Galaxies going faster than light ? [v.2]

[The God]

No. Above galaxies are parts of a local cluster, and galaxy clusters are hold together by gravity. This may change in some far away future once the expansion accelerates, but this is another question.

Such "expanding space" talk has nothing to do with GR, which does not provide any means for making a distinction. Don't forget, such sloppy talk about stretching usually depends on coordinates, and GR has no way to favor particular coordinates.

Cosmologies in reality care less, and prefer some coordinates. Like FLRW coordinates, or harmonic coordinates. But this is in no way done consistently. If one would, for example, consistently prefer FLRW in sloppy talk, one would not use the word "expanding", because in FLRW coordinates everything remains on its place, and the rulers (or what is held together by local forces) shrinks.

If I talk about voids as expansion of space, I use imprecise sloppy talk. So, do not expect precise definitions or qualifications.

Roughly, you have a topology consisting of voids, faces between voids, edges of voids and vertices. The voids expand, the faces expand in two directions, but, once the forces hold them together, shrink in the other direction until they become too thin - at this moment, the two voids start to become one bigger void.

Ruler shrinks and everything remains in place. This will further guarantee 200 more pages for this thread.

 

[The God]

Andromeda and the Milky Way are gavitationally bound to each other. How do you not know this?

But the space between them does not know that. You guys are pushing popo, in fact as I said all this expansion business is less than popo...pseudo.

 

[DaveC426913]

But the space between them does not know that.

Answered, as a logical extension of post 191.

You guys are pushing popo, in fact as I said all this expansion business is less than popo...pseudo.

Disparaging labels and arguments by incredulity are not substitutes for reasoned discourse.

Put your money where your mouth is. Try to show that CE contradicts observation.

 

[The God]

Answered, as a logical extension of post 191.


Disparaging labels and arguments by incredulity are not substitutes for reasoned discourse.

Put your money where your mouth is. Try to show that CE contradicts observation.

Believing expansion of universe is incredulity.

GR talks of spacetime expansion not of space. Any change in distance between object is always causal and calls for force. The concept of metric expansion, which is force free, is just mathematics.

Yes, red shift is explained by this, but we will have to search for more realistic solution not some metric solution. Will be done if not by me then by someone else, very soon, very very soon.

 

[DaveC426913]

Believing expansion of universe is incredulity.

The math in the theory backs it up. That's kind of the opposite of incredulity.

Will be done if not by me then by someone else, very soon, very very soon.

Fortunately, science is not a wish-based discipline.

Anyway, you've reggressed to a state of simply demanding that you're right, so unless and until someone come up with something that has teeth, the discussion stands as conforming with mainstream until shown (not supposed) otherwise.

 

[The God]

My position was made very clear in the starting itself, that in reality there is nothing like expansion of universe or photon stretching as envisaged. None could answer a simple question that GW, a part of GR, can create ripple in bound systems but expansion cannot take place. You could not even figure out the possibility of instability of orbital motion under expansion.

 

[paddoboy]

1. Would you call the space between Andromeda and Milky Way as void ?

Yes, but not "void" enough to allow spacetime expansion:

2. Is it correct that the space between Andromeda and Milky Way is expanding but Andromeda/MW are closing in faster?

No, as you are being repeatedly told expansion of the universe reigns supreme on scales larger than small clusters of galaxies etc. Within such small clusters gravity is strong enough to bind the cluster and give individual galaxies a Peculiar velocity large enough to overcome the smaller velocity of the Hubble flow: [Obviously understanding this observation conflicts with your agenda and fabricated fairy tale.]

3. If #2 above is correct, then surely the photon/light will stretch in transit, once the light leaves Andromeda?

Not at all: That's just part of your fabricated nonsense.

4. This one is far fetched...
Take two radial distance from earth, one at 5 mpc and second at 100 mpc ( any arbitrary large value would suffice to get rid of local aspect). Now even though we treat universe as isotropic, but still for argument sake let's assume that on one side of earth there is nothing between 5 mpc and 100 mpc, but on the opposite side, there are few objects. How do you talk of expansion on both the sides? The problem is you are supporting a view that void will have, without qualifying voids. I can have void at x distance on some direction, at the same time I can have mega cluster at x distance in different direction.

The spacetime surrounding Earth on both sides, out to and including the objects are gravitationally bound to Earth. Think of gravity as the warping curvature of spacetime: Quite a novel idea don't you think?
[Again simply GR]

 

[paddoboy]

My position was made very clear in the starting itself, that in reality there is nothing like expansion of universe or photon stretching as envisaged.

Your position is one that is well known, and as usual defies all observational data we have and of course GR and is the reason your stated position rests mostly in the fringes.
Again, over larger scales the Universe/spacetime is expanding and accelerating in that expansion rate, while smaller, more dense local regions are decoupled from the expansion rate.

None could answer a simple question that GW, a part of GR, can create ripple in bound systems but expansion cannot take place. You could not even figure out the possibility of instability of orbital motion under expansion.

Firstly all your questions have been answer despite your again fabricated claims otherwise. Secondly this forum is not the be all and end all of scientific scrutiny as you well know, and as we all know is open to any Tom, Dick and Harry to promote any unsupported fairy tale that their little heart desires. Thirdly if you have any evidence to support your claims then submit them professionally for peer review.
We all wait anxiously for the outcome.

 

[paddoboy]

No. Above galaxies are parts of a local cluster, and galaxy clusters are hold together by gravity. This may change in some far away future once the expansion accelerates, but this is another question.
.

Interesting take on the situation.
Generally though it is thought that gravity will and should have merged our local group by then.
Or are you promoting a "Big Rip" scenario some trillions and trillions and trillions of years into the future, where [if I'm reading you correctly] the acceleration in the expansion rate will continue unhindered, and even local groups will be ripped apart, solar systems ripped apart, so overcoming gravity, and even the strong nuclear, weak and EMF's eventually overcome by the acceleration in the expansion rate and we would all be ripped apart.
Observations of course show the Universe to be flat within very small ranges of tolerances and while the evidence for DE is observed [the acceleration] we really don't know how much this DE would continue.
It seems there are a few predictable long term fate of the universe scenarios.
https://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe

http://hubblesite.org/hubble_discoveries/dark_energy/de-fate_of_the_universe.php

 

[paddoboy]

Offering up the ubiquitously-accepted explanation (GR), based upon the ubiquitously-accepted standard cosmological model, which has been verified more than any other theory in the history of science - and, indeed, our modern world (including you) is dependent upon to function - is the exact opposite of trolling.

river knows that, but as usual river is unable to ever admit he is wrong, irrespective of how obviously wrong he is. river also supports the long defunct Electric/Plasma universe model that we have often crossed swords over.

 

[Daecon]

The God, if you think it's a "bad" explanation, then obviously you must have a different explanation for the observational evidence.

Let's hear your explanation then.

 

[paddoboy]

The God, if you think it's a "bad" explanation, then obviously you must have a different explanation for the observational evidence.

Let's hear your explanation then.

He hasn't got one. He prefers a "totally unknown quantity" so that he can imply his "god of the gaps".

 

[paddoboy]

Anyway, you've reggressed to a state of simply demanding that you're right, so unless and until someone come up with something that has teeth, the discussion stands as conforming with mainstream until shown (not supposed) otherwise.

And that Ladies and Gentlemen is the crux of the matter, despite the willful denial of both the god and river.

 

[Schmelzer]

Interesting take on the situation.
Generally though it is thought that gravity will and should have merged our local group by then.

Maybe, I have not cared. The question would be why should it merge them at all? The Solar system is quite stable over a long time. So, gravitational configurations stable over long times are obviously possible.

Or are you promoting a "Big Rip" scenario some trillions and trillions and trillions of years into the future, where [if I'm reading you correctly] the acceleration in the expansion rate will continue unhindered, and even local groups will be ripped apart, solar systems ripped apart, so overcoming gravity, and even the strong nuclear, weak and EMF's eventually overcome by the acceleration in the expansion rate and we would all be ripped apart.

If there is really an acceleration which is visible now, and if it is described by Einstein's cosmological constant, then this would be unavoidable. No reason to promote it, and I don't. But this would be the mainstream prediction. And if I don't mention the theory which I use, I mean the mainstream theory.

Not sure if this are "trillions and trillions" of years (again, not cared). The expansion would be exponential. And that means that one needs more time for this than the universe exists, but not that much more. But, ok, a factor 100 is not unreasonable, and this would be already trillions.

The Wiki is correct about a rather old state of the mainstream opinion, before acceleration was accepted mainstream. For $\Lambda>0$, which is actually the mainstream opinion, everything else like the curvature becomes irrelevant.

What I would promote is an alternative, (but don't worry, a published one) proposed by Wiltshire, the timescape scenario. In this approach, the accelerated expansion is simply an error of the homogeneous FLRW approach. One has to take into account that there are now big voids, that light is differently redshifted inside the voids, and that we are not in a void. Essentially, the inner parts of the voids expand in a faster way, but if we ignore this, and use a homogeneous model, these differences will be misinterpreted as an accelerated expansion. If we would sit in the center of a void, and evaluate it similarly homogeneously, it would look decelerating.

The funny thing is that there are now published papers which compare above scenarios. They are not decisive. But nobody questions the computations themselves. This is very strange. Given that taking into account inhomogeneity would lead to a fake acceleration, it should be already clear after this that pure FLRW is inappropriate to evaluate the question if the expansion is accelerating. What one would have to do to evaluate $\Lambda$ would be to consider a $\Lambda$CDM inhomogeneously to identify its size and the error bars. To continue to consider $\Lambda$CDM in the homogeneous FLRW ansatz is, once it has been found out by computations that inhomogeneity has some effects, already bad science.

 

[paddoboy]

Maybe, I have not cared.

Puzzling to say the least.

The question would be why should it merge them at all?

They are gravitationally bound?

The Solar system is quite stable over a long time. So, gravitational configurations stable over long times are obviously possible.

Sure, that's why I did say over "trillions and trillions of years"....certainly not
100% stable, and of course it's simply a result of observation [of our local group]

 

[James R]

Moderator note:

river has been warned for trolling this thread.

He has deliberately and repeatedly ignored information that has been presented to him time and again saying that the faster-than-light recession of galaxies is not a violation of the theory of relativity. He has now received 3 separate official warnings for trolling in this way.

As a result of accumulated warning points, river is now banned for 1 day from sciforums.