a related issue for comparison: if an electric charge oscillated up and down (in SHM) through a tunnel making a diameter of the Earth, would it radiate? The electromagnetic field around the charge is changing so it should radiate, but since the charge is in free fall, it should act like there's no radiative reaction force from the charge's change of acceleration (Abraham-Lorentz law.) If so, that would violate conservation of energy, since the radiation would not have to be "worked for" by pushing the charge against the RRF (as we must do in an antenna, etc.) If the EP is wrong, then maybe that would mean the charge doesn't have to act like it's in free fall (per "Einstein's elevator".)

I've heard similar before here and there. Supposedly, the explanation is: the radiation itself curves back around to push against the moving charge. I find that hard to believe intuitively, is it credible?

PS I previously had an entry, for the Contest "Is Reality Digital or Analog?" I again thank FQXi for giving me a forum.

Dirk Pons

David

Would indeed be nice to see dark energy and dark matter resolved with one mechanism.

Thank you

Dirk

[deleted]

Your essay is very focused. I gave it a fairly high rating because of this.

Benjamin Dribus

Dear David,

I think you're correct that this is an important problem and that more effort should be devoted to examining the validity of the equivalence principle, rather than simply assuming the existence of dark matter to explain the anomalous rotation curves. Personally, I think we should think very carefully about the effect of scale. Different types of interactions dominate at different scales: the strong/weak interactions on the nuclear level, the electromagnetic interaction up to ordinary scales, then gravity, "dark matter," and finally "dark energy" on the largest scales. It might be that "gravitational mass" loses its relevance for objects separated by great distances, because the interaction between them is of a different nature than usual gravitation. Anyway, I enjoyed reading your essay. Take care,

Ben Dribus

Juan Ramón González Álvarez

Dear David Brown,

Effectively, Milgrom equation implies that the equivalence principle has only a limited validity. The section 8 of my essay is devoted to the myth of dark matter (DM) and to the explanation of how MOND can be obtained from a more general theory [11].

Effectively the general theory explains what is the limit of validity of the equivalence principle. You correctly notice that the equivalence principle has been tested "to many decimal places", but only in situations where the corrections to GR vanish or are too small to be measured. Precisely there are many galactic phenomena where the equivalence principle fails and it is precisely there where GR (even assuming a hypothetical distribution of DM) cannot explain the observed phenomena. Due to geometrical constraints (inherited from the equivalence principle), dark matter theorists cannot distribute the hypothetical dark matter in arbitrary ways, and thus their constrained distributions cannot explain the fine-tuning details that are, however, explained by MOND and similar theories.

Regards.

Sergey Fedosin

If you do not understand why your rating dropped down. As I found ratings in the contest are calculated in the next way. Suppose your rating is [math]R_1 [/math] and [math]N_1 [/math] was the quantity of people which gave you ratings. Then you have [math]S_1=R_1 N_1 [/math] of points. After it anyone give you [math]dS [/math] of points so you have [math]S_2=S_1+ dS [/math] of points and [math]N_2=N_1+1 [/math] is the common quantity of the people which gave you ratings. At the same time you will have [math]S_2=R_2 N_2 [/math] of points. From here, if you want to be R2 > R1 there must be: [math]S_2/ N_2>S_1/ N_1 [/math] or [math] (S_1+ dS) / (N_1+1) >S_1/ N_1 [/math] or [math] dS >S_1/ N_1 =R_1[/math] In other words if you want to increase rating of anyone you must give him more points [math]dS [/math] then the participant`s rating [math]R_1 [/math] was at the moment you rated him. From here it is seen that in the contest are special rules for ratings. And from here there are misunderstanding of some participants what is happened with their ratings. Moreover since community ratings are hided some participants do not sure how increase ratings of others and gives them maximum 10 points. But in the case the scale from 1 to 10 of points do not work, and some essays are overestimated and some essays are drop down. In my opinion it is a bad problem with this Contest rating process. I hope the FQXI community will change the rating process.

Sergey Fedosin