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Not wanting to belive the acceleration universe model

  1. Apr 12, 2005 #1
    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
     
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  3. Apr 12, 2005 #2

    SpaceTiger

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    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.
     
  4. Apr 12, 2005 #3

    ohwilleke

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    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:

    The Kolb papers are:

    and

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

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

    A couple of papers critical of Kolb are found:

    Here:

    and

    here:

    If you ask me, this is good science in action.
     
    Last edited: Apr 12, 2005
  5. Apr 12, 2005 #4

    SpaceTiger

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    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.

    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?"


    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: Apr 12, 2005
  6. Apr 12, 2005 #5

    ohwilleke

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    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: Apr 12, 2005
  7. Apr 12, 2005 #6

    ohwilleke

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    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: Apr 12, 2005
  8. Apr 12, 2005 #7

    SpaceTiger

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    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.
     
  9. Apr 12, 2005 #8
    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.
     
  10. Apr 12, 2005 #9

    ohwilleke

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    :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.
     
  11. Apr 12, 2005 #10

    turbo

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    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: Apr 12, 2005
  12. Apr 13, 2005 #11

    Chronos

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    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: Apr 13, 2005
  13. Apr 13, 2005 #12

    turbo

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    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.
     
  14. Apr 13, 2005 #13
    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?
     
  15. Apr 13, 2005 #14

    turbo

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    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.
     
  16. Apr 13, 2005 #15

    turbo

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    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.
     
  17. Apr 13, 2005 #16

    SpaceTiger

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    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.


    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.
     
  18. Apr 13, 2005 #17

    turbo

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    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.
     
  19. Apr 13, 2005 #18

    SpaceTiger

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


    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.


    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.
     
  20. Apr 13, 2005 #19

    Chronos

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    See Arxiv site for posting papers there.
    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]?
     
  21. Apr 14, 2005 #20

    turbo

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    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: Apr 14, 2005
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