Alernatives: Cosmological redshift/BBE

[Skwinty]

OK DRD,

My question essentially is:

If you examine a redshifted spectrum, how do you determine what amount of redshift is due to:

Doppler effect
Earths motion.
Extra galactic body motion.
Gravitational effects.
Space expansion effects.

Where would you suggest I start reading?

 

[edd]

OK DRD,

My question essentially is:

If you examine a redshifted spectrum, how do you determine what amount of redshift is due to:

Doppler effect
Earths motion.
Extra galactic body motion.
Gravitational effects.
Space expansion effects.

Where would you suggest I start reading?

The short answer is you can't unravel them. The longer answer:

The Earth's motion compared to the rest of the universe is measurable by looking at the redshift/blueshift of the CMB - this should be uniform in every direction but there's a slight red and blueshift that can be measured and attributed to this - google term "CMB dipole"

The gravitational effects for a galaxy are small, so we basically ignore them.

Doppler effects and movements of the other galaxy - same thing right? Or am I misunderstanding you a bit? Anyway, these are 'peculiar motions' and basically can't be unravelled from the cosmological redshift (due to space expanding). They're not big though (for more distant things at least), and average out statistically - as many things move towards us as move away. It causes some funny effects in galaxy clusters. Google for "peculiar velocities", "fingers of god" and "Kaiser effect".

For distant objects the overwhelming majority of the redshift comes from the cosmological effect though.

 

[DeiRenDopa]

OK DRD,

My question essentially is:

If you examine a redshifted spectrum, how do you determine what amount of redshift is due to:

Doppler effect
Earths motion.
Extra galactic body motion.
Gravitational effects.
Space expansion effects.

Where would you suggest I start reading?

Perhaps with an introductory astronomy text?

Suppose someone hands you a spectrum, in the form of a squiggly line on a standard x-y plot (or graph or chart or whatever word you use).

Suppose the x-axis is labeled, in nm, Hz, Å, keV, or something else appropriate; suppose the y-axis is labeled 'relative intensity' or 'relative flux', or something like that.

Can you tell that it is "a redshifted spectrum"?

I guess it's possible that you might come across something like this, in some dusty archive, but even in the most extreme such case there would surely be wealth of other information about the spectrum, wouldn't there?

And with that extra information[ * ], you should find (or be able to reconstruct) things like:

* what object is this a spectrum of? Or, perhaps, what was the RA and Dec that the telescope/instrument was pointing to?

* when was it taken? And how long was the integration time?

* where was it taken (name of observatory/spacecraft/whatever)?

* what spectrograph (or other instrument) was used to take it?

* how was the x-axis calibrated?

Skwinty, can you confirm, please, that information of this kind would accompany the spectrum? Then I can walk you through how you might go about determining (actually 'estimating' would be a better word) the various components ...

[ * ] I'm assuming you have established, unambiguously, that it is a spectrum of something 'in the sky'

 

[Perpetual Student]

DeiRenDopa and/or sol invictus and/or anyone:

Do you think it is remotely possible that we have it all wrong regarding cosmological expansion and the big bang?
I am aware that cosmological expansion and the big bang are supported by a great deal of observational evidence and that GR provides a very strong theoretical framework for these theories.
Given that reality, this question may seem strange, but I have a nagging (but unsupported) feeling that there could possibly be another answer. However, I have absolutely no idea what any other answer might be.
I have been struggling to find a way to express my "nagging feeling." So, I’ll try this:
Could it not be that something other than cosmological expansion causes the red shift? And whatever that something else may be also accounts for the all the other supportive observations, like the CMB. By this I mean that something else would cause the red shift and the other phenomena that mimic expansion.
There are some examples in the history of science where a very wrong theory can find support from phenomena that turn out to be irrelevant or misunderstood.
For example, there were many supporting arguments making the earth the center of the universe. E. g.: if the earth turned, we would all be thrown off by the movement of the earth. Aristotelian physics made it so; it provided a “strong theoretical framework.” Another one: Stuff falls because its nature is to seek the center of the universe.
I don’t think very many physicists would take the position that our current understanding is the final word. There is yet more physics to be discovered.
You recall Plato's Allegory of the Cave. Similar to those cave dwellers (who saw only shadows), we see the universe through the EM spectrum, cosmic rays and extraterrestrial neutrinos. (I may be omitting something here). The universe may have more dimensions than four, there may exist types of radiation that are not detectible by us, and other forces or stuff that we cannot detect or describe or know about yet.
OK, now I know it’s easy to say, “Well, sure anything is possible.” That’s not exactly the response I am looking for. I’m aware of theories like “tired light” that have been examined and rejected as possible causes of the red shift. It seems that most research is done to confirm or develop nuances of cosmological expansion. Is anyone looking for alternative explanations for the red shift, other than “crackpots”?
So, there it is; I know all this is merely a layman’s naïve thoughts. If you can contribute any opinions or thoughts that may be interesting or helpful I would appreciate it.

 

[Skwinty]

The short answer is you can't unravel them. The longer answer:......

........For distant objects the overwhelming majority of the redshift comes from the cosmological effect though.

I understand cosmological redshift relates to the expansion of space.
Am I correct in this understanding?

How do you reconcile the seemingly contradictory statements that I have quoted from your post.

DRD:

Firstly, I have an introductory astronomy text by Ceceliia Payne Gaposchkin and Katherine Haramundanis.

The section on redshift really deals with the redshift -distance relationship and recession velocities.

Yes, the redshift spectrum X-Y plot will have all the necessary data attached such as the data you mentioned.

A quote from this text.

"It is thinkable that the redshifts are not velocity shifts, but have some other cause, such as the gravitational effect predicted by the General Theory of Relativity."

 

[Zeuzzz]

DeiRenDopa and/or sol invictus and/or anyone:

Do you think it is remotely possible that we have it all wrong regarding cosmological expansion and the big bang?

Yes. But some seem impervious to this reality. Some do not. http://www.cosmology.info/2008conference/

I am aware that cosmological expansion and the big bang are supported by a great deal of observational evidence and that GR provides a very strong theoretical framework for these theories.

Yes, but change some of the fundamental concepts underlying this evidence, and all of this evidence can act as strong evidence for a non big bang universe. All evidence is precarious depending on the axioms on which they are based.

Just watch this documentary, part two is probably the best starting point: http://www.youtube.com/watch?v=wchV5R9NhqY

Some extremely pertinent points are made by Lerner and others that no one yet has given adequate answers to.

I'm off on holiday now for a while and will remain lurking around for a week or two, but might pop back in for the odd comment when the odd blatent lie is posted.

 

[Reality Check]

DeiRenDopa and/or sol invictus and/or anyone:

Do you think it is remotely possible that we have it all wrong regarding cosmological expansion and the big bang?
I am aware that cosmological expansion and the big bang are supported by a great deal of observational evidence and that GR provides a very strong theoretical framework for these theories.
Given that reality, this question may seem strange, but I have a nagging (but unsupported) feeling that there could possibly be another answer. However, I have absolutely no idea what any other answer might be.
I have been struggling to find a way to express my "nagging feeling." So, I’ll try this:
Could it not be that something other than cosmological expansion causes the red shift? And whatever that something else may be also accounts for the all the other supportive observations, like the CMB. By this I mean that something else would cause the red shift and the other phenomena that mimic expansion.
There are some examples in the history of science where a very wrong theory can find support from phenomena that turn out to be irrelevant or misunderstood.
For example, there were many supporting arguments making the earth the center of the universe. E. g.: if the earth turned, we would all be thrown off by the movement of the earth. Aristotelian physics made it so; it provided a “strong theoretical framework.” Another one: Stuff falls because its nature is to seek the center of the universe.
I don’t think very many physicists would take the position that our current understanding is the final word. There is yet more physics to be discovered.
You recall Plato's Allegory of the Cave. Similar to those cave dwellers (who saw only shadows), we see the universe through the EM spectrum, cosmic rays and extraterrestrial neutrinos. (I may be omitting something here). The universe may have more dimensions than four, there may exist types of radiation that are not detectible by us, and other forces or stuff that we cannot detect or describe or know about yet.
OK, now I know it’s easy to say, “Well, sure anything is possible.” That’s not exactly the response I am looking for. I’m aware of theories like “tired light” that have been examined and rejected as possible causes of the red shift. It seems that most research is done to confirm or develop nuances of cosmological expansion. Is anyone looking for alternative explanations for the red shift, other than “crackpots”?
So, there it is; I know all this is merely a layman’s naïve thoughts. If you can contribute any opinions or thoughts that may be interesting or helpful I would appreciate it.

Yes the cosmological expansion theory could be wrong.
That is the fact about all scientific theories. They are never right. they are always at the mercy of the advent of a new better theory that matches the existing data and makes more falsifiable, testable predictions. So far no one has come up with an alternative that fits the criteria for a better scientific theory.

There are many scientists looking for alternatives to cosmological expansion. In fact some of the papers on Zeuzz's list are from reputable scientists. Also look in arXiv or do a Google Scolar search for "alternative explanation for cosmological redshift".

 

[DeiRenDopa]

DeiRenDopa and/or sol invictus and/or anyone:

Do you think it is remotely possible that we have it all wrong regarding cosmological expansion and the big bang?

Yes. But some seem impervious to this reality. Some do not. http://www.cosmology.info/2008conference/

I gotta hand it to you Z, you really are priceless!

Read what you wrote again ... your sentences can be read to mean that those who made presentations at that conference are "impervious to reality"!

I am aware that cosmological expansion and the big bang are supported by a great deal of observational evidence and that GR provides a very strong theoretical framework for these theories.

Yes, but change some of the fundamental concepts underlying this evidence, and all of this evidence can act as strong evidence for a non big bang universe. All evidence is precarious depending on the axioms on which they are based.

Which is, of course, true of all of science ...

But, as with all science, you go with what works best ... and in that regard there's no competition (none of the alternatives comes remotely close to the explanatory and predictive power of the current consensus cosmological models).

[...]

Some extremely pertinent points are made by Lerner and others that no one yet has given adequate answers to.

I'm off on holiday now for a while and will remain lurking around for a week or two, but might pop back in for the odd comment when the odd blatent lie is posted.

I'll check that out later, but am expecting that it'll contain nothing new, that we didn't cover - at great length - in the PC woo or not thread.

 

[DeiRenDopa]

DeiRenDopa and/or sol invictus and/or anyone:

Do you think it is remotely possible that we have it all wrong regarding cosmological expansion and the big bang?
I am aware that cosmological expansion and the big bang are supported by a great deal of observational evidence and that GR provides a very strong theoretical framework for these theories.
Given that reality, this question may seem strange, but I have a nagging (but unsupported) feeling that there could possibly be another answer. However, I have absolutely no idea what any other answer might be.
I have been struggling to find a way to express my "nagging feeling." So, I’ll try this:
Could it not be that something other than cosmological expansion causes the red shift? And whatever that something else may be also accounts for the all the other supportive observations, like the CMB. By this I mean that something else would cause the red shift and the other phenomena that mimic expansion.
There are some examples in the history of science where a very wrong theory can find support from phenomena that turn out to be irrelevant or misunderstood.
For example, there were many supporting arguments making the earth the center of the universe. E. g.: if the earth turned, we would all be thrown off by the movement of the earth. Aristotelian physics made it so; it provided a “strong theoretical framework.” Another one: Stuff falls because its nature is to seek the center of the universe.
I don’t think very many physicists would take the position that our current understanding is the final word. There is yet more physics to be discovered.
You recall Plato's Allegory of the Cave. Similar to those cave dwellers (who saw only shadows), we see the universe through the EM spectrum, cosmic rays and extraterrestrial neutrinos. (I may be omitting something here). The universe may have more dimensions than four, there may exist types of radiation that are not detectible by us, and other forces or stuff that we cannot detect or describe or know about yet.
OK, now I know it’s easy to say, “Well, sure anything is possible.” That’s not exactly the response I am looking for. I’m aware of theories like “tired light” that have been examined and rejected as possible causes of the red shift. It seems that most research is done to confirm or develop nuances of cosmological expansion. Is anyone looking for alternative explanations for the red shift, other than “crackpots”?
So, there it is; I know all this is merely a layman’s naïve thoughts. If you can contribute any opinions or thoughts that may be interesting or helpful I would appreciate it.

(bold added)

To add to the responses your post has already generated ...

I don't know why you chose to focus on the Hubble relationship, rather than the CMB, the primordial abundance of light nuclides, LSS (large-scale structure), or GR - as in "Is anyone looking for alternative explanations for the CMB/the primordial abundance of light nuclides/LSS/GR, other than “crackpots”?" - can you clarify please?

After all, the BBT - which seems to be at the root of your nagging doubts - would be in trouble if any of these turned out to have an alternative explanation (usual caveats apply).

But to look at "alternative explanations for the red shift" itself.

How would you go about searching for such explanations? No, seriously ... how do you think anyone - scientist, crackpot, layman - would actually do that? This is worth exploring, at least in part because it will show you - and Skwinty (and maybe even Zeuzzz) - just what the doing of science involves, through a concrete example.

And by spending some time on this, I think you'll work out the answer to your own question, in a far better way than if I simply typed a few hundred words ...

 

[Skwinty]

After all, the BBT - which seems to be at the root of your nagging doubts - would be in trouble if any of these turned out to have an alternative explanation (usual caveats apply)....

Thanks, you just answered my question to TT.

But to look at "alternative explanations for the red shift" itself.

How would you go about searching for such explanations? No, seriously ... how do you think anyone - scientist, crackpot, layman - would actually do that? This is worth exploring, at least in part because it will show you - and Skwinty (and maybe even Zeuzzz) - just what the doing of science involves, through a concrete example....

Well,I googled alternative explanations for the red shift and got loads of hits. Unfortunately I am not qualified to vouch for the integrity of these alternatives, hence my questions to people with qualifications in this field.

And by spending some time on this, I think you'll work out the answer to your own question, in a far better way than if I simply typed a few hundred words ...

I agree, that is why I ask for links, papers or book recommendations. I certainly don't expect anyone to write a tome when answering any of my questions. A little guidance is what I am looking for.

PS, what is MPS. I gather that PS refers to Philosophy of Science. does the M refer to Marxist?

 

[sol invictus]

Do you think it is remotely possible that we have it all wrong regarding cosmological expansion and the big bang?

It is remotely possible, yes. But the odds are so low I can't even estimate them.

Here's what would have to be wrong:

• GR (since there are no stable static cosmo solutions), Newtonian gravity (same reason), and in fact any theory in which gravity is attractive and there are no repulsive forces of comparable size acting over cosmological distances (same reason).
  
  
• that the redshift of distant objects is due to recession velocities (because if they are, the universe is expanding).
  
  
• that all of the myriad effects we see correlated with redshift - amounts of metals and other elements (you see those via absorption and emission lines in spectra), composition of stellar populations, shapes and configuration of large scale structures, etc. etc. - have some explanation other than that the universe was different when it was younger. Hard to imagine why, in a static universe, distance from earth would be correlated with so many changes in those things, isn't it?
  
  
• the simple explanation of the CMB that arises in BBT (in a static universe, it would have to be something like that there's a very hot, perfectly thermalized, perfectly spherical wall centered on the earth and about 13 billion lightyears in radius).
  
  
• the 2nd law of thermodynamics - if the universe is eternal, it should now be in equilibrium. Yet stars are still forming and igniting.
  
  
• as much of non-gravitational physics as is need to account for the redshift by some other means.

Point being, there's a vast array of many different kinds of evidence that all indicates that the universe is expanding and was very different in the past. For it all to have another interpretation is.... very difficult to imagine.

 

[DeiRenDopa]

[...]

PS, what is MPS. I gather that PS refers to Philosophy of Science. does the M refer to Marxist?

I wrote HPS (I think), which stands for History and Philosophy of Science.

AFAIK, it is nigh on impossible to do PS (or the PoS) without HS (the HoS), hence HPS ...

 

[Skwinty]

I wrote HPS (I think), which stands for History and Philosophy of Science.

AFAIK, it is nigh on impossible to do PS (or the PoS) without HS (the HoS), hence HPS ...

My bad once again, I am not thinking coherently as I have come down with flu. I guess the Feyerabend connection triggered that.

 

[DeiRenDopa]

The short answer is you can't unravel them. The longer answer:......

........For distant objects the overwhelming majority of the redshift comes from the cosmological effect though.

I understand cosmological redshift relates to the expansion of space.
Am I correct in this understanding?

How do you reconcile the seemingly contradictory statements that I have quoted from your post.

The trouble with short answers is that they can be quite misleading ...

Anyway, the path you and I are on, wrt your original question, will (I hope) lead you to understand what edd wrote (and if not, then I'm sure he'll jump in with his own corrections ...)

DRD:

Firstly, I have an introductory astronomy text by Ceceliia Payne Gaposchkin and Katherine Haramundanis.

The section on redshift really deals with the redshift -distance relationship and recession velocities.

The purpose of the introductory book is to lay the foundations - or framework - for the answers, not for you to read a para or chapter which directly answers your questions.

I'm not familiar with that particular book, but with Ceceliia Payne Gaposchkin as an author I doubt you could go wrong ...

Yes, the redshift spectrum X-Y plot will have all the necessary data attached such as the data you mentioned.

[...]

Good.

One result of many hundreds (thousands?) of years of work by thousands of scientists - not all of them astronomers - is a simple model of the Earth and the Sun that has exceptionally good explanatory and predictive power: the Earth is a rigid sphere which rotates on its axis and revolves around the Sun.

Of course that's an oversimplification, but for our purposes it gets us to the starting gate: whatever redshift you estimate your spectrum has (we'll get onto how to say this a little more precisely later), you can convert it to a 'barycentric' redshift by virtue of the work of thousands of diligent astronomers, engineers, physicists, etc.

IOW, you know when you took your spectrum, where you pointed your gadget, and where your observatory (telescope, instrument on a spacecraft, ...) was when you made your observation, and you can use this information to do a straight-forward transform into a frame of reference whose origin is the solar system barycentre.

And here might be an appropriate point to introduce "errors".

Whatever your spectrum is, it is not perfect, in almost any sense (and especially a Platonic one). There are (quantum) theoretic limits, but they are not directly relevant here. With some exceptions, the uncertainty, imprecision, inaccuracy, etc of knowing the *exact* time you took the spectrum and the *exact* location can also be left out, as can the estimated location of the solar system barycentre - the uncertainty in your derived 'wrt the barycentre' redshift arising from these sources of 'error' will be trivial (there are some exceptions, which I'm happy to go into if you're interested).

For the cosmological redshifts we will eventually get onto, the major sources of uncertainty in the estimated redshift in the spectrum have to do with things like the (spectral) resolution of the spectrograph, its precision and accuracy, and the faintness of the source (star, galaxy, quasar) ... oh, and the 'perfect' spectrum of the object itself!

But as you have the flu, it might be sensible to stop here and ask if you're OK with transforming what comes out of an instrument into a barycentric redshift ... leaving for later the (extremely important) details of how the squiggles in the graph get turned into something magic called a redshift in the first place.

Yes? No? Not sure??

 

[Dancing David]

I understand cosmological redshift relates to the expansion of space.
Am I correct in this understanding?

How do you reconcile the seemingly contradictory statements that I have quoted from your post.

DRD:

Firstly, I have an introductory astronomy text by Ceceliia Payne Gaposchkin and Katherine Haramundanis.

The section on redshift really deals with the redshift -distance relationship and recession velocities.

Yes, the redshift spectrum X-Y plot will have all the necessary data attached such as the data you mentioned.

A quote from this text.

"It is thinkable that the redshifts are not velocity shifts, but have some other cause, such as the gravitational effect predicted by the General Theory of Relativity."

Yes but that asks other questions:

1. If the gravitational/mass of an object is know or approximated and the amount of shift is higher related to distance, then what does that say?
a. That gravity becomes stronger with distance ?
b. That there is some source of gravity beyond the observable horizon, that is different from the observable universe?

 

[Dancing David]

Yes. But some seem impervious to this reality. Some do not. http://www.cosmology.info/2008conference/

Uh huh, sure Zuezzz, there are going to be papers all right but you have yet to produce any specifics that have not been addressed, so why not tell us what wonderful things they present at the conferenec? It should be better than you quoting material by Perrat that was way out of date as evidence.
'Each member of the first set of panels will focus on specific observational challenges to or problems with the consensus cosmology. Examples are the lack of Gaussianity or isotropy in the microwave radiation, the excessive apparent ages of high-z galaxies, the early formation of large-scale structure, discordant results for light element abundances, the surface-brightness / redshift relation, etc. Each member of the second set of panels will focus on a particular alternative cosmology, or on alternative explanations for the key phenomena of the universe, such as the origin of redshift, the microwave radiation, large-scale structure, gravitational forces, light element abundances, quasars, dark matter, and dark energy.'

The boldeed ones seem to be outrights lies!


So what are these wonderful anamaloies, really do tell.

Yes, but change some of the fundamental concepts underlying this evidence, and all of this evidence can act as strong evidence for a non big bang universe. All evidence is precarious depending on the axioms on which they are based.

Just watch this documentary, part two is probably the best starting point: http://www.youtube.com/watch?v=wchV5R9NhqY

Some extremely pertinent points are made by Lerner and others that no one yet has given adequate answers to.

I'm off on holiday now for a while and will remain lurking around for a week or two, but might pop back in for the odd comment when the odd blatent lie is posted.

Sure Zeuzz, these are such strong and perinent points that you can't post them.

the lie is that you say these things exist but you can't say what they are, what they mean or what data they represent.

Each of your points has been specifically addressed before, what new material are you bringing to the table?

 

[Skwinty]

But as you have the flu, it might be sensible to stop here and ask if you're OK with transforming what comes out of an instrument into a barycentric redshift ... leaving for later the (extremely important) details of how the squiggles in the graph get turned into something magic called a redshift in the first place.

No need to stop. If I blunder through incoherent thinking, I am sure it will be pointed out.
When you refer to barycentric, I presume you are referring to a triangulation process which would be mapped out when you make observations when the earth is in opposite positions in its orbit and thus showing a central point in the universe about which the earth and solar system is moving. If so, no problem.

I also understand that the spectra in question are compared to spectra obtained in a laboratory so that one would know the element or elements that the spectra are showing, otherwise the spectra would be meaningless. These spectra could be either emission or absorption spectra.

Am I on the right track here?

 

[Skwinty]

The trouble with short answers is that they can be quite misleading ...

I meant no disrespect to Edd, it just sounded a bit like saying "This equation is unsolvable, however the answer is 42"

 

[Skwinty]

1. If the gravitational/mass of an object is know or approximated and the amount of shift is higher related to distance, then what does that say?

I am not sure, but seems like the object is further away.

a. That gravity becomes stronger with distance ?

My understanding is that gravity is ruled by the inverse square law and that implies that gravity gets weaker with distance.

b. That there is some source of gravity beyond the observable horizon, that is different from the observable universe?

Wouldn't dark matter or dark energy have an influence on gravity, or create its own gravity. Also the dark matter or dark energy may have been in that specific location a long time ago and is no longer in that location when the redshifted photons arrive at our instruments?

 

[DeiRenDopa]

[...]

But to look at "alternative explanations for the red shift" itself.

How would you go about searching for such explanations? No, seriously ... how do you think anyone - scientist, crackpot, layman - would actually do that? This is worth exploring, at least in part because it will show you - and Skwinty (and maybe even Zeuzzz) - just what the doing of science involves, through a concrete example....

Well,I googled alternative explanations for the red shift and got loads of hits. Unfortunately I am not qualified to vouch for the integrity of these alternatives, hence my questions to people with qualifications in this field.

[...]

Not waiting for PS to post may be a little rude, but ...

Googling is like doing a literature search, isn't it, only more 21st century.

I think it's fair to say that there are unlikely to be any such <alternative explanations for the red shift> that Z and MM between them haven't already found and put on the table.

Anyway, with a slight change of focus - for your search of the literature - you could start with being a super-diligent MM ... find all the published results - of experiments done in the lab, under controlled conditions - that report not only "redshift" (because the experimenters might have used different terms), but anything that is a redshift.

If you do this, you'll find things like Doppler effect, Wolf effect, Compton effect, Raman effect, gravitational redshift, ...

What now?

(there are other 'google-based' paths to explore too - can you think of one?)