"Dark Flow" Discovered at Edge of the Universe

[quantum_wave]

If you don't mind, I will jump in here to advance your understanding of the current consensus of our expanding universe.

Excellent. I am one who wants to know the current consensus. My view of the current consensus is that it is BBT with inflation and the cosmological principle. BBT with Inflation, in my view is General Relativity that has evolved to include Hubble and Guth, and others of course.

The cosmological principle ala Thomas Gold who was of the opinion that the Cosmological Principle applies to both space and time. His view was that not only should the universe be homogeneous and isotropic from any point in space, but that should hold true at any point in time.

To me that is still the consensus but I am always open to learning.

Correct, spacetime, the aether, the Dirac sea or whatever else one may wish to name the vacuum of space. .

It will be interesting to discuss that with you but I take it that AN is referring to the geometry of spacetime.

To be more precise, two points in spacetime can separate faster than the speed of light if they are located far enough apart.

That is what I understand AN to be saying when we say spacetime can expand faster than the speed of light.

Well, neither mass nor spacetime moves in the local spacetime, so it is a bit of a misnomer to say that mass is "carried" by spacetime.

A bit of a misnomer but the point is that mass, let us say galaxies and not refer to “local spacetime” are detected to be moving away from each other (except in local groups) at an accelerating rate, and that separation from the perspective of General Relativity is that space is being added and as a result the galaxies are getting further apart. This is how I believe AN is referring to it but I posed the post to him to get his response to find that out.

Yes, other than the reference to 'carried away'.

Good, the “carried away” was from AN and I was posting the post to him so I used his terminology.

An object is not moving in its local spacetime, at least due to the expansion. The local spacetime is not moving relative to the object. Emitted light cannot be 'carried' because the local background is not moving.

Back to “local spacetime”. I am staying at the galactic scale when galaxies are observed to be moving away from each other, and in GR that motion is the result of the added space, I am trying to pin down the effect of galactic scale motion cause by added space on the EM that is already in the space between galaxies. By stating it, “I assume that is because the light that they have emitted is not carried with it as spacetime expands?”, I hoped to get AN’s response to the impact of added space on the EM already in motion through the space between galaxies as new space is added by the expansion of spacetime. Do you see why I posed the question? It was in response to AN's post and was designed to get AN’s response.

I'm not sure I understand exactly what you refer to when stating "carried with it". The speed of light will always measure as 'c' in a local frame of reference. Perhaps it is easier to think of the volume of space increasing over a period of time, say one billion years. Say two objects in space are separated by one billion lightyears when a photon is emitted by each object toward the other object. While those two photons are travelling through space, the volume of space each must travel through is increasing over time. Even though the photon is always travelling a 'c' when measured in its local spacetime, it can take each photon much longer than a billion years to complete their respective journeys.

I understand that to be what AN is saying and your answer is probably that same as what his would or will be. You confirm what I think is AN’s position.

Do you understand the true meaning when cosmologists state that the rate of expansion is increasing? Consider those two photons that were emitted when two objects were one billion lightyears apart. Assume those two objects were very distant to us, both located in the early universe when it was only four billion years old. Now assume two more objects emit photons when they are located one billion lightyears apart, but both of those objects are located closer to us in the modern unverse. It takes longer for the photons in our modern universe to complete the 'original' one billion lightyears trip than for the photons in the early universe. The rate of expansion is increasing. The rate of expansion was actually decreasing slightly until about seven or eight billion years ago, then the rate started increasing.

I understand that.

Got to leave for now, will continue my post at a later time.

OK, thanks. Come on back later.

I participate in threads like they are conversations but they often take several posts to converse. My post to AN was a part of what might be several posts. If he responds to my post to him, presumably his response will be similar to yours, and we will be at the point where I will have confirmed my understanding of what he is saying.

From there I will present my next post in the conversation to which I would be hopeful of a reply and a confirmation from him that he understands what I am posting (not agreement, but understanding). After several posts back and forth I will understand more about where he is coming from and I will have had the opportunity to confirm my understanding and to ask him to confirm his understand of my posts. It may never reach that point but that would be the reason for the conversation.

 

[StrangerInAStrangeLand]

-=-

I propose that instead of saying galaxies are moving away from each other, we use GG for Galaxy Groups.

 

[quantum_wave]

-=-

I propose that instead of saying galaxies are moving away from each other, we use GG for Galaxy Groups.

That is better.

 

[2inquisitive]

quantum_wave,

Excellent. I am one who wants to know the current consensus. My view of the current consensus is that it is BBT with inflation and the cosmological principle. BBT with Inflation, in my view is General Relativity that has evolved to include Hubble and Guth, and others of course.

In simple terms, yes, that is correct.

The cosmological principle ala Thomas Gold who was of the opinion that the Cosmological Principle applies to both space and time. His view was that not only should the universe be homogeneous and isotropic from any point in space, but that should hold true at any point in time.

To me that is still the consensus but I am always open to learning.

Thomas Gold proposed the assumption that the Cosmological Principle held not only in space, but also in time. His assumption was made in the 1940's in support of the Steady-State Theory of the universe. If the universe were homogeneous and isotropic through time, the universe could not evolve through time. We know this is not correct through our modern measurements. For instance, light can travel a comparatively greater distance over a one billion year period in the modern universe than in the early universe. This suggests that the permittivity of free space (the electric constant) may change (evolve) over time. Locally, the speed of light will always be 'c', but exactly what is 'c'? Of course, it is 299,792,458 meters per second. How is a meter measured? It is the distance light will travel in 3.3 nanoseconds. Due to the expansion of the universe, a meter today is comparatively longer than a meter in the early universe. A lightyear today is comparatively longer than a lightyear in the early universe. The difference is extremely tiny on a small scale, however. It is noticable on the scale of billions of light years, but virtually undetectable on the scale of a few hundred lightyears.

And if light is carried with the expansion of spacetime, and if the light emitted by two objects has not reached to each object, then the "faster than light" expansion between the two objects means that the light will never reach.

Once the two objects are receeding from each other faster than the speed of light, a horizon forms. No photons will ever be received from objects beyond the horizon.

If so then is that because the expansion of spacetime can't accelerate light while it can accelerate mass faster than the speed of light?

You have just introduced something of your own creation (accelerate light, accelerate mass) not contained in the consensus view. I thought you stated you were familiar with the consensus view?

Why wouldn't light travel faster than the speed of light if it was being carried along with the expansion of spacetime?

Do you mean a photon emitted by a distant object in the opposite direction to an observer's line of sight? The observer could never see nor measure such photon to even verify its existance.

If so does this mean that the speed of light is not invariant?

The speed of light is a constant in The Special Theory's inertial frames. It seems someone who claims to understand General Relativity would know that the speed of light can vary in non-inertial frames. For instance, the Shapiro Effect has been observed and recorded.

 

[quantum_wave]

Thomas Gold proposed the assumption that the Cosmological Principle held not only in space, but also in time. His assumption was made in the 1940's in support of the Steady-State Theory of the universe. If the universe were homogeneous and isotropic through time, the universe could not evolve through time. We know this is not correct through our modern measurements. For instance, light can travel a comparatively greater distance over a one billion year period in the modern universe than in the early universe. This suggests that the permittivity of free space (the electric constant) may change (evolve) over time. Locally, the speed of light will always be 'c', but exactly what is 'c'? Of course, it is 299,792,458 meters per second. How is a meter measured? It is the distance light will travel in 3.3 nanoseconds. Due to the expansion of the universe, a meter today is comparatively longer than a meter in the early universe. A lightyear today is comparatively longer than a lightyear in the early universe. The difference is extremely tiny on a small scale, however. It is noticable on the scale of billions of light years, but virtually undetectable on the scale of a few hundred lightyears.

Gold was wrong when he and others like Hoyle suggested that as galaxies separated, new matter formed in the space between them, i.e. a modified version of steady state. But the cosmological principle that he felt must be adhered to by any valid cosmology was expressed years after Hubble's 1929 analysis of the radial velocity of galaxies; a finding that translated into an expanding universe long before Gold became a player. Gold was born in 1920 and as you point out, his work that related to the cosmological principle was recognized in the 1940's. He knew that the universe was expanding and was part of the dying effort to salvage steady state. That infamous distinction does not detract from his promotion of the cosmological principle which holds true today.

Once the two objects are receeding from each other faster than the speed of light, a horizon forms. No photons will ever be received from objects beyond the horizon.

You have just introduced something of your own creation (accelerate light, accelerate mass) not contained in the consensus view. I thought you stated you were familiar with the consensus view?

Do you mean a photon emitted by a distant object in the opposite direction to an observer's line of sight? The observer could never see nor measure such photon to even verify its existance.

The speed of light is a constant in The Special Theory's inertial frames. It seems someone who claims to understand General Relativity would know that the speed of light can vary in non-inertial frames. For instance, the Shapiro Effect has been observed and recorded.

Well I guess you have eliminated me as you personal source of information about what is and what is not GR.

Fine, because though you lay it on me that I have claimed to understand GR and yet have made statements that belie that fact, I wasn’t reciting what I thought GR to be, I was reciting what I thought was implied by ANs post. It was to test my understanding of what he was saying and not of what GR says because I wanted to get to the discussion of the effect of GR expansion on the observed EM wavelenght and how the dark flow would effect it as well. I guess that discussion will not happen, at least not with AN.

However, I don't claim to have intimate knowledge of GR as you say I claimed; I deny that I claimed I did.

 

[Scientific Method]

Amazing the sort of mythology and fairy tales that pass off as science these days.

Unfortunately this sort of science fiction is a direct violation of the scientific method.

The edge of the universe has never been observed.

The edge of the universe cannot possibly be observed from Earth or anywhere else in the universe.

There is no edge of the universe.

 

[Scientific Method]

Strange that the article does not mention how far away the anaomaly is.

Not that strange once you realize that fiction doesn't need to bother itself with hinderances such as numbers and measurements.

 

[quantum_wave]

Amazing the sort of mythology and fairy tales that pass off as science these days.

Unfortunately this sort of science fiction is a direct violation of the scientific method.

The edge of the universe has never been observed.

The edge of the universe cannot possibly be observed from Earth or anywhere else in the universe.

There is no edge of the universe.

Not that strange once you realize that fiction doesn't need to bother itself with hinderances such as numbers and measurements.

Maybe, but being completely misinformed isn't part of the scientific method either. The dark flow is just fluctuations in the cosmic microwave background detected in the 3 year WMAP data. The data captured is detected in the CMB "generated by the scattering of the microwave photons by the hot X-ray-emitting gas inside clusters", according to this abstract.

Why do you say it is a violation of the scientific method?

Here is a list of other articles and abstracts by A. Kashlinsky on the subject and related subjects published in the Astrophysical Journal of the American Astronomical Society. http://www.iop.org/EJ/search_author...ype=all&datetype=all&sort=date_cover&submit=1

 

[quantum_wave]

Oh hey, here is the full text of the 21 January 2009 Dark Flow article by Amanda Gefter in the New Scientist. http://pil.phys.uniroma1.it/~sylos/NewScientist210109.pdf

Usually they make you subscribe to get the full text. I guess Francesco is a subscriber. http://pil.phys.uniroma1.it/~sylos/

Seems his specialty is research on the large scale structure of the universe.

 

[Scientific Method]

Why do you say it is a violation of the scientific method?

The scientific method requires observation and experiment. It is impossible to observe the edge of the universe from the Earth let alone anywhere else in the universe because the universe has no edge. Futhermore, no experiment has ever been performed on Dark Anything.

 

[D H]

Amazing the sort of mythology and fairy tales that pass off as science these days.

For crying out loud! The original post refers to a lay article written some weblog that comprises "a talented and experienced team of Web architects and editors." The cited article

• Abuses some terminology (It should have said "observable universe", not universe) and
• Is a tad late (Dark flow came out nearly a year ago).

The big question: So what? Since when does erroneous reporting in a lay article on some aspect of science invalidate the science being reported?

Here is a better written lay article on this topic: http://www.space.com/scienceastronomy/080923-dark-flows.html

Here is the scientific article on which these lay articles was based: http://arxiv.org/abs/0809.3734

Unfortunately this sort of science fiction is a direct violation of the scientific method.

How, pray tell?

The edge of the universe has never been observed.

The edge of the universe cannot possibly be observed from Earth or anywhere else in the universe.

The article erroneously talked about the edge of the universe. The observable universe, which is what they should have said, does have a boundary. The lay term for boundary is edge. Get off your high horse.

There is no edge of the universe.

You know this for a fact? Prove it.

Not that strange once you realize that fiction doesn't need to bother itself with hinderances such as numbers and measurements.

Trolling again?

The scientific method requires observation and experiment.

No, it doesn't. Read up on what the scientific method really is. It is a tad difficult for astronomers, archaeologists, paleobiologists, and practitioners of various other branches of science to conduct experiments. Astronomers cannot move planets, stars, and galaxies around to see what they will do. They have to be satisfied with observation only for the most part. Archaeologists and paleobiologists would need a time machine to enable conducting experiments in their fields. They too have to be satisfied with observation only. This does not mean these fields are not science.

It is impossible to observe the edge of the universe from the Earth let alone anywhere else in the universe because the universe has no edge.

Once again, you know this for a fact? The truth is, we do not know the very large scale topology of the universe -- yet.

Futhermore, no experiment has ever been performed on Dark Anything.

Astronomers use the term "dark", as in dark matter, dark energy, and now dark flow, to mean an effect that has been observed by not yet explained.

 

[Scientific Method]

Astronomers use the term "dark", as in dark matter, dark energy, and now dark flow, to mean an effect that has been observed by not yet explained.

You mean astologers not astronomers. Astronomers rely upon observation. Dark Matter and Dark Energy have never been observed. By definition they cannot possibly be observed. Our eyes can only observe electromagnetic radiation such as visible light from baryonic matter.

"It's not that most of the matter and energy in the universe is dark, but that most cosmologists are totally in the dark about the real nature of the universe." -- Wallace Thornhill, physicist, October 2006

 

[D H]

You are trolling again, Scientific Method.

We cannot observe dark matter and dark energy (yet). What we can observe is that the distribution of baryonic alone is not consistent with galactic rotation. We don't know what causes this inconsistency, but there it is plain as day. Assuming that galaxy rotation is a consequence of gravity, there must be some kind of matter out there that we cannot see (yet). Dark energy is similarly a discrepancy between model and observation at a very large scale than galaxies.

By way of analogy, consider the discovery of Neptune. Discrepancies between the modeled and observed orbit of Uranus said something else is out there. By assuming the discrepancy in gravity was caused by some dark (dark meaning unknown) planet, astronomers deduced where this dark planet should be. They searched the vicinity of this predicted location and voila! Neptune.

 

[quantum_wave]

BTW, Wallace Thornhill is the "electric universe" guy and is part of the Kronia Group. My stuff is more mainstream than that .

 

[AlphaNumeric]

You mean astologers not astronomers. Astronomers rely upon observation. Dark Matter and Dark Energy have never been observed. By definition they cannot possibly be observed. Our eyes can only observe electromagnetic radiation such as visible light from baryonic matter.

I can't see radio waves, doesn't mean my TV doesn't work. I can't see the wind but it can still blow a tree over. I can't see my voice but I can still speak.

Moderator comment: Be nice now. Disparaging remarks deleted.

 

[Dr Mabuse]

You once started a thread about a roar coming from deep space but never responded to any replies. I found that thread interesting too.

Is there anything new on those high altitude balloon experiments related to the "roar" and is there any connection between that roar from deep space and this dark flow in your opinion?

Well, the connection between the two did cross my mind actually.

There's certainly no reason to rule out the two being connected as of yet as so little is known on both events.