If you want to look at the data yourself, use any search engine and Type in Dr. Adam Riess and High-z Supernova Search. You will see the curves yourself. The only thing is that you are going to have to transpose the coordinate system to reflect normal expressions of acceleration. Their Hubbell plot has distance as the y axis and velocity as the x axis. Most people are used to velocity (z red shift indicates recessional or cosmological velocity) being the y axis. To see it properly, tip you head to the side and you will discover that the slope is negative which means deceleration.

snowflake

Freddo

Freddo you said that "You seem to have come to the conclusion that the findings confirming an expanding universe do not take into account the expansion of space and time dilation when reconciling the results. "

There are relativistic compensations as well as "dust" compensations that have to be made, which are ok. For example the length of time that the novas burn must be adjusted for relativistic effects. This is accounted for in the previously referred plots.

snowflake.
Freddo

From the www.space link the article ends with
"An explanation of the dark energy may involve String Theory, extra dimensions or even what happened before the Big Bang. At present nobody knows. The ball is now firmly in the theorists court."

Here I am.

The “dark energy” they keep looking for is extracted from our own universe. As space expands it extracts energy from everything. Since balloons seem to be popular, a small tight skinned balloon has more energy than a balloon that has been stretched out.

snowflake

Thanks guys

I will post more mistakes soon.

snowflake

Yes. It's true that the results of general relativity are sometimes counterintuitive and the mathematics are difficult to understand. However, it's also true that it does an excellent job of explaining the things we see.

Unfortunately here, you're making the mistake of comparing the velocities of two different objects (a nearby object and a far away object), and then trying to make a claim about the acceleration of the objects. It should be clear that you cannot determine anything about the acceleration of an object by looking at how its velocity differs from that of an entirely different object. Instead, what you'd need to do is look at a galaxy, and measure it's recession speed. Now wait a few billion years and look at that galaxy again. It will be receding faster, hence, it's accelerating. Now, we can of course use data from the recession of more than one galaxy to determine that this will be the case without having to actually wait the few billion years.

You also seem to be confusing the difference between the recession velocity and the rate of expansion. If the universe is expanding at a constant rate, galaxies will still recede faster as they get further away, proportional to the distance. However, the whole point of the discovery of the universal expansion is that the rate of recession actually increases faster than proportional to the distance.

You aren't stating anything new here. Most descriptions of the Big Bang discuss the fact that since it's space itself that's expanding, any point in the universe will seem to see everything receding directly away from it. Whether you consider this to mean that there's no center to the expansion, or that the center is wherever you happen to be is purely semantics, and astronomers will commonly use both phrases.

To swap the x- and y-axes on a graph, you don't rotate it; you reflect it in the line y=x. Positive gradients remain positive and negative gradients remain negative.

This is exactly what I was going to say, I just didn't get here fast enough. You can't make any determination about the acceleration of an object based on the observation of another object. Closer objects may not be moving as fast but that doesn't say anything about the farther objects that are.

__________________
"Eternal vigilance is the price of supremacy"
------------Mark Twain

"Women are like Voltron. The more you can hook up, the better it gets."

Hi Gray
“ Unfortunately here, you're making the mistake of comparing the velocities of two different objects (a nearby object and a far away object), and then trying to make a claim about the acceleration of the objects.”

I am not making a mistake. The velocity of a near by object is observed near the present. A far away object is observed in the past. The fact that I generalize that relationship is just describing the nature of the “expansion” . Don’t for get that a distant galaxy observing our galaxy would say our galaxy is “moving” (receding) faster than a near by galaxy. By knowing how others perceived us (one object) we can say we (one object, the Milky Way Galaxy) is moving faster in the past than the present. This conclusion would be reached by every sentient being in every galaxy. The expansion of the universe is slowing down.

snowflake

Hi Robin

If one sticks with the following convention, the graph of Hubbell’s “constant” will prove to describe deceleration.

If time is the x axis and “0” represents the beginning of time and is located at the origin, later dates are positive or moving to the right.

If velocity (z or recessional “speed”) is the y axis with 0 at the origin and increasing values move up,

Then the slope will be negative, indicating deceleration!

Again the reason for the “mistake” astronomers make is that they do not properly use time. They make measures of time assuming that “now” is at the origin.

snowflake

Hi Grey

you said
“Yes. It's true that the results of general relativity are sometimes counterintuitive and the mathematics are difficult to understand. However, it's also true that it does an excellent job of explaining the things we see.”

General Relativity is a consistent description of reality but I am not so convinced it does an excellent job of explaining the things we see. A tremendous number of extremely smart people have tried to unify General Relativity with the other fundamental forces or description of nature, including Einstein himself. No one has been able to establish a viable relationship that unites Quantum Physics with General Relativity. The two theories have clashing descriptions of what happens at a singularity.

Also regarding the application of general relativity to describe the expansion of space I have an issue with. It is assumed that to determine what is happening, a sphere of spacetime is wrapped around “us” and with in that sphere the matter interacting with all the surrounding matter creates the curvature of space. Matter curves space and the curvature of space tells matter how to move. The thing is, once one establishes curvature around us, move over a few million light years over and establish another description of space. There is also a curvature but it is telling our galaxy to move towards it. Repeat the same process for the galaxy with a galaxy on the other side equally far away. The curvature of space is telling our galaxy to move towards it, The net effect is to cancel each other out.

If general relativity is correct, (which I believe) it is incomplete. And even Einstein believed that.

snowflake

Pi man
"The most logical conclusion is not that several million scientists forgot to factor in something that obvious..."

It is not several million scientists, in reality it is only a handful, it is just that many just repeat each other. When it was discovered that type 1a galaxies with high red shifts were even further away than thought, it just looks like the universe is “accelerating” away. If we describe the past as a positive value then this perspective results. This then means that the future becomes negative and we are moving in a negative direction. This is an unconventional sign convention.

Also, there are a lot of others that describe the expansion of space as decelerating. They are just tolerant of the inconsistent description of space. If you want, check out NASA ADS search site by typing in declaration of space. I have included one of the “hits” below.
An introduction to mathematical cosmology
Authors: Islam, Jamal Nazrul
Journal: An introduction to mathematical cosmology. 2nd ed. / J. N. Islam, Cambridge, UK: Cambridge University Press. ISBN 0-521-49973-9, 2002, XII + 248 p.
Publication Date: 00/2002
Origin: ARI
Keywords: COSMOLOGICAL MODELS, FRIEDMANN UNIVERSE, ROBERTSON-WALKER METRIC
Abstract Copyright: Cambridge University Press
Bibliographic Code: 2002aitm.book.....I
Abstract
This book provides a concise introduction to the mathematical aspects of the origin, structure and evolution of the universe. The book begins with a brief overview of observational and theoretical cosmology, along with a short introduction to general relativity. It then goes on to discuss Friedmann models, the Hubble constant and deceleration parameter, singularities, the early universe, inflation, quantum cosmology and the distant future of the universe. This new edition contains a rigorous derivation of the Robertson-Walker metric. It also discusses the limits to the parameter space through various theoretical and observational constraints, and presents a new inflationary solution for a sixth degree potential. This book is suitable as a textbook for advanced undergraduates and beginning graduate students. It will also be of interest to cosmologists, astrophysicists, applied mathematicians and mathematical physicists.

There are others that use deceleration to describe the expansion of space since they use a more standard sign convention.

snowflake

cyreks comment:

About the expansion of space:
This idea is based on the 'casimir experiment'.
Two plates in close proximity being pushed together in a vacuum.
Thus, they attributed this to the space outside the plates which was greater than the very close space between the plates.

This can be explained in another way.
There is no such thing as a perfect vacuum in these experiments.
There is always some molecules left in these vacuums.
Therefore, the outer space having much more molecules and greater leeway for movement than the space between the plates will be colliding on the outside of these plates with their momentum to cause them to move towartd each other.

Therefore, the space is not the cause of this pressure but instead, it is molecular collisions and their pressure that is the cause.

__________________
aka Michael Cyrek

I'm afraid that you are. You simply can't judge the acceleration of an object by comparing the speeds of two different objects. In the second case, you're making a related, but slightly different mistake. In this case you're measuring the speed of the same object (the Milky Way), but you're doing it in two different reference frames, which are in motion relative to each other. Again, nothing can be said about the acceleration of an object under such circumstances; I could pick arbitrary reference frames and come up with any value for the acceleration I wanted using this method. The velocity and acceleration of an object are only meaningful if I'm being consistent about which object I'm referring to and which reference frame I'm measuring it from.

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.

Now, now, let's keep this polite. Suggesting that anyone who points out a flaw in your reasoning or who disagrees with you must not be sentient is, I would suggest, not proper etiquette for a discussion.

This, I disagree with. Except in cases where quantum effects need to be taken into account, general relativity has passed all the tests thrown at it.

This I agree with. However, even though we don't have a complete quantum theory of gravity, we do have some useful insight into some of the features such a theory would have to have.

This isn't quite accurate. Under general relativity, the individual effects of matter can be seen as local curvature, which we perceive as gravitational attraction. However, the overall structure of matter in the unvierse also contributes to a global curvature. If the net density is high enough, general relativity predicts that the expansion would slow down and eventually reverse, while if it's not above that critical density, it will slow down but not stop. Of course, the presence of a nonzero cosmological constant plays havoc with that, but the overall result is still the same.

To be precise, that result is that the rate of expansion may be affected by the matter in the universe. While your visualization seems to contradict this, remember that it's not your conception of a theory that determines what that theory would predict, it's the mathematics that does that, and the mathematics of general relativity clearly indicate that the rate of expansion can change based on gravitational attraction. Of course, as you say, relativity may be wrong, but remember that it is well tested.

I'll agree with this, too. There's no question that we still have work to do to understand the universe!

Hi, and welcome to the board.

While you could, of course, be right that there is a mistake in the High-z Supernova group's work that no-one has noticed yet - after all, no-one is infallible - I'm sure it's not as simple as that they drew the graph with time running downwards, then forgot that meant positive gradients indicate deceleration.

The expansion of the universe is not measured as a speed - that is, it is not measured in metres per second. It is measured by the Hubble constant, which has the SI unit s^-1, although it is usually expressed in km/(s Mpsc) (kilometres per second per megaparsec). Currently, the Hubble constant is held to be about 71 km/(s Mpsc). This means an object 1 Mpsc away is moving away from our galaxy at 71 km/s, an object 2 Mpsc away is moving at 142 km/s, and so on. Note that, even with a constant rate of expansion - constant Hubble constant - distant objects have a greater speed than near ones.

What Dr. Riess's team discovered, if I've understood correctly, is that very distant objects are moving slower than they should be. For large values of d, objects d Mpsc away are moving at less than 71d km/s. And, the further the object you view, the smaller the ratio of speed to distance becomes.

As you say, the more distant the object, the further in the past we are viewing it. Conclusion: the Hubble constant is increasing with time. That is what is meant by "the expansion of the universe is accelerating".[/i]

One correction - I shouldn't have called the group Dr. Riess's. Brian Schmidt was the team leader.

So if I have a rubber band and stretch it out in a perfect circle, it won't contract again because each point in the rubber band is being pulled equally in either direction.

__________________
Everything I need to know I learned through Googling.

Oh, sorry, didn't see your post, ToSeek. Oh, well, I was going to say....

Grey's doing an admirable job clearing up some misconceptions in this thread. I wanted to go back to one of the first things Snowflake claimed:

That's correct. BUT your chosen galaxy also exerts a gravitational effect on all those other galaxies around it, doesn't it? If they are all receding due to the expansion of space, your galaxy's mass will be slowing them down, if only a small amount. The same is true for every galaxy. If the galaxy configuration in the universe was static, gravity would have them all attracting one another, leading to a very big crunch.

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

Gray

You said the following.
“I could pick arbitrary reference frames and come up with any value for the acceleration I wanted using this method. The velocity and acceleration of an object are only meaningful if I'm being consistent about which object I'm referring to and which reference frame I'm measuring it from.”

Remember that earlier I gave an example about me entering into a room at a certain speed and slowing down. I would describe my motion as deceleration. So would every one else observing me walk in the room. Since each person can establish their own “frame of reference” around themselves, and since each one of the people in the room would also describe my motion as “decelerating”, this would seem to negate the assertion that “arbitrary reference frames” yield any desired effect.

You are still right, but if one is looking for a UNIVERSAL description, then your approach of arbitrary reference frames does not lend itself to a UNIVERSALLY accepted description of reality. For example if you were in the room on the far side of the room with your coordinate system oriented so that positive directions were in the direction of the door I entered the room, the direction of the acceleration vector that you would describe my change in velocity would correspond to a POSITIVE value, just like you asserted, and which is opposite to my description of deceleration. So, if instead you decide to try and describe reality such that everyone describes reality the same way, then instead of your coordinate system, you would look for a universal coordinate system which allows everyone to describe the same events the same way, plus is plus and minus is minus. An object moving faster in the past than the present is decelerating. If all objects were moving faster in the past than the present, then all objects were decelerating. If all galaxies were moving faster in the past than the present, all galaxies are decelerating. This kind of universal frame of reference requires a measure of time that establishes when measurements are made.

The measure of time, which records “when”, corresponds to another independent dimension of time. But I drift.

snowflake

You're right. There is not a mistake from the plotting of the graph. However, that is not to say that the High-z supernova results might not be mistaken. Rowan-Robinson has pointed to several problems with the high-z supernova results. Click on "pdf" to read the article.

Rowan-Robinson points to two major problems with the High-z supernova results. First, the teams did not properly account for extinction by the host galaxy. Second, many of the supernova were not observed before maximum. The evidence is much weaker if only supernova that were observed before maximum are used.

Hi Cougar

Ok, so I am in my galaxy and I am pulling everything towards me: and all the other galaxies are pulling everything towards each other. If the galaxies are uniformly distributed and are distributed way beyond what we can ever possibly observe, then every galaxy is pulling each other in every way resulting in no “crunch”. Just as there is a galaxy pulling one way, there is another galaxy pulling in the opposite direction. Just as my galaxy is pulling another galaxy towards me, there is a corresponding galaxy pulling that galaxy away.

An infinite distribution of small particles does not collapse into mass. This is one of the problems that face theorists about the formation of galaxies. Galaxies can form if the matter in space can be “lumped” but if the distribution is uniform and “infinite” then things stay disbursed.

snowflake

Mistake # 4
Recessional red shift

Given the fact that an object moving at the speed of light does not change ( Remember the Special Relativity “twin” problem; the twin that travels at the speed of light does not age, if the twin can not age, than he or she does not change) Then how does the wave length of light associated with distant galaxies increase with the expansion of space, as predicted by general relativity? The photons from galaxies are moving at the speed of light so they should not change.

(general relativity is right about this, it is just that the explanation is incomplete).

snowflake.

If you accept the Big Bang theory, then the universe cannot be infinite as there was a finite amount of matter at the outset. If there is a finite amount of matter, then either there's an edge to the universe or else the universe is like my rubber band or the surface of a balloon. Either way, gravity will have a retarding effect.

__________________
Everything I need to know I learned through Googling.

But we are not observing the motion of the distant galaxies, we are observing the relative expansion of space between us and the distant galaxies. Ignoring all the issues of the accelerating universe for the time being, as well as delays generated by the speed of light, if space is expanding uniformly everywhere, then the more distant the galaxy the more expansion is going on between us and that galaxy. (Remember the usual analogy of the balloon blowing up or the raisin cake baking.) There's a linear correlation there, and that's what the Hubble constant measures. I haven't done an analysis, but my guess is that the delays generated by the speed of light would be a linear function as well and would just reduce the Hubble constant somewhat.

__________________
Everything I need to know I learned through Googling.

The explanation is not incomplete at all! Our explanation conforms exactly to what we measure!

You can view the problem in one of two (that I know of) ways:

Think of an object emmiting light at 500 Mhz (or 500 million times a second), near the lower end of the spectrum. If the object that emitted the light is moving toward you, the the number of wave peaks of the light start coming at you faster:

The result is that the light frequency will increase, and the light will shift toward the blue (which is higher frequency).

If the light source is moving away from you, the waves will be stretched, and the wave peaks will come less often:

The result is that the light frequency will decrease, and the light will shift toward the red (which is lower frequency).

An equivelent way of viewing it is this way:

As the light source is receading from you, the space is stretching, and therefore is stretching the light, and increasing the wavelength:

Now, you may say that these are not two different ways of looking at the same problem, but they are. The Hisenburgh Uncertainty principal makes it perfectly valid, and since it conforms to all observation, it is the best theory we have yet.

I'd disagree with this. It's possible to have a Big Bang with an infinite amount of mass; that would correspond to either a flat or open curvature. I have a terrible time getting my head around it, but it works mathematically.

Nobody (well, at least no serious cosmologist that I'm aware of) ever claims that the distribution of matter was perfectly uniform, since that would indeed preclude formation of structure. Quite the reverse, one of the tests of cosmological models is to see just how much anisotropy they predict, and whether that correctly accounts for the structure we see in the universe today. Using computer models, it's possible to get an idea of which Big Bang models can't possibly be accurate, and which are at least possible.

However, although a perfectly isotropic distribution would prevent structure from forming, ToSeek is still correct that such a distribution of matter could collapse. In his rubber band analogy, even if the rubber band were an infinitely stretched line, it would still contract, even though each point on it is pulled in both directions. It's perhaps not completely intuitive, but when dealing with the infinite intuition often fails.

But your room analogy does not correspond to what you describing in the case of galaxies. In the first case, everyone in the room is pretty much standing still, so they share the same reference frame, and you really are decelerating. In the case of galaxies, the people are all moving at different speeds, and remember that they can only measure your relative velocity to them. This woould be like if you said that one person sees you moving at 5 mi/hr and another sees you moving at 3 mi/hr. So what's your acceleration given these two observations? We have no idea. To know, you'd need to know how the two people who did the measurements are moving relative to each other.

If you say that it was one person doing both measurements separated in time, that does not correspond to measuring the velocity of one galaxy nearby and another far away. Nor does it correspond to two different observers making measurements on our galaxy. Instead, it would correspond to making a measurement on a single galaxy, waiting a while (since the speed of galaxies doesn't change much, you'd have to wait a very long time here), and then measuring the speed of that same galaxy again. If you do that, you'll find that it's moving away from you faster.

Hi Pi Man.

I am impressed with your creative ability to draw using just a keyboard. Unfortunately you are a victim of a previous “mistake” in astronomy regarding the “Doppler shift” of galaxies. When Hubbell published the first paper correlating the increased wavelength of the spectra from the light of galaxies to the distance of the galaxies, he stated that this effect was a Doppler effect. Similar to the Doppler effect we hear when a car drives by. The increased wavelength was due to relative motion.

Einstein and Minkowski changed the interpretation of the “Doppler shift” associated with distant galaxies with the application of General Relativity. Instead, the increased wavelength of the spectra from galaxies was due to the expansion of space itself. As a photon travels through an expanding space time field, the energy of the photon is diminished, or its wavelength is increased.

Hubbell never accepted this consequence of General Relativity. He believed that the effect was due to the actual motion of the galaxies. It was a Doppler effect just as you so elegantly illustrated in you email.

Since the “reddening” of light was first described as a Doppler effect, the use of the term “Doppler effect” has persisted for the last 80 years. Most “modern” astrophysicists are careful to not use the term “Doppler effect” in describing the increased wavelength of the spectra from distant galaxies. Now most use the term “Cosmological” shift or a “recessional” shift/effect. This is what is taught currently in most Colleges and Universities at this time.

Thank you for your carefully explained and crafted email. You could still be right, maybe it is both a Doppler shift, and a recessional shift that are influencing the observed spectra from galaxies. “Modern” or current theory asserts that the red shift is primarily due to the expansion of space.

But if it is a Doppler effect, we have to be moving in a dimension that we are not directly aware of, in a fourth dimension. I actually advocate this idea, but I still am also a believer in General Relativity. I believe both relationships are in effect. But it will take a bit of explaining to describe our motion in a fourth spatial dimension.

snowflake

Hi ToSeek

You stated “If you accept the Big Bang theory, then the universe cannot be infinite as there was a finite amount of matter at the outset. If there is a finite amount of matter, then either there's an edge to the universe or else the universe is like my rubber band or the surface of a balloon. Either way, gravity will have a retarding effect.”


From our perspective, we have not observed the outermost galaxies. If we look out 10, 20 or 30 billion light years out, there is only so far we can see. When we look to this edge, we see lots and lots of galaxies. It is as if we are surrounded by a sphere of galaxies. Where is the edge? I too believe as you do that the Universe is limited, but it is extremely big. If we imagine being located at the center of our observable universe and pick the most distant galaxy we could see, I believe that on that most distant galaxy there is someone like me, thinking that that most distant galaxy he can see in one direction is our Milky Way galaxy. My imaginary counter part then turns his “Hubbell like” telescope half a circle away, (they don’t’ use degrees in this galaxy.) and observes a whole vast array of galaxies that we, on our Milky Way Galaxy, cant even see. The universe is ****** big. (Excuse my French).

If the observable universe were the size of a beach ball, with us in the center, then it is possible to imagine a large room full of beach balls, with each beach ball representing the observable universe for the galaxy residing in the center of each ball.

I believe it is extremely unlikely that we just happen to be in the center of the Universe, with 100 billion galaxies to be in the center is unlikely, but a possibility. I also believe that it is extremely unlikely that what we see of our universe represents the extent of our universe.

General Relativity limits the effect of gravity to a region of space that is observable; it ignores the effect of what is outside our observation. When one reviews the calculations on the collapse or expansion of the universe, the amount of matter found within the observable universe is included. (Some also make adjustments to this size due to the expansion of space). General Relativity totally ignores the galaxies beyond our observation. My counter part on the most distant observable section of the universe should be drawn towards our Milky Way Galaxy, But my counter part has an equal number of galaxies pulling him away from our galaxy. SO NOTHING SHOULD CHANGE. Yet observation tells us this is not so. So to avoid this, Astrophysicists simply ignore the possible effects of outside our observation, curve space-time and use this to explain how space is expanding.

(Another way to resolve this is to not curve space but to allow space to change by another dimension. A straight line is one dimensional, If I curve a straight line, it now has properties that are expressed by two dimensions. (Granted a curve line is usually described a one dimensional, but I hope you can see how I call it “two” dimensional. ) By allowing space to change in another dimension it is possible to “curve” space, just as a line is curved by inducing properties of another dimension. ) (General Relativity curves space by the use of the Metric, I curve space by allowing another dimensional measure that is structurally tied to the fabric of space-time.)

snowflake

Grey

You stated “one of the tests of cosmological models is to see just how much anisotropy they predict, and whether that correctly accounts for the structure we see in the universe today. Using computer models, it's possible to get an idea of which Big Bang models can't possibly be accurate, and which are at least possible. “

I think it is important to note that there is NO MODEL that predicts the formation of galaxies. All simulations assume a “lumpiness” that is not found or explained. While fluctuations in the CBR indicates that some “lumpiness” was prevalent at the very early beginnings of the Universe, there is no explanation as to how these turn into galaxies. Everything is so hot and ripped apart, nothing appears to be able to have matter clump together. This is one of the reasons Paul Dirac believed that gravity was a function of cosmic time.

You also stated that “ In his (ToSeek’s) rubber band analogy, even if the rubber band were an infinitely stretched line, it would still contract, even though each point on it is pulled in both directions. It's perhaps not completely intuitive, but when dealing with the infinite intuition often fails.

Are you really content with accepting a theory that defies intuition? If something else were more intuitive and which also predicted the same kinds of physical effects would you consider it?

Also, General Relativity does not use an infinite size “ball” or rubber band to explain gravitational collapse. They use the extent of the observable universe. The assume a size and try to find the amount of matter in that sphere, establish the critical density and try to predict the expansion rate of the Universe.
If we are at the center of mass of the entire universe, then General Relativity is correct, If we are not, then General Relativity is certainly incomplete.

snowflake

The two are equivelent. Two different ways of thinking of the same situation, just like wave/particle duality (if you've ever studied QM). There aren't two seperate processes at work, it's one and the same process viewed two different ways. It's not one or the other, they are both true because they are equivelent.

Huh? The fourth spacial dimension? Why would it require any motion in any direction not already seen? 8-[ The GR method of looking at it is that space is stretching (or the distance between us and the distant galaxy is stretching) and therefore is stretching the wave pattern of the light. Why is there a need for another spacial dimension in that?

Whether the universe is infinite in extent or finite in extent, there is no center of mass (at least not within this universe).