Dear Amrit,

I've read your article. According to my understanding of your work, you are searching for a source of mass and energy, not how they work, especially how they induce gravity as a physical process. It seems you also deny the obvious scientific fact, that is the observable universe is expanding with an accelerating rate. We also need to represent the attraction and repulsion of gravity mathematically. I myself don't believe in most of the so-called Standard Model, but at least what have been observed are not total illusions. Please refer to my article ON REPULSIVE GRAVITY on RG for details and calculations.

Kind regards,

Vu.

Under general relativity gravity can be thought of as the curvature of space-time.

If we add in the cosmological constant which has a repulsive effect, then that  affects the expansion of the Universe,.

Given the presence of energy inherent in the vacuum then  the two come together rather nicely.

Gravity is due to the energy density gradient, the cosmological constant or more succinctly quintessence forms the energy required to produce the expansion of the Universe. 

Dear Andrew,

I would be nice if relativistic gravity could be described like what you have described. But except for the mathematical description of the energy density gradient, we still have no ideas of what the cosmological constant and the so-called quintessence form of energy are. It's very hard to fathom how to require something that we don't really know to do a job that we want them to do. As a matter of fact, a researcher on RG (Link below) has suggested to me that my energy-momentum tensor can be seen as a variation of the cosmological constant. I can give you a simple reasoning for this. If the cosmological constant can be designated with some form of matter then that kind of matter should be able to produce some form of energy in the form of a potential. So why don't we use potential instead of some kind of unknown matter for Einstein' s field equations of general relativity. Furthermore, all of this can be formulated using only matter that are defined and observable in classical physics.

Kind regards,

Vu. 

www.researchgate.net/profile/Agostino_Prastaro

In Newton's gravity gravitational field is created by mass. In Einstein's gravity the source is energy momentum tensor, and effects are deformations of metric tensor. That is space-time itself becomes a dynamic system which responds to changes in energy-momentum tensor. 

In a λCDM cosmological model, Ωλ=69.2±1.2% according to Planck satellite data. Here λ represents a cosmological constant which is associated with a constant dark energy of empty space.  λ is not a function space or time. A property of cosmological constant is that it has negative pressure p=-ρc2 which contributes to the energy momentum tensor, causing accelerated expansion. Intuitively we understand this phenomenon as follows. As the universe expands, more space is created and because dark energy is an inherent property of space, more repulsive energy is brought into the system. Consequently universe undergoes accelerated expansion.

Dear Biswajoy,

Your description of the expanding universe is great, except for the fact that we don't really know anything about dark matter and dark energy. We all agree with you that the source of Einstein's gravity is the energy-momentum tensor, also except for the fact that we also don't really know anything about it, besides those that can be uphold from classical physics. I think the problem is not caused by a lack of variety of resources, but those resources that are available have not been used to their potentials. Yes! It's all about potentials.  

Kind regards,

Vu.

Dear Vu B Ho,

You have asked, "So why don't we use potential instead of some kind of unknown matter for Einstein' s field equations of general relativity?" You are right when you propose this idea. In fact, this line of thought has been pursued for long time, may be for more than last 10 years. People model dark energy not like some arbitrary constant sitting in an equation, but like a scalar field that has a potential. People use similar ideas to model dark matter as well. People also use a single field that can together explain dark matter and dark enegy. I would have liked to give an extensive list of such works. But, I do not have it ready. Below is one paper to start with: https://www.researchgate.net/publication/299524358_A_scalar_field_dark_energy_model_Noether_symmetry_approach

Article A scalar field dark energy model: Noether symmetry approach

The simple answer is we would need to either : simulate Dark Matter technically and implement it through a quantum mechanics level solution, OR, actually obtain or recreate Dark Matter. Once having either of these cases we would need to activate it and redirect the tremendous amount of energy in a multitude of wavelengths, all at the same time. Seemingly technically impossible and dangerous, of course. I would suggest considering the first method, which requires us to model the Dark Energy as a particle type, and then explore some of the less hazardous related forms that are less energetic, that may provide the properties we desire for technology. Sorry if this sounds like science fiction. I assure you it is not.

Dear Sanjeev,

I've tried to read the paper that you linked to but I could not obtain it. Thank you anyway. I know, as you said, that people have used scalar potentials to model dark matter because, actually, that's what Einstein himself discussed and then modified his field equations by adding the repulsion term with the cosmological constant. My question was posed just to express my representation of the paper. Please let me know when those papers that you've referred to are ready.

Kind regards,

Vu. 

Dear Mark,

What is STAR-SEND TECHNOLOGY? In fact it sounds more like you are preparing for some kind of star war than science fiction. I don't know how to simulate something that we don't really know and how to recreate something that has not been created yet. Up to now, dark matter is more of a supplementary idea than material. 

Kind regards,

Vu.

@ Vu B Ho: It is always possible to play with mathematical equations and "find" repulsive gravity with a positive mass. However, physically, there is absolutely no evidence for such a behavior with non-rotating objects.

With rotating objects, you get the possibility of repulsion, as shown by the standard GEM theory.

https://en.wikipedia.org/wiki/Gravitoelectromagnetism

Dear Thierry,

It seems you have not read my work. The main idea is we need to find a useful model with repulsive gravity in order to explain why the observable universe is expanding with an accelerating rate without relying on exotic matter. Not just to play around with mathematics. I am a very down-to-earth physicist who would not hire a pure mathematician to do a physics job. I read the Wiki that you linked to but I could not find anything in there that can be used to explain and predict the accelerating expansion. As a matter of fact, I myself had proposed a model in my PhD thesis that shows that gravity could be a coupling of two electromagnetic fields. Maybe it was just a flash of thought. 

Kind regards,

Vu.

@ Yu:  why would the universe expand at all? Because Zwicky told so and because it then better complies with GRT? No alternatives have seriously been considered like a recoil effect for example. Zwicky in the first place used a hand waving argument by citing the Compton effect. The papers of Lyndon Ashmore explain this interesting alternative. 

Dear Thierry,

Why would the universe expand is a very hard question to answer, if not impossible. My answer is that that is the way we, with our limited physical constitution, could perceive of what we could observe. And this is also true for all other physical phenomena. Right now we still don't even know what an electron is and how it behaves right in front of our eyes, so how would we know what the universe is and why it expands. A closed 4-D spacetime manifold can only be perceived mathematically but not physically. Even in mathematics we still don't know what an infinity is. Therefore it is impossible to try to explain something by using something else that we don't really know, unless we consent with the idea of a finite universe within itself. The job of a humble physicist is to try as much as possible to model an observable universe in terms of a mathematics that we can understand within our constitutional ability. On the other hand, even though it sounds extreme, I believe that the universe is a biological system where elementary particles and their basic interactions are produced to form structures, probably through evolution, and with this belief we can think of the expansion of the observable universe as part of the working of the whole biological system. 

Kind regards,

Vu.

Dear Vu: did they "observe" the expansion of the universe,  or did they just guessed it after observing the redshift?

Dear Thierry,

This is a nice point that is needed to be discussed and it is very much depended on our perception of the physical phenomenon. Not only in physics but in general, we need some kind of rules in order to interpret a result. If it has been established that a redshift is due to a movement then if we observe a redshift from an object then the best possible way to interpret it is to say that the object is moving. However, the physical process that we observe as expansion could be classified by some types of measurements other than redshift. If they all arrive at the same conclusion then nothing else we could do other than to accept it. I am trying to interpret the expansion of the observable universe as a topological flow but I still don't know how.

Kind regards,

Vu.

Dear Vu: Saying "If it has been established that a redshift is due to a movement then if we observe a redshift from an object then the best possible way to interpret it is to say that the object is moving." is not wise.

By saying that, you perfectly incarnate the mainstream behavior, whereby there is a tunnel vision in gravity theory and in cosmology.

However, the most likely, the motion is only one of the possibilities, and even more likely, the redshift is an addition of several physical processes.

The discrepance between the quasars' redshift and that of the galaxies they are bound with is a counterproof that is found by Arp, but systematically depleted by the mainstream. Other reasons exist to not consider cosmological redshift as motion alone.

Dear Thierry,

You are absolutely correct when you say that the perception of motion is only one of the possibilities to interpret the observed redshifts. My statement is not about incarnating the mainstream behaviour but about if we accept a rule then we must interpret according to that rule. However, the relationship between redshift and motion has been verified and used widely in physics therefore it is very difficult to argue against it, in particular if we want to convince people to believe otherwise. I myself don't really like those ideas and formulations of the so-called standard models of modern physics, in particular the Big Bang theory. I don't know what made them think that they have discovered almost everything therefore set themselves standards for other people to follow. To my opinion, what we have discovered so far is no more than a scratch of the unknown. Unfortunately that may stay until people can open their mind to view through the vision tunnel, as you have said.

Kind regards,

Vu

Dear Thierry,

I have looked at Arp's works. I think it would take much more than his works to argue against the view that the universe is expanding based on redshifts. Theoretically we can argue against the view of expansion of space by applying a temporal dynamics. According to the temporal dynamics that I have developed, we can assume space to be a stationary continuum on which time will change with respect to spatial position. Using the temporal dynamics, we can determine time as a function of space. Then by inverting we obtain space as a function of time. In this case the view that space is changing with time is an illusion. Please refer to my article A TEMPORAL DYNAMICS: A GENERALISED NEWTONIAN AND WAVE MECHANICS for more details.

Kind regards,

Vu.

Working Paper A TEMPORAL DYNAMICS: A GENERALISED NEWTONIAN AND WAVE MECHANICS

Dear Vu: The first question then must be: is time what a clock measures or is it an intrinsic property of matter?

The answer is that it is what a clock measures. Time dilatation in Special Relativity is an artifact and doesn't reflect any intrinsic physical reality.

The life extension of fast moving unstable particles (mesons, muons), the allaged "proof" of time dilatation is in fact due to a physical process that holds the particles together. If we consider particles as a sum of negative and positive charged sub-particles, it is clear that the magnetic field, originated by the velocity, induces a radially oriented Lorentz compression force that holds the particle together and delays its desintegration.

So, the physical properties of particles are changed by a velocity. Each particle will have its specific time dilatation, depending on the internals. Some elementary clocks will follow the time dilatation factor of Special Relativity, but others will show a different one, as it has been proven by the late Prof. O. Jefimenko.

Hence, "temporal dynamics" are unfounded.

Dear Vu B Ho:   Your attachment looks interesting to me. But the repulsive gravity, is nether theoretically proved properly & so far away from the practical. But for the positive mass is not not possible to have the repulsive gravity. The gravity only appears attraction in nature. 

The repulsive or reverse gravity is only exists in the dark matters. Which contains enough dark energy & also contains a huge negative mass theoretically.

You have given one expression that I attached here, this negative sign is only to be appeared while the negative mass is present otherwise not. Once you have already taken the mass negatively then I didn't understand your ambiguity.  So in the sense of negative mass the reverse gravity/ repulsive gravity could be generated somehow.

IT IS NOT POSSIBLE TO GENERATE THE REPULSIVE GRAVITY FROM ANY POSITIVE MASS.

I hope the attached information would be helpful for your work.

http://news.nationalgeographic.com/news/2012/02/120215-dark-energy-antimatter-physics-alternate-space-science/

http://phys.org/news/2012-01-repulsive-gravity-alternative-dark-energy_1.html

http://mnras.oxfordjournals.org/content/252/1/53.abstract

Dear Thierry,

To time a clock is a ruler to space, according to my perception of existence. Time and space are basic structures for matter to evolve. They both are intrinsic properties of existence. Either we consent or don't consent because no arguments can resolve the conflict. A collision of contradicted viewpoints certainly occurs on the ground of uncertainty. It is normal that you may view differently and accordingly your perception of time may be different. The working of a clock depends very much on motion, and you cannot define motion without any conception of time. In the end we have to start from somewhere as far as our limited physical constitution allows us to do. All physical theories can be said to be unfounded and you can find faults in any scientific theory because all scientific theories must be based on either axioms or principles, which are accepted unknowns. As I have said, what we have uncovered so far is no more than a scratch on the surface of the unknown, and who (a creator themselves) created the creator is the hardest question you can ask.

Kind regards,

Vu.

Dear Vu: Now we get to where it is all about: the monotheist Jewish culture, and via the Romains to the Christian culture, independently to the Moslim culture. GRT, Big Bang, the universe's expansion, all are based upon that, without any further open minded investigation, completely biased for all the published research that is performed nowadays in these domains...

The divinisation goes so far that it brought the denial of the basics of physics, whereby waves must be propagated through a medium of which the natural constants are essential physical components.

The non-event of the Michelson-Morley experiment was taken as proof of thet denial. How silly!

Needless to say that I absolutely disagree with your views, especially when you say: “All physical theories can be said to be unfounded.../...”.

No, there are theories that are good, others imperfect and others not even wrong but completely idiotic. In the latter, I count the intrinsic time dilatation and length contraction, the alleged expansion of the universe and the alleged dark matter.

Soudip Sinha Roy: "It is not possible to generate the repulsive gravity from any positive mass "

That is not correct. The rotation of masses can give both attraction or repulsion depending from the mutual orientation of the spin vector. This gravity forces adds to the normal Newtonian gravity.

It gives very interesting features:

There exist fast spinning stars that don't fall apart because of an inwards gravity force due to velocity.

Also, the planets about the Sun that are spinning in the same direction, undergo a gravity force that tends to inverse the planet's spin direction. This is due to the Sun's spin, but it is very weak.

Accretion discs about fast spinning stars are spinning locally, which correspond to additional gravity forces that are both attractive or repulsive.

You will find more about that in my work, and an introduction in the following link:

https://en.wikipedia.org/wiki/Gravitoelectromagnetism

If you are interested in, last year I gave an explanation in two papers for dark matter (http://arxiv.org/abs/1503.07440) and dark energy (https://hal-ens-lyon.archives-ouvertes.fr/ensl-01122689). In this solution, the dark matter is explained in the frame of general relativity (no unknown matter, no modification of the theory) by the second component of gravitation (similar to a magnetic component of electromagnetism as it can appear in linearized general relativity also called gravitomagnetism). This solution implies that the clusters must generate this “gravitic” field and as a consequence of that, the spins of two neighboring clusters should be roughly parallel. This unexpected situation has just been verified (see the paper « Alignments of radio galaxies in deep radio imaging of ELAIS N1 », R. Taylor and P. Jagannathan, http://dx.doi.org/10.1093/mnrasl/slw038). To explain dark energy (a repulsive gravitation), I also use the “gravitic” field but this time, the “gravitic” field of a matter with negative gravitational mass and positive inertial mass. I show that this matter is necessarily the traditional antimatter (and not an unknown matter). It also allows to understand why the principle of equivalence of masses is verified with a large accuracy. But it also implies that the equivalence of masses can be violated and I give the conditions to that. All of that is compliant with general relativity (the principle of equivalence of masses has inspired general relativity but general relativity doesn’t imply the principle of equivalence of masses!). Just like electromagnetism can be attractive or repulsive because of the sign of the charge, general relativity can be attractive or repulsive because of the sign of the gravitational mass (but the inertial mass is always positive!). This solution implies a variation of the Hubble “constant”. This fact is likely verified (see "A 2.4% Determination of the Local Value of the Hubble Constant", Adam G. Riess et al., http://arxiv.org/pdf/1604.01424v1.pdf)

http://arxiv.org/abs/1503.07440

https://hal-ens-lyon.archives-ouvertes.fr/ensl-01122689

http://dx.doi.org/10.1093/mnrasl/slw038

http://arxiv.org/pdf/1604.01424v1.pdf

Dear Thierry,

I think I should borrow George Orwell's expression to express your way of thinking. All orthodox thoughts are equal but your orthodox thoughts seem to be more equal than others. One or two findings of faults here and there in the theories of other people will not help. All that you need to do is to formulate a grand convincing theory that can be used to cover all aspects of physics, not few proofs to show side effects of existing theories. If you have the right to reject people's theories without careful examinations then you should also expect the same for your theories or those who you are in favour. If you could tell me why the universe exists without using any further assumptions then I would definitely say that your theory would be absolutely founded. But remember I can always ask you the next question following your answer, whatever it might be.

Kind regards,

Vu.

Dear Stephane,

I've read your papers. Your papers say they don't modify general relativity, just to linearise it. I am not sure if linearisation is a form of modification? Another thing is your papers say other forms of dark matter have not been observed and then they propose negative mass themselves. Has any kind of negative mass ever been observed? Your papers are interesting though. I had works on linearised general relativity myself. They can help to explain few things but are not fundamental as the original field equations.

Kind regards,

Vu.

Dear Soudip,

I have read those works that you referred to and they all discussed about exotic matter. My work shows, a theoretical proof as you said, that normal matter can produce repulsive gravity within the framework of general relativity and it can be used to explain why the universe is expanding with an accelerating rate. In principle, negative mass can exist, however they relate to different type of dynamics than those that have been formulated in physics. If you are interested you can have a look at my work to see the difference A TEMPORAL DYNAMICS: A GENERALISED NEWTONIAN AND WAVE MECHANICS.

Kind regards,

Vu.

Working Paper A TEMPORAL DYNAMICS: A GENERALISED NEWTONIAN AND WAVE MECHANICS

Dear Vu: it is a typical answer from GRT proponents against non-proponents that they should find a theory that covers all physics before they would be able to compete with GRT.

I don't believe that it is useful being nice for your theory in order to make you being nice for my preferred theory... It only matters to get the theory that works with the most possible issues without biased views nor fabricated concoctions.

Besides, does GRT covers all physics? No, it covers the bending of light, that's all. The rest is pure biased fantasy. And all the metrics that have been invented have in fact nothing directly to do with GRT itself. They are instead concoctions and fabrications that mutually are contradicory and that are very vaguely "based" upon the original GRT.

All the accepted and published observations do only cover what is suitable for the monotheistic GRT theory. However, when precise calculatens are necessary as for binaries, Gravitoelectromagnetism is used or PPN which have free parameters and just make a curve fit.

Annexed, you will find the theory of Gravitoelectromagnetism or better Gravitomagnetism, and the many issues it covers, including dark matter.

I also add Lyndon Ashmore's suggestion for the cosmologic redshift that is due to a recoil effect of hydrogen. This is much more interesting than a fabricated mathematic theory that invents the repulsion of masses without any substantiated physics.

http://gsjournal.net/books/De-Mees-Gravitomagnetism-and-Coriolis-Gravity-2011-A4.pdf

Article A Proposed Recoil Interaction Between Photons and The Electr...

Stephane le corre : your approach is in the right direction. However, concerning the disc galaxies it is important to understand that a disc galaxy was formerly a spherical galaxy but that the second (velocity-dependent) component of gravity transmitted the (global) angular momentum in the bulge to the surroundings. That made the orbits swiveling (while keeping their orbital radius more or less untouched). The swiveling happens by the second gravity field that transmits the angular momentum, which align them prograde (same direction as the bulge's angular momentum).

Due to the swiveling, the initial mass distribution of the spherical galaxy changes drastically, causing (after a Newtonian mass integration) the right orbit velocities, nearly constant.

You will find in my book (see link above) a very simple explanation of the constant velocity curve (page 19) and a more extended one (page 109).

Thierry De Mees; Several simulations has been realized to know if the "gravitic" field (Lense-Thirring effect) of the own galaxy can explain the velocity of the matter at its extremities.

Even taking account the non linear terms of general relativity, it is impossible to explain the curve of galaxies' speed at the end in the frame of general relativity.

The high value of rotation speed must be obtained not only at 5kpc of the center but at least at 20kpc for the stars of the galaxies and also at least at 100 kpc for the dwarf satellite galaxies.

Once again, with general relativity and with only the visible matter of the galaxy, it is impossible to explain these rotation speeds. Your calculation doesn't work for such a distance (100 kpc).

The only solutions are to make the assumption of a new theory (for example the MOND theory) or the assumption of an external effect (for the most popular assumption it is the dark matter and for my solution it is the gravitic field, generated by the clusters of galaxies, which embeds our universe ).

Your theory that you call MAG theory (Maxwell Analogy for Gravitation) is very similar to gravitomagnetism. But gravitomagnetism is general relativity. As I said before, general relativity cannot explain the rotation speed without an external effect.

Your explanation can't work! Except if the gavitomagnetism that you use is different from the linearised general relativity. In these conditions, you made another MOND theory.

But then, I'm not sure that it is a better solution (i.e. more easy to accept) than the dark matter!? Your approach is in the wrong direction.

Vu B Ho: As I wrote in my papers, the negative mass must be the gravitational mass of the antimatter (if it is not, my solution is wrong!). Antimatter is a kind of matter that has been observed. There are some experiences that try to determine the sign of the mass of the antimatter (for example AEgIS)

Of course, a mathematical linearisation is not a modification of a theory. The linearisation doesn't modify the paradigms of the theory and must be used in the conditions that does not modify the results of the exact theory!

Stephane le corre : NO! That is wrong. Gravitomagnetism is *not* general relativity. It was developed in 1893 by the guy who is at the basis of every electronic chip in the world, Oliver Heaviside. This genius found the line theory which states that every line has its impedance defined by its length. He wrote many great books on electromagnetism available on the internet.

The mainstream know very well that they need this theory, so they fabricated a similar one, very vaguely derived from GRT with lots of trickery, and by using the perturbation theory, they need oblate spheres to imitate Heaviside's gravitomagnetism.

However, in gravitomagnetism we use full spheres.

At high distances, the curve found by gravitomagnetism still works! Did you even read my explanation that the orbits *swivel* to the equator and that so, the mass distribution becomes totally different, allowing a different orbit velocity at each radius? Did you even look at my calculus before using the biased view that “it can't work”?

The mainstream dogma is that angular momentum cannot be transferred to the surroundings by gravity. Though, the Gravity Probe B, due to the Earth's rotation, is totally explained by Gravitomagnetism, and that theory precisely shows a magnetic-like field, velocity-dependent, that makes orbits swivel in the same direction, like magnets orient in the same direction.

When a decent theory is used, all problems become resolved, but MOND is just a curve fit, like all the GRT metrics, which are *arrangements* to make things fit.

Annexed I list the successes of gravitomagnetism.

For example, you can read the course of general relativity "HOBSON et al. “Relativité générale”, ISBN 978-2-8041-0126-8, 2009 December. It demonstrates that the linearized general relativity leads to the gravitomagnetism. You can read a summary of this demonstration in my paper.

Effectively (as I said in my paper) Gravity Probe B has demonstrated the Lense-Thirring effect (gravitomagnetism) predicted by general relativity.

Several serious researchers have tried to explain the rotation's speeds by the own gravitic field of the galaxies. But general relativity (and gravitomagnetism) can't explain these speeds. In other words, your results means that these researchers don't know how to use gravitomagnetism!? I'm very skeptical about this.

Until now, there is no observation that contradicts the general relativity. All the successes of gravitomagnetism are also successes of the general relativity! If it is not, you have a scoop.