Hi Grey

It is good to hear from you again. I know that your mind is made up, and you feel that your explanations are adequate but this is obviously not an opinion I share. The fact that the poll is showing ever increasing numbers of people not convinced that the universe is “accelerating” is showing that the nature of the arguments against me are not that convincing. While about 75 percent continue to stick to convention, the very fact that percentage is decreasing over time indicates that there are fundamental questions and issues concerning the exact nature of the expansion of space-time. If the arguments made by you and others representing the “Establishment” were that sound and lucid, there would be no doubt that the universe was accelerating. More importantly, notice that the doubt is increasing over the course of the discussion. (Those who may argue that since the “majority rules” they must be right, should know that eventually the truth will prevail, the same kind of realization of knowledge has happened in the past where the majority thought one way, but eventually the truth prevailed. “The Earth revolves.”)

(I must admit that in part, I am also a member of the “Establishment”. It is my belief that the principles behind General Relativity make up a part of the description of the expansion of space-time. Based upon an Einstein-Minkowski theoretical model of the universe, the universe is decelerating. The conflict between theoretical models and observation are a part of the issue here. Without a universally accepted theoretical model that accounts for observation, both the theoretical models and the interpretation of observations are suspect. Being a theoretician by nature, my faith falls to theory, but a theory is worthless if it does not conform to observation. )

I am glad you provided links to previous discussions. You, distinguish your self by trying to provide a logical argument to support the “accelerating” description of space-time. After reviewing my responses to your arguments, I am still convinced my replies were convincing and logical. (My opinion, not yours, I know you feel the exact opposite).

For example you tried to give the following example to refute my assertion the universe is decelerating.
Grey
“Perhaps a concrete example would help. Say we're running a race between a Porsche and a Yugo. We'll be using sonar to keep track of the positions and velocities of each vehicle as the race progresses (we're using sonar rather than radar so that we're sure to have a noticable propagation delay). The gun goes off, and both drivers push the accelerator to the floor. Unfortunately for the Yugo driver, the Porsche accelerates about twice as fast, and quickly leaves the Yugo behind. A short time into the race you check your sonar readings, and see that the Porsche is moving at 150 km/hr and the Yugo is moving at 75 km/hr. But wait, you reason, the Porsche is farther away, so there was actually a four second delay in receiving that reading and only a two second delay for the Yugo. So the speed was 150 km/hr four seconds ago and only 75 km/hr two seconds ago. Therefore, you surmise, the vehicles must actually be decelerating.”

I think you are trying to use this example as proof of how a universe that is accelerating, as is each car, which then results in the observation that gives the appearance of decelerating.

You example is imaginative but it is not valid because it does not reflect the cosmological model that we, presumably, both agree upon. One of the principles involved with the cosmological model is that all galaxies are experiencing the same effects at the same time in history. There is no preferential distribution of the velocities associated with the cosmological expansion of space-time. All galaxies start off at the same time with the same general cosmological or recessional velocity. All galaxies start off as fast moving “Porsche’s”. If they did not, gravitational collapse would have pulled all the galaxies back together. Gravitational forces would slow the expansion of space-time causing them to slow down. In the past the galaxies would be traveling faster than the present, due to gravitational forces. An object moving faster in the past than the present is decelerating. The universe is decelerating.

Snowflake.

Supernova Ia's have very close to the same intrinsic luminosity regardless of distance, so there's no sampling bias as you assert, and the lengthening of the light curves, which isn't always so slight, fits quite well with Einstein's time dilation equation.

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Everyone is entitled to his own opinion, but not his own facts.

HI Cougar

Let me get this straight. You accuse me of

“you, in your neglect of studying current cosmological findings and your total reliance on your insipient intuition, you are promoting flawed ideas and spreading false assertions.”
What is wrong with insipient intuition? That was a characteristic of Einstein.

You also stated

“According to observations, as the universe expanded and the volume of space increased, the CC got the upper hand, and the expansion began to accelerate, as it continues to do today. If you could read the graph correctly, you would see that this is the necessary conclusion.”

Note that you have to come up with some fudge factor for theoretical models to make sense of observations. This has got to be somewhat disquieting to you at some level. What principles determine when the cosmological effect occurs and does not occur? What determines the magnitude of the CC effect? How does it interact with gravity and why?

Also it appears you do not know how the read the graph of the rate of expansion. Locally, up to about a red shift of about .05 Hubbell’s constant is constant. This means that the expansion of space time within the last 500 million years or more, the rate of expansion has been constant. V=Ho x D. (Depending upon the model regarding the distance actually traveled while space expands and how the speed of light may or may not be effected while traveling through an expanding space time field.) This means that for at least for the last billion or more years the expansion of space time has been relatively constant. (Actually it is slowing at such a slow rate it appears constant. According to my Uniform Expansion Theory the expansion of space time is described by a Hyperbolic curve, which asymptotically approaches 0 after an infinite amount of time, we are now in the flat part of the hyperbolic curve. http://www.uniformexpansion.com/gpage5.html)

Since Hubbell’s constant is constant locally, this means that currently the expansion of space time is constant. It is NOT CURRENTLY accelerating at an ever-faster rate. It is only when observations are made of the past, is there any deviance from the linear rate of expansion. Notice that any talk of divergence from acceleration or declaration of the universe only occurred when high red shift 1asn’s were discovered. These are measures of actions happening in the past, not the present. Locally for almost a billion years the rate of expansion has been linear.

An object moving faster in the past than the present is decelerating.
The universe is decelerating.

Snowflake

I don't have a subscription to see the whole paper, so I can only see the abstract. How many quasars were in the sample? What types of "quasar variability" is Hawkins talking about? In general, the thing about quasar variability is that any variations are not at all regular, so a more distant quasar could very well have shorter (intrinsic) variations than a closer one. If all quasar variations were the same, then this paper might be onto something, but I wouldn't be that surprised if there was a systemic behavior where earlier quasars exhibited more rapid variations, hence confounding any search for the effects of time dilation using quasar variability.

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Everyone is entitled to his own opinion, but not his own facts.

Labeling the cosmological constant with the derogatory term "fudge factor" does not detract from its apparent applicability or the fact that it has a specific place in Einstein's field equations. It doesn't explain the observations, but it provides a quantitative description for them.
It may very well be some residual dark energy left over from the inflationary epoch, 10^-29 seconds after the big bang.
The cosmological constant is just that - a constant per unit volume of space. As earlier noted in this thread, as a cubic parsec of space expands to two cubic parsecs, each cubic parsec will contain the same amount of dark energy as the original cubic parsec. Dark energy doesn't thin out. It stays constant per unit volume of space.
Wrong again. Please recall that the expansion of space is imperceptible unless you're looking over huge distances. It's imperceptible within our galaxy, which is pretty big. It's practically imperceptible within our local group of galaxies, which covers a LOT of territory. But the acceleration of the expansion is much, much more imperceptible, and that is why it only shows up out around z=0.4, which is a LONG ways away.

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Everyone is entitled to his own opinion, but not his own facts.

HI Cougar

When the Ptolemaic System was the rage, the policy was to add ever increasing offsets and epicycles to the model to have the theory correlate to observation. Adding extra constants, dark energy, dark matter, at various concentrations at various times to our present models indicates history is repeating itself.

Snowflake

Also you stated the following.

“Please recall that the expansion of space is imperceptible unless you're looking over huge distances. It's imperceptible within our galaxy, which is pretty big. It's practically imperceptible within our local group of galaxies, which covers a LOT of territory. But the acceleration of the expansion is much, much more imperceptible, and that is why it only shows up out around z=0.4, which is a LONG ways away.”

Stating that galaxies expand, in association with the expansion of space time, is not the position of the “Establishment”. Galaxies are “gravitationally bound” (It is apart of my theory, are you starting to agree with me? Do atoms also expand?)

The following quote is from “Modern Astrophysics” by Bradley W Carroll Dale A. Ostlie. It is a popular text used in Astrophysics courses. It illustrates the central issue I have with the “Establishment” regarding the nature of the expansion of space-time.

“It is important to realize that although the universe is expanding, there is no compelling evidence that the constants that govern the fundamental laws of physics (such as Newton’s gravitational constant, G) were once different from their present values. Thus the sizes of atoms, planetary systems, and galaxies have not changed because of the expansion of space (although the latter two may have certainly gone through evolutionary changes). “

(Of course I feel that there is compelling evidence that the constants of nature are varying, but in a way that is locally un measurable. Events viewed with an historical separation indicate this. My model does not require enormous amounts of dark matter, dark energy and black holes, for which there is no direct observation of, only inferences made to keep gravitational structures stable.)

Whether or not galaxies expand was an issue that was previously argued by Spaceman Spiff in my discussion about the Hertzsprung-Russell diagram and Stellar Evolution. http://www.badastronomy.com/phpBB/vi...amp;highlight=

He maintained the standard position that galaxies are gravitationally bound, so there is no expansion of galaxies due to cosmological expansion. This is the standard model represented by the “Establishment”. In fact he stated that there was no observation of such an effect. Actually the recessional expansion of a galaxies could be observed, it should be about 2 meters/sec, which is detectable, (contrary to your assertion that it would be imperceptible). Unfortunately the variation of the motion of stars within galaxies is about ten times that amount, masking the effect. Also, since different evolutionary situations can be proposed for a galaxy to evolve, it becomes possible to create a model that continues to exempt galaxies from expanding, despite the observed red shift. (There presently is no good theory describing the evolution of galaxies leaving the field full of speculations.)

Snowflake

Hi Cougar
Look at the graph again. http://www-supernova.lbl.gov/public/...ysicsToday.pdf
Pick an interval of time, or distance measure that represents say a quarter of the total graph. Note that for intervals of time within the present 500 million years (corresponding to a z of .05) the graph is flat. V =Ho x d. As one looks at galaxies (1asn’s) further in the past, the departure from linearity is observed and the further away the galaxy the larger the separation from linearity. It is only in the past that the deviation from linearity is observed. “Presently” the expansion of space-time is essentially constant. Thus the expansion of space-time can not be presently “accelerating”, all evidence of any change in the rate of “acceleration” is revealed by looking at events in the distant past.

Snowflake

Here is the paper on astro-ph. The author thinks that microlensing explains it and incorrectly dismisses local quasars on the grounds of detected host galaxies.

Hawkins is another case of the researcher not believing his own results, but being honest enough to post them anyway - anyone who believes there is a BB conspiracy should take not of this.
Yes Cougar, there may a reasonable explaination, but Hawkins could not find one, just as no one can find a good expanation for the apparent proper motion of quasars.
It is not a constant, according to Riess 2004, the acceleration 'jerked' in the past and the acceleration rate has been decreasing ever since. So in the current supernova scenario, eons ago the universe started collapsing, then there was a big jerk when the acceleration function kicked in, followed by a gradual decline in the acceleration rate. As Cougar pointed out, it is impossible to measure the expansion rate locally, and we do not know what switches this cosmic tractor beam on and off. We don't know why it has preferentially accelerated blue galaxies more than red ones. We are clueless as to what the current rate is. Or we could be clueless about what the supernova are really telling us.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

The semester is over, so I have a bit more time to do relaxing things. The fact that discussing physics and astronomy is something I find relaxing would probably be odd to some people, but fortunately, few of them would be like to frequent this bulletin board.

My mind is never permanently made up on any scientific issue. I'm always willing to be convinced if there is evidence supporting an unusual claim. I just think that you fail to understand that the logic you're using is flawed.

Actually, it seems that very few agree with your contention that the expansion is decelerating. Most who disagree that it's accelerating instead think that there is another explanation for the redshift.

It's amusing that you consider this "convention". If you'd suggested that the expansion of the universe was accelerating ten years ago, everyone would have said it couldn't be. The reason that the physics and astronomy community overwhelmingly believe this to be the case is that the observational evidence has forced them to, even though it was contrary to all expectation. I'd certainly agree that there are fundamental questions about the expansion of the universe, though. Observation says it's accelerating, but we really don't know why!

I believe that what I'm doing in the car example is showing what you're doing when you compare galactic velocities. You look at a distant galaxy, determine it's recession velocity to be greater than that of a closer galaxy. You then notice that the light you receive from the more distant galaxy is older, and hence that you are observing this galaxy further back in the past, effectively. But then you try to say something about the acceleration of these galaxies by comparing these velocities directly. Thus, you're comparing the velocities of two different objects, just like in the Porsche/Yugo example. Comparing the velocities of two different objects doesn't tell you anything about the acceleration of either one.

Whoops. Although I agree that it is a cosmological principle that all galaxies experience more or less the same thing, they certainly don't all start off with the same recessional velocity relative to any given point. Why would they? They're more or less randomly scattered* through the universe now, just as they were in the past. Both now and in the past, the recessional velocity relative to any randomly chosen galaxy (say, ours) is roughly proportional to their distance, so the velocities are widely distributed. If the velocity of all the galaxies started out almost exactly the same relative to us, we'd see a big hollow shell of galaxies, all at about the same distance.

That's exactly what everyone thought a few years ago. It makes sense theoretically, and we'd all still believe it, except for that tiny little problem that it's contradicted by observation. Actually, it's a pretty exciting time when a natural assumption like this gets overturned, because now we get to try to figure out what the heck is going on.

* Actually, there's some pretty interesting structure in the distribution, but it's not really relevant to the discussion at hand.

Not nessisarily.

For example. Lets say I'm driving my car down the highway at sixty mph. Traffic gets thick and I slow to 25 mph. Then traffic clears and I begin to accelerate to 60 mph again. I am moving slower then I was originally but I am accelerating.

I dunno if that applies here cause I didn't read all of the thread, so I'm just sayin.

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"Most editorials are written by people that love to argue but got kicked off debate team for not making any sense." -Seanbaby

This is not quite correct.
When the Perlmutter "stretch", Humay "D(15)B" or Riess "MCLC" are used, the statistical width of the light curve, and therefore the brilliance of the supernova Ia DECREASE with increasing distance. This represents a distance/luminesity anti-correlation, and that should never occur. I will admit that for my intrepretation to be true, the local SN Ia sample are over represented by small SN Ia, but this is more logical than the mainstream conclusion that distant SN Ia are smaller, and therefore the local sample are over represented by bright SN Ia.

There is also the collaborating evidence from gamma-rays - SN Ia researchers contend SNe Ia explosions are nearly perfectly spherical, and therefore their are no vectored gamma rays. John Middleditch has shown quite conclusively this is not true, and therefore the lightcurve widths should have a fairly broad distribution even if the peak magnitude is very tight. Our survey techniques, where snapshots are taken over periods of days and even weeks, certainly favor the detection of longer light curves over increasing distances, not the shorter ones required by the Riess & Perlmutter interpretations.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

Hi Grey
You stated the following
"Whoops. Although I agree that it is a cosmological principle that all galaxies experience more or less the same thing, they certainly don't all start off with the same recessional velocity relative to any given point. Why would they? They're more or less randomly scattered* through the universe now, just as they were in the past. Both now and in the past, the recessional velocity relative to any randomly chosen galaxy (say, ours) is roughly proportional to their distance, so the velocities are widely distributed. If the velocity of all the galaxies started out almost exactly the same relative to us, we'd see a big hollow shell of galaxies, all at about the same distance."

To which I respond with.

Whoops. All galaxies experience the same recessional or cosmological expansion at the same time historically. At the beginning of time, assuming you adhere to the BB, must expand at extremely fast velocities to avoid gravitational collapse of the universe. It is like a very fast expanding sponge carrying Poppy seed galaxies. When the sponge first expands the rate is very fast and all the poppy seeds in the sponge expand at the same rate. As the expansion of the sponge slows down the recessional velocity of the poppy seeds in the sponge slow down. The poppy seeds do not distribute themselves in a big hollow shell of poppy seed galaxies.

You also stated the following

The reason that the physics and astronomy community overwhelmingly believe this to be the case is that the observational evidence has forced them to, even though it was contrary to all expectation. I'd certainly agree that there are fundamental questions about the expansion of the universe, though. Observation says it's accelerating, but we really don't know why!

To which I respond with

The real surprise is not that space is “accelerating” it is that the rate of deceleration did not conform to expectation. The rate of deceleration should have been greatest when the universe was young due to gravitational interaction. This is not indicated by the dimness of 1asn’s. The rate of deceleration in the past appears to be not as great as it appears to be now, based upon the measure of 1asn’s. This observation is what results in what is called “acceleration”. It is assumed that some other factor is “accelerating” galaxies now to conform to the observation but the overall motion of the galaxies is actually deceleration. Stating otherwise is resulting in confusion.

I know why this observation of the unexpected deceleration occurs, and with the knowledge that this will again subjugate me to derision I will state that the assumption that high red shift 1asn’s are the same as local supernovas is a wrong. Since gravity is a function of time, (according to my uniform expansion theory, which was a belief of Dirac and Gamow) it takes less mass to form a supernova in the past. This reduced mass results in a smaller explosion, which appears dimmer. Once these supernovas are adjusted for this effect, the assumed distance becomes not further but closer than what a linear Ho would predict. This is in closer agreement with expected results from gravitational interaction, as predicted by the simplest application of general relativity.

Snowflake

Problem here Snowflake, according to (Riess 2004) and (Tonry 2003) There was a decline in the acceleration rate before as well as after the peak. This makes the less mass assumption an even less probable interpretation. In any case, when you assign different physical properties to similar events occurring at very great distances, you are straining the credibility of your thesis.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

I am interested in this thread for all the wrong reasons.

The arguments presented against acceleration are compelling, and the voting in favour of it. Funny that!

Politics anybody?

And the % in favor of acceleration is about the same as the supposed dark energy content of the universe and the value of the Hubble Constant.

Seriously, most people go with the mainstream view. If the question was asked 10 years ago, deceleration would have gotten the most votes.

Yep. Coincidences do not always make for compelling evidence. Shame!

The universe is not accelerating or decelerating. If you apply Zwicky's exponential formula for 'tired light' redshift to non adulterated redshift data ( i.e. data that has not been fiddled to take into account expansion) it fits beautifully.

-Welcome back Lyndon! Do you know if Zwicky had an explanation for his exponential curve fit? Reference? Thanks!

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jwj

It's a big universe out there...is it really unwinding, really burning out?

Hi Jerry Jensen

Thanks for the post.
You stated the following.

"Problem here Snowflake, according to (Riess 2004) and (Tonry 2003) There was a decline in the acceleration rate before as well as after the peak. This makes the less mass assumption an even less probable interpretation. In any case, when you assign different physical properties to similar events occurring at very great distances, you are straining the credibility of your thesis."

I am a bit confused as to what you are calling the “peak”.

I also realize that adding my application of a uniform expansion complicates the credibility of my arguments, it is just that the application of the theory restores the observational evidence back to a conformance of theoretical expectations that have been assumed to be right for decades. The cosmological expansion rate of galaxies is fastest in the past and slows in a smooth and hyperbolic like rate. High red shift 1asn’s are closer than a linear rate of expansion, not further, as presently assumed.

Snowflake.

Hi dgruss.

Thank you for the posting on time dilation and Quasar Variability

I would like to have a discussion of the Hawkins paper as separate topic. Initially this topic was posted by Dunash on this BB on January 10, 2002, but there was no follow up discussion of his posting. http://www.badastronomy.com/phpBB/viewtopic.php? I searched the BB for other postings on this topic and I thought I remember it as part of a topic involving red shift but it does not pop up as a topic using the BB search function.

This paper indicates that something is wrong, and it should be talked about.

Snowflake

How big is the Universe?
Hi Darksand,

You stated the following.

“Maybe this has been here before but....

If the universe is expanding faster and faster, tel me this, when we see a galaxy on the edge of our observable universe say 15 Billion light years away, we see it 15 Billion Years ago, so it would be much furter away now. This would be proof that the unverse is expanding faster than light, isn't it? or maybe its older than 15 Billion Years, we just can't tell, can we?”

This should probably be part of another thread but since darksand mentioned it here, and it pertains to his observation, the following link is interesting. It states that the present size of the universe is bigger than we presently measure (it will make sense when you check out the site).
http://www.space.com/scienceastronom...ay_040524.html
Most probably someone will make this a separate topic.

Snowflake

Hi Soupdragon2

Thanks for your honesty.

Snowflake

[/quote]
Not back - just passing through. He must have had an explanation for it and I am trying to find it - without success at present. One paper says it is the effect of gravity 'pulling the photons back' but I am not happy with this and need more references before I believe it.

Yes thanks, I found this link already on another forum, and it explains my Question and supports my observations (well I used it to contradict a accelerating universe, I didn't think someone would believe an expantion so much bigger and faster than the speed of light, but I was wrong), I must say that this story is tilting my point of view to the accelerating Universe. I was also looking for evidense for a contracting or decellerating universe, but i think I have now enough data that contradicts this point of view, also it was a Coincidence to find the answer to my question you Quoted.

[Edit: My Bad English]

Come to think of it, if you look far enough into the depths of space, you will be viewing a time when the universal expansion was decelerating, because with less space, there wasn't as much dark energy, and the gravitational effect of all the mass in the universe was stronger than the expansive effect of the dark energy. But the universe continued to expand, and with the additional space, the effect of the dark energy eventually became stronger than the gravitational effect (which drops off with the square of the distance), so at that point the expansion began to accelerate, as it continues to do today.

So the expansion has decelerated in the past, and today it is accelerating.

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Everyone is entitled to his own opinion, but not his own facts.

You seem to be saying that amount of dark energy increases when amount of space increases. Where this energy comes from?

As I have complained elsewhere, the supernova researchers are calling the shots; if we listen to them, the universe is still accelerating, but the rate of acceleration is slowing (Alec Filippenko's lecture at APS Denver May, 2004).

A more honest answer is that the proper motions of galaxies and stars near us make it impossible to say what the direction and force of 'dark energy' are at present. The sudden change in the rate (the cosmic 'jerk' Adam Riess bases on the sudden change in supernova attenuation at z~0.5) has know known physical cause, and if you accept this theory, you have no way of predicting whether or not a similar event is happening right now.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

If dark energy fits into Einstein's GR field equations as the cosmological constant, as is consistent with all observations, then the amount of dark energy per unit volume of space stays constant. So as a volume of space doubles because of expansion, then the amount of dark energy also doubles. Contrary to intuition, as space expands, the dark energy pervading that space does not "thin out". It stays constant per unit volume.

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Everyone is entitled to his own opinion, but not his own facts.