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whatdofisheat
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hey does anyone have some therios in short or a website of which a nother expanation for the redshifting of distant objects? or anything against the coman model for acceleration i would love to see it thanks all
Exact model universe fits type IA supernovae data with no
cosmic acceleration
B.M.N. Carter, B.M. Leith, S.C.C. Ng, A.B. Nielsen, D.L. Wiltshire
http://www.arxiv.org/abs/astro-ph/0504192
9 pages, 5 figures, aastex
Abstract:
The unexpected dimness of Type Ia supernovae at redshifts z <~1 has over the past 7 years been seen as an indication that the expansion of the universe is accelerating. A new model cosmology has been proposed by one of us [gr-qc/0503099], based on the idea that our observed universe resides in an underdense bubble remnant from a primordial epoch of cosmic inflation. Although there is no cosmic acceleration, it is claimed that the luminosity distance of type Ia supernovae data will nonetheless fit the new model, due to systematic effects. In this paper the hypothesis is tested statistically against the available type Ia supernovae data by both chi-square and Bayesian methods. The model gives good agreement if the density parameter, Omega_0, is taken to be the density in ordinary baryonic matter only. If low Omega_0 parameter values are accepted, then the model would dispense with both dark energy and non-baryonic dark matter, and an alternative explanation would be required for galaxy rotation curves and dynamical measurements of Omega_0 on the scales of clusters of galaxies.
http://arxiv.org/hep-th/0503117
Primordial inflation explains why the universe is accelerating today
Edward W. Kolb, Sabino Matarrese, Alessio Notari, Antonio Riotto
4 pages, one figure
Report-no: FERMILAB-PUB-05-024-A
"We propose an explanation for the present accelerated expansion of the universe that does not invoke dark energy or a modification of gravity and is firmly rooted in inflationary cosmology."
http://arxiv.org/hep-ph/0409038
Effect of inhomogeneities on the expansion rate of the Universe
Edward W. Kolb, Sabino Matarrese, Alessio Notari, Antonio Riotto
19 pages, 2 figures Version 2 includes some changes in numerical factors and corrected typos. It is the version accepted for publication in Physical review D
Journal-ref: Phys.Rev. D71 (2005) 023524
Abstract: While the expansion rate of a homogeneous isotropic Universe is simply proportional to the square-root of the energy density, the expansion rate of an inhomogeneous Universe also depends on the nature of the density inhomogeneities. In this paper we calculate to second order in perturbation variables the expansion rate of an inhomogeneous Universe and demonstrate corrections to the evolution of the expansion rate. While we find that the mean correction is small, the variance of the correction on the scale of the Hubble radius is sensitive to the physical significance of the unknown spectrum of density perturbations beyond the Hubble radius.
The Effect of Inhomogeneities on the Luminosity Distance-Redshift Relation: is Dark Energy Necessary in a Perturbed Universe?
http://arxiv.org/abs/astro-ph/0501152
Authors: Enrico Barausse (SISSA, Trieste), Sabino Matarrese (Physics Dept. and INFN, Padova), Antonio Riotto (INFN, Padova)
Comments: 19 pages, 2 figures. Phys. Rev. D, in press. replaced to match the accepted version
Report-no: DFPD 04/A/27
Journal-ref: Phys.Rev. D71 (2005) 063537
The luminosity distance-redshift relation is one of the fundamental tools of modern cosmology. We compute the luminosity distance-redshift relation in a perturbed flat matter-dominated Universe, taking into account the presence of cosmological inhomogeneities up to second order in perturbation theory. Cosmological observations implementing the luminosity distance-redshift relation tell us that the Universe is presently undergoing a phase of accelerated expansion. This seems to call for a mysterious Dark Energy component with negative pressure. Our findings suggest that the need of a Dark Energy fluid may be challenged once a realistic inhomogeneous Universe is considered and that an accelerated expansion may be consistent with a matter-dominated Universe.
http://arxiv.org/abs/astro-ph/0503553
Do Large-Scale Inhomogeneities Explain Away Dark Energy?
Ghazal Geshnizjani, Daniel J.H. Chung (UW-Madison), Niayesh Afshordi (Harvard)
4 Pages, no figures
"Recently, new arguments (astro-ph/0501152, hep-th/0503117) for how corrections from super-Hubble modes can explain the present-day acceleration of the universe have appeared in the literature. However, in this letter, we argue that, to second order in spatial gradients, these corrections only amount to a renormalization of local spatial curvature, and thus cannot account for the negative deceleration. Moreover, cosmological observations already put severe bounds on such corrections, at the level of a few percent, while in the context of inflationary models, these corrections are typically limited to ~ 10^{-5}. Currently there is no general constraint on the possible correction from higher order gradient terms, but we argue that such corrections are even more constrained in the context of inflationary models."
Can superhorizon cosmological perturbations explain the acceleration of the universe?
http://arxiv.org/abs/astro-ph/0503582
Authors: Christopher M. Hirata, Uros Seljak
Comments: 16 pages, 1 figure, to be submitted to PRD
We investigate the recent suggestions by Barausse et al. (astro-ph/0501152) and Kolb et al. (hep-th/0503117) that the acceleration of the universe could be explained by large superhorizon fluctuations generated by inflation. We show that no acceleration can be produced by this mechanism. We begin by showing how the application of Raychaudhuri equation to inhomogeneous cosmologies results in several ``no go'' theorems for accelerated expansion. Next we derive an exact solution for a specific case of initial perturbations, for which application of the Kolb et al. expressions leads to an acceleration, while the exact solution reveals that no acceleration is present. We show that the discrepancy can be traced to higher order terms that were dropped in the Kolb et al. analysis. We proceed with the analysis of initial value formulation of general relativity to argue that causality severely limits what observable effects can be derived from superhorizon perturbations. By constructing a Riemann normal coordinate system on initial slice we show that no infrared divergence terms arise in this coordinate system. Thus any divergences found previously can be eliminated by a local rescaling of coordinates and are unobservable. We perform an explicit analysis of the variance of the deceleration parameter for the case of single field inflation using usual coordinates and show that the infrared divergent terms found by Barausse et al. and Kolb et al. cancel against several additional terms not considered in their analysis. Finally, we argue that introducing isocurvature perturbations does not alter our conclusion that the accelerating expansion of the universe cannot be explained by superhorizon modes.
In fact, a paper with quite a few respectable co-authors is currently attracting a great deal of academic interest in the physics community and is being discussed (with a great deal of skepticism) in over in another forum on the boards right now (quite frankly, it appears to be in the wrong forum). The link is here: https://www.physicsforums.com/showthread.php?t=68576
I don't disagree that we need to make theory match what we observe, instead of the other way around. But, I think that what we "want to believe" can be a reasonable proxy for good physics intuition, and that intuition can be a good way to generate a hypothesis to test againt the data.
Keep in mind that Einstein's GR basically flowed from his agenda to show that some axioms held while others did not.
Good physics intuition: "Based on my previous experience, it seems odd that the universe is acting this way. Let me see how else I might be able to explain this."
Bad physics intuition: "I don't like that idea, so I don't believe it. How can I reaffirm my belief?"
ohwilleke said:I don't think it is bad physics intutition to give the latter a serious look as a hypothesis, even thought the latter is driven by what we want to believe, because what we want to believe is that the universe acts the way we have observed it to act in human history until twenty years ago.
The problem may be that the latter doesn't seem to be a theory of everything, and the former is a theory of more than everything.ohwilleke said:What is going on within and outside the theoretical physics community right now is that a lot of people are saying something along the lines of:
"What is going on here? My theories are leading me to a universe where 70% of the universe is made up of dark energy that I have no good explanation for, and most of the balance is made up of dark matter which would have to be made up of WIMPS that I have yet to observe and don't have a good theory for explaining the distribution of, and my quantum physicists are coming up with theories with ten or eleven dimensions most of which are curled up, many universes, giant soap bubble like branes, more undiscovered particles than you can shake a stick at, and more without making any concrete predictions that I can check. Maybe I need to sit down a see if I can find any other approach that can explain the data without predicting so many phenomena that I don't have any evidence to back up."
then, some other folks come along and say:
"Maybe we can explain the universe with some superhorizon ordinary matter distributions, no dark matter, no dark energy, just a few undiscovered particles, no singularities, only the four dimensions we all know and love, a tweak in GR due to quantum effects that affect the strength of infrared portions of gravitational fields, and a some results which can be compared to observations."
I don't think it is bad physics intutition to give the latter a serious look as a hypothesis, even thought the latter is driven by what we want to believe, because what we want to believe is that the universe acts the way we have observed it to act in human history until twenty years ago.
Mike2 said:The problem may be that the latter doesn't seem to be a theory of everything, and the former is a theory of more than everything.
With all due respect to someone lucky enough to be able to make a living at astronomy, there is a disconnect here that needs to be addressed. Our observations are getting better and better and they will continue to do so. The critical differences in opinion stem often from different interpretations of those observations.SpaceTiger said:Neither do I, and I'm not sure why you would think that your example fits more into my "Bad Intuition" category than the good one. Let's also keep in mind that this person isn't exploring alternative models on their own, he/she is looking to be convinced by someone else's model. I don't have any objection to exploring alternatives, I just reacted negatively to the poster's wording (particularly in the title). We astronomers get consistently harassed by ignorant members of the general public who happen to have read a book by Arp (or someone equally nutty) and think they suddenly understand cosmology better than the rest of the astronomical community.
No rebuttal? Perhaps they didn't feel the need to roll in the mud, or realized that the "statistics" used in the N-T paper were transparently flawed.Chronos said:Oh please, if Newman-Terzian is so patently flawed, why didn't Arp, or anyone else, publish a peer-reviewed rebuttal? I'm still waiting for Arp's list of high redshift objects superimposed smack in front of of a low redshift object.
Could it be that the smaller, surrounding galaxies are more redshifted because there are not enough periphreal stars to balance the gravitational redshift of the black hole in the center of each of those surrounding galaxies?turbo-1 said:The situation: Eleven small galaxies in the gravitational hold of a much larger, massive host. The challenge: Come up with a rational explanation of why ALL ELEVEN companions appear redshifted to us, using only proper motion to cause the redshifts.
I believe that you're on the right track, Mike, although I would characterize the redshift relationship a little differently. No matter, though. You have thought about this situation a bit, you have come to the very logical conclusion that some intrinsic property of the satellite galaxies must be causing the excess redshift. There is only about one chance in 177,000 that all those satellite galaxies can be moving away from us simultaneously, leaving no satellites with redshift equivalent to or less than the massive host. Proper motion and doppler redshift cannot explain what we see in this system.Mike2 said:Could it be that the smaller, surrounding galaxies are more redshifted because there are not enough periphreal stars to balance the gravitational redshift of the black hole in the center of each of those surrounding galaxies?
As for the rebuttal, I've never submitted a paper to a peer-reviewed journal, but if someone here will tell me how to navigate the process, I will be happy to do so. Only Junior High math is required for this one. Chronos, can you help out a member of the loyal opposition?Chronos said:Oh please, if Newman-Terzian is so patently flawed, why didn't Arp, or anyone else, publish a peer-reviewed rebuttal? I'm still waiting for Arp's list of high redshift objects superimposed smack in front of of a low redshift object.
ALL 11 companions are currently exhibiting significant proper motion
turbo-1 said:If the smaller objects are physically associated with (and gravitationally effected by) the more massive object, we would reasonably expect about half the smaller objects moving around that massive galaxy would be moving toward us relative to the host, and would therefore be blueshifted in relation to the host.
Yes, which is excessively generous to the opposition, since any orbital inclination of a companion galaxy that is rather perpendicular to our line of sight, or any proper motion of a companion galaxy that is presently about perpendicular to our line of sight to M81 will result in NO measureable redshift.SpaceTiger said:We can't measure the proper motions of galaxies. He's using the radial velocities, which is what we're claiming the redshift measures.
Anyway, he's just treating this like a coin flip. That is, if there are N galaxies orbiting a more massive galaxy, then the probability of them all moving in the same direction relative to the massive galaxy is just:
[tex]P(N)=\frac{1}{2^N}[/tex]
Certainly! And if the same analysis was applied to the Sun and to the planets that circle it, and Newman and Terzien insisted that we treat all of the bodies exactly the same statistically (regardless of their masses) everybody here would be questioning their logic and their methods (and likely their sanity!). The fact that the astronomical community allows this kind of behavior when it's directed against Arp and the Burbidges does not speak well of the character of the community.SpaceTiger said:Same as the probability of getting N successive heads on a coin flip. There's more to the story, however. Look at the phrase I highlighted; it's the important one. If the galaxies were orbiting the most massive galaxy in the cluster and it was feeling a negligible influence from them, then this analysis would be correct. However, if this isn't the dynamical situation, then his analysis collapses. Can you see why?
turbo-1 said:Yes, which is excessively generous to the opposition, since any orbital inclination of a companion galaxy that is rather perpendicular to our line of sight, or any proper motion of a companion galaxy that is presently about perpendicular to our line of sight to M81 will result in NO measureable redshift.
Certainly! And if the same analysis was applied to the Sun and to the planets that circle it, and Newman and Terzien insisted that we treat all of the bodies exactly the same statistically (regardless of their masses) everybody here would be questioning their logic and their methods (and likely their sanity!).
The fact that the astronomical community allows this kind of behavior when it's directed against Arp and the Burbidges does not speak well of the character of the community.
See Arxiv site for posting papers there.turbo-1 said:As for the rebuttal, I've never submitted a paper to a peer-reviewed journal, but if someone here will tell me how to navigate the process, I will be happy to do so. Only Junior High math is required for this one. Chronos, can you help out a member of the loyal opposition?
How is that moving the goalposts. I asked you to kick the ball between the goalposts and you claim foul because I didn't stipulate the shortest distance between the goal posts. I concede, if we draw a great circle between the right and left goal post, a miss to the right is still between the goalposts, in a global sense. Does not your dictionary suggest 'superimposed' means blocking the view of an object in the background [i.e., directly in front of]?turbo-1 said:As for finding a high-redshift object superimposed in front of a low redshift object, here you go.
http://arxiv.org/abs/astro-ph/0409215
When I showed you this before, though, you immediately moved the goalposts and insisted that I had to show you a high redshift object superimposed DIRECTLY over the center of a low redshift object.
Newman and Terzian chose to base their paper on the local group, of which we are a member, which made it possible for them to employ some sleight of hand. Consider only the M81 association and do the math. Now, try to keep a straight face when you apply the N-T concept that the huge mass of the host galaxy can be ignored, so you can pretend that ANY of the galaxies has an equal chance of being redshifted relative to any of the others. This is not just wrong - it goes way beyond that.SpaceTiger said:But they're not doing their analysis on the planets around the sun, they're doing it on a cluster of galaxies. Read my post again. You seem to have completely missed the point.
turbo-1 said:Newman and Terzian chose to base their paper on the local group, of which we are a member, which makes it possible to employ some sleight of hand. Consider only the M81 association and do the math. Now, try to keep a straight face when you apply their concept that the huge mass of the host galaxy can be ignored when evaluating the possibility that ANY of the galaxies has an equal chance of being redshifted relative to any of the others. This is not just wrong - it goes way beyond that.
The galaxies in the M81 group were uncontroversially considered group members when Arp made his analysis. Have they since been all designated "background objects" to avoid the redshift problem? Who arranged this decoupling, if I might ask?SpaceTiger said:Since the galaxies considered in the M81 group were not satellite galaxies either, then it doesn't make sense to apply Arp's reasoning. Like I said, if you want to demonstrate this point, you're free to do so with Monte Carlo. If you think there's a paradox, the burden of proof is on you, not me.
Remember also that under BB cosmology, only about 1% of the cluster's mass is visible to us, and there is growing evidence that galaxies' redshifts are related to their morphologies.SpaceTiger said:Remember, in the solar system, almost all of the mass is in the sun. In a cluster, even the largest galaxy only represents a small fraction of the total mass.
It might make sense to you, since GR gravity exhibits massive failures on cluster scales (which can only be fixed by huge infusions of Dark Matter, distributed just so). Let's model these movements based on the masses of the matter that we see (observation drives theory), and see if we can derive some deeper truth from the observations.SpaceTiger said:EDIT: To correspond with your addendum (your second paragraph), I would just like to emphasize my point above. The total mass of the cluster is much larger than that of any single galaxy, so it makes more sense to treat galaxy dynamics in the context of motion in a larger potential, not motion around a central mass.
turbo-1 said:I just finished an additional edit ST, without knowing that you had already posted, so heads-up. Sorry.
The galaxies in the M81 group were uncontroversially considered group members when Arp made his analysis. Have they since been all designated "background objects" to avoid the redshift problem? Who arranged this decoupling, if I might ask?
Remember also that under BB cosmology, only about 1% of the cluster's mass is visible to us,
It might make sense to you, since GR gravity exhibits massive failures on cluster scales (which can only be fixed by huge infusions of Dark Matter, distributed just so). Let's model these movements based on the masses of the matter that we see (observation drives theory), and see if we can derive some deeper truth from the observations.
I apologized for the cross-posting before. I didn't mean to annoy you, but other thoughts occurred that might have clarified the post.SpaceTiger said:Please post it all at the same time or make a separate post. That's really annoying.
OK, so you agree that they are companions of M81. That is a start. As far as complexity is concerned, gravity is both fundamental and simple, as both Newton and Einstein have shown, although the calculations needed to explain differences in their models is rather complex. The calculations needed to get a probe from Earth to Saturn can probably be done as accurately with Newtonian gravitation as with GR. Anyway, the upshot is that multi-body systems with one hugely dominant mass obey logical rules. These rules apply every time. No exceptions. This applies to the M81 system.SpaceTiger said:Gah! Gravity is not that simple. As I already explained, being a member of a "group" or a "cluster" does not mean that the galaxies can be treated as orbiting around a central mass. There was no decoupling and nobody's treating them as background galaxies. The situation is much more complex than can be treated with your simple "high school" statistics.
Please do not assume the existence of dark matter, just explain the observations in light of what we see, just like in local gravitationally bound systems. There is not a single instance in which dark matter has been detected in our cluster, in M81's cluster, or in any other cluster. It is exactly this failing that I am attempting to address with this example. Look at M81 and its companions and explain why all eleven of the small galaxies are redshifted with respect to M81. Simple problem. If you can reasonably model a distribution of dark matter that can cause such an improbable situation, please make your case, but please don't invoke "dark matter" as if it were some obedient genie that makes every discrepant observation somehow reasonable and say "case closed". That's equivalent to asking for a free pass because "the dog ate your homework".SpaceTiger said:I was assuming the presence of dark matter in the statements I made above. If anything, this fact weakens your case.
What nutty physics? There is a well-established and non-controversial set of observations that prove to us that all eleven of the accepted companions of M81 have significantly more redshift than M81. I'm trying to find a way to explain this observation. If you want to deny the validity of the observation, then have at it with observations of your own. If the observations (all eleven of M81's companions are redshifted compared to the massive host) are not controversial, then it is incumbent upon you to show how (with normal, well-accepted physics) this can possibly be so. If my basic and logical statistical analysis of the system is somehow "nutty physics", we might just as well fold up our tents and leave the physics to the politicians, the spin doctors, and the astrologers.SpaceTiger said:You were trying to show that there was a paradox within the context of the standard model, so it's circular reasoning to start invoking nutty physics to defend the presence of the paradox.
turbo-1 said:Anyway, the upshot is that multi-body systems with one hugely dominant mass obey logical rules. These rules apply every time. No exceptions. This applies to the M81 system.
Please do not assume the existence of dark matter, just explain the observations in light of what we see, just like in local gravitationally bound systems.
It is exactly this failing that I am attempting to address with this example. Look at M81 and its companions and explain why all eleven of the small galaxies are redshifted with respect to M81. Simple problem. If you can reasonably model a distribution of dark matter that can cause such an improbable situation, please make your case, but please don't invoke "dark matter" as if it were some obedient genie that makes every discrepant observation somehow reasonable and say "case closed".
What nutty physics? There is a well-established and non-controversial set of observations that prove to us that all eleven of the accepted companions of M81 have significantly more redshift than M81.
whatdofisheat said:hey does anyone have some therios in short or a website of which a nother expanation for the redshifting of distant objects? or anything against the coman model for acceleration i would love to see it thanks all
Would chit happens suffice? Every pasture has its pies, finding the cow is the hard part.turbo-1 said:What nutty physics? There is a well-established and non-controversial set of observations that prove to us that all eleven of the accepted companions of M81 have significantly more redshift than M81. I'm trying to find a way to explain this observation.
So what if they are redshifted? What does that prove? The odds against todays lottery being the numbers they happened to be are astronomical. What does that prove other than statistics can be manipulated to produce absurd conclusions? That was the point of Newman-Terzian. Anyone who understands probability theory will quickly recognize the error in Arp's reasoning.turbo-1 said:If you want to deny the validity of the observation, then have at it with observations of your own. If the observations (all eleven of M81's companions are redshifted compared to the massive host) are not controversial, then it is incumbent upon you to show how (with normal, well-accepted physics) this can possibly be so. If my basic and logical statistical analysis of the system is somehow "nutty physics", we might just as well fold up our tents and leave the physics to the politicians, the spin doctors, and the astrologers.
The reason that the standard model needs dark matter in clusters is because these discordant redshifts, when interpreted as proper motion, result in galaxy velocities so high that the cluster would immediately fly apart. Simply insert 100x as much DM as visible mass, and the problem is fixed, right? :yuck:SpaceTiger said:The whole point of this argument was to show an inconsistency in the standard model. Dark matter is part of the standard model, so you can't ignore it in making your arguments.
turbo-1 said:The reason that the standard model needs dark matter in clusters is because these discordant redshifts, when interpreted as proper motion, result in galaxy velocities so high that the cluster would immediately fly apart.
If there is so much gravitational effect from dark matter that it dramatically affects galaxy rotation curves and the lensing effects of clusters, then are photons coming from distant galaxies redshifted more that otherwise because of the additional gravitational well they have to climb out of due to the surrounding dark matter?SpaceTiger said:Again, you're mixing up proper motion and velocity. Proper motion refers to an angular motion on the sky and it's always orthogonal to an object's redshift. Nevertheless, dark matter was not invoked to explain this particular paradox, nor is it needed to resolve it, so it's just a red herring.
I apologize for the imprecise terminology, but there are hundreds, more likely thousands of papers out there written about clusters that invoke dark matter to supply the gravitational attraction need to bind clusters and keep them together. The standard model absolutely needs DM in clusters to hold them together. Indeed, many large-scale searches for DM have been modeled using cluster geometry as tracers of DM distribution. If there is a model that can explain the Fingers of God effect without invoking intrinsic redshift and without the need for DM to help bind the clusters so they don't fly apart, can you point me to the paper(s)?SpaceTiger said:Again, you're mixing up proper motion and velocity. Proper motion refers to an angular motion on the sky and it's always orthogonal to an object's redshift. Nevertheless, dark matter was not invoked to explain this particular paradox, nor is it needed to resolve it, so it's just a red herring.
The acceleration universe model is a cosmological model that suggests the expansion of the universe is accelerating due to the presence of a mysterious force called dark energy. This model is supported by observations of distant supernovae and the cosmic microwave background radiation.
The traditional Big Bang model suggests that the expansion of the universe is slowing down due to the gravitational pull of matter. However, the acceleration universe model proposes that the expansion is actually speeding up due to the repulsive force of dark energy.
The main evidence for the acceleration universe model comes from observations of distant supernovae. These observations show that the light from these supernovae is dimmer than expected, indicating that the expansion of the universe is accelerating. Additionally, the cosmic microwave background radiation also supports this model by showing a slight unevenness in the distribution of matter, which is consistent with the presence of dark energy.
Some scientists have proposed alternative explanations for the observed acceleration of the universe, such as modifications to the laws of gravity or the presence of a large void in the universe. However, these explanations have not been supported by enough evidence to challenge the acceleration universe model.
The acceleration universe model has significant implications for our understanding of the universe. It suggests that the expansion of the universe will continue to accelerate, eventually leading to a "Big Rip" where all matter is torn apart. This model also raises questions about the nature of dark energy and its role in the evolution of the universe.