Not wanting to belive the acceleration universe model

In summary: We suggest that the present expansion is the result of a transient phase of rapid expansion following the inflationary epoch."This paper discusses a model where the universe is accelerating, but does not involve dark energy. The paper tests the model against data from type Ia supernovae and finds that it agrees well. This suggests that the model is plausible and has testable consequences.
  • #1
whatdofisheat
24
0
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
 
Astronomy news on Phys.org
  • #2
Ugh, this is such bad science. So much time has been wasted trying to create theories for things people didn't want to believe. People need to learn that nature doesn't answer to their desires.

If the universe isn't accelerating, then future observations, will give us reason to think otherwise. There is value in creating new theories to explain certain phenomena, as long as they have testable consequences, but nature should always be approached with an open mind, not an agenda.
 
  • #3
I think Space Tiger is a bit premature here.

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

The gist of the paper by Wiltshire, et al, is an argument if you assume that that there is a moderate density of ordinary matter beyond the observable universe that the plain vanilla Friedman equations, applied correctly, implies an absence of both dark energy and accelleration. An earlier paper by Kolb, et al (as in a few days or weeks), involving a different group of physicists, follows the same line of reasoning with a slightly different analysis. Both papers reinterpret the model dependent parts of the conclusions that have been drawn from the supernova data which forms the lynchpin of the conclusion that we are in an accellerating universe comprised mostly of dark energy.

It may not pan out, but it is hardly "bad science", as attested by the fact that ten legitimate physicists are willing to put their names on these papers.

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. While the discipline as a whole needs an open mind to judge new theories with, scientific agendas are an important driving force that can push individual researchers to ferret out new discoveries and propose new theories.

Keep in mind that Einstein's GR basically flowed from his agenda to show that some axioms held while others did not. He surpassed previous scientists because his axioms were different from the ones the intuition of other scientists led them to pursue, but he had to hold fast to his agenda for years before he could discover if it would really work, or even be theoretically consistent, and made many mistakes along the way (at one point, he was putting out so many papers, many of which corrected prior papers, that his fellow researchers couldn't keep track of which was which).

For the lazy who don't want to go through the linked PF discussion, the most recent version of the Wiltshire paper is as follows:

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.

The Kolb papers are:

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."

and

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.

Kolb's papers rule out dark energy only, not accelleration.

Another paper along the lines of Kolb and Wiltshire is this one:

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.

A couple of papers critical of Kolb are found:

Here:

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."

and

here:

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.

If you ask me, this is good science in action.
 
Last edited by a moderator:
  • #4
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 assume you're talking about the Kolb et al. paper. The Kolb et al. paper does not assert that the universe isn't accelerating, rather it says that it's accelerating without need for dark energy.

As for the paper you did link, it's talking about a possible error in the observations that would lead us to believe that the universe is accelerating, which is exactly what I just said about the possibility of new observations (or in this case, re-analysis of the old ones).

The difference between this person and the paper you linked is that this person is starting with a belief and then trying to verify it. More than being bad science, it's just bad critical thinking.

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.

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?"


Keep in mind that Einstein's GR basically flowed from his agenda to show that some axioms held while others did not.

Einstein was re-evaluating physics because observations couldn't be explained by classical theory. In this case, the guy is claiming he doesn't believe the observations.
 
Last edited:
  • #5
In regard to your first matter, I editted the post quite a bit to add links to the papers. My initial link is a link to a PF discussion. In regard to the match between observation and theory, there is a disconnect between observation and theory right now.

Dark energy and dark matter are both major unexplained phenomena which flow from our current observation. One of the driving forces behind the current wave of theoretical physics is to get a better grasp of what is going on with these hypothesized phenomena. These papers are one stab at doing that. Physics now isn't that different in terms of having data that is a poor fit to the existing model from what we saw in the early 1900s.
 
Last edited:
  • #6
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?"

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.
 
Last edited:
  • #7
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.

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.
 
  • #8
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.
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.
 
  • #9
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.

:rofl:

Next thing you know, they'll decide a theory of everything was too hard and refocus their efforts on developing a theory of nothing.
 
  • #10
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.
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.

For instance, Arp cited the fact that all 11 of the companions that orbit around M81 are redshifted with respect to M81. He did not make the observations, and those observations are entirely uncontroversial. What he did do was suggest that the odds that ALL 11 companions are currently exhibiting significant proper motion away from the Milky Way with respect to their massive host is very small, and that may be additional evidence that objects can have intrinsic redshift. This is a very reasonable analysis based on a set of very basic uncontroversial observations. Of course Arp's idea was immediately attacked by Newman and Terzian:

http://adsabs.harvard.edu/cgi-bin/n...J...441..505N&db_key=AST&high=3325b47acc06425

The authors misstated Arp's premise and then applied statistics in a very creative way :yuck: to downplay the improbability of something truly implausible.

Here are the real statistics - all high-schoolers should be able to follow along easily. Let's say you have a large galaxy and eleven associated smaller galaxies: 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. If the host has one object it around it, there is one chance in two (1/2) that the object would be redshifted with respect to the host. If there are two objects, there is one chance in four (1/4) that both objects would be redshifted relative to the host. To save time, we will extrapolate: if there are eleven objects around the host, there is only one chance in 2048 that all eleven objects will be found to be redshifted relative to the host.

Now Arp used this very simplistic and generous 1:2 ratio, although depending on the inclinations of the orbiting companions, many of them should show no redshift or only modest redshift due to proper motion. If we assume that there is one chance in 3 that any companion will exhibit a significant redshift relative to the host (a more realistic ratio than the overly-generous 1:2) the chances that all eleven of the companions will be significantly redshifted with respect to M81 at any given time is 1 in 177,147.

In the paper cited above, Newman and Terzian de-coupled the massive host galaxy from any gravitational effects on the associated small objects, and then restated the problem as a simple matter of ordination, saying in effect "there is one in twelve chances for the host galaxy to have the smallest redshift so that's a 1/12 chance for the observation that all the smaller objects will be redshifted relative to the large massive galaxy." That has to be one of the most cynical applications of "statistics" I have ever seen. The fact that the Newman-Terzian paper was refereed and published should be embarrasing to all those involved. This is just one tiny example of how blind adherence to orthodoxy ("I don't like the implications of the observations!") can motivate some to try to suppress and marginalize real scientists. The authors could not dispute the observations, so they used pseudo-math to "prove" Arp wrong. This is lame, and it is wrong on many levels. If you ever wondered why so many people (myself included) signed that infamous letter in the New Scientist, now you know.

http://www.cosmologystatement.org/
 
Last edited by a moderator:
  • #11
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.
 
Last edited:
  • #12
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.
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.

If anyone here can refute my statistical analysis of the M81 system, I welcome you to do so.

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.
 
  • #13
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.
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?
 
  • #14
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?
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.
 
  • #15
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.
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? :smile:

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.
 
  • #16
ALL 11 companions are currently exhibiting significant proper motion

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]

Same as the probability of getting N successive heads on a coin flip. There's more to the story, however.


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.

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?

To elucidate, let's try exploring the other limit; that the galaxies are all equivalent and moving randomly through space. In this case, all of the galaxies are equally likely to be the most or least redshifted one, so the probability of the "dominant" galaxy having the lowest redshift is:

[tex]P(N)=\frac{1}{N}[/tex]

Surely we must be agreed up to this point, as this is just basic statistics.

Now, here's where the astrophysics comes in. The galaxies in a cluster cannot be said to be orbiting around the most massive member, with it being stationary relative to them. There are galaxies that can be thought of approximately in this way (called satellite galaxies), but Arp wasn't just counting satellite galaxies. He included larger galaxies, like the Milky Way and M33, which will themselves have a non-negligible effect on the "dominant" galaxy (M31, according to Arp). Furthermore, in the standard model (the one he's trying to show to be inconsistent), there is a lot of unseen intracluster matter (and even a lot that is seen in the intracluster medium) which will be effecting the motion of the galaxies in the cluster. All in all, it's not consistent with the picture of one galaxy being orbited by the rest.

Does this mean that the galaxy velocities should be treated as a uniform random distribution, as assumed by Newman and Terzian? Probably not, but given what we know, it's a much better approximation than Arp's. To get a better approximation of the relevant probability, one should do Monte Carlo simulations, evolving the motion of a set of galaxies of equivalent masses to the Local Group galaxies, each iteration having different initial conditions. If you're so set on verifying Arp's arguments you could do this yourself and determine more accurate probabilities.

I wouldn't count on it being particularly shocking, however. There are two further reasons why I think Arp's result is uninteresting (in the way that he intends, that is). The first is that galaxies in clusters tend to have very little angular momentum relative to on another, so the motion of two very massive galaxies relative to one another ought to be nearly radial. This means that, in the Local Group at least, it should not be so surprising if M31 has an unusually small or large redshift relative to the Milky Way. Since they're the two most massive members of the cluster, their gravitational interaction will be the strongest, so it's not a bad approximation to treat them as a two-body system with low eccentricity motion. If the motions of the other galaxies are randomly distributed, then there is a larger than 1/6 chance that M31 will lie at one of the extremes (that is, either the smallest or largest redshift).

The other reason it's uninteresting is that these probabilities were calculated after the observation. That is, Arp was looking for something unusual in the redshift distributions and reported the first one he found. This is sort of like looking for license plates that say funny things and then reporting the probability of seeing the first funny one you saw (OMG, it's 1 in a million!). The appropriate probability to calculate is rather the probability that the distributions would be such that Arp would write a paper about them. This is obviously not possible to do, but it's at least worth considering that if the "dominant" galaxies had had the highest redshifts, he also would have pointed it out as unusual.
 
  • #17
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]
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:
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?
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.
 
  • #18
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.

As long as the redshift can be measured, this fact doesn't matter. It's already taken into consideration by the statistics.


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!).

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.


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.

What behavior are you referring to? I read their paper and it seemed to me a very good estimate of the relevant statistics, in lieu of detailed modelling.
 
  • #19
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? :smile:
See Arxiv site for posting papers there.
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.
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]?
 
  • #20
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.
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.

Imagine you have a galaxy massing many billions of suns surrounded by satellites massing perhaps several millions of suns each. It does not require months of time on a supercomputer to decide that the massive host probably does not exhibit lots of proper motion due to the gravitational influences of one or more of the small companions, and the small companions cannot help orbiting the massive host. Once we have introduced a bit of logic to the problem, we do the math. Again, there is a HUGE negative probability that all eleven of M81's companions are significantly redshifted with respect to the host.

Again, take the scenario (One hugely massive galaxy surrounded by eleven small satellites) and explain why all eleven of them are currently significantly redshifted with respect to the host.

Forget the appeals to "Newman-Terzian was peer-reviewed" and similar arguments that ascribe "truth" to ideas backed by authority and concensus. Let's just discuss the observations and try to explain them in our own personal world views. You and Chronos and anybody else here are all cordially invited to explain this situation and to falsify with logic my assessment of the situation. I cannot do it without either invoking a huge coincidence or considering some intrinsic properties that affect the redshifts that we see.
 
Last edited:
  • #21
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.

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, 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.

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.
 
Last edited:
  • #22
I just finished an additional edit ST, without knowing that you had already posted, so heads-up. Sorry.

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.
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? :devil:

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.
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.

http://arxiv.org/ftp/astro-ph/papers/0408/0408348.pdf

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.
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.
 
  • #23
turbo-1 said:
I just finished an additional edit ST, without knowing that you had already posted, so heads-up. Sorry.

Please post it all at the same time or make a separate post. That's really annoying.


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? :devil:

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.


Remember also that under BB cosmology, only about 1% of the cluster's mass is visible to us,

I was assuming the presence of dark matter in the statements I made above. If anything, this fact weakens your case.


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.

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.
 
  • #24
SpaceTiger said:
Please post it all at the same time or make a separate post. That's really annoying.
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:
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.
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:
I was assuming the presence of dark matter in the statements I made above. If anything, this fact weakens your case.
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:
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.
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.
 
  • #25
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.

No it doesn't. That's exactly what I'm saying. M81 is not the only mass worth considering in the M81 group. In particular, M82 and NGC4236 are massive galaxies that will have a noticable effect on M81.


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.

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.


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".

The concept of falsification seems to escape you, but it doesn't matter. The dark matter in the M81 group seems to be proportional to the visible light anyway, so the relative contributions of M81 and its "companion" galaxies would be about the same.


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.

You know that's not what I'm referring to. A quote from your previous post:

"It might make sense to you, since GR gravity exhibits massive failures on cluster scales..."
 
  • #26
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

Lol i hate posting a reponse to a thread when there's like 3 pages done because I am not sure if the topic is even on topic anymore. What you say is absolutely scientifically absurd and is why a lot of scientific arguments are so annoying. Although there's arguments for both sides... just becuase you don't want to believe something is true doesn't mean its not true. This can result in the most annoying arguments. If you get a group of people who all say that speed addition for speeds nearing c is normal and c being a 'speed limit' is not something they want to believe... well... that's just going to result in a lot of wasted time. Nature doesn't care what you want to believe and what you don't want to believe. You can find some wacko to write a paper saying relativity all BS and these people could make a thread going "I don't believe c is the speed limit, id love to see some information that its wrong" and point them to that paper and ugh... bad bad science and i wouldn't want to have an argument with such people.

One of my professors said it beautifully once. He says non-science students constantly ask (about electromagnetic propogation) "Why does nature know to have e/m waves travel based on our right hands? (right hand rule) and he goes "nature does not care what hand we like to use and nature does not set its rules based on human ambition. If it didnt travel like that, we'd call it the left hand rule or something else we could identify it" or something to the effect.
 
  • #27
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.
Would chit happens suffice? Every pasture has its pies, finding the cow is the hard part.
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.
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.
 
Last edited:
  • #28
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.
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:

There is evidence that the redshifts of associated galaxies can vary and the variation correlates to the morphology of the galaxies:

http://arxiv.org/ftp/astro-ph/papers/0408/0408348.pdf

This kind of redshift differential is responsible for the radial smearing (fingers of God) effect seen in cluster surveys. Standard cosmology says that the smearing is due to the proper motions of the glaxies, but then we need huge amounts of DM to explain why the clusters don't simply fly apart. If galaxies can have intrinsic redshifts in addition to their cosmological redshifts, then their proper motions can be reasonable, and DM is not needed to keep the clusters together.

Despite decades of diligent search, no dark matter has ever been detected anywhere. Perhaps it is time to let observation drive theory.
 
  • #29
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.

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.
 
  • #30
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.
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?
 
  • #31
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)?
 

1. What is the acceleration universe model?

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.

2. How does the acceleration universe model differ from the traditional Big Bang model?

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.

3. What evidence supports the acceleration universe model?

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.

4. Are there any alternative explanations for the observed acceleration of the universe?

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.

5. How does the acceleration universe model impact our understanding of the universe?

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.

Similar threads

  • Astronomy and Astrophysics
Replies
7
Views
108
  • Astronomy and Astrophysics
Replies
4
Views
2K
  • Astronomy and Astrophysics
Replies
13
Views
1K
Replies
3
Views
2K
Replies
35
Views
1K
  • Astronomy and Astrophysics
Replies
12
Views
4K
  • Astronomy and Astrophysics
Replies
2
Views
2K
  • Thermodynamics
Replies
4
Views
203
Replies
1
Views
927
  • Programming and Computer Science
Replies
8
Views
2K
Back
Top