Dark matter causes moon receding and earth’s rotation slowing?

[peter]

I did internet search about the history of earth moon system for my biophysics project and found a paper which is very interesting “The evolution of Earth Moon system based on the dark matter field fluid model”.

The link is arxiv.org/ftp/arxiv/papers/0704/0704.0003.pdf

This paper describes the evolution of earth moon system based on the dark matter with non Newtonian physics method and fits the data very well. It claims that the dark matter causes the moon receding and the earth’s rotation slowing, shows that the receding and rotation rate change follows a special relationship, and predicts that the Mars’s rotation should be slowing also. The model may not be perfect but the idea seems inspiring. I think that the measuring the Mars’s rotation rate change and comparing it with the prediction is the only way to test if this model stands. Does anyone have such reliable data about the Mars’s rotation rate change?

In current cosmology, the dark matter and dark energy is a very hot topic. It is believed that there is about 85% or more matter in the universe is called dark matter and dark energy, which is currently invisible. The Newtonian physics may be limited because it is only based on the visible matter which is about 15% or less of the matter of the universe. How the dark matter and dark energy interact with the visible matter and influence the physical behaviors of the visible matter objects will be interesting . The future physics including the dark matter and dark energy will be very romantic.

[modest]

Hello peter - your post is intriguing and I wish I had responded sooner. I just read the paper and feel completely unqualified to judge it as plausible or even possible but will remark on some things that stuck me as I was reading it.

 

I guess I should summarize first: the paper presents a theory whereby the earth-moon system is affected by the presence of a dark matter field. The particles of the field are quiescent with earth and permeate the normal baryonic matter of the system. The field is allowed to impart energy (very much like fluid dynamics) to the system's mass. After the formalism of the field and system, the paper projects into the past and claims agreement with geologic evidence. The main consequence of the field and nature of the agreement discussed is the recession of the moon and lengthening of the earth-day over the last 4.6 Gyrs.

 

Quotes are from: The evolution of the Earth-Moon system based on the dark matter field fluid model

 

The popular theory is that the tidal friction causes all those changes. However, based on tidal friction model and the current Moon-Earth system data, the tidal friction should be stronger and the recessional rate of the Moon should be greater in the past because the Moon was closer, the distance of the Moon would quickly fall inside the Roche's limit (for earth, 15500 km) in which the Moon would be torn apart by gravity in 1 to 2 billion years ago. This, however, never happened.

 

Well, this is stated as fact in the paper’s first paragraph. This immediately set me back. I’ll explain why after this quote:

 

The tidal friction theories explain that the present rate of tidal dissipation is anomalously high because the tidal force is close to a resonance in the response function of ocean (Brush 1983). Kagan gave a detailed review about those tidal friction models (Kagan 1997). Those models are based on many assumptions about geological (continental position and drifting) and physical conditions in the past, and many parameters (such as phase lag angle, multi-mode approximation with time-dependent frequencies of the resonance modes, etc.) have to be introduced and carefully adjusted to make their predictions close to the geological evidence.

 

Also from the first paragraph. So, the paper very quickly dismisses all previous research into the topic. Perhaps it must to be a completely tenable theory itself but this puts me back straight-off. Though I’m no expert - I don’t think we can so equivocally state that the recession rate was so much higher in the past as currently. There are many competing factors. Obviously higher tides and a faster rotation rate would work toward a greater recession rate in the remote past, but there is also the competing factor that the moon’s angular momentum was less in the past and recession is proportional to angular momentum. We also could consider friction less substantial when earth was hotter or the opposite snowball-earth effect on the tides in times past working toward lowering recession at past epochs. This is all in addition to the drifting continents and oceans whose effect may be a very large factor. There are meteor strikes and earthquakes and a hundred other things I’m not smart enough to even think to consider all having an effect on past recession of the moon. And, why are we rejecting resonance? Isn’t this exactly the kind of system that would be subject to resonance? I think we know far too little about earth’s crust and elasticity today much less billions of years ago to definitively say how these competing factors work over time. But, okay… Moving on…

 

(1) the gravitational force, (2) the centripetal acceleration force; and (3) the repulsive force of the dark matter field fluid.

 

The paper considers these three factors affecting the earth-moon system and among those three, two are considered in equilibrium:

 

Therefore, the gravitational force and the centripetal acceleration force can be approximately treated in equilibrium at any time.

 

So, the recession rate is examined as a direct effect of some fluid like field excluding all other factors. The formalism is indeed very simple and straight-forward. There is no fine-tuning or other innate problems of that kind as far as I can tell.

 

Fig. 2 shows the geological data of solar days year-1 from Wells (1963) and from Sonett et al. (1996) and the description (solid line) by this dark matter field fluid model for past 900 million years. One can see that the model agrees with the geological and fossil data beautifully.

 

And indeed it does. At least for the past billion years one is tempted to agree there is some non-Newtonian-fluid-like field being the main cause of lunar recession. Its appeal is its simplicity. However, what is not considered in this theory may be problematic. In order to be a geological-fit one must ignore, or seriously suppress, any contribution tidal bulge has on the moon’s recession. I find myself unable to do that. Also neglected (as the paper points out) is the earth and moon’s interaction with the sun and the moon’s elliptical orbit which is treated as circular. For such a near-perfect fit to the geological evidence - the paper introduces some serious margin of error (which also is not calculated).

 

So, I was left kind of conflicted about the paper. The evolution of the earth-moon system is definitely an open question in my book and dark matter may well play a role in its evolution. It’s a beautiful idea and (given there is geological evidence) a testable one in our most-local system. However, the paper struck me as more an opening question than any definitive answer. We certainly know less about dark matter than tidal interactions. Extrapolating the effect of either 4.5 billion years is going to be deleterious. Like I said, I feel very unqualified to judge how plausible this paper could be. I do think it is a very good angel or perspective into possible effects of dark matter and their interaction with baryonic matter.

 

To answer you question about mars: Yes - pathfinder has helped in giving data about the change in mars' rotation...

Mars Pathfinder Science Results

The change in rotation would seem to be seasonal and tied to atmispheric conditions there is also precession data. None of this would, yet, rule this paper in or out, I would think.

 

- modest

[peter]

Hello, Modest,

Thank you for your reply. After reading your comment and reading the paper again, I feel that there are some things needed to be discussed. However, I am not an expert in this area to judge this model.

As the paper indicated, the tidal friction models are based on many assumptions and carefully adjusted parameters. For my understanding, those assumptions and parameters include all possible competing factors (like those you mentioned) one can come up with in order to explain why the moon’s recession rate was slower in the past, this is a reasonable approach when there is no other better theory for the evolution of the Earth-Moon system.

The model proposed in the paper gives an alternative description of the evolution of Earth Moon system. This model can calculate how the moon’s rotation changes, the tidal friction can not. To me, the most significant part of the model is the equations 17 and 18, tidal friction can not give such relationships. As you said, the model is very simple and straight-forward. It seems over-simplified, the actual case could be much more complicated when involves the dark matter. I agree with you “I do think it is a very good angel or perspective into possible effects of dark matter and their interaction with baryonic matter.” A more sophisticated/comprehensive model could be developed in the future.

 

However, I do not agree with your comment “However, what is not considered in this theory may be problematic. In order to be a geological-fit one must ignore, or seriously suppress, any contribution tidal bulge has on the moon’s recession.” Since the model fits the geological data so well (Fig.2), this indicates that all other factors are not significant. I do not think that anyone will introduce additional factors into his theory when it fits the experiment data perfectly. In reality, people do it other way, when a model does not fit the data, people will introduce additional factors to make the revised model fit the data. It seems that, to some extent, the tidal friction theory is like this.

This model makes us think:

Dark matter does exist ????

The Newtonian physics is limited and the physics of the dark matter is “complicate and interesting”.

[modest]

Hello, Modest,

Thank you for your reply.

 

Sure, and I forgot to thank you for your post and referencing the paper which was intriguing. A very good post - thank you.

 

As the paper indicated, the tidal friction models are based on many assumptions and carefully adjusted parameters. For my understanding, those assumptions and parameters include all possible competing factors (like those you mentioned) one can come up with in order to explain why the moon’s recession rate was slower in the past, this is a reasonable approach when there is no other better theory for the evolution of the Earth-Moon system.

 

I agree. There are many parameters involved when modeling past recession based on tidal friction. This is because earth has been an evolving and dynamic system from its inception. Any model of this is going to look like a finetuned mess even if it's absolutely correct.

 

The author of this paper points this out (as a negative) right after claiming such models certainly put the moon inside Roche's limit in 1 - 2 billion years. He claims our most-believable tidal models call for too much past recession then later claims past tidal interactions were negligible. So, the paper is (at best) making different tidal claims. I think this is a result of the basic logic behind the paper and my main question:

 

If our best model predicts too much past recession, why are we adding a parameter that adds to past recession?

 

Of course, the paper doesn't answer this but rather says we need to disregard all tidal interactions without explaining why. Because of this, it seems like this can't be treated as a real solution - in my very humble opinion. In fact, there is probably something wrong with my logic above - that's just what's stuck in my mind.

 

The model proposed in the paper gives an alternative description of the evolution of Earth Moon system. This model can calculate how the moon’s rotation changes, the tidal friction can not. To me, the most significant part of the model is the equations 17 and 18, tidal friction can not give such relationships.

 

Well, I think tidal friction is directly related to how fast the moon rotates around the earth. Through conservation of energy - as the earth slows its rotation, the moon must speed up.

 

However, I do not agree with your comment “However, what is not considered in this theory may be problematic. In order to be a geological-fit one must ignore, or seriously suppress, any contribution tidal bulge has on the moon’s recession.” Since the model fits the geological data so well (Fig.2), this indicates that all other factors are not significant. I do not think that anyone will introduce additional factors into his theory when it fits the experiment data perfectly.

 

I think we have to be cautious of coincidence. It is coincidental that the moon is the same angular size as the sun. We live in the exact time for this to be the case and there is nothing wrong with that. There is a cool coincidence between hubble's law and the rate of lunar recession that I won't present here because it is also coincidental. The relationship between this model and the past billion years of geological evidence may be coincidental. We would have to be cautious not to throw away all of our existing work (which is what this paper proposes) in favor of a relationship that could be nothing more than coincidence. Without evidence of how dark matter interacts with normal matter or evidence of such an interaction in other celestial bodies I don't think this model can be distinguished from pure coincidence. But, this is just my opinion - I'm certainly not claiming that's the only way to interpret this paper.

 

- modest

[peter]

Well, I think tidal friction is directly related to how fast the moon rotates around the earth. Through conservation of energy - as the earth slows its rotation, the moon must speed up.

- modest

This is misunderstanding. The "moon rotation rate change" in my post means that the moon rotates about its central axis, not rotates around the Earth. The tidal friction can not calculate the rotation rate change of the moon about its central axis.

I agree with you that we have to be cautious of coincidence. Too much "coincidence" should mean something.

[modest]

This is misunderstanding. The "moon rotation rate change" in my post means that the moon rotates about its central axis, not rotates around the Earth. The tidal friction can not calculate the rotation rate change of the moon about its central axis.

I agree with you that we have to be cautious of coincidence. Too much "coincidence" should mean something.

 

In a tidal model these are different ingredients in the same soup. The moon rotates once around the earth every 27ish days and also once around its axis every 27ish days. This leaves one side of the moon always facing earth. It is earth's effect on the moon's 'tides' that caused this relationship - so I think this is a rather good test of the tidal models. I certainly see nothing lacking here.

 

-modest