Accelerating Universe / inverse acceleration?

[uncommonsense]

It is my understanding that according to the mainstream view, galaxies in the universe are each/all accelerating away from one another (accelerating expansion). I have researched to find many opinions suggesting gravity may have a causal role in this acceleration of expansion.

However, if I understand mainstream view, and also Einstein's elevator regarding acceleration and gravity, then likewise an individual galaxy (call it galaxy "A") is accelerating away from all others, except inversly upon itself. This is probably better described by saying that each individual entity within galaxy "A" that is capable of gravity is accelerating inward upon itself. So my question is wether the mainstream views such acceleration as a potential cause of gravity, rather than the other way around? In the alternative my question is: what am I minunderstanding about acceleration?

[DrWho]

I have researched to find many opinions suggesting gravity may have a causal role in this acceleration of expansion.

Where did you hear that? The expansion is a repulsive force (dark energy) which is stronger than gravity at cosmic scales.

So my question is wether the mainstream views such acceleration as a potential cause of gravity, rather than the other way around?

That question is based on a false premise. Gravity and dark energy aren't related, ie, one doesn't cause the other.

[uncommonsense]

Thank you DrWho.

And so then my questions are:

Regardless of the nature or source of the repulsive force that is causing accelerating expansion (call it dark energy), the acceleration of all galaxies away from eachother is accepted. And so if all bodies in our galaxy, viewed individually, are accelerating in, well in any direction, would each body not experience the force of such acclelleration?

If not why not? I am curious as I can't find the answer yet on the web. I'm not looking for anwers to what force is causing the expansion, just answer to whether, under current understanding of acceleration, the force of the acceleration is experienced by the acelerating objects.

[DrWho]

Regardless of the nature or source of the repulsive force that is causing accelerating expansion (call it dark energy), the acceleration of all galaxies away from eachother is accepted. And so if all bodies in our galaxy, viewed individually, are accelerating in, well in any direction, would each body not experience the force of such acclelleration?

Bodies in our galaxy aren't accelerating in any direction. At these small scales, the bodies are gravitationally bound to the galaxy itself and even to the galaxy cluster it may be in.

If not why not? I am curious as I can't find the answer yet on the web.

Because the the dark energy force is extremely weak at local scales (such as galaxies and galaxy clusters). At these smaller scales, gravity is a much greater force and so trumps the repulsive force.

[uncommonsense]

Bodies in our galaxy aren't accelerating in any direction. At these small scales, the bodies are gravitationally bound to the galaxy itself and even to the galaxy cluster it may be in.

Perhaps I was misunderstood. I understand that bodies within galaxies are not accelerating anywhere in relation to their home galaxy, but rather in relation to the rest of the universe. If this is how you understood me, then are saying that when two systems acclerate away from one another, its parts do not?

Because the the dark energy force is extremely weak at local scales (such as galaxies and galaxy clusters). At these smaller scales, gravity is a much greater force and so trumps the repulsive force.

Is such force synonymous to acceleration force? I was asking about acceleration. Did you mean "acceleration" instead of dark energy?

Thanks for your patience, I want to understand this.

[uncommonsense]

Still waiting for reply. In the meantime, I found this, which seems to support at least a closer look at Acceleating expansion v. gravity

You declared the fields that were called for in the clock example also as merely fictitious, only because the field lines of actual gravitational fields are necessarily brought forth by mass; in the discussed examples no mass that could bring forth those fields was present. This can be elaborated upon in two ways. Firstly, it is not an a priori necessity that the particular concept of the Newtonian theory, according to which every gravitational field is conceived as being brought forth by mass, should be retained in the general theory of relativity. This question is interconnected with the circumstance pointed out previously, that the meaning of the field components is much less directly defined as in the Newtonian theory. Secondly, it cannot be maintained that there are no masses present, that can be attributed with bringing forth the fields. To be sure, the accelerated coordinate systems cannot be called upon as real causes for the field, an opinion that a jocular critic saw fit to attribute to me on one occasion. But all the stars that are in the universe, can be conceived as taking part in bringing forth the gravitational field; because during the accelerated phases of the coordinate system K' they are accelerated relative to the latter and thereby can induce a gravitational field, similar to how electric charges in accelerated motion can induce an electric field. Approximate integration of the gravitational equations has in fact yielded the result that induction effects must occur when masses are in accelerated motion. This consideration makes it clear that a complete clarification of the questions you have raised can only be attained if one envisions for the geometric-mechanical constitution of the Universe a representation that complies with the theory.

That was Einstein, by the way.

Die Naturwissenschaften, 29 November 1918.

[Caillyn]

Uncommonsence: Are you asking about whether we can experience the force of accelerating expansion of the universe? i.e. galaxy cluster A is accelerating away from galaxy cluster B due to the expansion of the universe, would there be a measurable acceleration force for an observer in galaxy cluster A with respect to cluster B?

If thats what you are asking ( thats my take on your question, if im wrong about that, ignore the rest of this ), then i would say that as the expansion is happening evenly in all directions ( as the universe, on average, apears to be uniform in all directions ), then any expansion/acceleration force in any one direction would be cancelled out by the expansion/acceleration force in the opposite direction, which would apply for all directions around the observer, resulting in a net force of zero. ( im only talking about the large scale expansion, not local gravitational forces )

[uncommonsense]

Uncommonsence: Are you asking about whether we can experience the force of accelerating expansion of the universe?
i.e. galaxy cluster A is accelerating away from galaxy cluster B due to the expansion of the universe, would there be a measurable acceleration force for an observer in galaxy cluster A with respect to cluster B?

Yes

If thats what you are asking ( thats my take on your question, if im wrong about that, ignore the rest of this ), then i would say that as the expansion is happening evenly in all directions ( as the universe, on average, apears to be uniform in all directions ), then any expansion/acceleration force in any one direction would be cancelled out by the expansion/acceleration force in the opposite direction, which would apply for all directions around the observer, resulting in a net force of zero. ( im only talking about the large scale expansion, not local gravitational forces )

Your description of the big picture makes sense to me, but your inclusion of the words "cancelled out" and "net force of zero" do not. Can you kindly offer some references that explain the behavior of forces under such conditions? I am still looking. Do you know your conclusions to be true, or are you guessing. Guessing is cool, but I am looking fo something more...............substantial

[cosmocrazy]

Uncommonsence: Are you asking about whether we can experience the force of accelerating expansion of the universe? i.e. galaxy cluster A is accelerating away from galaxy cluster B due to the expansion of the universe, would there be a measurable acceleration force for an observer in galaxy cluster A with respect to cluster B?

If thats what you are asking ( thats my take on your question, if im wrong about that, ignore the rest of this ), then i would say that as the expansion is happening evenly in all directions ( as the universe, on average, appears to be uniform in all directions ), then any expansion/acceleration force in any one direction would be cancelled out by the expansion/acceleration force in the opposite direction, which would apply for all directions around the observer, resulting in a net force of zero. ( im only talking about the large scale expansion, not local gravitational forces )

Maybe there is a way around this?

your description makes sense and I can see how a net force value could be cancelled out. But this is based on 2 objects within space/time, maybe if we consider the force value relative to space/time itself, in this I mean what if space/time is expanding everywhere at C and anything with mass opposes this expansion which is measured as a force of gravity, the greater the mass the greater the opposition, could this work?

[uncommonsense]

In a different thread a gave an example of a standard observation - a 10 oz lead ball and a 10 ton lead ball, barring friction, fall to earth at the same rate of change in distance, and I made note that as for rate of change of distance, two different masses acted identicle in a steady value gravity field (of earth). This occures even though we accept that More mass = more gravity. I then described these results as being attributed to an apparent "steady" force.

Below is my resonse to a member's explanation that the reason the balls fall at same rate is directly due to more mass = more gravity.

That doen't make sense to me and so I responded:

There is a "force", can't think of it's name, that applies to a "motionless" mass that resists motion. Otherwise it take no force to move a still mass.

In the example I gave, the earth did not gain or loose it's mass = gravity proportions, i.e. it didn't get bigger or smaller (in a mass sense). It is my understanding that the earth's gravity has a certain value regardless of whether these two objects are in its gravitational field.

And yet the 2 different balls experienced the same rate of change in distance under the power of the same value of force.

Perhaps a better example is to imagine a large box in space far away from any noticeable gravity caused by masses, imagine yourself in the box. The inside of the box is a coordinate system, and you are at rest relative to that coordinate system.

A rope is attached to the box and the box is pulled thru space at an accelerating speed. You will feel a force towards the opposite side of the box as the rope. You will move in that same direction. As you move, take a pen, a 12 oz lead ball, and a grain of sand out of your shirt pocket and notice which one hits the side of the box first.

They, and you, all arrive together, as a result of a single value force in the opposite direction. That is what I meant by "steady"

The point is, All of the above seems jives with GR (Based upon my readings of Einstein himself) and I am looking for resources that may explain a similar relationship between Acceleating Universe and Gravity, either for or against. There surely is something. My searches in google and wiki and others give irellevant hits. Maybe I'm not using correct search terms.

Anyone?

[uncommonsense]

Any feed back at all?

[cosmocrazy]

Grant Hutchinson has kindly offered me this link http://www.scientificamerican.com/ar...ut-the-2005-03 in Scientific American. Particularly page 5, the section entitled "Is Brooklyn Expanding?"
It may offer some insight.

[Frog march]

if the universe were a 3-sphere then the analogy would be the surface of a balloon expanding, ie the expansion(an acceleration of any expansion) would be at right angles to the surface(ie the 2-dimensional space of the 2-sphere analogy).

So if that were true then our universe's expansion and accelerated expansion would be at right angles to our 3 dimensions, so we wouldn't feel it directly.

But I have the feeling that the shape of the universe, expansion/accelerated expansion, are linked with local gravity...

[sirius0]

There is some deep thought in your questions here. Perhaps your answer is 42 ?

If what I think you are asking is correct than some others are missing parts of what you want. I hope I hit a few of those parts.
Einstein's elevator experiment demonstrates the equivalence between an assumption someone may make about being in a gravity field when they are being accelerated in the lift. There is no meaningful distinction between gravity field causing a reactive force that the passenger feels against the floor when stationary and the same effect when the lift is accelerating in outer space (there is a slight conical effect because our gravity is towards the centre of the planet whilst the apparent gravity of the accelerating lift is truly parallel)

Also the way Einstein presented this elevator idea was to compare one who is stationary in the lift feeling the reactive force between them and the floor to one who from our perspective is not in any gravitational field getting the same reactive force from their perspective due to the lift being accelerated from our perspective. The only reason I say this is because you state that the galaxies accelerating should be able to feel the force. But when I accelerate due to actually falling in a gravitational field then from my perpective I don't feel any force, I am in free fall. So gravity and acceleration are equivalent but in a counter intuitive (or almost inverse) sense.

You apear (quite cunningly) to be saying that if gravity and acceleration are equivalent then why can't acceleration induce a gravity field. Well it does, every second a mass is accelerated it gains kinetic energy and if it gains kinetic energy then via the other equivalency gains mass. This increase in energy/mass will increase the gravity field.

The idea that gravity is causing a contraction of matter in on itself is also cunning in that the universal expansion can be understood to be equivalent to all the objects to be shrinking.

But what this idea doesn't explain is why galaxies that are gravitationally bound together overcome this expansion via this mutual gravity. For instance we are in a galaxy group that is gravitationally bound and expansion it would appear, will never occur for us and the group due to the very gravity you feel should be expanding us.

Sorry if I have put words in your mouth but I found it most efficient to get my point over.

[Kwalish Kid]

Where did you hear that? The expansion is a repulsive force (dark energy) which is stronger than gravity at cosmic scales.

The acceleration of expansion is due to dark energy. The expansion itself is a feature of gravity. It is through the General Theory of Relativity that the contents of the universe, including dark energy, couple to the geometry of the universe in order to alter the rate of expansion.

[Kwalish Kid]

The idea that gravity is causing a contraction of matter in on itself is also cunning in that the universal expansion can be understood to be equivalent to all the objects to be shrinking.

But what this idea doesn't explain is why galaxies that are gravitationally bound together overcome this expansion via this mutual gravity. For instance we are in a galaxy group that is gravitationally bound and expansion it would appear, will never occur for us and the group due to the very gravity you feel should be expanding us.

This is an excellent way of describing this.

[uncommonsense]

Cool. Answers. Thanks bunches ALL. I need to respond collectively as I have so far failed to pose my question in manner that is clear. I seem to have been minunderstood and that is most often attributed to poor communication (on my part).

So, I'll try again, my question is:

This is not a proposal, but rather a ponder - picture the universe just as mainstream says it exists: clusters of galaxies accererating away from one another in ALL diresctions. However, picture our galaxy as containing only a single Sun and no other mass bodies. Picture Sun behaving just like a galaxy in terms of accelerating expansion. It experiences all galaxies accererating away from it, and all other galaxies experience it accelerating away from them. Then imagine if the force in my OP question was real - and it was applied upon every surface location of Sun (in a direction towards center) with equal force value - behaving just like what we call gravity.
Now pop in another body of mass within the local vicinity of Sun that has a much smaller mass - call it Planet. Based upon the model, Planet would individually experience the same effect as descibed above for Sun. So how would gravity work on a local level as an "attracting" force between Sun and Planet?

As a descriptive aid, view this "force" in question along a single axis perspective ONLY, in a straight line out into space on opposite sides of Sun ( like a straight line right thru the center and out each side- continuing as far as imaginable into the universe, in opposite directions). All bodies/mass/ that this line passes thru, throughout the entire universe, are accelerating away from sun, on both opposing sides of Sun, and, Sun is accelerating away from them, in both directions respectively.

Many changes in motion and expressions of all mass throughout the universe over our gage of time have brought things to be located as they are in our time. And in our time, Sun is in "equalibrium" with the universe's acceleration - on both sides. So sun can be said to experience equal "pull" (call it whatever) in both direction, and so from accross the expanses of the universe, there is an average equal distribution of acceleration force from both directons.

Now, planet passes thru this line and by so doing causes unequal pull in one of the two directions. How?
You must view the situation relatively. Prior to local interferenceby Planet, Sun was in balance with all galaxies in the universe (in this hypo, along the single line), as the space beteeen it and the rest of the universe was expanding uniformly in all directions. From Sun's relative perspective, it was stationary and was like the knot in the halfway point of a rope, in tug of war, and all universal mass holding (located on) the rope were pulling in opposite directions, in a stale mate ("equalibrium")

Then - Planet jumps in on one side. But Planet is local to Sun and the two do not counter-acclererate from one another. Therefore, the rest of the expanding universe treat the two of them as one mass - and acceleration acts upon them as such. However the system has lost balance from Sun's relative perspective. How? Recall prior to Planet passing by, Sun was balanced and was relatively "still" compared to all universal masses on each side of rope, ie, Sun was at a point in space where it was balanced by opposing forces. Now, however, Planet, a local, non counter-accelerating mass, is on the rope - off center to one side. So now the new "center of acceleation force" becomes a point in space somewhere between Sun and Planet, and the rest of the universe is pushing/pulling (whichever) them together towards this point in space as if they were both the same body of mass. Use your intuition to guess how far this lnew balance point location would be from Sun, and from Planet. And so both Sun and Planet do move to the new balance point. Sun nudged, and arrived, Planet had to travel much further due to the difference in its mass / inertia properties. Keep in mind that for ease of explanation we are considering in this scenario, the acceleration force from only two opposing directions, while it would actually come from every available set of opposing directions.

And so -------- the scenario which forms my question is of a universe that, as we experience it, must have accelerating expansion of mass clusters - clusters of wich their individual parts do not expand away from eachother - at least not at such noticeable rates, in others words only at trivial rates, if at all. It is a scenario designed for the question as my original question did not express these relationships as clearly as the scenario above. This is not a proposal. I am merely seeking reference materials that relate to the question.

I do not claim that matter is squeezing in on itself thereby resulting in the expansion of space. I do not claim bodies withing galaxies accelerate from one another. Another answer appeared to mistake terminal velocity for the limit of gravitational acceleration in all of space, and described such as a "free fall". Unless I'm confused, I thought in the absence of friction, graitational acceleration far exceeds tv thru earth's atmosphere.

I read Brooklyn Falling. Doesn't seem to get to my question, unless I am misreading something..

Anyone have anything else? Any reference media at all would be helpful.
Thanks a million

Looking forward to ANY comments.

[loglo]

I think the issue Uncommonsense is having is due to picturing DE as a force. When viewed as a metric expansion these issues don't appear. Distances just get greater without a force being applied to the matter being carried along.

The only problem then is with trying to picture nothingness expanding.

[uncommonsense]

I think the issue Uncommonsense is having is due to picturing DE as a force. When viewed as a metric expansion these issues don't appear. Distances just get greater without a force being applied to the matter being carried along.

The only problem then is with trying to picture nothingness expanding.

Great article. Thank you. Can you point out the parts that support "our accepted behaviors of acceleration and inertia do not manifest when apparent distance/apparent acceleration/apparent motion of mass appear, but are actually actually metric expansion of space instead"?

Or something thereabout, cause I think that was your claim. I couldn't find it, but am not saying I didn't miss it.

[loglo]

Great article. Thank you. Can you point out the parts that support "our accepted behaviors of acceleration and inertia do not manifest when apparent distance/apparent acceleration/apparent motion of mass appear, but are actually actually metric expansion of space instead"?

Or something thereabout, cause I think that was your claim. I couldn't find it, but am not saying I didn't miss it.

I make no claim to know what is really real or actually actual. This is a science forum!

As for the Wiki article I was thinking specifically of the paragraph "Local Perturbations". Also please keep in mind Kwalish Kids post. There is expansion and acceleration of the expansion. DE is only responsible for the later acceleration and only became important at the point where all the clusters were already really far apart. That is why it is modelling it as an affect of space makes it easier to understand (for me at least).

[uncommonsense]

I make no claim to know what is really real or actually actual. This is a science forum!

OK, you did but didn't. That sounds more like science to me

As for the Wiki article I was thinking specifically of the paragraph "Local Perturbations".

Read it 10 times (cause i'm slow) And still don't see how it says that. But we all wear different goggles. Mine are usually dirty.

I sincerely appriciate the dialog and look forward to more.

[Kwalish Kid]

One thing that might clear things up, uncommonsense, is that everything is gravitationally attracting everything else, just like we expect. That is, our galaxy, even our shoes, are pulling everything else in the universe and vice versa. The power of gravity to influence fades out over distance, so the main impact we see of gravity near to us is the influence of gravity to keep shoes on the ground and planets in orbit.

A little farther out, we see gravity keeping the Milky Way together and keeping our local cluster together.

Superimposed on the entire universe, however, is a natural tendency to drift apart. This is simply part of the fabric of space imparted, as far as we can tell, as an initial condition. Where we live, gravity has entirely overcome this tendency, at least as far as our local cluster is concerned. But gravity is not enough to overcome this in general. So galaxy clusters are drifting away from each other at a predictable rate.

In the past, the density of all matter and galaxies meant that gravity actually slowed down this drift, since it was overcoming it. After a while, however, dark energy boosted this drift and is accelerating it. Dark energy works through the equations governing gravity, but because of its specifics, it works contrary to the normal pull and its effect actually gets stronger with distance.

[loglo]

OK, you did but didn't. That sounds more like science to me

The Big Bang is a model, not reality. While there is a certain correspondence between the two I don't expect the universe to behave as if the BB was "The Truth". That is science!

Read it 10 times (cause i'm slow) And still don't see how it says that. But we all wear different goggles. Mine are usually dirty.

I sincerely appriciate the dialog and look forward to more.

Don't worry, on reading the entire article I can understand your confusion. It is not the best Wiki article I have read, I should have vetted it first.

It appears to me though that your confusion arises from thinking that everything in the universe is pushing away everything else in the universe that it is not bound to it in some manner (gravitationally, electromagnetically etc).

As far as DE is concerned it is more accurate to picture that every empty void of sufficient size is "pushing" away the galaxies around it which makes the voids larger. This in turn causes the "pushing force" to increase relative to the gravitational forces of the surrounding matter causing the voids to grow larger still. Since it is natural to question how empty voids can push galaxies away from each other, I find it easier to picture the space within the void is itself being "added to" or is stretching which is closer (IMHO) to the meaning of the theory.

But as KenG would say that is all just ontology anyway. The real way to understand universal expansion is to start digging into the guts of theory itself. That means some understanding of General Relativity is required at the least.

[uncommonsense]

One thing that might clear things up, uncommonsense, ..........[entire post quoted]...., it works contrary to the normal pull and its effect actually gets stronger with distance.

Thats just how I understand it, thank you.

loglo It appears to me though that your confusion arises from thinking that everything in the universe is pushing away everything else in the universe that it is not bound to it in some manner (gravitationally, electromagnetically etc).

My understading is that the latest view is of an expanding metric.



Thanks for all the explanations, and I certainly do appriciate the help. Please recall I am not presenting info for a debate, rather I proposed a model and am looking for reference media for or against any similar models. I still have not found any.



And so, as I my question was misunderstood by more than one, I will repose it in simple form:



Wanted: any research / reference / web blogs / ofeering analysis for or against or neutral the following scenario:



universe is in state of galaxy/galaxy clusters with space between them, space of which its metric is expanding at an accelerated rate, which expansion is not noticed (not occuring) localy within the galaxy clusters, which such galaxy clusters experience this expansion as if each were in the "center" and all others were moving away from it, wich expanding metric is responsible for a particular red shift of electromagnetic waves (light) passing thru it.



There are no known "bubbles" around galaxy clusters that would prevent forces from acting upon its individual bodies of mass



Each body of mass as a member of the galaxy cluster experiences the accl. exp. metric from all directions, although only from non local origins, namely the entire universe except anything within its own galaxy cluster;



relatively, each body of mass in any given galaxy "experiences" "acceleration" in all directions, but does not experience change in distance in any one direction; however this acceleration is expresses by a contraction in the space metric in a field surrounding the body.



The universe is homogonous and isotropic; notwithstanding trivial irregularities, all bodies of mass in each galaxy cluster are in a state of relative equiforce regarding the univesal acceleration, modulo fast moving masses;



Locally, if a small mass wanders close to a much larger mass the equiforce position of each become unbalance and, as the two bodies are local (ie not part of the universal expansion) then the rest of the universe beyond their locality will "treat" them as one mass in that - as the "force" is equal from all directions, one possible outcome would be that the new "center of force" which the 2 masses will now share, will be a location in space between the centers of the 2 bodies that is a representation their respective inertias' - hence the large body will barely move while the small one will "move towards the large body" Similar smaller masses of all values will move toward the large body at the same rate in change of distance due to the equivalancy priciple.



Equally true, and relatively speaking, the above process is described and understood as a field of compressed metric surrounding the body caused by an equal and opposite reaction, in all directions, to universal accelerating expanding space metric, whereby, just as in classic acceleration which creates a "false" force in the opposite direction, such "false" force will maintain a static value of metric compression as a result of an opposite continual acceleratiing metric expansion.

All smaller masses wandering into the field with a previously established momentum, will necesarily follow the path of least distance which is toward the large mass. All smaller masses of varying value that come into large mass' field of compressed metric, will move thru the field at equal rate of chane in distance because, as the "attraction" is a result of the smaller masses moving from a larger space metric to a smaller metric, only distance is at play. Therefore due to classic laws of momentum and inertia, each will convert its energies into kinetic respective to its mass, resulting in equal acceleration rates (another way to know equivelancy principle?)





OK, NOT A THEORY FOR DEBATE. IT IS MOST ASSUREDLY WRONG. VERY LIKELY JUST BABBLE. That is why I am researching it, and the only way to hunt down resources is to explain what you are looking for. Thats it.



If anyone has access to those paid publication sites, I am more than willing to pay.



Any suggestions as to search words I should be useing?



Thank you.

[uncommonsense]

Whew. Grinding away. Found my very first bit of research. FYI.

http://vixra.org/pdf/0908.0005v1.pdf

Still looking for more. Thank you.

[djinn]

uncommonsense - maybe this (and the other links on page 45) might be of use to you. I find it a very clear explanation of expansion (and it has lots of illustrations )
http://www.astro.princeton.edu/~aes/...onsBigBang.pdf