Sunday, May 22, 2011


Sean Carroll writes about breakdown of classical gravity in Cosmic variance. Recall that the galactic dark matter problem arose with the observation that the velocity spectrum of distance star is constant rather than behaving as 1/r as Newton's law assuming that most mass is in the galactic center predicts.

The MOND theory and its variants predict that there is a critical acceleration below which Newtonian gravity fails. This would mean that Newtonian gravitation is modified at large distances. String models and also TGD predict just the opposite since in this regime General Relativity should be a good approximation.

  1. The 1/r2 force would transform to 1/r force at some critical acceleration of about a=10-10 m/s2: this is a fraction of 10-11 about the gravitational acceleration at the Earth's surface.

  2. What Sean Carroll wrote about was the empirical study giving support for this kind of transition in the dynamics of stars at large distances and therefore breakdown of Newtonian gravity in MOND like theories.

In TGD framework critical acceleration is predicted but the recent experiment does not force to modify Newton's laws. Since Big Science is like market economy in the sense that funding is more important than truth, the attempts to communicate TGD based view about dark matter have turned out to be hopeless. Serious Scientist does not read anything not written on silk paper.

  1. One manner to produce this spectrum is to assume density of dark matter such that the mass inside sphere of radius R is proportional to R at last distances. Decay products of and ideal cosmic strings would predict this. The value of the string tension predicted correctly by TGD using the constraint that p-adic mass calculations give electron mass correctly.

  2. One could also assume that galaxies are distributed along cosmic string like pearls in necklace. The mass of the cosmic string would predict correct value for the velocity of distant stars. In the ideal case there would be no dark matter outside these cosmic strings.

    1. The difference with respect to the first mechanism is that this case gravitational acceleration would vanish along the direction of string and motion would be free motion. The prediction is that this kind of motions take place along observed linear structures formed by galaxies and also along larger structures.

    2. An attractive assumption is that dark matter corresponds to phases with large value of Planck constant is concentrated on magnetic flux tubes. Holography would suggest that the density of the magnetic energy is just the density of the matter condensed at wormhole throats associated with the topologically condensed cosmic string.
    3. Cosmic evolution modifies the ideal cosmic strings and their Minkowski space projection gets gradually thicker and thicker and their energy density - magnetic energy - characterized by string tension could be affected
TGD option differs from MOND in some respects and it is possible to test empirically which option is nearer to the truth.

  1. The transition at same critical acceleration is predicted universally by this option for all systems-now stars- with given mass scale if they are distributed along cosmic strings like like pearls in necklace. The gravitational acceleration due the necklace simply wins the gravitational acceleration due to the pearl. Fractality encourages to think like this.

  2. The critical acceleration predicted by TGDr depends on the mass scale as a ∝ GT2/M, where M is the mass of the object- now star. Since the recent study considers only stars with solar mass it does not allow to choose between MOND and TGD and Newton can continue to rest in peace in TGD Universe. Only a study using stars with different masses would allow to compare the predictions of MOND and TGD and kill either option or both. Second test distinguishing between MOND and TGD is the prediction of large scale free motions by TGD option.

TGD option explains also other strange findings of cosmology.

  1. The basic prediction is the large scale motions of dark matter along cosmic strings. The characteristic length and time scale of dynamics is scaled up by the scaling factor of hbar. This could explain the observed large scale motion of galaxy clusters -dark flow- assigned with dark matter in conflict with the expectations of standard cosmology.

  2. Cosmic strings could also relate to the strange relativistic jet like structures meaning correlations between very distant objects. Universe would be a spaghetti of cosmic strings around which matter is concentrated.

  3. The TGD based model for the final state of star actually predicts the presence of string like object defining preferred rotation axis. The beams of light emerging from supernovae would be preferentially directed along this lines- actually magnetic flux tubes. Same would apply to the gamma ray bursts from quasars, which would not be distributed evenly in all directions but would be like laser beams along cosmic strings.

For more about TGD based vision about cosmology and astrophysics see the chapters of the book Physics in Many-sheeted Space-time.


At 12:53 AM, Blogger Ulla said...

At 5:35 AM, Blogger ThePeSla said...

Interesting Matti that our humble theoretician posted on this after you have and I will post on it after Lubos. And Ulla, your reference also is part of the picture. But clearly what Lubos proposes is very much TGDish and even reminds me of what math puter programs may draw in my quasic plane. Holography as a principle is not quite everything.

Anyway the formula on the illustration as a generalization of the inverse square law (why things are round, Ulla, and why space is three dimensional mostly)is but a vague suggestion for the dark matter, depth and span of space and time, and the inverse very much TGD-like but I added the dark energy here as plus or minus unity. :-)

No wonder it is hard to understand global warming without at least the TGD in the new physics!


At 6:10 AM, Anonymous Matti Pitkanen said...

The posting of Lubos is a joke. The contents of the posting have nothing to do with TGD. The posting is a parody of both MOND and of entropic gravity a la Verlinde.

First of all, if super string models manage to predict something it is that gravitation in long length scales is Newtonian. MOND proposed just the opposite. Therefore Lubos is the last one to suggest something like MOND.

I want to emphasize that TGD view is totally differeng from Verlinde's: no nonsense talk about holographic screens or emerging dimensions and about giving up gravitons. The entropic character follows from the generalization of S-matrix to a collection of S-matrix, M-matrix, and U-matrix with M-matrix being analogous to thermal S-matrix: therefore thermalization of all bosons at very long lines of generalized Feynman graph.

At 7:05 AM, Blogger Ulla said...

With my link I wanted to remind of the inflanatory scenario of Big Bang. It started from entropy low(?) with a strong acceleration creating heat (high entropy?)(=gravity?), and now again a strong acceleration (?). Then I thought of Penroses rings and the cyclic Universe.

Not even if time is an (low entropic) arrow from Big Bang this scenario is ok. This means that the first moment was timeless, or negative time, negentropic, "living" (subsystem?)? At least if we follow the charachters from biology.

Nima talks of a whole hidden (entangled=negentropic?) space, which is the dark aspects of our Universe, not vanishing, but growing. Dark matter seems to be clear, but dark energy is bound to the acceleration (gravity, size) and cosmological constant (deficit of gravity/surplus of energy?).

Note that Nimas version also has U-matrix between hidden space and locality. His background gluons were fantastic. The whole thing can be interpreted as a ZEO, note also gravitational ZEO. I guess it is not so long before he admit the failure of M-theory.

Who cares what Lubos says?

At 9:18 PM, Anonymous Matti Pitkanen said...

I looked again the posting of Lubos. Maybe he is serious after all! He starts from the observation that acceleration has dimension 1/length for natural units hbar=c=1 and identifies acceleration as length and says that when this length is larger than the scale of holographic screen, something strange happens.

The identification of acceleration as length is questionable. For causal diamonds situation would correspond to a change of momentum assignable to graviton. When the wavelength of graviton is for is larger than the size scale of CD something should happen. Lubos suggests that Newton's law is modified. In TGD the interpretation would be that this kind of momentum changes are below measurement resolution defined by the CD: this is much less dramatic.

Lubos is not able to explain why the change from 1/r^2 force to 1/r force should take place. It would be interesting to read a politically non-correct opinion of a clone of Lubos about the idea of Lubos;-).

TGD explanation is much less romantic if one forgets dark mater. Newton is right. There are long string like objects with finite thickness creating 1/rho gravitational potential. It is ironic that string model people have managed to miss also this Golden Opportunity!;-): explanation of dark matter in terms of strings with cosmological length scales!
The problem is of course small hbar which suggests that strings have lengths not much longer than Planck length. Large bhar saves the situation.


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