A Critical Look at the Standard Cosmological Picture by Daryl Janzen

[deleted]

This is part 3

Ok, I understand that expansion is one explanation to df vs d. Then, what do I argue? Based on the preceding historical discussion, I ask: Is the expansion the only possible explanation? If, according to the conclusions drawn from the essay, the aether is reconsidered, the answer clearly goes in the negative. As we have seen, all that is required is to explain the relation df vs d. The theory of waves can easily reproduce this. And it tells us that the larger the distances the more energy is dissipated/scattered by the aether and therefore light will appear red shifted for an observer on the earth. In this model there is no expansion and space is essentially Euclidean avoiding in this way the horizon and flatness problems. This also explains Olber's paradox even if the universe were infinite in extension. The CMBR it is not interpreted as a relic radiation but it is just the signature of a thermodynamic system in equilibrium, etc.

This model also implies that not only the determination of red shifts is in need of corrections but also the distances; for the luminosity is function of the light energy per unit area. Moreover, we can see that this model is quite simple, explains many problems, it is more consistent and could lead to new insights.

So I hope you have understood my points and I will be looking forward to seeing any response you may have.

Best regards

Israel

DANIEL ALVES

Dear Daryl

Congratulations for your essay, I see it relies on very clear and strong arguments. Unfortunately I haven´t studied cosmology in depth yet (it would take me an amount of time I don´t have to completely understand all the major points in your essay). I think I can´t make any major contributions to the debate. I just would like to point out that just as 3+1 ADM formalism of GR, there is an alternative formulation from purely Machian first principles in which the basic building blocks are parameterized shapes of the universe (this parameterization is arbitrary, however there is one distinguished parameterization which could have a relation with your ''cosmic time''). It is the research of Julian Barbour, Shape Dynamics.

I also invite you to take a look in my essay , for it discusses absolute and relational (and possible extensions of it) conceptions of motion.

Best Regards,

Daniel

Daryl Janzen

Dear Israel:

My apologies for not responding to your detailed post until now. I haven't been in a position to dedicate a great deal of time to these comments, and I couldn't properly respond to you without doing that. Your initial statement bothers me because you still really don't understand how cosmological expansion is commonly thought to be connected to the observed redshifts, and your statement tells me that you aren't really very willing to try to understand the theory you're wanting to argue against. When you wrote that I didn't answer your question about estimating radial velocity of galaxies, but instead alluded to the explanation of expansion, you really missed my point, that your question is basically a false start: it's equivalent to asking why humans have come to the consensus that the sky is green. We haven't. Nor are cosmological redshifts really supposed to be associated with recessional velocities. You're going to argue that Einstein wrote that bit about a connection to Doppler shifts in Appendix IV of Relativity (more about that below), but Einstein was a very poor cosmologist, who never put more than half-hearted thought into the problem after his 1917 paper, and caused far more harm than good because of this, and because of the fact that he took the wrong stance on a couple of key issues. For instance, as I wrote in my essay, the paradigm he largely helped to create accepts a description of cosmic expansion that stands without explanation.

So, more to my point that your question is equivalent to asking why the sky is green:---redshifts are obviously quite naturally associated with recessional velocity, according to the Doppler effect---therefore, the fact that everything beyond a point is redshifted gives the impression that everything is moving away from us; but the early cosmologists didn't like this, and opted for the more objective viewpoint, especially after Hubble confirmed the redshift-distance relation, that the redshifts are caused by a global expansion of space. In an expanding model, distant galaxies *do* incidentally physically recede from each other (physical distances increase in time), but the redshift is *not* actually caused by the associated recessional velocity, but is supposed to occur because light loses energy by travelling through expanding space. We actually assume that any Doppler shift there may be in the spectra is completely negligible and every source remains forever at rest in space, as I noted before. The effect is therefore more similar to your tired light-type idea than you've realised, except that there are a number of factors, such as the agreement with big bang nucleosynthesis theory and the description of fluctuations in the cosmic background radiation (you should read the Wikipedia article) that are consistent with actual Cosmic expansion. Furthermore, theories like yours and Steady State, where 2.7 K should just have to be assumed without cause, as the temperature of space (or aether), are objectionable because they don't lead to an explanation of why that should be. Since our main problems in cosmology have to do with a lack of explanation of things that are already very well described, I see it as a step backward to lose the consistent detailed explanation of the CMB. If we don't care to explain things, and are comfortable with descriptions of things as being the way they are because the way they are is quite simply the way they are, then we might as well opt for the most trivial such theory, empty of *any* explanation at all; viz., that everything and all the Laws of physics Are because of an omnipotent Being. With such a theory, you can't lose: you can't not describe every observation that might be made.

So I wasn't avoiding your question about recessional velocities, but since a connection between redshift and "recessional velocity" has little to do with the standard cosmological picture, I attempted to correct your misunderstanding of that and move the discussion forward. I'm sorry you misunderstood my intent.

Now, there are a number of issues in your historical overview that I'd like to touch on specifically, but I'll do that in a separate post. I hope what I've written here does now allow the discussion to move forward.

Daryl

Daryl Janzen

Here are some comments on specific points in your posts:---

1. First of all, on the reported red/blueshifts during the 1910s, you should be aware of what de Sitter wrote in his 1917 paper where he derived his famous solution: "Spiral nebulae most probably are amongst the most distant objects we know. Recently a number of radial velocities of these nebulae have been determined. The observations are still very uncertain, and conclusions drawn from them are liable to be premature. Of the following three nebulae, the velocities have been determined by more than one observer..." Therefore, even in 1917, *one of the world's foremost astronomers* would only reliably quote three measurements. Note that he does speak of "recessional velocity" as synonymous with redshift, according to the Doppler effect, even though he was trying to promote a model that's very much like yours, in which there was no actual expansion or radial velocity: his original solution described light from a fixed distant source as being redshifted due to the space-time geometry.

2. "The other crucial point is that we have evidence to start to generate the idea that if most of the nebulae are moving away it is probable that we are at the center of the universe or some sort of explosion. This is one of the most natural realizations on the basis of the prevailing conceptual-theoretical framework of that time." This is a primitive inference, not a natural or well-reasoned one---like the geocentric view. As my previous quotation from Eddington was meant to show, cosmic expansion was thought to provide a far more natural explanation of the redshift-distance relation than an explosion with us at the centre.

3. When discussing theoretical developments during the 1920s, you can't bring Friedman's or Lemaitre's works into the mix because nobody knew of them. In fact, de Sitter *never* knew of Friedman's second paper, and Einstein likely never did either, even though he lived much later. Eddington's book, "The Expanding Universe", was published in 1933, after Hubble showed the linear redshift-distance relation.

4. If nothing else, you really have to understand that "radial velocity" is used synonymously with redshift for historical reasons, and not because anyone has ever fixated on the inference that the redshifts should result from the Doppler effect. There was no "idea of correlating distances (d) with v" as you've written; only an observation that distances *are actually* correlated with redshifts, with the latter word being used interchangably with "recessional velocity" for historical reasons.

5. I can't believe you actually think it's my contention that there should be some explosion with us at the centre!?! I haven't stated that in any discussion here, and I'm certain it's wrong. I have stated repeatedly that I think the most natural and consistent explanation of the redshift-distance relation is cosmic expansion. I don't know where that paragraph came from. Then, the following paragraph about redshifts greater than 1 was actually an argument I previously put to you, so I don't see why you've restated it.

6. Then you quote something from Einstein's Appendix IV to "Relativity: the special and the general theory". He did not write that in 1924. Hubble made his observation in 1929, and Einstein makes reference to that in the quote. Einstein first referenced Hubble's and Friedman's (1922) work in an article in 1931, and this appendix has to have been written after that. The last paragraph of his that you quote displays a lack of understanding of FLRW cosmology. As I've said before, I personally don't think Einstein was much of a cosmologist---and he certainly didn't speak for the status quo, e.g. with many views that directly opposed those of other cosmologists *who were actually interested in, and working on the problem*, such as Eddington and Lemaitre. Einstein did not take any part in developing cosmology in the 1920s.

7. "So, Hubble's law expressed as correlation v vs d is meaningless and even misleading within the context of expanding spaces (FRWL, etc). Under the expansion programme Hubble's law have a straightforward meaning only as relation df vs d." This is the point that I made to you in my previous comment, about which you wrote, "Unfortunately you did not answer any of my questions about the estimation of the radial velocity of galaxies. Your reply was alluding to the explanation of the red shift according to the expansion model." You should maybe go back and read that.

8. "all that is required is to explain the relation df vs d". Be careful here: a phenomenon is not *explained* by inventing a model that's capable of describing it. Explanations answer questions of the sort "why should...?"---e.g., why *should* such an aether as you propose exist, that would cause *precisely* the isotropic redshift-distance relation that has been empirically constrained? and why should the CMB have all the properties that we've observed, etc.? Any answer that comes *anywhere near* to resembling "because that's just the way it is" (as in, 2.7 K is just the temperature of the aether) means you don't have an *explanation* at all. The big bang theory actually does provide a consistent and reasonable explanation of many of these things. One thing it doesn't explain though, as I've discussed in my essay, is why the Universe *should* expand in the first place. It also doesn't expain why the Universe should appear to be so precisely flat, or why it should look the same in regions that weren't previously in causal contact. The inflation scenario is supposed to supply the explanation for that; but inflation is a mess, e.g. as a recent article by Steinhardt in Sci Am clearly tells.

These are the types of problems we face in cosmology. They can all be simply answered with the statement, "because that's just the way it is"---but that's not an explanation. Either way (i.e. explained or not) the standard model does an excellent job of *describing* the data.

[deleted]

Cosmic past,present,future

Big Bang; Present; Big Crunch

c=10^30; c=10^10; c=10^-10

G=10^12; G=10^-8; G=10^-28

h=10^-28; h=10^-28; h=10^-28

alfa =10^-3; 1/137; 1

e=0,1 ; e=e ; e=12

[deleted]

Dear Daryl Janzen!

I am sorry. I apologize for my poor English.

I greatly enjoyed reading your essay.

In my article, I show that negative mass(energy) provides an explanation for dark matter and dark energy.

Article : Negative mass and negative energy

Computer simulation on negative mass

If you read my essay, I will be very happy^^

==============

For the observation or evidence of negative mass(energy)

In 1998, an observation by both the HSS team and SCP team obtained a negative mass density from inspected field equations over 70years.(field eq. has a Lamda=0)

SCP(Supernova Cosmology Project) team : If Lamda=0, Omega_M= - 0.4(±0.1)

http://arxiv.org/abs/astro-ph/9805201 refer to 7P

HSS(The High-z Supernova Search) team : If Lamda=0, Omega_M = - 0.38(±0.22)

http://arxiv.org/abs/astro-ph/9805201 refer to 14P

However, the two teams which judged that negative mass and negative energy level could not exist in our universe based on "the problem of the transition of the energy level of minus infinity" and they instead revised the field equation by inserting the cosmological constant.

We must to know that not the equation has disposed the value, but our thought disposed the value.

Moreover, we considered vacuum energy as the source of cosmological constant Lamda, but the current result of calculation shows 10120, which is unprecedented even in the history of Physics.

However, if "the problem of the transition of the energy level of minus infinity" does not occur, and thus negative and positive mass can coexist, what would happen?

It is well known that a cosmological constant can respond to the negative mass density.

peff = -Lamda/4piG

Lamda is positive, so peff is negative.

==================

Have a nice day!

--- Hyoyoung Choi

Israel Perez

Dear Daryl (Part 1)

Thanks for your reply, I very much appreciate it. It was not my intention to make things messy but quite the opposite. This is why I wanted to focus on only the physical interpretation of the red shift. I would like to apologize for this inconvenience.

The questions I raised were aimed at clarifying the issue of how astronomers and physicists of that time come up with the idea of expansion. For instance, based on what evidence they concluded that space could have been expanding? So, I found that most astronomers (from 1880s to 1930) were using the Doppler formula to calculate the radial velocities of galaxies according to the observed red shift. The fact that Hubble and some others reported in their publications graphs v vs d is a clear indicative that they were not understanding how to interpret the red shift (you may recall that Hubble was reluctant to accept the idea of expansion). From the correlation v vs d many people inferred that most of the galaxies were moving away in the sense of the special relativity and not in the sense of expansion. But as you and I notice, this procedure is correct for relatively short distances (some pc) [i.e., local objects] but for larger ones (Mpc or more) the cosmological red shift dominates above the Doppler effect and reporting v vs d turns out to be misleading (I hope you agree with me up to this point). You say that for historical reasons they still use velocities, meaning implicitly red shift. Ok, I have no problem with this.

So, astronomers (de Sitter, Eddington, etc.) come up with the idea that space may have been expanding. Now, under this scenario the relationship red-shift vs d is straightforward. As you say, light loses energy due to the expansion of space. I do clearly understand that the expansion model provides an explanation of the Hubble's flow. I am just questioning whether this is the only possible explanation. Of course, the answer goes in the negative. My essay argues that no experiment forces us to abandon the aether hypothesis and therefore one can reconsider it. So, assuming the aether as a medium for the propagation of light we have the mechanism to make light to lose energy. Do you agree? If you do, we have two approaches that explain the same phenomenon. According to your view the most natural explanation of the cosmological red shift is expansion. I concur with this only and only if the universe had no aether, but if there is aether the most natural explanation is that the aether makes light to lose energy. I hope you agree.

Now, you may coincide with me on this, but obviously as a good and critical scientist you are this is not enough to persuade you to change your mind about the big bang model (BBM) because as we both know a good model has to account for many other observations such as the CMBR and the abundance of the elements. So you argue:

"Since our main problems in cosmology have to do with a lack of explanation of things that are already very well described, I see it as a step backward to lose the consistent detailed explanation of the CMB."

Ok, at first sight this may look as a step backwards instead of forwards as we all expect. Actually, this would depend on the theoretical framework that we have in mind. From my view, I can see, after revisiting the history of physics, that the BBM has arrived at a dead end (of course, I am aware that you do not share this opinion in view of the fact that you have a different background in your mind). So, one way I see to get out of the puzzle is to go backwards and retrace a more suitable line of reasoning; unfortunately as I could realize, the price to pay for this is too high and not many physicists are willing to even entertain another view [As you may have realized during your participation in this contest, it is really hard to convince other people of your ideas. I think this is the most difficult part]. Despite this I am sure that my ideas could be of great scientific value and this is the reason I insist on them. I hold that they can be used to solve most problems of physics. So let us start by briefly reviewing some of the most important problems. Above we have stated that the red shift has another explanation, but there is more to account for.

to be continued

Israel

Israel Perez

Part 2

In this respect you also recognize that the BBM has some weaknesses such as: "why the Universe *should* expand in the first place. It also doesn't explain why the Universe should appear to be so precisely flat, or why it should look the same in regions that weren't previously in causal contact. The inflation scenario is supposed to supply the explanation for that; but inflation is a mess.

In addition to those problems, I have checked in the literature for some others and I realize that the BBM has real serious problems. Despite that some of its hypotheses are reasonable they do not suffice to solve all of them. One big problem is the baryon asymmetry. You told me as well that the BBM accounts for the abundance of the elements. I found that there is still some controversy with the fitting of the model for the light elements, namely: H, deuterium, He-4, He-3 and Li-6 and Li-7. The model makes acceptable predictions for most elements except for Li-7 where the discrepancy is big. If with the aim of fitting the Li-7 abundance one changes a little bit the values of the parameters of the model, the predictions for the other elements drastically change. In other words, the spectrum of variation of the parameters is very narrow so that a minute variation results into a high deviation from the experimental values. It seems that there is no solution to fit Li-7 into the model without disturbing the predictions of the others. Another big problem of this kind has to do with the half-lives of isotopes of molybdenum 92 and 100 whose values range from 10^18 to 10^25 years, much older than the age of the universe. This is called the molybdenum anomaly. Similarly occurs for one of the Xenon isotopes. So, how is the BBM going to solve this? Of course, adding ad hoc hypothesis, such as reconsidering the birth of the universe, is not the correct path.

Moreover the fact that the light elements were produced in the earlier stages of the Big Bang means that the observable universe has a finite amount of fuel (hydrogen) for star formation and as time goes by there will be a moment in which the fuel will be utterly depleted. Therefore, one can conclude that the universe will some time in the future be in total darkness, a lugubrious and objectionable scenario.

There is also a controversy in relation to the red shift. Some astronomers and cosmologists (starting some time ago with Halton Arp and some others) argued that there are some quasars at relatively the same distance showing red shifts as if the quasars were quite distant from each other. More recently, many astronomers argue that there were mistakes in the techniques used in the past to measure the red shifts, but it seems that the problem has not been settled.

With respect to the acceleration of the expansion there are so many questions: what is the mechanism that causes the acceleration of the expansion? Where all this energy to accelerate the expansion comes from? How could we justify that the expansion of space at great distances is expanding at velocities faster than the speed of light? Clearly, the inflation scenario sounds more like an ad hoc hypothesis to try to save the model than a plausible and fundamental solution. Some other fundamental questions such as: What caused the Big Bang? How can the universe be created out of nothingness? Are there really many universes? Were the laws of physics emerged along with the universe? What will be the fate of the universe? etc. Clearly, this state of things leaves much to be desired of this the BBM.

The proposal I support is less ambitious and more moderate but it can be helpful to solve many problems not only at cosmological scales but also at microscopic ones. It makes no assumptions about the origin or fate of the universe since these statements can only be inferred indirectly under the assumption that the laws of physics do not change at all times (past or future), but so far we do not know if this is true nor what the laws are.

One can assume that the universe could be either infinite in extension or finite; this is irrelevant for the moment, but in any case the aether assumption explains the Olber's paradox, again, without expansion. Since the model does not require expansion, space is flat and Euclidean, thus accounting for the flatness problem. This is another great advantage and a very simple solution.

To be continued

Israel

Israel Perez

Part 3

Now, the temperature attributed to the CMBR was already explained before the BBM dating back to the beginning of the XX century. The temperature of the CMBR can just be seen as the result of a system in thermodynamic equilibrium. For instance, the simplest model supposes that there are two stars separated by some distance, so we just have to calculate the density of energy radiated by these stars and by using the Stefan-Boltzman law we will find that in a given volume of aether between the stars the temperature will be around 3 K. Actually, more detail calculations show that the temperature is 2.7 K, in agreement with the present observations. So, the CMBR can be interpreted not as a relic of the cosmic explosion but as a state of thermodynamical equilibrium between the radiation emitted by all the stars in the observable universe and the aether. This explains at once the horizon problem as well.

The explanation of nucleosynthesis is by far more complicated and in order to get satisfactory results there is still a lot of work to do in this area. All that I can say is that the approach is somewhat similar to that given by the steady state model. Since it is assumed that the universe is much older than the BBM predicts, there is enough time for the universe to form the light elements by stochastic processes (In the future I would like to develop further this part. I think that it also has the potential to solve the baryon asymmetry problem). Actually, stochastic theories have shown that not only quantum mechanics is emergent from the zero-point field (or a Planck plasma) but also Lorentz symmetry. Which means that the notion of aether assuming a PSR is not in contradiction with Lorentz symmetry. This opens many doors for unification at all scales, another great advantage.

The reintroduction of the aether could solve the particle duality problem and make QM a local theory. The proposal has also the potential to solve the problem of the arrow of time, the fly-by and pioneer anomalies, the dark matter problem, etc. etc. etc. So these are some of the virtues of this approach and the big progress physics could make. Otherwise, I see no other way how physics could advance. I am aware that this contradicts *well established ideas* but some times this is the price to pay for the progress. If you have better ideas to solve the problems at least of the BBM I would appreciate you could let me know. As well if you are interested in my proposal we can discuss it. I must tell you that it is still in development, there are many things to do here but I think that the bases are more solid than the prevailing paradigm.

Cheers

Israel

Daryl Janzen

Dear Israel,

Thanks for your posts. I'm glad it seems we're coming to some consensus about what the expanding universe model entails for redshifts. In response to what you've written, I mostly have some criticisms.

First of all, you didn't say anything about how you envision the CMB anisotropy power spectrum as emerging in a non-expanding model. Since that's probably considered the best evidence for expansion, you can't leave that out.

Your objection that the ultimate fate of the Universe that's suggested by the empirical evidence is "lugubrious and objectionable" is very weak, and rather detracts from whatever else you might say. My kids have to go to bed every night despite the fact that they don't want to. "I don't like the sound of that" is not a valid objection to Physical Reality, if it is as the best evidence suggests.

You should be cautious in bringing up Halton Arp. From what I recall, his main argument was based on a single photographic plate that was never reproduced. I think that was a picture of the nearby galaxy and distant quasar that you're referring to.

My answers to the questions in the third last paragraph of your second post: It's metrical; There is none; If space expands an infinitesimal amount, two points far enough separated will physically recede from each other faster than c, but this doesn't contradict the light postulate which has to do with a speed limit for objects moving through space; I have an idea; I don't think it was; If I can complete my theory, I think it will supply real evidence to support that; In my view, yes; It's as you said above.---Actually (with regard to your final comment in that paragraph), I'm pretty happy with all my answers to these questions, and I make no assumptions about the origin or fate of the Universe either; I only try to reconcile a logically consistent picture with the empirical evidence.

Referring to your next paragraph, I make no assumptions about the extent of the Universe, but infer from a theory I see as naturally reconciling with empirical evidence. Olbers' paradox is explained as well with expansion, so that's fine either way. *Assuming* Euclidean space does not explain why it *should* be flat. It doesn't resolve the flatness problem. We can just as easily presume flat expanding space in the standard model. It's why it should be flat that's the problem.

Please show me a reference to a calculation that shows that the ambient temperature of an aether should be 2.7 K. As far as I know, the temperature of the CMB was only predicted by Gamow, Alpher, and Herman.

Since the horizon problem has to do with the fact that the things as far to the right as we can see, and those as far to the left as we can see, look the same in spite of the fact that, according to the BBM, they could never have been in previous causal contact, your theory, which assumes a priori that space simply is homogeneous and isotropic, can't *explain* the horizon problem any better than the BBM without inflation does. Either way, isotropic and homogeneous space can simply be assumed.

Steady State was finally rejected because it can't explain elemental abundances, and you're saying your model is similar in this regard, but less developed? I'm sorry to say, but this is not very inspiring.

A resolution of baryon asymmetry is also something I see potential for in my theory, in a manner like that proposed recently by Massimo Villata.

Actually, I think Lorentz symmetry is an implicit property of four-dimensional fields with pure positive Lambda, and that it doesn't emerge through any physical process.

With regard to a comment in your last paragraph, I should say that what I'm concerned with are well-*founded* ideas, and I'm so far convinced that the expansion scenario *is* well-founded.

You've asked if I think I have better ideas to solve these problems, and I think I do. I've alluded to them in some of my answers here, and covered them in (perhaps pedantic) detail in my thesis. If you are interested in considering them, allowing that I am happy with cosmic expansion, I invite you to have a look at it. I think this discussion could get quite interesting if we both have a better idea of where the other is coming from. You may keep in mind that I suggest a completely different physical mechanism than the one in FLRW cosmology, for our redshift observations to be *exactly* as they've been observed. But the model, with this mechanism, doesn't suffer from the many problems that have been discussed.

Best regards, Daryl

George Ellis

Reply 1:

"However, you responded to me on your thread that you "don't think simultaneity is particularly important", and I disagree. Consider the elementary RW model, with zero curvature and scale-factor equal to 1, in which surfaces of constant t are the uniquely geometrically and physically determined surfaces of constant time. As you know, these surfaces are not synchronous in the proper coordinate system carried by an inertial observer moving through the universe as t passes."

My point is that synchronicity those coordinates does not affect any physical interactions. Those happen on timelike or null world lines.

"Nevertheless, if we say that the surfaces of constant t are the uniquely geometrically and physically determined surfaces of constant time, then we've defined a global simultaneity-relation amongst the events of the emergent space-time continuum." Yes they are and that's because any specific realistic solution of the Einstein Equations has preferred time lines and spatial sections. The solution breaks the symmetry of the theory. Special relativity is misleading in in this regard, as is the de Sitter universe. In present day cosmology the preferred reference rest frame is define by the cosmic microwave background radiation.

"I'm not sure why you don't think it's important to clearly make the distinction that uniquely determined surfaces of constant time define such a global simultaneity-relation, since this is opposed to the commonly conceived meaning of the theory. ... you argue in your paper that "the associated surfaces of constant time are uniquely geometrically and physically determined in any realistic spacetime model based in General Relativity Theory". As stated above one must distinguish between the theory in general and its applications to realistic solutions. It is the latter that have preferred time surfaces.

"I'm sure you're aware of the "Andromeda paradox" that Penrose poses in The Emperor's New Mind: two people walk past each other on the street, and in one of their frames, simultaneously with the event where their worldlines intersect, there's a fleet of Andromedeans debating about whether they will come to invade the Earth, while in the other's frame the Andromedeans have long since left for Earth. This paradox emerges, as Penrose describes, because "The 'now' according to one observer would not agree with that for another." I've made the point above: what we think is "now" over there is a psychological construct that has no influence on the course of events.

"But the paradox is identically resolved when surfaces of constant time are uniquely geometrically and physically determined; i.e., when we do attach geometrical and physical significance to the coordinates, in defining surfaces of global simultaneity. Accordingly, the event at the fleet's location in Andromeda that truly occurs simultaneously with the intersection of the two people's worldlines on Earth, viz. which really happens "now" for both of them, is uniquely well-defined in both of their frames, through the prior global simultaneity-relation given on the uniquely defined surfaces of constant time, although the two events will not be described as *synchronous* in one or both of the frames, since the universe has to be tilted in at least one of their frames." Agreed.

George Ellis

Reply 2:

"You wrote that the cosmological model given by equation (4) of my essay is inhomogeneous. The slices of constant r, which I've argued should describe surfaces of constant cosmic time, are translation-invariant, since the metric doesn't depend on spatial coordinates" Ok I see, r is the time coordinate, not a spatial coordinate (see the signs in the metric); and t is a spatial coordinate.

You are modelling spatially homogeneous surfaces in the de Sitter hyperbloid. The coordinate notation is very misleading.

"You also noted that the model has no dynamic matter in it... ... in cosmology we take the description of perfect fluidity to be valid on the large scale, but if space-time is a substantive manifold that's truly warped under the influence of mass, so that the local passage of time is really influenced by localised mass, is it really very consistent to say that there should be a cosmic time that passes at the same rate in our Local Group as it does in the Coma cluster?" This issue of averaging scales in cosmology is a deep and difficult issue, see my GR10 Lecture. One needs different coordinate systems and metrics that represent different scales.

"Although the description of space-time that's given by Einstein's equations seems to coincide with the idea of a substantive manifold that truly dynamically warps under the influence of mass .. if an absolute cosmic time is required in order to counter the implication that we must only imagine ourselves as existing in a block universe, it seems that some more definite background metrical structure must be required to account for that." We can assume an absolute cosmic time.

"And that's exactly what the RW metric provides in standard cosmology; therefore, although the local passage of time will be different in different gravitational fields and in different states of motion, the standard model still describes uniform global evolution." Correct "The same is true in the SdS cosmology I mentioned in my essay, given the description of r as the cosmic time coordinate." Ok. "The difference, however, is that in FLRW cosmology the overall curvature of space and the evolution of the scale-factor are supposed to be determined by the large scale average energy content of the universe." Indeed. And that's what leads to the success of the theory of nucleosynthesis and of structure formation and predictions of CBR anisotropies and Baryon Acoustic Oscillations. Your model doe snot include all this. "we find that the overall empirical and theoretical consistency of the theory implies that the perfect fluidity of matter should be a good approximation to the large scale average; but it's really debatable whether the large scale distribution of matter really has approximated very well as a perfect fluid since structure formation": yes its a question of averaging scales. Peebles, Rees, and many others have argued this works out OK.

"Now, the idea that the evolution of our Universe might really need to be described through a well-defined background metric, through which space-time emerges as the map of events that occur in the Universe, seems better suited to a metric-affine theory, whereby the metric and local connection are independent quantities and gravitation is described in terms of torsion rather than curvature. If this were the case, then regardless of what the background metric would be (i.e., regardless of the triviality its stress-energy tensor), space-time would be described locally through different solutions to the Einstein field equations." Various people have argued for torsion. There is no evidence it is actually needed.

"Therefore, if the SdS cosmological background could be used as such to describe the existence of galaxies on its fundamental worldlines, and if the distribution of galaxies would appear isotropic from every such perspective" The latter would not be the case, as it is not a FLRW geometry. It's an anisotropically expanding model. "It would be a legitimate cosmological background for a universe that *should* expand at all times, at a well-defined rate that would turn out to be modelled precisely by the flat LambdaCDM scale-factor, regardless of the actual curvature of space or its global energy content." You have not given a prescription as to why the worldlines defined by (4) are to be preferred over any other ones. How are they singled out?

"Therefore, it would agree with empirical observations in our Universe, going a large way towards explaining why the Universe does expand, and would eliminate the flatness problem as well as the need for large amounts of dark matter and dark energy---and the horizon problem would no more be a problem than the requirement to account for that particular background metric. But then, it should be noted that this particular metric has the same form as the one that will describe the final state outside every bound cluster of galaxies in our Universe." It has a singularity at r= 0 so does not avoid the need for a start to the universe.

George Ellis

Reply 3:

"With regard to the idea I've described here, in which the expansion rate of the Universe would not be at all influenced by its material content, as it would occur purely as a result of the cosmic background structure, it may be of interest to note that Abraham Loeb's essay describes a possible unexplored phenomenon which would give us cause to seriously reconsider this fundamental assumption of standard cosmology." Well its not only of cosmology its gravitational theory. It describes solar system dynamics, structure formation, black holes and their interactions, and gravitational waves. The assumption is that the gravitational dynamics that holds on small scales also holds on large scales. It's worked so far.

George Ellis

Israel Perez

Dear Daryl

Here is my reply.

Well actually I didn't see any question concerning the anisotropy of the CMB, that is why I didn't make any comment about it. To answer your inquiry, we can consider the aether, for the sake of simplicity, as a perfect fluid, static and homogeneous. In such case we would expect an isotropic distribution of temperatures, exactly the same everywhere. Obviously, this is an idealization just as when in solid state physics we model a solid as a perfect crystalline structure of atoms, with not any single defect or impurity whatsoever. Everywhere we measure inside the solid we will find the same electrical or electronic properties. The real situation however is that actual crystals have defects, they are neither truly homogeneous nor truly isotropic and therefore if we measure its real properties we will find they are anisotropic depending on the degree of defects or impurities. With the aether the idea is similar. The aether is not a perfect fluid, it has slight imperfections (inhomogeneities) which are reflected as anisotropies in the temperature, etc.

Yes, I totally agree that this argument "lugubrious and objectionable" is very weak, I just mentioned it as an argument alluding to the fact that the BBM loses scientific credibility by making lugubrious and untestable predictions. In this sense, the same situation occurs with string theory. Even theoreticians do not believe in this theory due to the exotic predictions it makes. It is just an analogy.

"You should be cautious in bringing up Halton Arp." Well Harp is just one case, there are some others. And I do not think Harp would risk his career and reputation for only one picture. He must have more convincing evidence, actually he has it (visit his web site). Neither me nor you will make such a claim with only one picture.

You: "If I can complete my theory". I would be glad if you could comment a little bit further on some of your answers. As far as I can see you are still working in some ideas of your proposal.

According to the paper I have the first calculation of the temperature of the CMBR dates back to 1896, then Eddington in 1926, Reneger in 1933, Nernst in 1937, then Alpher, Herman and Gamow, etc. I will send it to you ASAP.

As to the horizon problem, I think that the fact that explanation is simpler than the BBM is a great advantage. In the future refinements will be considered. As I told you before the model is still under construction so, I prefer not to make affirmations until the model becomes so strong to challenge the present paradigm. Be patient.

You: Steady State was finally rejected because it can't explain elemental abundances, and you're saying your model is similar in this regard, but less developed? I'm sorry to say, but this is not very inspiring.

I said similar not the same as the steady state model. Again, this part is still under construction and not much can be said so far. I know that the model has to reproduce the observations, that is the basis. I hope also that this will solve the baryon asymmetry By the way you said that your model could solve this problem according to Massimo Villata. Could you comment about it, please. Or do you have any reference?

Thanks for sending me your thesis, I appreciate it. Now I understand why you said is "pedantic", actually it is.. lol. I found it very interesting but it will take some time to read it. As far as can see you are very happy with expansion, unfortunately I am not. Not because I do not like it, but because, I have other principles. After many unsatisfactory attempts to find the quantum theory of gravity theoreticians wonder which theory, quantum mechanics or GR, is fundamentally wrong. I will drop the latter. I do not find it well-founded. Basically, current physics assumes that (1) there is no aether(PSR) and therefore (2) EM fields are not states of any bearer. I hold the opposite view. These two assumptions lead me to conclude that there is no need of expansion. I have found that they are very natural, logical and consistent. And more important they suffice to solve most problems of physics. So, as long as I don't find better tenets, I will hold them. In any case, despite our differences in our approaches, I am open to discussion any time.

Best Regards

Israel

[deleted]

Garyl,

After reading your paper(rather finishing reading it, after a long pause) and your exchanges with Israel, I thought I might make a some observations/ask questions. First off, I would say I agree with Israel that universal expansion is unnecessary, but rather than defining space as an ether, would describe it as an infinite equilibrium state(necessarily filled with varying levels of energy, which then define any measure of it). Remember centrifugal force is due to the interaction of spin and inertia, not some outside reference.

I first began to question the logic of universal expansion, some decades ago, upon learning that expansion and gravity are inversely proportional. If expansion is balanced by gravity, then why would the universe as a whole continue to expand? Consider it in terms of the rubber sheet analogy of gravity. Flat space is treated as a rubber sheet, which is deformed by the weight of gravity. If expansion balances this effect, leaving an overall flat space, then the compression of gravity is perfectly matched by expansion in the areas not so compressed. When you consider that light from distant sources most effectively travels through the areas not occupied by gravity and mass, then it would be most affected by this opposite effect of gravity/expansion. If fact, Einstein first proposed the cosmological constant as a balance to the compression of gravity. Thus as light passes through this expanded area, it is first redshifted, then the further it travels, the more the effect is compounded, thus redshift is proportional to distance. Eventually it is so shifted as to appear traveling/receding faster than light and this creates a horizon line, beyond which light is no longer visible. But radiation will still travel over this horizon line and that would explain both Olber's paradox and CMBR. In fact ever more distant galaxies are constantly being discovered, that push the limits of how galaxies can form within the time constraint of BBT to the very limits of what is plausible. Currently what appear to be significant galaxy structures have been found out to 13 billion lightyears(1, 2, 3, 4, 5,), which means they would have to form in about 700 million years. Given our own galaxy takes 225 million years to make just one rotation, this seems to be a theoretical stretch.

While you point out to Israel that redshift is due to cosmic expansion and not doppler effect, it should be noted that a constant speed of light is still being assumed. According to theory, two galaxies x lightyears apart, will grow to 2x lightyears apart, as the universe doubles in size(if such a concept is applicable), eventually they will disappear altogether. This naturally assumes a constant speed of light over increasing distance. So I am really confused! Cosmology argues space is expanding, because light from distant galaxies is redshifted proportional to distance, yet then assumes this expansion can be calibrated in constant units of lightspeed!!!!? So which is it? Does space expand, or is there a stable measure of space, according to C?

I have to say about the only response anyone has made to this, other than to ignore it entirely, was Lawrence Crowell, explaining the C is measured locally, not galactically. To which I asked why then do we use lightyears as the measure of cosmic distance. No response to that.

I've been wondering if gravity is not so much a property of mass, but an effect of energy condensing into mass and creating a vacuum. (Nature abhors a vacuum.) M=e/c2. Gravity waves would then be the radiation shed by fusion. That would explain why no dark matter is observed, but there is an abundance of cosmic rays in and around galaxies.

I will leave it at that, as I'm sure you are busy, but will leave this link to an article by one of the chief engineers on the Hubble telescope, about his impressions of cosmology and cosmologists.

[deleted]

Daryl, not Garyl. Sorry about that.

Daryl Janzen

Dear George:

I think, judging from your comments, that we share a common idea that "any specific realistic solution of the Einstein Equations has preferred time lines and spatial sections". In order to provide such a description, Newtonian background structure can be added to solutions which, due to the tensorial formulation of the theory, is often considered redundant from the point of view of relativity. According to this additional structure, two events that happen at the same time in arbitrary coordinates won't truly have occurred simultaneously; the description of space-time, and particularly the description of what's synchronous, that's given by a non-fundamental observer isn't the same as the description given by one who sits at rest in the universe. Of course in reality, even for observers at non-relativistic speeds and in weak gravitational fields, the structure of absolute space and time is apparent; e.g., even though every galaxy in the Universe, including ours, has some peculiar motion through absolute space, we can still form a good description of what's actually going on directly from the redshift data we receive, because Doppler and local gravitational red/blueshifts are negligible compared with cosmological redshifts---so that, according to the expansion scenario, the rest is just noise. It's only through the CMBR that we're actually able to precisely determine the velocity of our own absolute motion, which is evident in the dipole anisotropy. But then, from the perspective of a neutrino or someone falling towards a black hole, "space" appears to be something very different from actual expanding space. But the question is, does this matter for cosmology, where we're interested in the description that would be given from the perspective of roughly fundamental observers?

To show that it does, the point of my essay was to begin pushing the limits of what's possible in a theory that truly admits that absolute space and time are actually demanded by cosmology; i.e., the point was to show that in this case, when an absolute simultaneity-relation is assumed, events that are truly simultaneous are not synchronous, except in very special cases. This allowed me to forward an argument that the absolute spatial slices in cosmology should not necessarily be assumed a priori to be synchronous in the frames of fundamental observers, as they have been. Because, although that's the case in special relativity, it even isn't so in the case of constant inertial motion through a (three-dimensional) special relativistic universe, so it certainly shouldn't be thought to be that way in general. Therefore, from the point-of-view of formulating general relativistic space-time with preferred timelines and spatial sections, FLRW cosmology assumes a priori an extraordinarily special background structure.

So my point is that despite the fact that all physical interactions happen on timelike or null world lines, an EBU has an evolving present boundary---a spatial slice that defines cosmic simultaneity---and if we make this definition of absolute simultaneity, as something we consider necessary for a realistic description of nature, then it's important to make the distinction clear in regard to what's commonly thought due to the misleading nature of special relativity and the operational definition of simultaneity, which I've argued is the very reason why the extraordinarily special RW background structure is assumed. If it's more realistic to assume an absolute simultaneity-relation, and we do that, then I think it is important to make the distinction that *truly simultaneous* events are not *synchronous* in arbitrary frames in this interpretation of relativity theory---that the two words define different aspects of the physical description that only sometimes coincide.

There are two reasons why I think this is important: (i) simultaneity and synchronicity are commonly assumed to mean the same thing in relativity---see, e.g., postulates 3 and 3' here, which David Mermin bridges with the statement, "The third postulate comes in an obviously equivalent version"---so, basically, it's the general *non*-equivalence of "simultaneity" and "synchronicity" in *the realistic interpretation of special relativity that's consistent with cosmology* that's the reason why special relativity (whether formulated in Minkowski or de Sitter space, with or without torsion) is so misleading; and (ii) the common idea that synchronous events in a given frame occur simultaneously in that frame has to do with Lorentz covariance, and is therefore closely related to general covariance, which comes to mean that the coordinates actually can have no immediate metrical significance. But if we assume an absolute foliation, and therefore preferred coordinates against which all local space-times should measure, then the coordinate basis of the prior foliation should always be significant in any local frame, where it describes a true simultaneity of events that occur in an EBU. If so, general covariance really shouldn't be a fundamenal aspect of Physical Reality, but should at best be related through some aspect of the physical description of this emergent Reality. As you've written, "any specific realistic solution of the Einstein Equations has preferred time lines and spatial sections. The solution breaks the symmetry of the theory." But should the theory and its basic principles be taken as fundamental aspects of nature that reality simply doesn't live up to? i.e., should general covariance be thought to be a fundamental aspect of our Universe if our Universe does have Newtonian structure that breaks that symmetry? Rather, one might suppose that the symmetry of the theory is not an essential property of the Universe, but appears so locally because of some other aspect of Physical Reality.

Therefore, if, as you say, "one must distinguish between the theory in general and its applications to realistic solutions. It is the latter that have preferred time surfaces", I think it's time to start taking coordinate systems more seriously if we care for a theory that's going to accurately describe Physical Reality, rather than simply one that provides an interesting mathematical exercise.

Daryl

Daryl Janzen

I also have some comments more specific to yours which I'd like to add:---

"what we think is "now" over there is a psychological construct that has no influence on the course of events." I disagree: As I pointed out in my essay, when we think of ourselves as existing "now" in a three-dimensional evolving Universe, our intuition only tells us that the present three-dimensional Universe is evolving with us---that everything exists with us at the present instant---and *not* that the direction of evolution in proper time is necessarily orthogonal to the three-dimensional present. As far as intuition goes, the three-dimensional Universe could be like the enduring one-dimensional universe that I've described in my essay, which is not orthogonal to the proper time axes of observers B and C. This is why my next statement, which you agreed with, makes sense.

"One needs different coordinate systems and metrics that represent different scales." I agree with this, but I still think the background structure of three-dimensional space with universal duration needs to be assumed a priori for these to scale relatively to.

"Various people have argued for torsion. There is no evidence it is actually needed." Is there evidence it's not? I thought teleparallel gravity offered an equivalent description.

"The latter would not be the case, as it is not a FLRW geometry. It's an anisotropically expanding model." I think you presume too much. All that's necessary is isotropic *appearance* of the spatial slices that aren't synchronous in the frames of fundamental observers. I have a question for you. In a closed RW (neglecting GR and thinking only of test-particles) universe, since the 3-sphere is parallelisable, we can define a bundle of fundamental worldlines as all rotating through the universe at the same velocity, perhaps uniformly accelerated, in one direction. Would the universe be synchronous in the fundamental frame, and would the simultaneous hypersurfaces be described as isotropic? I think not on both accounts. But will the universe appear to be isotropic to fundamental observers? I think so. If the universe is monotonically expanding, say, then those world lines will fan out as the universe increases in size in cosmic time, so that, from the perspective of every one, the universe will still appear to be isotropically expanding, since at every value of cosmic time the universe will still contain an isotropic and homogeneous distribution of test-particles.

"You have not given a prescription as to why the worldlines defined by (4) are to be preferred over any other ones. How are they singled out?" r is taken as the cosmic time direction because the fundamental observers are taken as those which would come to rest where the gravitational potential vanishes identically. These are the geodesics satisfying -g_{tt}dt/dtau=1 (e.g., they come to rest at r=infty when Lambda=0 or at r=0 when M=0). The derivation of the appropriate line-element is about four pages long, starting on page 170 of my thesis. Since they all evolve through timelike r purely due to the isotropic gravitational potential, r is the most sensible choice for the cosmic time coordinate, despite the fact that slices of constant r are not synchronous in the fundamental frame. The synchronous spatial slices are Euclidean slices that always extend from the singularity at r=0 to r=infty.

"It has a singularity at r= 0 so does not avoid the need for a start to the universe." Since r is the timelike coordinate and, in a sense, the "radius" of the universe, and the geometry is only singular right at r=0, simply existing at any infinitesimal time is enough to go on existing, and thereby expand. This expansion is a pure metrical property. In contrast, as I noted in my essay, a pure FLRW universe, where the expansion rate depends on the energy-content, must be decelerating from the first moment of existence, with the cosmical repulsion due to Lambda totally negligible. Whereas the SdS universe expands simply because it exists, the only *reason* an FLRW universe expands has to be the singularity, where the theory is undefined. There is therefore no reason why such a universe *should* expand, so expansion is unexplained. For these reasons, the "start" of the SdS universe avoids having to be the *cause* of everything.

Best,

Daryl

[deleted]

re First post "the point was to show that in this case, when an absolute simultaneity-relation is assumed, events that are truly simultaneous are not synchronous, except in very special cases. " Agreed. "it's important to make the distinction clear in regard to what's commonly thought due to the misleading nature of special relativity and the operational definition of simultaneity, which I've argued is the very reason why the extraordinarily special RW background structure is assumed." The RW metric is not assumed because of special relativity. Its based on spatial homogeneity and isotropy.

"If it's more realistic to assume an absolute simultaneity-relation, and we do that, then I think it is important to make the distinction that *truly simultaneous* events are not *synchronous* in arbitrary frames in this interpretation of relativity theory---that the two words define different aspects of the physical description that only sometimes coincide." true. Note that if the family of observers are rotating there are no simultaneous space sections for them.

"should the theory and its basic principles be taken as fundamental aspects of nature that reality simply doesn't live up to? i.e., should general covariance be thought to be a fundamental aspect of our Universe if our Universe does have Newtonian structure that breaks that symmetry?" Its a fundamental aspect of the laws but not the solutions. I agree that's tricky bit it seems to be the way it is. But you should look at perturbed FRW models to really get to grips with this.They are much better models of the universe than exact FRW models.

George Ellis

Daryl Janzen

"The RW metric is not assumed because of special relativity. Its based on spatial homogeneity and isotropy." It is based on spatial homogeneity and isotropy *and* the assumption of an absolute cosmic time, or causal coherence amongst a bundle of fundamental worldlines *and* the assumption that the bundle of fundamental worldlines are hypersurface-orthogonal. This last assumption means that events that are simultaneous in cosmic time are synchronous in the fundamental rest frame. Just because that is the case in a special relativistic universe (by which I mean an RW metric with absolute cosmic time t, a(t)=1, and K=0), does not mean it's a good assumption to make in general, if we're going to admit a different definition of simultaneity than the operational one. On the other hand, if we're happy with the operational definition of simultaneity, it's the only assumption that makes sense.

"Note that if the family of observers are rotating there are no simultaneous space sections for them." You mean there is no spacelike surface describing the space they are "actually" rotating through, as cosmic time progresses? If there's an enduring three-dimensional space (or EBU with boundary), and the events of space-time form the map of events that occur in that space (or boundary) as it evolves, then however warped their description may be in the proper frame, there have to be spacelike surfaces that contain the events that happened simultaneously, at the same value of absolute time. They won't be synchronous, but we've already established that's something generally different from simultaneity. I've discussed my reasoning for this some more in a post to Peter Jackson that I wrote on Sep. 5, 2012 @ 03:15.

"Its a fundamental aspect of the laws but not the solutions. I agree that's tricky bit it seems to be the way it is." If general covariance is not an aspect of our Universe, then I think it's not appropriate to hold up as a fundamental law. I agree that emergent space-time and motion through enduring space should be constrained by Lorentzian metrical structure somehow, but I don't think general covariance and the associated meaninglessness of coordinates is the correct approach to describing this. I think that any coordinate system that's used should be interpreted consistently with the description of what's *actually* going on, since that's what the theory starts to be about when we begin making distinctions between events that are synchronous and those which are *actually* simultaneous.

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