I imagine an observer looking all move away from him. And now I imagine all the observers in all the Universe... And I think that this estrangement of all is an illusion, or a limit of our senses.

But I know that it can be explain like a point in a growing bubble.

(Sorry for the simple explanation).

I think we need the distances from us of all, and then (if the expansion is the same in all direction) we can know the redshift because the expansion of the object, and more or less of this implies another relative movement about us.

Dear Ana Maria, yes the general picture is just that we are using our physical laboratories and telescopes at the Earth and also space observatories to detect photons, neutrinos, protons, gravitons, and other known physical particles, so to measure the distances to all astrophysical objects and also construct the observed physical properties of the astrophysical objects, which will related to the different cosmic distances and hence cosmic times.

The astrophysical nature of the cosmological redshift can be derived from the system of such observations by using different cosmological models for interpretations of actual observations.

E.g. Hubble(1929) demonstrate that there is a linear relation between redshift and distance of the nearby galaxies and conclude that this is a new cosmological phenomenon due to De Sitter effect in a static universe (so Hubble never consider his z vs. r law as a result of real systematic motion of galaxies) . Later Lemaitre (1933) interpreted redshift as an effect of expanding space in FLRW model, so the Hubble law was interpreted as redshift – velocity law in the “Hubble flow of nearby galaxies”.

To answer the question on astrophysical nature of cosmological redshift we need construct a crucial observational test which can distinguish between this two radically different behavior of galaxies : 1) redshift exist but distance between galaxies is constant or 2) redshift exist and galaxies change distances with time so that they are receding. Such test will help to understand the nature of cosmological redshift: 1) is it a result of gravity of the cosmologically distributed matter or 2) result of motion of galaxies (Doppler effect) or expansion of space (continuous creation of space volume, i.e. new cubic centimeters between galaxies.

Such crucial test has not been fulfilled yet, though there are several suggestions which can be realized in near future by using 40 m large telescope.

Our (the) existence cannot be explained without expansion. This implies redshift about every position. If it is, the relative distances must increase. If the matter not increase the Universe density must decrease (to lose other references). I don't know if it is observed. (The matter can be created).

I think it is necessary a complete vision of all is know now, for general people.

[Si la "experiencia" te hace crecer, el Universo siempre crece. (artistic)]

Please do not make strong clames about the things (like our existence) which much higher than human's mental ability. One can only compare possible theoretical models of the universe by constructing crucial experiments/observations.

No possible without observer.

Existence of observer is a part of the existence of the Universe with its physical laws which was created just right to be compatable with life, action and observation.

I have some thoughts that I think are not often considered in this debate.

Supernovae generally emit light that is highly luminous (resulting in relatively high photon detection counts) of for a relative short period of time. It would seem, therefore, that any Doppler effect imparted to the emitted light by the relative velocity of the emitting object must be extremely limited, since the emitting object may only exist as a luminous object for a brief period of time.

As I understand, even high z SNe exhibit significant redshift (even ignoring their host galaxies' emission). This would seem to argue against the Doppler effect of the emitting objects' relative motion being a significant contributor to cosmological redshift.

However, while a discrete packet of SN light is propagating away from its emission source (in all directions), it seems that it may not be often considered that the Milky Way is and has been effectively receding away for the duration of the light packet's propagation.

Because the SN light is restricted to a discrete packet (emission duration), any Doppler effect that might be imparted by the recession velocity of the receiver (MW) could only include the immediate recession velocity of the receiver - not any past recession velocity that has occurred during the light's propagation duration. This also seems to argue against any significant contribution to cosmological redshift by either the recessional velocity of either the emitter or detector.

From this I have to conclude that cosmological redshift is almost entirely imparted by the expansion of spacetime, increasing the physical space between each light wave as it propagates through expanding spacetime.

Regarding mathematical proofs of varying alternatives, I don't do math, but I suspect that various methods might be compelling even though they might not accurately represent the actual mechanism producing the observed effect.

I hope this line of reasoning is understandable.

Please let me know if there's something I've overlooked...

To be finite light speed (c) distance implies a retardation. How we see the delay in our observation?

Dear James, your argument is not clear. Cosmological redshift is universal and light from any source of radiation including SN and its host galaxy. Also cosmological redshift the same for any spectral range of a source from radio to gamma emission.

Dear Ana Maria, yes your note is very important. Delay effect is observed via slowing the variable processes in very distant sources, like in SN light curves.This effect is predicted by all suggested mechanisms - space expansion, Doppler effect, and gravitational effect by matter distributed between source and observer.

Dear Yurij, perhaps I missed what is not clearly stated in your question: the Chodorowski, Bunn & Hogg, and Melia case isn't a thinly veiled argument against universal expansion inferred by cosmological redshift, is it?

The experimental facts are that at superclusters scales and beyond all the objects are red shifted isotropically, ie the apparent recession speed is the same in all the directions at the same distances. This is called "Hubble's flux" and is interpreted as the expansion of spacetime in between the superclusters.

At galactic and galaxy cluster scales, there is not a since the proper motions of the objects dominate, so that some are receding, others incoming , therefore some are red shifted , others are blue-shifted,. In addition, the "local" gravitational binding forces at these scales dominate by far against expansion, ie the spacetime in between galaxies and cluster of galaxies do not expand (it can be calculated).

The classical example is that of a leavening cake with raisins inside: while the cake leavens, the distances between raisins increase but the raisins themselves do not expand. The cake is the spacetime, the raisins are the superclusters.

Emanuele, yes - thank you. Since mass and its gravitational effects are localized and not Isotropically disperse, distant light traversing spacetimes curved by local concentrations of massive objects should not be imparted with universally isotropic redshift - correct?

Also, shouldn't light traversing a gravitationally curved space first be blueshifted on its approach, then redshifted as it departs, producing a net neutral spectrum shift?

It would seem that any gravitational spectrum shift imparted to very distant light should only produce an isotropic redshift if it had universally preceded from a gravitationally dense spacetime to a more disperse spacetime - also inferring a temporally expanding universe.

Dear Emanuele, you rise very important subject about observation of the Hubble law and inhomogeneity of the matter distribution in the Universe. In observational cosmology this problem is known as the “Hubble-deVaucouleurs paradox” (see i.g. arXiv: 0810.0153 and references there).

The problem is that the very good linear redshift – distance relation (which is true Hubble Law, discovered him in 1929) is observed deeply inside the inhomogeneous galaxy distribution. It was established by independent measurements of redshifts and distances to the local galaxies

Karachentsev & Makarov, Astron.J., 111, 794, 1996;

Karachentsev & Makarov, Astrofizica, 44, 5, 2001;

Ekholm et al., Astron.Astrophys., 368, L17, 2001 (arXiv: 0103090);

Karachentsev et al., Astron. Astrophys., 398, 479, 2003 (arXiv: 0211011).

So the linear Hubble law starts from the very small distances about 1 Mpc with the small velocity dispersion about 30 km/sec, while the scale of super clusters is about 100 Mpc.

The puzzle is that the linear Hubble flow is the strict prediction of the Friedmann model only for the case of strictly homogeneous matter distribution.

In many papers and books there is wrong claim that the Hubble law exists only at distance scales of super clusters. For example in the good book by Weinberg “The first three minutes”(1977), he noted that actually Hubble could not discovery the linear redshift law within so inhomogeneous galaxy distribution at scales 1 – 10 Mpc. However modern observations clearly demonstrate good linear redshift law just within local volume.

There are several suggestions for solution of this paradox, such as the manifestation of homogeneous dark energy distribution at small scales (Chernin A., Phys.Usp.,44,1153, 2001) and cosmological gravitational origin of the linear redshift law for D=2 fractal matter distribution (Baryshev Yu.,2008, arXiv:0810.0162).

Dear Yurij, thank you for your very interesting remark, that redshift is already proved down to 1Mpc! This supports the aspect, that cosmological redshift is a quantum effect of the photons jumping from the source of light to our observation equipment. The free energy of a photon could be reduced by this process, since it quantum-leaps over a part of the potential of the whole space in the universe. It has its maximum distance, where the potential difference sums up to c^2. I could prove this theory mathematically under the premise that the whole universe is a kind of a bloch-sphere. But this results in a non-Euclidian space too. Therefore also the interpretation of the Supernova Cosmology Project could be revised.

Dear Georg, your idea about quantum nature of cosmological redshift is very interesting. Several years ago I came to similar thought on a possible explanation of the observed cosmological redshift (http://arxiv.org/abs/0810.0162 and our book BT2012). However in my opinion your Quantum Information Theory strictly speaking is not a theory and not about information. As I see in your presentation of QIT actually it is an interesting hypotheses on the quantum structure of matter and space, and the word "information" can be replaced by "fundamental entity" or so on.

To be a physical theory a suggested idea should have mathematical instrument for calculation of new predictions for experimental results, which can distinct between different hypotheses and not only give new explanation of known things. I think that your idea in wright direction and cosmological redshift may be an observational effect predicted by QIT which can be tested by a crucial astrophysical test such as future Sandage's dz/dt of changing z with time.

If I understand what is meant by "photons jumping from the source of light to our observation equipment," why would even finite duration 'bursts' of type Ia supernovae photons, presuming consistent peak emission luminosities, indicate their distance, based on the diminishment of their observed luminosities?

How would 'jumping photons' luminosities be diminished as a function of the distance between their emission source and our detectors? As I understand, since the 'jumping photons' would not have physically traversed the entire distance, their properties should not be altered in any way relating to the separation distance between their emission source and detector...

Let me try to answer your remarks as precisely as possible within this small text field.

Yurij, your paper is definitely interesting and adds up to a few similary furmulae. E.g. the total mass of the universe results according my calculations to m = c^3 / (H*G), where H is Hubbles constant. It differs from your formula (16) in the refered paper only by a factor 2. This is, because your calculation is based on Einstein's field equations and I found another one. As you say, a theory is worthy, if it predicts some unknown effects, which could be observed later. Furtunately QIT is capable to do so, but also it revises known models like SRT, GRT or even Newtonian mechanics in a very subtle way. E.g. the mass of our universe results with the formula above in 2,1*10^53kg, which is remarkable close to the current estimations of the visible mass by astronomers. (QIT does not need dark matter to understand the movements of galaxies.)

Just please do not prematurely draw conclusions about the very precisely and newly defined items of QIT, like the definition of information. Information according to QIT is the relation between two different quantum states. E.g. the aggregation of many different quantum states to one "fundamental entity" deliveres the matrix of elementary particles in our universe. Therefore we can predict all possible entities with their qualities within a complete scheme for the first time! (This works alike Mendeleev's periodic table.) There are about 10^93 entities in our universe (mostly photons and neutrinos, followed by protons, electrons and neutrons - the last three together about 10^80)) in our universe.

James, as always you ask most fundamental questions, which I appreciate! The quantum leaps of particles (entities) are very easy to unserstand in QIT as a transfer of information between two quantum systems. Many of such transferes, which we call interactions in the physical sense, define the lattice of our space-time. Therefore the space in our universe is closed in itself - the universe as a wholei has no surface and therefore is not a body! Only parts of the universe can be confined from the rest of it.

If a photon transferes its information (energy) from one distance place in the universe to another, like quoted above, it has to change the information about its location! Since this information has to be provided by the photon itself, its free information for the next interaction with matter, which represents its energy E=hv, will be decreased in proportion to the length of the jump compared to the longest possible jump, which is defined by the greatest difference in information by all possible positions in our finite space-time. This effect is called energy attenuation. Please be aware, that this effect conserves the energy, according QIT.

This effect does NOT explain the diminished luminosities of photons coming from distant super novae, but the underlying structure of space-time does. This is because the longest distance....

The red-shift of the spectra of distant galaxies was and is first an observation. This red-shift was modeled as the Doppler effect of the movement of galaxies. The problem is that there has been no credible model for the cause of the recession of these galaxies. For some time, there has now been a model that predicts the recession of the galaxies independent of the red-shift. Indeed, it predicts the red-shift and its increase with galactic distance, and also the acceleration of this recession. I have been modeling the life-cycle of the Universe, developing the Big-Bang-> Fizzle -> Big Bang model. The model is based on the process of the formation of the Universe (electron and protons) from the pre-BB energy singularity and the present massive radiative conversion of Mass to Energy in the form of Photons (e.g., solar radiation). The model predicted that the solar system is expanding, predicting the experimental results that Mars changed from liquid to frozen water about 3.7 Byr ago.

Back to the Hubble Enigma: The same model, applied to the Universe, leads straightforward to the result, that the Hubble-constant is H0= ku/2, where ku is the radiative mass loss constant of the Universe. The reported and confirmed range of Hubble constants is 30 to 98, with a statistical average of 66.9 (std. dev. 9.9). This indicates that the different Hubble constants reflect different radiative mass loss constants in different parts of the Universe. The model also predicts the acceleration of the expansion of the universe.

Sorry to interrupt the discussion. But I believe that is more to the Red-shift than people generally think. A speed of light that was greater in the past will yield larger wavelength at the time of the emission of the light quantum. And so the Red-shift could really be a mixture of expansion and changing speed of light. Please read my paper in Journal of Modern Physics,3,4 2012. Best regards, Paul Smeulders

Dear Paul: yes, I agree with you. The red shift is measured by means of the frequency of the incoming photons: that is c/wavelength (c the speed of light). Since the wavelength of the photon should estrech as the cosmological scale factor R (an expanding universe streching wavelengths) then the redshift should be proportional to 1/R unless... c varies with the expansion of the universe !!!! And if it decreases with expansion (so I think), then the red shift runs faster thatn R as we go deeper in space.

I disagree that the "problem is still open", other than the usual disclaimer that anything in science is subject to modification upon new observational evidence. I recommend Ned Wright's page for those who wish to know what the generally accepted model of cosmology is:

http://www.astro.ucla.edu/~wright/cosmology_faq.html

Quoting from his FAQ: "In one view, the spatial positions of galaxies are changing, and this causes the redshift. In another view, the galaxies are at fixed coordinates, but the distance between fixed points increases with time, and this causes the redshift. General relativity explains how to transform from one view to the other, and the observable effects like the redshift are the same in both views."

There is no controversy nor disagreement about whether the redshift is due to motion or expansion. They are one and the same (aside from relatively small motions of galaxies with respect to their nearby surroundings).

Also see Michael Weiss's answer to a question on the topic:

http://math.ucr.edu/home/baez/physics/Relativity/GR/hubble.html

I agree with Jay. One description is made in comoving coords (galaxies at rest, space stretching), the other is in physical coords(space fixed, galaxies receding).

However, the "classical" Doppler shift explanation of cosmological red shift fails when red shifts are large. For that case you need the complete machinery of the FRW metric and consider the change of H during the light travel, (pretty much the same as to get proper distance of a cosmological objects).

Dear Jay and Emanuele,

the real bases of Friedmann cosmology is the gravitation theory and General Relativity is one possibility among modern consideration in theoretical physics.

I know the Wright page and even sent him some questions but without an answers.

Actually he is not a specialist in the theory of gravitational interaction developing within theoretical physics.

The paradoxes of the expanding space physics are presented for specialists in my paper arXiv:0810.0153, where exact GR equations are considered. The main strange thing is that exact relativistic Friedmann equation is completely identical to non-relativistic Newtonian equation of the gravity force for expanding ball of mass.

And this is not an approximation, as claimed in many papers, but strict mathematical fact within general relativity. This fact leads to many other paradoxes, including violation of velocity of light for receding galaxies and energy non-conservation in expanding space.

Your problem is that you consider an physical analogy as a true physical understanding of much more deeper physical phenomenon, which should be described by corresponding mathematics.

Mathematics is great. GR is mathematics, not reality. GR agrees with observations. Does the mathematics you are talking about predict any observations different from GR? If so, does it agree with reality, and if not, what is the point?

Yes, any feasible gravity theory agrees with existing observational facts such as perihelion shift, bending of light, gravitational redshift, precession of rotating bodies

and so on. But there are predicted new gravity physics effects according to which it is possible to distinct between GR and other gravity theories. The first alternative to GR is the tensor field gravity theory which consider gravitational phenomena as other fundamental physical interactions.

So the point is to perform crucial experiments which demonstrate which theory is closer to reality.

Paul Smeulders, you base your proposal of a variable velocity of light on a paper on the observation of galaxies.by Bouwens & al. in 2004. The number of galaxies measured since then is enormous I wanted to see whether that result has been upheld, but no, none of the newer papers by Bouwens & al. never mentions their 2004 paper. Therefore I do not believe in yor proposal.

Paul Smeulders and Matts Roos: I have found some recent papers from a group of researchers, including Bouwens, that claim measurements giving a red shift - size relation of the order of (1 + z)^(-1) . Paul, I think that your proposal deserves more research effort. Thank you.

Dear Antonio, Thank you for your comment. There is even more to it. As you have seen in my paper of April last year, the clocks also change with the expansion: they all run faster at higher z+1. And that implies that the expansion is not just over space but over space-time. This then leads to an apparent exponential change of the Red-shift even if 1/(z+1) is changing linearly in real time. So the acceleration of the expansion over time is an artefact of this space-time expansion. No Dark Energy is required at all. I will be presenting that at the MIFP meeting in Rome on the 25 of March this year and will try to publish it soon after that meeting. If you are interested I can send you a Power Point presentation but that presentation will also be on the Website of the MIFP.. Best regards, Paul

Dear Paul: thank you for your information. Regarding .... " I can send you a Power Point presentation but that presentation will also be on the Website of the MIFP...." I would very much appreciate it sending me your power point presentation. I am very interested. My e-mail is: [email protected]

Best wishes,

Antonio

Dear Yurij,

in the listing of possible solutions for the red shif problem you can also place an idea presented by Stanislaw Bellert in "Astrophyssics and Space Science" in 1970 (http://adsabs.harvard.edu/full/1970Ap%26SS...7..211B). He concept is related to the metric of space and properties of electromagentic waves.

Dear Yurij and all it may concern,

'The Pearlman SPIRAL cosmological redshift hypothesis and cosmology model is an alternate hypothesis on the cause of Cosmological Redshift (CR) might help answer the opening question as it it greatly reduces the time it took for that CR light to reach us from where it originated. So much less time for gravity to pull on it, 5776 years versus up to about 13 billion years.

Also assuming the actuality SPIRAL explains why CR is from previous, not ongoing cosmic expansion, so is  consistent with a currently static/stable steady state oscillation universe not an expanding one. Which would falsify standard cosmology model with it's  premise of CR due to ongoing Cosmic Expansion.l.

please advise if your research helps confirm it. TY, rmp

I completely agree with and appreciate the question asked by Mr. Baryshev. This is the strangest enigma ... Is any question really 'closed' when it comes to astrophysics in relation with higher physical sciences? In my humble opinion, there are two fundamental issues regarding the puzzles around cosmological redshift. First, It will be apparently and utterly foolish if I ask: Is the redshift a scalar quantity or vector quantity? Is it measurable? Second, if the redshift is a completely observed phenomenon, then is it a phenomenon at all? Why humans are observing 'that thing' in the way it is being observed?

I think creation of more conjectures can help at the initial stages of assessing redshift as an astrophysical process at the best and illusion at the worst. Furthermore, the physicochemical attributes of distant stars must also be determine, and we should further ask questions like: Are there varieties of black holes to be determined on the basis of their chemical compositions or natures? if not, then why?

I am attaching some links to help in more fundamental and newer ideas.

http://journalofcosmology.com/JOC25/HOW%20A%20BLACK%20HOLE%20UNIVERSE%20THEORY%20MIGHT%20RESOLVE%20SOME%20COSMOLOGICAL%20CONUNDRUMS.pdf

http://en.cnki.com.cn/Article_en/CJFDTotal-YNSK201502004.htm

http://arxiv.org/abs/1504.04746

Arghya Ray,

Your questions have mostly been answered here already by Jay R. Cummins in March.

Instead of referring to occasional links to papers with abstracts you think look interesting, why not read those links yourself? The questions you pose are answered in the scientific literature - or the answers are not known. In both cases Research Gate is not the first place to look for answers.

@ Matts Roos 

The question was:

"What is the astrophysical nature of the observed cosmological redshift?"

The main part of my answer is: 

"I think creation of more conjectures can help at the initial stages of assessing redshift as an astrophysical process at the best and illusion at the worst."

Of course my answer is not completely dependable, but I am trying to hint toward more conjectures that we will have to face in near future.

Dear Yurij

could you partecipate to this thread???

I need your contribution.

https://www.researchgate.net/post/The_gravitational_redshift_is_a_phenomenon_based_on_gravitational_time_dilation_dont_we_want_to_exclude_definitely_any_loss_of_energy_of_photons

To all it may concern,

The Pearlman SPIRAL an alternative cosmological redshift hypothesis and cosmology model is now published under the title 

'Distant Starlight and the Age, Formation and Structure of the Universe'

Dear Yurij

The Cosmological Redshift Manifests the Curvature and Interpreted as a Degree of Hyperbolicity of the Spacetime  Hubble’s law describes a  uniformly expanding flat universe. Hubble’s law doesn`t explain why distant objects were receding fastest. There is an approximately linear relationship between redshift and distance at small scales for all the FLRW models, and departures from linearity at larger scales can be used to measure spatial curvature. Locally the spacetime is flat. For distant objects, the imprint of the curvature is significant, where the spacetime does no longer remain flat. The redshifts from such distant objects increase according to the increase in the curvature of the hyperbolic spacetime. The cosmological (gravitational) redshift can be interpreted as a degree of the hyperbolicity of the curved spacetime.  The Universe is globally hyperbolic as we did prove mathematically [S. A. Mabkhout, Phys. Essays 25, 112 (2012)]

Book The Hyperbolic Universe.

Article The Cosmological Redshift Manifests the Curvature and Interp...

Dear Salah,

to understand the physical nature of the cosmological redshift one should perform the crucial experiments/observations which can distinct between different suggested interpretations  .

The first thing for testing is the reality of increasing with time the distances between galaxies (Sandage 1995, Astronomical problems for the next three decades ). Intriguingly up to now there is no direct testing of this basic for SCM phenomenon, but modern technology is very close to test reality of global expansion.  Such tests are: 

Sandage (1962) test of the change of redshifts of distant objects with time, which is about  1 (cm/s)/yr , which is one of the task of the future Extremely Large Telescope (30m - 100 m).

Kopeikin (2014) test in the Solar System - by using Doppler-tracking observations of celestial bodies contain some terms of the cosmological origin that are proportional to the Hubble constant H_0. 

Of course we expect also new physical tests of the reality of expansion which will be based on modern and future achievements of technology. The references related to the problem of the cosmological redshift one can find in

https://arxiv.org/pdf/1702.02020.pdf

one annual test SPIRAL calls for testing it's prediction/s is the distance to the nearest source of  CR light. 

per SPIRAL over time we should notice an average increase of 1 LY per annum,

Dear Yurij and all

7 years after the post of your question a possible answer can be found in the presence of (dark) particles stream having high density. Some evidences of this stream could be found in the results of an (unfortunately) amateurish experiment I invite you to read Preprint ON SOME EVIDENCES OF A NEW KIND OF SIGNAL OF COSMOLOGICAL ORIGIN