Cosmological Red Shift

We'll disagree on the last two of those, but thanks for telling me. I can tell you why I disagree about them but we probably should start a thread for each if you want to talk about them and stick with redshift on this thread.

On the claim that gravity is not a conservative force, you are right, this is incorrect, in classical terms. However, in GRT terms, it is nonconservative; under GRT gravity is replaced by the stress-energy-momentum pseudotensor. Because the stress-energy tensor is on the right side of the Einstein Field Equations, you can think of it as joint conservation of energy and momentum under GRT, which otherwise would be unphysical because GRT deals specifically with non-inertial reference frames. This is an extremely complex area and I would defer to a real relativist, which I'm sure we have around here.

 

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Schneibster,

If you are right, then I stand convicted of a charge which I tried to slap on Paddoboy/RussWatters.....mis-interpretation, and that will make my position very untenable. I will exit with due apology to both Paddo and Russwatters....unconditional.

You have attempted to include space expansion in the relative motion category, which is not correct..But before that I need to know what you say about..

1. Pound Rebka Experiment : No relative motion, yet Red/Blue shift. Here also nothing happened in flight ?
2. CMBR, you mean to say that these photons with such huge redshift, have not gone any change in wavelength/energy all along (with respect to whichever frame you choose, the Hot Plasma now non existent or Earth which was non existent at that time..any frame you decide.)
3. Z = 4, you mean to say that relative motion between Earth and that galaxy is 4c ?
4. You mean to say that Dopler shift which is SR and Cosmological Red shift which is GR domain...are both a result of relative motion..
5. How does a photon know, when getting emitted with predestined z, that he has to pass through such and such expansion before reaching Earth ?


PS : http://arxiv.org/pdf/0808.1081v2.pdf, i got this ArXiv paper after posting above, this paper supports your view, but it presents an argument against the existing point of view. This justifies the OP to an extent that spacetime expansion concept is problematic and has differing views.

 

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Not sure where you got that. I said that space expands and since galaxies are in space, the galaxies appear to move. Please quote where you think I said different.

But in that case the light fell through a gravity field, and at any point along its path one could theoretically find a redshift caused by whatever the difference in the emitting and absorbing locations due to their position in the gravity field. But there is no gravity field of this type between a distant redshifted galaxy and our galaxy, since they are too far apart to interact measurably. You're comparing apples and oranges.

The frame of Earth then is not the frame of Earth now, and you have to stick to a single frame for consistency. There isn't any Hot Plasma frame; the Hot Plasma was everywhere and there was nothing else. When we see CMB, we are directly seeing the surface of last scattering, as it was moving relative to where we are now 13 billion years ago. In that frame, the CMB is microwave and always was. The situation is no different.

A lot of popular science books have talked about the expansion of the universe redshifting the light, and you've taken them literally as if it happened just like in the Pound-Rebka experiment. It doesn't work like that.

That's not what Z=4 means. Z = (f<emitter> - f<observer>)/f<observer> which means that Z = 4 indicates that the frequency at emission is five times the frequency at observation; you don't have to go faster than light for that to be true. I could run the numbers using the SRT equations but I'm lazy and there's a nice calculator over at Hyperphysics that gives 0.923c.

I asked above, and I'm asking again: where do you claim I said this?

Doesn't have to. In the emitter's frame, the photon is of the correct energy to have the frequency emitted; in the observer's frame, the photon is of the correct energy to have the frequency observed, and that is always so for both emitter and observer. They're different frames; you can't take the frequency from one frame and pretend it's "changed" just because you changed frames. When you changed frames, you had to convert the frequency to the new frame, and when you did you find that is exactly what you see.

 

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Schneibster

Cosmological Redshift has nothing to do with relative motion....

Do you agree with above ?

 

It depends how you define "motion." Specifically, what frame you choose.

When we think about or imagine "motion," we think about ourselves moving relative to our immediate surroundings. That is our intuitive, classically based notion of "motion." In that sense, no, neither we nor some galaxy we have observed at Z=4 is "in motion," at least not enough to account for observed redshift. Not enough by many orders of magnitude.

However, there is another definition of motion, and that definition is that either the distance between us and some faraway object is increasing or decreasing, or the direction between us and that faraway object is changing. In this sense, yes, depending upon the frame chosen, either we, or the galaxy at Z=4, or both, are "in motion." Specifically, the galaxy at Z=4 and we are moving apart at about 0.923c.

A bunch of popular books about cosmology have made a real mess out of trying to explain exactly what's going on in this case, and you're trying to apply your intuitive concepts to something that they do not apply to; it's just the same as with quantum mechanics, where questions that, in your intuition, have definite answers do not. The answer is not yes, it is not no, it is, well, it depends how you define that. It depends what frame you choose, and it depends on whether you think motion is relative to things close around you, or relative to things far away.

Next, remember that all inertial frames, that is frames that are not accelerated, or in a gravity field, are on equal footing. You are imagining that a light ray (or a photon, if you prefer) is moving relative to space itself, that there is some magic special "spacetime frame" that it is moving relative to. There isn't. Light moves at c relative to all inertial frames. If those frames are in different states of motion, then they will see light of a different frequency, but they will all see the light moving at c.

To top it all off, the Doppler effect is linked to both these kinds of motion. There isn't a special kind of Doppler effect for either one; it's the same Doppler effect either way. If the distance between remote objects is increasing you will see a redshift in the light streaming from one of them to the other; if the distance is decreasing, blueshift. And it doesn't matter whether it's the space expanding, or the objects moving relative to their local background, it's all the same.

So when you use terms like, "Cosmological Redshift," I know that you have not understood me-- most likely because you don't want to, because it breaks some prior, incorrect idea about cosmology that you don't want to give up. I can't help you with that. You'll have to fix that attitude, or you aren't ever going to "get it."

Sorry, man, that's just where it's at. There's no way around it, and my side is supported by all the data we have. That's it. Wrap your head around it if you want to learn; ignore it and go away if you want to hold on to whatever it is you are imposing on the world. If you won't open your mind you won't, and that's the end of it.

 

paddoboy:

My apologies if I have offended you or Russ_Watters in any way. That was not my intention. I spoke on the matters according to my own understandings and readings of your responses and the literature on the relevant theory. I note that perhaps you don't realize the self-contradiction because you have a layperson's impressions which are formed by pop science 'explanations'; nevertheless, your comments appear contradictory in effect when scrutinized more scientifically and logically. If you carefully re-read and properly understand the important distinctions I made in my last post regarding those aspects, your understanding regarding what affects wavelength and what determines 'perceived frequency' may become more clear and therefore consistent.

Take the distinction between wavelength and perceived frequency:

Did you understand that frequency is affected by relative through-space Doppler scenario motion of the receiver relative to the photon lightspeed at reception, which Doppler effect component 'value' would be the same whether in expanding or non-expanding spacetime scenario; because locally at reception location, the receiver's only Doppler-effective motion is proper motion through space locally; because even in the cosmologically expanding case the local receiver is moving with the 'cosmological recession' component space itself.

And so is the photon, once it enters that same local segment of space, irrespective of expanding or non-expanding cosmology scenarios In which case the interaction event at absorption between receiver and photon involves only the relative speeds of the receiver and photon at that moment in that local space.

Have I made it clearer? The local interaction in local space does not have regard to what the source or receiver is doing locally except for the normal proper through-space motion which is qualitatively and logically different and separate component from 'cosmological recession' assumed 'relative motions'.

Once more, the wavelength can only be changed in transit once the emission rate at source determines that wavelength. At reception, the perceived frequency depends only on the receiver and photon relative speeds at interaction in local event space which for all intents and purposes is always a Doppler component separate from any wavelength component added in transit. Have I made that clearer?


Essentially the Doppler effect values would be the same even in the 'cosmological expansion' scenario because locally the cosmological effects do not contribute motional difference values. In effect the receiver is essentially stationary with respect to local space which is supposedly expanding, taking the receiver along with it. Of course as already explained in my previous post, the normal through space motion and gravitational well effects also play a part locally. But it is the scientific and logical consequence of the theory of expansion that at no stage does the cosmological expansion space 'motion' have any active Doppler-like contribution to make to the local through-space motional relativity between receiver or photon, since the receiver and photon both are supposedly in the same space and having both moving-through-space and static-with-space motional and non-motional states simulataneously locally at interaction.

Hence the Doppler redshift values for "perceived frequency" can only ever reflect a base local-through-space component; while the wavelength attenuation in-transit through-space travel also adds the 'cosmological expansion' effect component as a non-Doppler redshift value.

I note you earlier posted a statement claiming that there was an in-transit effect on wavelength itself due to "curvature" variation between early Big Bang epochs and now. If theory can identify and explain the mechanism involved in that action by "spatial curvature" on the photon in-transit, then perhaps theory will have the answer sought by The God and his OP query?

That is as well as I can explain to another layperson the separate Doppler and nonDoppler contributions mechanisms which the expanding universe theory implies and requires if its explanations are to be consistent with the implications of the assumptions regarding the with-space and through-space aspects as it affects photon wavelength during transit and affects perceived frequency during absorption in local space.

If I have failed to explain to your satisfaction, paddoboy, then I can only apologize for my failure. Thanks for the responses and your patience; and I hope no offense is further taken on your or Russ-Watters' part.

 

I'm not offended one iota.....Just remember that Russ is his own man just as I am. To derisively label us together is the mark of a troll.
Also you certainly need reminding that the links I supply are all reputable and to again derisively label them as "pop science" is also the way of trolls, as is evident in other threads on certain topics.
And finally I asked you to supply an example of my contradiction: You have not done that and simply repeat the unfounded accusation. Need I say more?
And yes, I am certainly a lay person just as apparently are you and the god, differences being that I do not suffer from any delusions of grandeur by pretending that I'm going to rewrite 21st century cosmology from the comfort and anonymity of a science forum.

I'm also not wasting my time going through your again repeatable jargon, since you have yet to answer the questions I put to you.

In summing and making this post short and sweet, the inferences of the god, and apparently yourself in denying that cosmological redshift happens, and as a result spacetime expansion, is not supported by anything either of you have said:
Cosmological redshift, along with spacetime expansion and extending to SR/GR, are as certain as any scientific theories can be without claiming total certainty.
Total certainty of course at this time is the sole domain of the theory Evolution.
And further more as I have told the god many times, if he or you had anything of substance or a concrete nature, to support whatever it is you are claiming, [the god's position is clear as he denies GR and Cosmological redshift and expansion] you and/or he would not be here: You would be preparing a paper to revolutionise 21st century cosmology and getting ready for this year's Nobel.
To that I say sweet dreams!

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Damn you Schneibs! I've been trying to get that message across to the god and others here for years; You succulently sum it up admirably after two days!

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That's what I meant in my previous post. These "would be's"pretenders come here and imagine that what they are infesting this forum with is somehow being absorbed and implemented by academia and mainstream science in general, instead of course just being a total waste of bandwidth in cyber space.

 

paddoboy:

Why do you always make disparaging remarks about what people are doing and why according to your opinion?

I am here to discuss the science and try to make sense of the many old and new mainstream science explanations so that I can get an ongoing consistent understanding of what it says and what it does not say.

You seem prepared to superficially and uncritically accept any link or assertion as long as it's a mainstream one. If you really do believe that science and its understandings and explanations evolve, then why do you keep trying to shut down conversation by use of personal attributions and disparagements of both members and the site itself?

Upon my arrival here, you tried to drag me into your personal scraps and stratagems against persons. Then you kept trying to convince me that the site was useless for science discussions because you expected nothing of interest or importance to arise in discussion or from site encouragement of member interactions on the science OPs irrespective of who posts them. You also keep reminding everyone that listens that they will not change science mainstream direction; forgetting that mainstream changes direction only when some new idea hits the scene. Unless you are claiming that all non-mainstream scientists and laypersons are too stupid or unequipped to have an original idea or perspective, then please have some respect for members who wish to have conversations with learned members without being lectured to about how useless the site and its members are in the mainstream scheme of things.

You have a right to your opinions, but when science is involved, your opinions as a layperson disparaging the site and its members is even more useless and stupid than what you claim this site and its members are.

If you are not intending to spend intellectual effort and necessary time perusing complex posts dealing with subtle matters which you as a layperson should take more care to discern before you dismiss and disparage and repeat that mantra of yours to divert attention from your own lack of proper intellectual engagement on the issues raised, then just do not respond as if you intended to and then beg off with such lame excuses blaming the other person instead of your own lazy, combative and dismissive uncritical layperson's attitudes of which your posts have been redolent since my first reading of your posts upon my arrival.

Please put me on ignore and don't again repeat to me your mantra about this site's failings and its members futility and irrelevance. Thanks.

 

Is that right?
Let's see, you are the one that [1] labelled my links as pop science, [2]accused me of contradiction without offering an example, [3] and labelled me derisively with Russ.
You don't see just a hint of hypocrisy?

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Ignoring your rant, again, Cosmological redshift, along with spacetime expansion and extending to SR/GR, are as certain as any scientific theories can be without claiming total certainty.
Total certainty of course at this time is the sole domain of the theory Evolution.

 

paddoboy:

My last two posts explained at length where the contradictions in your responses and understandings lay. You did not respond to the details regarding the distinctions I made for your benefit. You just blew me off and assumed yourself to have a better understanding of the issues involved just because you "agree with mainstream" links and explanations, without even stopping to think you may have a pop science level of understanding and misunderstanding of what you think you know of mainstream theory and its implications in detail. I did not deny Doppler or Cosmological aspects involved in redshift perceived. I only discussed the separate component aspects of wavelength and perceived frequency and what logically and physically is implied in the conventional expansion theory affecting both and the mechanisms involved. That is on-topic according to The God's OP question and subsequent discussion points. You appear to have made your mind up that unless he and everyone agrees with your understandings (misunderstandings) and failure to engage in detail on each aspect and its implications in logic and in physics theory, then you have some god-given right to either dismiss or disparage from your own claim that you agree with mainstream. When you do not actually understand mainstream theory enough because you are layperson with feuding-personality games to play here, you are not in any position to tell others they are useless or futile because this site is what you think and what you try to dictate to others with your repeated rants against those who do not meet your approval. I have learned my lesson. I will not be trying to explain anything to you ever again, since my attempts to do so have been met with your usual personal dismissive and irrelevant retorts ignoring the complexities and subtleties involved in the explanations.

Please put me on ignore and go your way and I'll go mine.

 

Nope, not at all.

There you go again. Again my links are reputable...You have none, and also are a lay person.
Let me reiterate: Mainstream theories are mainstream theories because they has already run the gauntlet and have progressed to accepted theoretical status for obvious reasons.
No alternative idea or theory will come from any science forum, no matter how much you chose to dress it up and make emotive excuses.
The scientific method is a tried and true system that works although not perfect.
Try it, you'll be surprised.

No, I put no one on ignore. I have been here for 2.5 years os so and continue to do what I hope I do best.
What I do is not up to you.
This is a public forum, and if people chose to deride accepted mainstream science without evidence, or claim other alternative hypotheticals in the science sections, then I'll refute to the best of my ability.

 

Science is still incomplete though and there still a lot we don't know. Pretending that science already knows everything there is to know when it obviously doesn't is foolish.

For example how life began. The origin of life is still a big mystery. Science still can't explain how life began.

And so is the nature of consciousness. No one know what consciousness is or why we have it and science doesn't know either.

 

Cosmological redshift, along with spacetime expansion and extending to SR/GR, are as certain as any scientific theories can be without claiming total certainty.
Total certainty of course at this time is the sole domain of the theory Evolution.
And further more to those denying cosmological redshift and universe/spacetime expansion, if they had anything of substance or a concrete nature, to support whatever it is they are claiming, they would not be here: They would be preparing a paper to revolutionise 21st century cosmology and getting ready for this year's Nobel.
To that I say sweet dreams!

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Sorry Schneibs...couldn't help myself and needed to use that paragraph again.

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paddoboy:

The theory is what it is at any one stage in its evolution. It is your understanding (misunderstanding) of that theory at its present stage, and its explanations and implications, which may be not as mainstream-consistent as you may believe it is based on your obvious pop-science and uncritical belief that you know mainstream because you link to it and believe it says what you think you believe. The scientific method is not in question. Your attitude and continued disparaging remarks in lieu of detailed engagement instead of blogging your personal opinions and mainstream links, which are themselves the subject of discussion, is what is in question whenever you distract from your own inability to explain in turn from your own understandings in detail of the complexities and subtleties which seem to be anathema to your understanding efforts (if efforts they can be called).

Please stop addressing me or continuing to excuse your failure to engage properly regarding scientific and logical details which have been presented for your benefit, but which you blow off whenever the going gets too scientific and logical for you to hold your own to any original or competent level of engagement.

So please ignore me and stop intruding in my discussions with learned members; and cease harassing me to explain things to you, since you have shown you are not interested in explanations, but only in opportunities for you to go into your disparaging agenda about this site and its futility and that of anyone who does not admire your uncritical and pop science level of participation (if participation it can be called).

 

Yep, certainly and I have said that same thing in this thread at least twice.

The theory of Evolution is not a theory of the beginning of life, just as the BB os not a theory of the beginning of the universe.

All true pluto but all off topic matey.

 

Anything that removes time as a variable removes both energy and inertia, opening the door to ridiculous propositions like perpetual motion machines and reactionless thrust.

The "stretching of space" does this, by exactly this technique. So does the Casimir effect, wormholes with either or both ends fixed in space and any other throwback to aether theory, absolute space, or absolute time.

Absolute space is static, with a geometry conceived as if time doesn't exist, and the universe of energy transfer events we inhabit is anything but. Solids, the atomic structure of which is mostly empty space between particles composed of bound E=mc^2 energy and their relative motions and respective time dilations are as dynamic as it gets.

Cosmological redsifts are due to a combination of relative motions or proximity to a gravitating body. Inertialess space is the same identity as invariant light travel time in every direction. We have recently seen just how much space "stretches" when a GW from a black hole merger passes us. It still isn't enough stretch to allow perpetual motion machines or reactionless thrusts to exist, nor for absolute curvature of absolute spacetime to be grafted into inertialess space with any real, consistent mathematics that supports it.

 

You can choose any frame you like. In it for every CMB photon with X eV of red shift in that frame, there is another, going exactly in the opposite direction with X eV of blue shift. As I said the total energy released symmetrically in all directions from the initial plasma shortly after the BB is "frame invariant." That total CMB energy is what I speak of, not measurements in any frame.

It would be hard work to add up the total red and blue shift energies in a particular frame, but no matter want frame is selected, the total red + blue shifted energies is zero. (Not the total energy, of course). I gave you an example in last paragraph of post 118 with photons A & B traveling in opposite directions. Did you not understand it?

That is true, but the "Earth's frame" or coordinate grid, spans the entire universe. So if you look at these microwaves in a frame with high speed wrt the "earth's frame" some photons which the frame is "running into" will be blue shifted and some just catching up to an observer's point, fixed in that fast moving frame they will be red sifted, but the same energy amount.

What it all comes down to is the question: Would the CMB still be isotropic if viewed from a frame moving with 99% of C wrt to earth's frame? I think not because those CMB photons that fast frame is "running into" will, in that frame have been blue shifted and the photons are just catching up to the observer in that fast moving frame from "behind” will be red shifted. The total energy of the CMB photons that and observed receives does not depend on what frame he is in. It is “Frame invariant.”

If that were not true, then one could defined a “preferred frame” as the one in which the total CMB energy received was least.

I think this is nonsense. Frames do not have any location, not one 10 miles from Earth nor one 13.6 billion light years from earth. They are coordinate grids than extend through out the entire universe.

I agree. I never suggested they stop, except when they cease to exist by being absorbed, which only a very tiny fraction do. That was my point.

For example, if we could send an observer back in time, by about 6.8 billion years, he would find the average over the entire volume of the universe (with about half its present radius) that the density of matter was greater by about a factor of 8, and photons traveling in that more intense gravity field would be red shifting faster, converting some of the energy into gravitational potential energy faster as energy must be conserved and individually they are with less energy as they red shift.

Again, for at least the third time, I am NOT using any frame, and I am not measuring the photon's energy. Only noting that all those, which have not been absorbed, continue converting their intrinsic energy into gravitational energy as the continue on their merry way from the surface of that very hot plasma sphere that "went transparent" when it had cooled enough to let the photons inside it escape.

Again. I am not measuring photon energy and I am not using any frame. I only accept the standard model of the post inflation evolution of the BB. I. e. there was a plasma that was filled with photons, in a black body distribution at the temperature of that plasma, and they were essentially trapped inside it as they were constantly scattering off charges, perhaps free quarks, but that plasma was expanding and cooling. Eventually it was too much neutral matter to keep the photons contained within its self, and they were set free, to climb away against the gravitational field. I. e. become every more red shifted, conserving energy, as their gravitational potential energy increased. Once the peak of their Black Body distribution was a gamma ray, then later an X-ray, then later UV light then later visible light etc. I believe in conservation of energy – so postulated that the energy lost by photons as they red shift appears in their gravitational potential.

I like to think of these CMB photons as “climbing up” from a deeper gravity well, much like photons escaping away from near a black hole's event horizon do (red shifting). It is meaningful to say that with out reference to any frame or measurement too, at least for the total energy of the escaping photons. Admittedly you can chose a frame in which the BH is rapidly moving. Then the Hawking radiation photons leaving from one side will have different energy than the photons escaping from the other, opposite side, but again, the total energy escaping is "frame invariant."

 

Do you understand what is red/blue shift ? Its not a theory, its an observed fact, a reality......none here is disputing that, the discussion is on the explanation provided, not on their existence. This shows that you type without fully understanding what is being discussed..

and the funny part is on the explanation side also you are apparently doing ding dong..

 

Schneibster,

So basically you are validating the OP...

What you are saying that this stretching/lengthening of photon due to expansion of spacetime is popscience.....a crude way to explain the observed redshift. ?

although I do not completely agree with you on few points raised, but after seeing that arXive paper I realised that there is a decent amount of disagreement over the explanation of these shifts even among mainstream active guys. This disagreement is quite same as that on whether the spacetime is a thing or not.