A statistical principle will never govern a deterministic force, let alone an action-at-a-distance like Newton's law. Gravity is not an entropic force caused by the "changes in information in the position of material bodies." Gravity acts even in the absence of motion. But it can cause a reduction in the entropy with respect to the reference state at infinity. The nature of the interactions, discussed by Verlinde, do not lead to increases in entropy; rather, they cause a reduction in entropy from a uniform state to a more constained one through the application of a constraint. The force is mechanical and not entropic in origin.

In analogy with the polymer model discussed by Verlinde, the entropy decreases when the elongation increases that is caused by an applied tension. All this has been worked out long ago in Lavenda, "Thermodynamics of Extremes" (Horwood, 1995) Sec. III.2.3 and V.4.1, and (partially) previously by Callen ("Thermodynamics" Wiley, 2nd ed. , 1985, p. 80) in his 'rubber band' model, where the internal energy is given by an ideal gas (like Verlinde's). See also Frenkel, "The Kinetic Theory of Liquids"(Oxford U. P., 1946). The entropy reduction is proportional to the square of the elongation (and not the elongation itself because that can be of either sign), which is the Gaussian limit. With the internal energy given by an ideal gas, all that can be concluded from the analysis is that the ratio of the force to temperature is independent of the temperature, and can only be a function of the stretching.

Setting the minimum characteristic radius of a normal star (V.123 in Lavenda) equal to the Unruh temperature gives the radius of the star as the Compton wavelength! [Something is missing like the cube root of the number of protons in the star that multiplies the Compton wavenlength (V.138) to obtain the radius,] The Unruh temperature picks out Newton's law, automatically because the force to temperature ratio is constant. Verlinde also recognized this by the appearance of 'c' in a nonrelativistic framework. He even tells us to forget about it. However, he uses a completely ad hoc a relation between the number of bits used and the area. Going through his derivation, he does get Newton's law but iff the temperature is given by the Unruh temperature! So it is no more general than postulating Unruh's temperature to begin with! Moreover, why can't the Bekenstein expression for the entropy in terms of the area of the horizon be used in (3.10) to related it to the number of bits used? Because together with the law of equipartition of energy (3.11) and the second law, it gives an incorrect relation between entropy and energy.

Finally, the motivation behind the paper---Jacobson's derivation of Einstein's equations as an equation of state from the second law---is invalid because dQ=TdS(=TdA/4)=0 for Einstein's equations, and Jacobson's derivation is 0=0. Einstein's equations are adiabatic; they are not thermal equations of state.

I am supporting Erik Verline's thesis about the gravitational potential, because I have proposed a cosmological model with three fundamental constants turned into functions of the gravitational potential, and a gravitational field has a temperature associated with the gravitational potential as well. Even the gravitational waves essentially are black body radiations. The information is carried by the magnetic flux or neutrino flux associated with the gravitational potential.

Thank you, Guoliang and Joachim, for your comments. best wishes

Dear Victor,

you mentioned Wheelers "It from Bit". Because of that I recommend to look into the latest essay contest of the Foundational Questioning Institute (FQXi). Even the prize-winning essays are interesting for you.

Here is the link:

http://fqxi.org/community/essay/winners/2013.1

Best wishes

Torsten

The only way to express gravitation (as well as any other entity or phenomenon)

is by means of a written or spoken account of what you know about it, i.e. information.

If the reason of the question is to ask whether gravitation consists of information,

the answer, obviously, is `No'. Information is stored in articles, books, and all kinds of memories. Information is `about entities or phenomena'; it is not itself an entity or a phenomenon.

I think that information, in general. is contained in any system that has a non-zero energy. In other words, a quantum of energy can be adscribed to one bit. Following this way of thinking the information content in the seeable universe is about 10^122 bits. The equivalent" mass" of one bit is 10^(-65) grams. Therefore the gravitational field, having energy, it also has an equivalent number of bits, information.

The it from bit and bit from it is a chicken and egg approach and can only lead to perpetual motion. It can be used as a viewpoint, or point of departure, but one will always be able to start with either the bit or the 'it' or show that both approaches are actually the same. Gravity explained as an entropic force caused by changes in the information associated with the positions of material bodies is an interesting approach, but it all boils down to J Wheeler's statement that mass here affects gravity (spacetime curvature) there. This is an observable fact, and can be 're-described' in alternative approaches or gedanken experiments, of which the entropic force is one.

Of course 'information' flows freely in the universe, and one could probably describe the universe to some level of approximation using (as example) modulation types, as we typically use modulation to transmit information and demodulation to extract/decode information on Earth. With this modulation example available detected energy (our observations, which can all be de-modulated) can be described in terms of amplitude modulation, phase modulation, angular modulation and different types of digital modulation. All of our detected energy will be emitted (from source) and will become sampled 'information'.

To some extent that is already how we measure and see the universe...detectors on optical and radio telescopes, gamma and x-ray telescopes etc. We de-modulate the signals to 'understand' the universe.

So we actually have a modulation type view of the universe.

All the information flowing in the universe affects the observable nature of the universe. So, yes gravitation can be expressed as information (as it is) so can all the other observables. This does not mean to imply that gravity consists or is made up of information, it simply means gravitation contains or provides information. I add this last sentence in case this is misread.

Recently I proof that quantum mechanics can be generate by an extesnion of the entropy idea and by information space. I also create Synthetic Physics where common commutator model join electromagnetism , gravity and quantum mechanics. In conclusion I am ready to write a new paper where information iis the key element for all physics or synthetic physics.

A statistical principle will never govern a deterministic force, let alone an action-at-a-distance like Newton's law. Gravity is not an entropic force caused by the "changes in information in the position of material bodies." Gravity acts even in the absence of motion. But it can cause a reduction in the entropy with respect to the reference state at infinity. The nature of the interactions, discussed by Verlinde, do not lead to increases in entropy; rather, they cause a reduction in entropy from a uniform state to a more constained one through the application of a constraint. The force is mechanical and not entropic in origin.

In analogy with the polymer model discussed by Verlinde, the entropy decreases when the elongation increases that is caused by an applied tension. All this has been worked out long ago in Lavenda, "Thermodynamics of Extremes" (Horwood, 1995) Sec. III.2.3 and V.4.1, and (partially) previously by Callen ("Thermodynamics" Wiley, 2nd ed. , 1985, p. 80) in his 'rubber band' model, where the internal energy is given by an ideal gas (like Verlinde's). See also Frenkel, "The Kinetic Theory of Liquids"(Oxford U. P., 1946). The entropy reduction is proportional to the square of the elongation (and not the elongation itself because that can be of either sign), which is the Gaussian limit. With the internal energy given by an ideal gas, all that can be concluded from the analysis is that the ratio of the force to temperature is independent of the temperature, and can only be a function of the stretching.

Setting the minimum characteristic radius of a normal star (V.123 in Lavenda) equal to the Unruh temperature gives the radius of the star as the Compton wavelength! [Something is missing like the cube root of the number of protons in the star that multiplies the Compton wavenlength (V.138) to obtain the radius,] The Unruh temperature picks out Newton's law, automatically because the force to temperature ratio is constant. Verlinde also recognized this by the appearance of 'c' in a nonrelativistic framework. He even tells us to forget about it. However, he uses a completely ad hoc a relation between the number of bits used and the area. Going through his derivation, he does get Newton's law but iff the temperature is given by the Unruh temperature! So it is no more general than postulating Unruh's temperature to begin with! Moreover, why can't the Bekenstein expression for the entropy in terms of the area of the horizon be used in (3.10) to related it to the number of bits used? Because together with the law of equipartition of energy (3.11) and the second law, it gives an incorrect relation between entropy and energy.

Finally, the motivation behind the paper---Jacobson's derivation of Einstein's equations as an equation of state from the second law---is invalid because dQ=TdS(=TdA/4)=0 for Einstein's equations, and Jacobson's derivation is 0=0. Einstein's equations are adiabatic; they are not thermal equations of state.

I doubt about. We have many evidences that gravitation is very close related with the differential geometry involved for every space-time we study. Besides geometrical arguments I agree with Bernard Lavenda' s remark about:

"A statistical principle will never govern a deterministic force, let alone an action-at-a-distance like Newton's law"

Dear all, thank you for all your answers so far. There are many among you who think that we should be more careful before treating gravitation as information, but as we know in arxiv.org there are many papers discussing ideas related to Verlinde's paper. For instance, there is proposal of entropic dark energy by Smoot et al.(2010). So it seems to me that such entropic gravity is a plausible idea, see also wikipedia entry on entropic gravity.

In this regard, allow me to note that around 1999-2000 i wrote a html article where i discuss gravitational wave equation based on Shannon entropy. The idea is quite different from Verlinde. It includes prediction that mass can be expressed as information. If any of you wants to read my article on this issue, i can give you the url of that article ( i didn,t publish it in a journal).

Best wishes

Dear Dr. V. Krasnoholovets

Thank you for explanation on your inerton theory. Yes i read some of your papers in the past. Best wishes to your future experiments.

Dear Torsten and Resconi, thank ou for your answers, i will read the cited fqxi papers soon. With regards to your Synthetic Physics, it seems interesting to link many physics theories to bits. Perhaps you already know a book by Kantor, an inventor, his book has title: information mechanics. He tried to express all particle physics plus gravitation in terms of bits.

There is also a 1989 Santa Fe publication book with title Complexity and The Physics of Information edited by W. Zurek. That book includes many papers including a seminal paper by John Wheeler, where he explained in detail about it from bit.

I once had each copy of Kantor,s book and that Santa Fe book, but my copies were lost. But if you wish, perhaps you can search on amazon.com

Best wishes

If you allow me to add a very light two bits, I would say that gravity is the field which arises when one quantizes points. By ´point quantization´ I mean replacing coordinates by noncommuting operators. The requirent that the product be nevertheless associative as expressed by Jacobi identities places restrictions on the algebra of operators. This has been worked out in explicit models. One finds a

relation between curvature and commutator whch yield second-order equations for the metric.

To return now to your point, which I guess is a generaliziation of the black-hole relation Does the above help? Not a bit! But it gives a concret answer to another question which might be related to it.

If I may add I think Wheeler was more to the point (pun intended) when he thought of gravity as a distribuiion of defects in a solid.

May I suggest that you read Sections 44.4 (Pre-Geometry) and 44.5 (Calculus of Propositions) of the great Misner, Thorne and Wheeler "Gravitation"?

Along those lines is the article by Patton and Wheeler on pre-geometry and information (if you can find a copy - anyone out there have one they can post?): Patton, C.M. and Wheeler, J.A. (1975) Quantum Gravity, edited by Islam, Penrose and Sciama, Oxford.

The paper by Bohm, Davies and Hiley is technically difficult, but worth a go: http://arxiv.org/ftp/quant-ph/papers/0612/0612002.pdf

The difficulty with such conceptual discussions is to sort out the serious from the ill-conceived or plain nonsense. There is very little of the first, but an enormous amount of the last.

Dear Dr. Bernard Jones, thank you for your references. I will try to read them. Best wishes

Dear V. Krasnoholovets, your theory seems to be an interesting one. Have you predicted any special case where the presence of 'inertons' will be unambigously obvious and without any other 'overlapping condition'? Thank you.

@V. Krasnoholovets

Thanks for the remarks.

Please note that I did not recommend MTW "Gravitation" in hte context of this discussion - I only recommended those specific sections which I would regard as at least interesting in the context of the present discussion.

MTW is, as the title says, a book on gravitation and a fine one at that. Those last chapters honour the imagination of John Wheeler, who, along with Zel'dovich, is perhaps the most innovative physicist I have ever met.

In the strict exact way the information relies on the concept of probability and

statistics. It represents the degree of statistical dependence of two (or more)

random variables and so it is suitable for describing statistical system or statistical

behavior. In the Newton and Einstein theory the description of physical laws is

deterministic. This is why the information, as a probabilistic concept, is not suitable

for the description of classical gravitation. However, in the quantum

gravity this concept can play an important role.

Dear Victor Christiant

Thank you for the information. In your replay there is a misunderstand of my work. For the fist poinr information is not connected with bits but with geometry. Information space and its curvature or torsion given by Fisher information or other metric give us the structure the information to relate a multidimesnional type of entropy with quantum mechanics. Information is not always connected with probability but with geometry. I use to connect geometry with commutators relate to Gauge. So with

gauge theory and metric with a novel structures of commutators give us the formal description of Maxwell equation , generalisation of Einstein equation and quantum mechanics with Casmir effect. So if you read my paper Synthetic Physics you have the opportunity to discovera new general theory Beyond the Kantor and Zurek work.

Thank you, Dr. Vladimir Majernik, for your answer. Best wishes

Thank you, Resconi. Could you please give an exact url of your paper? Best wishes

Yes in reserachgate at my name you see my paper with Licata

hi

I am more an experimental physics guy who rely more on experimental results than theory. Can your explanations work for these experimental results.

When a beam of light is passed between two mobile masses, the masses are getting closer to one another.

I could give a summary of the results that were published in Physics Essays, Dec. 2011 on the effect of light on gravitational attraction.

Have a good week

Louis

Hi Louis: I have found that the source of gravitation, the gravitational atraction, is due to the total relativistic energy of each system. This means that gravitation is due to energy, and therefore it includes a photon gas. Then your experimental results are by these results explained ok: the beam of light atracts the two mobile masses when passing between them and therefore the masses atract each other (due to the energy of the photons). These results will soon appear in the Journal "Astrophysics and Space Science" and I will upload it here shortly.

Hi Louis: I have added here my paper in the "Astrophysics and Space Science" that has been approved for publication on January 17, 2014. It includes the theoretical grouns to consider gravity source to be the relativistic energy of the system, thus including photons.

Sorry Louis, here is the attachment

Dear Antonio, I read your article and found it very interesting. Could you suggest a proper experiment to show and clarify the primary nature of your suggested relation between G and c? Since it is so fundamental it is most probable to exist an experiment that proves it. Thank you.

Hi.

Thanks for your answer. There is a point that has to be clarified. If we accept that nothing can go faster than c, then light going between 2 masses of 100 g cannot affect the 2 masses because what light would be sending to the masses would have to go faster than c. The vector of light going East to West for example is = to c. Then anything leaving light at an angle has to go faster that c.

Is it possible that light going from East to West interferes or blocks some of what was going from North to South, thus shielding some of its effect. That would give a push to the mass and they would seem to attract one another. If so, that means that light can really interfere with what is the force of gravity.

Louis

Interesting paper Antonio. If you want to, I can fix the grammar a bit before it is published as it stands.

Thank you very much Ludwig. Publishing is already in its course, so it is late for fixing. Thank you any way.

Dear all contributors, thank you so much for all your answers and comments. Here allow me to upload a summary of this discussion in pdf file. Hopefully this file may stimulate further investigation. best wishes

As long as nobody knows what gravity actually is, and how it relates to the other realities of the Universe, one can speculate, but definitely can’t know if it contains information.

Of course, its information is well known since Kepler and Newton, that it is the force holding masses together. We even have equations to use this for information.

Einstein did not know what gravity is and how it relates to the known energies. His pasting gravity on mass as curvature of space is unreliable, since he started with gravity. There is no cause – effect determination. To determine what gravity is and how it relates to the other energies, one cannot start with gravity as one of the starting theorems.

I did model the formation of the Universe as a crystallization process, converting the pre-BB energy into mass particles. Gravity is not in the theorems. The surprising result (!) of the modeling was that gravity is anti-energy. Following up the processes in the Universe, this energy is in the form of photons.

Note: I have been a scientist for over fifty years and the model is based on my research on crystallization ‘from scratch’, using only real effects ((crcpress.com, free viewing, look under Ingo Leubner; no guess-variables). Since then I have been studying, presenting, and submitting papers on astrophysics to journals and Research Gate for thirteen years. The gravity-model was used to model and predict events in the Universe, and in the solar system, since all physical constants are known. Why is Sedna in the process of leaving the solar system?

Dear Ingo, can you give us a link with a presentation or publication of your 'model the formation of the Universe as a crystallization process'?

Thank you.

Dear Ingo: please let me know if your anti-energy photons may have an equation of state like this:

pressure = (- energy density).

Thank you

Demetris, Thank you for upgrading my comment. Thank you also for your encouragement to put this all together. I am in the process of condensing the original manuscript. I will let you all know at the Research Gate discussion when it is ready.

Antonio: I have not gone into those details. However, separating the photons from the bending of space clarifies that the photons have twice the gravity of energy-equivalent mass particles. The reason for this is, of course, that they are moving at the speed of light. This has significant consequences, both theoretical and experimental. I will publish the information at this discussion, when I am ready. I will need to proof-read it again.

Dear Ingo, Demetris, and Antonio. Thank you for your comments and best wishes to your work.

I think there is a certain confusion, related to the application of the entropy concept from Physics and the equivalent idea from Information Theory. The latter was borrowed from the former by Nyquist, and a couple of decades later developed by Shannon and Kolmogorov. Stephen Hawking has been pushing this concept in association to the evaporation of black holes since the seventies, but once in a while he changes his mind about it.

@Marcelo. Thanks for your answer. Best wishes

Here in RG I have uploaded published research papers that deal with this question of gravity and information. First, it seems that information has energy, and there is some experimental and theoretical evidence that this may be the case. The energy of one bit can be identified with the self gravitational potential energy of any fundamental particle, the minimum quantum of energy in the universe, hH, where h is Planck´s constant and H the Hubble parameter. Since entropy is an extensive property it can be considered proportional to the mass of the system under consideration. Then one has a link between Entropy-information-gravitational potential energy. This strongly hints that gravity has an information content. In fact the dark energy component of the universe can be adscribed to have an amount of information of the order of 10^122 bits.

@Antonio and @Manuel. Thank you for your answer. Best wishes

Entropy: A concept that is not a physical quantity

https://www.researchgate.net/publication/230554936_Entropy_A_concept_that_is_not_a_physical_quantity