PDA

View Full Version : Problem with Red shift



snowflakeuniverse
2003-Sep-08, 05:00 AM
There is a problem with the present standard model describing the cosmological or recessional red shift that is used to describe the expansion of space.

Light when it is emitted from an element carries with it the identity of the element. It is as if every atom is like a bell and just as a bell produces a particular frequency when hit, so to do atoms in that the frequencies of light emitted from an element are specific to that element. This makes it possible to determine the chemical makeup of distant stars by looking at the spectra or frequencies of light observed.

One of the startling discoveries of science was the evidence that the further away a galaxy is , the more “red shifted” the spectra of a galaxy. Initially it was thought that this meant that galaxies were actually moving away, a Doppler like effect similar to when one hears the pitch drop from the noise of a passing car.

This interpretation of the “red shifting” has fallen away due to the extremely unlikely possibility that we would be located exactly in the middle of over 100 billion galaxies. The present standard model is to assert that the red shifting is due to the expansion of space. It is as if the wavelength of light is stretched out with the expansion of space itself as the photon is traveling through space. (The longer the wavelength, the less energy associated with the photon. Notice this violates conservation of energy, which is predicted by general relativity).

There is a problem with this model.

Most of you are familiar with the Famous Twin Paradox. One twin travels at the speed of light for 20 years while the other stay home. When the moving twin returns home he finds that he has not aged yet his twin is now 20 years older. If one travels at the speed of light, time stands still. Nothing changes.

Since a photon travels at the speed of light, then according to Special Relativity, time stands still and the photon will not change. If a photon cannot change while traveling at the speed of light, how is its energy diminished or wavelength increased?

snowflake

VanderL
2003-Sep-16, 03:28 PM
Maybe the answer is that we, the observers, are moving away?
Probably too simple.

snowflakeuniverse
2003-Sep-17, 06:44 AM
Hi
Were are we receeding to? A galaxy on our left sees us move to the right. A galaxy on our right sees us move to the left.

snowflake

VanderL
2003-Sep-17, 09:48 PM
I guess space (space/time or whatever that is) is expanding in every direction so all galaxies are moving away from each other. The real problem is that the expansion has never been measured directly. It is only assumed, based on the fact that we know that doppler effects are real. So since we haven't thought of other ways that can explain redshift, we are stuck with an expanding universe even though evidence is available that shows that redshift must have another component, Halton Arp again.

StarLab
2004-Nov-09, 01:36 AM
Red shift...it'd be nice to expand on this string as a sister companion to the current popular string in Alternative Theories. So if any of you out there don't want to waste time reading the entirety of that string but still want a constructive say in the issue, please do post here. ;)

Moseley
2004-Dec-10, 04:56 PM
Sorry, got to this one a bit late. Do not fully understand why something further away MUST be moving faster away from us than something nearby although I can comprehend red-shift indicating speed away and blue-shift towards from notion of receding or approaching wavefronts.
Does Planck's E = hf not suggest that any loss of energy by a photon will directly affect its frequency? If so red-shift is also a manifestation of photons uniformly losing energy although I can offer no explanation as to how this may come about.
I may have confused several ideas.

Tim Thompson
2004-Dec-10, 09:03 PM
Shouldn't this be in the Alternate Theories section?


Snowflakeuniverse: Since a photon travels at the speed of light, then according to Special Relativity, time stands still and the photon will not change. If a photon cannot change while traveling at the speed of light, how is its energy diminished or wavelength increased?

Actually, according to special relativity, at the speed of light, time does not stand still, it becomes undefined, and does not exist.

The energy & wavelength of any photon necessarily depend on the reference frame that the energy & wavelength are measured in. It follows, therefore, that a photon does not have "an energy" that is intrinsic to the photon. In the reference frame of the photon, energy, like time, is not a defined quantity. Energy only exists as a measured quantity, and its value depends on how it is measured (i.e., in what reference frame the measurement is made).

Your "problem" does not exist as a legitimate problem because you have misinterpreted special relativity (the role of reference frames in measurement), and you have wrongly assumed that the energy is intrinsic to the photon, which it is not.

antoniseb
2004-Dec-10, 09:17 PM
Originally posted by Tim Thompson@Dec 10 2004, 09:03 PM
Shouldn't this be in the Alternate Theories section?
This thread was created before there was an alternative theories section. But yes, that's where it belongs.

Thanatos
2004-Dec-12, 03:25 AM
No energy loss with redshift. The energy density is merely diluted. Draw a wave pattern on a rubber sheet then stretch it.

VanderL
2004-Dec-12, 09:45 AM
No energy loss with redshift. The energy density is merely diluted. Draw a wave pattern on a rubber sheet then stretch it.

Well, it takes energy to "stretch it", so energy must come from (or go to) somewhere, or am I off here?

Cheers.

(Q)
2004-Dec-12, 03:17 PM
Universal expansion is stretching the wavelengths - the energy is not lost.

JESMKS
2004-Dec-12, 11:17 PM
If your streching the wavelengths, doesn't the wave front have to move faster than c to make room for all the expanded wavelengths?
Jack

imported_WINSTON
2004-Dec-13, 03:53 AM
Also note:

1 At the speed of light, mass is supposed to be infinite. Why are electrons and photons not infinite in mass? [Rhetorical question]

2 Why do only photons stretch, nothing else? [ answer obvious, theoretical tweaking] It's a "carrier" particle like gravitons, and the carriers of the electroweak and strong forces. theres no reason they shouldn't "stretch" [as well as baryonic matter].

3 Measure the width of the original photon scattering, adjust for the expansion of the U since that time[stretch it]. The width of CMBR theoretical does not match observed, unless the expanding U changes speed radically several times for no apparent reason [other that to tweak BB theory..]

4 Measured speed of our galaxy, 54k/s. This means we are one in a billion galaxies that "happens" to be at the center of the Universe [if you believe Big Bang theory].

5 The "expanding" universe suddenly shifts from decelleration to acceleration, after 15 billion years, and just at the time we are watching? Not a big[unbelievable]coincidence? The people who would have never in a million years predicted it, accepted it immediately without questioning the sheer illogic of the concept.

6 There are other proven causes of redshift, such as the Compton effect. There are possibly other reasons, but mainstream physicists don't necessarily go looking for them. We have not tracked a photon for more than one second. How can we be certain of how it behaves over billions of years?

Discovering a redshift component, finding that the U is not expanding or contracting, would be semi-disastrous to big-bang theory. I say semi because I believe that these theorists will suddenly claim that they predicted this:
That we have just gotten to the point of maximum expansion, and that we are going to start collapsing.

Someday observational evidence will be so strong that the average guy going down the street will believe that BB theory is wrong. Comedians will tell jokes about it, movies and TV parodies willl come.

The mainstream scientists, being the last to "get it", will suddenly proclaim THEIR new discovery of a steady state universe. They will immediately recieve public praise and Nobel Prizes for their achievements, followed by massive funding to lead THIS theory into some scientifically incorrect places.

antoniseb
2004-Dec-13, 03:59 AM
Originally posted by WINSTON@Dec 13 2004, 03:53 AM
Why do only photons stretch, nothing else?
Photons do not stretch, and people arguing that they do are misunderstanding cosmic expansion. Photons are emitted at the wavelength they are at for the whole flight to our detectors. The dopler shift is because the object that emitted them is moving away from us at a significant fraction of the speed of light.

imported_WINSTON
2004-Dec-13, 05:36 AM
Photons are emitted at the wavelength they are at for the whole flight to our detectors.

This is contrary to expansion theory, as far as I have seen. CMB photons were supposedly emitted (scattered) shortly after big bang, and have supposedly changed wavelength since that time by stretching. Since we are "close to the center" of the U, there should be very little Doppler shift of CMB, since they began where we are sitting[an echo from a stationary object would be at c as well].

Sidenote:These photons are believed to be "echoed" contrary to observed behavior of photons. They would also need to bounce off of empty space, again not observed or predicted by proven theory.

The Doppler effect is for starlight photons. With due respect, I think you've confused Doppler with Expansion, or you haven't swallowed the "Expansion" bit the way other theorists see it. Even time and space are not constant, but stretch, according to these theorists.

antoniseb
2004-Dec-13, 01:25 PM
Originally posted by WINSTON@Dec 13 2004, 05:36 AM
CMB photons were supposedly emitted (scattered) shortly after big bang, and have supposedly changed wavelength since that time by stretching.
No, that is not the current model. CMB photons were free to go through the now transparent universe starting about 380,000 years after the big bang. Since then the photon that happen to be passing us from this era are getting progressively longer wavelength, because we are seeing them from progressively more distant objects, moving progressively faster from us at the time of emission. The individual photons are NOT stretching.

imported_WINSTON
2004-Dec-13, 08:23 PM
In reference to cosmic microwave background radiation(photons):

because we are seeing them from progressively more distant objects,

If a photon encounters an object, it will be absorbed, wont it? How can a photon strike a star and return to us with no change?

Some theorists say that these photons bouced off of the empty space at the fringes of our U.
Space is stationary, has no property of motion to create a doppler effect.

antoniseb
2004-Dec-13, 11:36 PM
Originally posted by WINSTON@Dec 13 2004, 08:23 PM
How can a photon strike a star and return to us with no change?
What are you writing about here? There are plenty of photons that get to us, never having struck something opaque. I also don't know what you mean be 'return to us'. We did not send these photons.

Some theorists say that these photons bouced off of the empty space at the fringes of our U. Space is stationary, has no property of motion to create a doppler effect.
I don't think anyone is saying that the CMB photons are bouncing off of empty space. They are the photons that shine through as the early opaque Hydrogen plasma cooled to form atomic Hydrogen. The Hydrogen plasma that we are seeing as the CMB was/is moving away from us very fast.

JESMKS
2004-Dec-14, 01:28 AM
The tired light theory for the red shift didn't seem to fly, so here is another idea that we can try on for size. I understand the light from hydrogen fusion is bright red (APOD- December 8, 2004). When the universe was young, most of the light from young galaxies came from the fusion of hydrogen, giving off bright red light. In time these galaxies became contaminated with impurities (the byproduct of fusion). This gradual contamination created changes in the frequencies of the omitted light. The older the galaxy, the more complex the mixture of frequencies.

When we look at distant galaxies we see them as they were when they were very young and their light came primarily from the fusion of hydrogen. Closer galaxies are much older than the distant galaxies and give off a greater mixture of light frequencies (because of greater contamination) and may even appear as white light. The red shift could result from the age of the observed galaxies, the nearer galaxies (the older ones) give off a mixture of light frequencies and as we observe younger and younger galaxies (at greater and greater distances) the light shifts toward the red spectrum. Just an idea for discussion.
Jack

imported_WINSTON
2004-Dec-14, 06:15 AM
The Hydrogen plasma that we are seeing as the CMB was/is moving away from us very fast.

You are saying that there is a wall of Plasma at the edge of our U continually/currently emmiting photons, seen as CMBR? I have not heard that version of BB theory.

This "early plasma" was the Universe we see now, wasn't it?

I didn't say it, big bang theorists say CMBR photons came from the time of scattering, in the early stages of big bang. Yet sometimes BB theorist use different versions of BB theory to satisfy different arguements.

Assuming version A:
"CMBR photons-scattered in the early stages of big bang"
[This occurred very near our present position near the center of the U.]

Proven observed properties of photons:
1 Travel in a straight line at c.
2 Absorbed by collision with matter.

Since these photons haven't been emitted for 14.5 billion years, one would expect them to race outward at c, unless they collide with matter and are absorbed. As we are still sittin' here in the center of the Universe 14.5 billion years later, we should se NO CMBR photons. Unless they RETURN by the ECHO I've heard of so often.


[b]. I also don't know what you mean be 'return to us'. We did not send these photons

When they say the "echo" of the big bang-What is an echo, if not a "return"?

Who is "we"?

antoniseb
2004-Dec-14, 10:23 AM
Originally posted by WINSTON@Dec 14 2004, 06:15 AM
You are saying that there is a wall of Plasma at the edge of our U continually/currently emmiting photons, seen as CMBR? I have not heard that version of BB theory.
Yes, as we look out and see the Universe from here, that is the current view of it. I'm surprised you haven't heard of it.

Since these photons haven't been emitted for 14.5 billion years, one would expect them to race outward at c, unless they collide with matter and are absorbed. As we are still sittin' here in the center of the Universe 14.5 billion years later, we should se NO CMBR photons. Unless they RETURN by the ECHO I've heard of so often.

I'm sorry, I can't tell if you are pulling my leg about what you believe about the big bang [you do, afterall, appear to work at the Ministry of Truth]. We are not at the center, and there is no photon echo. With passing time we merely see slightly further away, and the average wavelength of the CMB will get slowly longer.

imported_WINSTON
2004-Dec-15, 05:11 AM
We are not at the center

Where are we located?

For a Universe 15 billion years old to expand to 50 billion light years across, the leading galaxies will have to travel at almost twice the speed of light. Galaxies at opposing edges of the U would move at more than three times the speed of light away from each other. Most of the galaxies are travelling at high speeds in BB theory, while the Milky Way is moving at 600k/s. That would LOGICALLY put us very near the center of the U, unless you apply some other phenomenon or force.

NOTE:This is one of many problems with BB outlined by Hawking, how events can occur simultaneously across the U without communication.

On my desk, at the ministry:

"The pioneer probe off course, they don't know why"

This may not prove any alternative theory necessarily, but it knocks a dent in SR. I have heard this arguement countless times:

"Special Relativity is proven. Our space program applies it with accuacy."

imported_WINSTON
2004-Dec-15, 06:12 AM
As the universe expanded and cooled there came a point when the radiation (photons) decoupled from the matter - this happened about a few hundred thousand years after the Big Bang.

Looking back at the CMB we see the surface of "last scattering", when the photons last significantly interacted with the matter

The CMB is the background of radiation left over from when the Universe was very hot and dense. As the Universe expands it cools, and so we see the background radiation as microwaves

You'll find that every mainstream site says this:

The CMBR are not presently being emitted (not for past 14 billion years).
Cooling, not Doppler, changes the wavelength.

I feel strange, arguing BB when I don't believe in it.


The inference is that our entire local group of galaxies is moving in a particular direction at about 600 km/s.

However, the speed of galaxies throughout the U are explained away thusly:
"Doppler speed is zero for local groups".

This is a phenomenon not necessary by any proven theory, another exception to the laws of physics.

antoniseb
2004-Dec-15, 05:43 PM
Originally posted by WINSTON@Dec 15 2004, 05:11 AM

We are not at the center
Where are we located?
We are here. There is no center.

Most of the galaxies are travelling at high speeds in BB theory, while the Milky Way is moving at 600k/s. That would LOGICALLY put us very near the center of the U, unless you apply some other phenomenon or force.
No, the whole idea of the Hubble expansion is that galaxies that are near each other do not experience MUCH relative velocity. A good fraction of the MW's 600km/s is toward the 'Great Attractor', most likely a large galaxy cluster we can't see because our galaxy's dust clouds block our view. It doesn't matter where in the universe you are, the galaxies near you won't be moving away rapidly. I'm thinking you knew that already.

Erimus
2004-Dec-16, 01:06 AM
<<1 At the speed of light, mass is supposed to be infinite. Why are electrons and photons not infinite in mass? [Rhetorical question]>>

1.) Like every other material object, electrons cannot travel at exactly light speed.
2.) Photons are massless.

imported_WINSTON
2004-Dec-17, 04:00 AM
Why are electrons and photons not infinite in mass? [Rhetorical question]>>

1.) Like every other material object, electrons cannot travel at exactly light speed.


A photon is not a "material object" now?

OKAY,sure. Let&#39;s say electrons don&#39;t travel at c ( although it is proven that electricity/EM travels at c). At 99.99% of the speed of light, their mass should be immense compared to an electron at relative rest inside a neutron[but is not]

It&#39;s hard to argue against BB theory.
They describe space :
Static and dynamic, moving but stationary.

The shape of the U:
Soccer ball shaped, and parodoxical shaped[ so that if you go in a straight line you end up where you started].

Space between matter
Empty and filled. No EM median or undiscovered particles, No aether; but filled with an invisible dark energy/dark matter fluid.

Gravity:
Constant and variable. Gravity wells force E=m/d^2 up and down to allow for large groups of galaxies to collapse in an "expanding" Universe.

[That&#39;s enough for now]

imported_Redshift
2004-Dec-20, 05:06 PM
I&#39;m going to describe my view of the universe. First, my assumptions:

1. Redshift is not Doppler, but rather is some other phenomena, a portion of which is intrinsic, we as yet do not fully understand.

2. The intrinsic portion of the total redshift of an object follows a linear function, but we don&#39;t have the necessary data to be able to figure out the constant to a high degree of accuracy.

3. The intrinsic portion of the total redshift of an object is a measure of distance.

Okay, fine. Since redshift is an indicator of distance, there should be some point at which all light is redshifted so much that we can no longer detect it. The edge of this shell we could call the limit of the visible universe. For the sake of discussion, let&#39;s say it&#39;s 15BLY, so that would make our visible universe a sphere 30BLY in diameter. And this sphere is a "window" on the existing cosmos. As our position changes relative to the universe, so does our visibility sphere.

This would mean that the CMB is merely the last thing we see before the universe outside of our 30BLY sphere becomes unobservable to us. The reason we see the CMB is because our position is not static, so as the edge of the sphere changes position, the amount of light-producing matter on the "edge" changes with time, causing the slight perturbations we see in the CMB.

This would mean several things:

1. The universe is not expanding.

2. The BBT is false.

3. The universe is, for all practical purposes, infinite in extent, and we see only a 30BLY diameter sphere of it.

4. We will never be able to see beyond this sphere. That does not mean we will never be able to travel beyond it by some exotic, as yet unimagined, method. It only means we will never be able to seebeyond it utilizing the normal electromagnetic methods we use now.

This pretty much lays out what I believe is really going on. I&#39;d like your feedback&#33;

Regards,
Redshift

antoniseb
2004-Dec-20, 05:33 PM
Originally posted by Redshift@Dec 20 2004, 05:06 PM
First, my assumptions: 1. Redshift is not Doppler...
This would mean several things: ... 2. The BBT is false...

There are some opposed to the big bang who do not even think that redshift is a distance indicator, so your position is moderate compared to them.

Concerning the model that you&#39;ve described, I&#39;m wondering about a few things:
- why do we see galaxies from z>6 mostly as immature star-burst galaxies, with no large stable old spirals and ellipticals?
- why do we see no light at all from about z=9 going back to the cosmic microwave background?
- why is the CMB as uniform as it is if it really represents highly redshifted optical and UV emisions.
- why do we see no stars in our galaxy and surrounding globular clusters with ages apparently older than 13 billion years?
- why do we see quasars from only a limited range of redshifts, and almost none of them nearby? [implication is that there was a specific time when they were more common then they are now].
- why hasn&#39;t all of the matter in the local universe been converted to Iron and other middle-weight elements?
- what is the source of the energy of stars? is it Hydrogen fusion? what is the infinite source of Hydrogen, and where are all the dead star cinders?

imported_Redshift
2004-Dec-20, 11:01 PM
Thanks for the questions...


why do we see galaxies from z>6 mostly as immature star-burst galaxies, with no large stable old spirals and ellipticals?
I don&#39;t know the answer to this question. Can you tell me where you reference the information you give here...I&#39;d like to read the articles, etc.

why do we see no light at all from about z=9 going back to the cosmic microwave background?
I believe it&#39;s because the light is too far redshifted.

why is the CMB as uniform as it is if it really represents highly redshifted optical and UV emisions.
I would have to say to this one that it&#39;s uniform and leave it at that.

why do we see no stars in our galaxy and surrounding globular clusters with ages apparently older than 13 billion years?
I believe it&#39;s because stars just don&#39;t last much longer than that.

why do we see quasars from only a limited range of redshifts, and almost none of them nearby? [implication is that there was a specific time when they were more common then they are now].
I believe Arp has an answer to the quasar question. I agree with Arp that quasars are a lot closer than is currently believed.

why hasn&#39;t all of the matter in the local universe been converted to Iron and other middle-weight elements?
Here again I agree with Arp that matter is recycled by ejection from AGN in the form of young quasars, etc.

what is the source of the energy of stars? is it Hydrogen fusion? what is the infinite source of Hydrogen, and where are all the dead star cinders?
Similar answer to the last question, but yes, I believe hydrogen fusion fuels the stars.

Please bear in mind that I am an interested amateur.

Regards,
Redshift

imported_Redshift
2004-Dec-20, 11:02 PM
Ugh, sorry about all the [QUOTE] junk...not used to formatting on this board.

Regards,
Redshift

antoniseb
2004-Dec-21, 12:09 AM
Originally posted by Redshift@Dec 20 2004, 11:02 PM
sorry about all the [QUOTE] junk
You had a missing "[" in front of one of the "QUOTE"s. I fixed it for you.

antoniseb
2004-Dec-21, 12:15 AM
Originally posted by Redshift@Dec 20 2004, 11:01 PM
Please bear in mind that I am an interested amateur.
Actually, that&#39;s all I am. So, I will argue against you as I argue against anyone who tells me I am wrong. That is, I re-examine my position, and then give observations that support my side, or seem to undermine your side.

In this case, the lack of light from z>9 is not because it is red-shifted too much, because we have far-infrared and microwave detectors that should be able to detect them if they are there.

Concerning stars, the current theories say that red dwarfs should live much longer than 13 billion years.

Concerning the theories of Halton Chrisitan Arp, I have argued against them in other threads. Here, I will simply say I disagree with his conclusions.

Nevyn
2005-Jan-03, 11:42 PM
Could someone please explain to me why scientists think that red-shifted light is evidence for an expanding universe, when we know for sure that light passing through a gas is also &#39;red-shifted&#39;. Do scientists think that light travelling billions of light years would not pass through some gas? Even though the very galaxies themselves are formed from this gas?

antoniseb
2005-Jan-04, 04:15 AM
Originally posted by Nevyn@Jan 3 2005, 11:42 PM
we know for sure that light passing through a gas is also &#39;red-shifted&#39;.
Actually, we have not observed light going through a gas becoming redshifted. Light going through a dust may get reddened, by having it&#39;s bluer photons removed, but this is not the same as redshifting.

So far, the only two observed ways that light can get red-shifted are:
- doppler redshift by being emitted by something moving away from us a high speed
- gravitational redshift by being emitted from a deep gravitational potential well, such as the surface of a neutron star.

The CREIL and Plasma Universe people talk about something that has never been observed.

Nevyn
2005-Jan-04, 04:31 AM
Sorry, I may have worded that badly. If I am correct, then there is no difference between red light and red-shifted light apart from the mechanism that created it. So that&#39;s just a name game (and if I am wrong there, please tell my why). So when we detect the light, there is no way to determine if it is red light or red-shifted light.

And does it matter if it is dust or gas? Either way, light travelling billions of light years through space would come across something. And if it is more likely that the bluer photons are removed by collisions, then wouldn&#39;t most light that reaches us be red?

And if light hitting dust (or gas or whatever) removes the bluer frequencies AND the red-shifting effect takes place, then wouldn&#39;t the reder light that is left after the dust collisions be shifted such that it goes past the red part of the spectrum and we no longer see it?

antoniseb
2005-Jan-04, 04:46 AM
Originally posted by Nevyn@Jan 4 2005, 04:31 AM
If I am correct, then there is no difference between red light and red-shifted light apart from the mechanism that created it.
You are not correct. I am assuming you are fairly young, and/or relatively new to astronomy, because this is pretty basic stuff.

You cannot tell by an individual photon whether it is red because it was created red, or whether it was blue in the frame of reference of the object that created it, which just happens to have been travelling away from us at a large fraction of the speed of light.

You can, however, look at many photons and see the spectrum of light, and observe how far to the red various well-known lines have been shifted, especially the Lyman Alpha & Beta lines.

When astronomers say that light from an object is red shifted, they mean it.

madman
2005-Jan-04, 09:08 AM
here&#39;s a rough illustration

the coloured bands below represent a spectrum received from a galaxy (many different elements emitting light produces the spectrum)

the black lines are caused by the galaxy absorbing specific wavelengths instead of emitting them...these black lines will occur at specific points on the spectrum and are known to be related to specific elements/energy states.


http://hometown.aol.com.au/Profnim/newpics/shift1.jpg

"doppler shifting of light" is the theory of why the black lines are sometimes found to be in a diffferent place than would be expected normally.

http://hometown.aol.com.au/Profnim/newpics/shift2.jpg

finding the black lines shifted to the right, means the light was redshifted...and vice versa.
the black lines have been shifted as a coherent group (they have the same distances between them as you would expect if they weren&#39;t shifted)

Nereid
2005-Jan-04, 02:11 PM
To WINSTON and JESMKS: I&#39;ve read your posts here, and I must say that my impression is you may find time spent trying to understand present day physics (esp General Relativity and its application to the Universe) would be well spent. I&#39;d be happy to assist you with that understanding, for it seems to me that you are very confused as to what these physics theories actually state.

Alternatively, perhaps we could start with the good observational results, and work back to consistency with theory? This might be easier for you, and might help several others here too.

For example, let&#39;s look at supernovae. Hundreds of these are observed every year, and the mechanisms behind each type (with a couple of rare exceptions) are well understood. So, we observe a &#39;transient&#39; in the sky (something which wasn&#39;t there before), take its spectrum, watch how its brightness rises and falls, across the EM spectrum. We note that it appears to have a &#39;high redshift&#39;, z = 1, say. We note that the light curve and spectrum resemble those of &#39;local&#39; supernovae (of a certain type). We measure the degree of &#39;reddening&#39; (which is NOT redshift, as was pointed out earlier), using standard techniques. We conclude that the transient is a distant supernova - based on a comparison of its light curve and spectrum with &#39;local&#39; supernovae. We observe several hundred of these transients, with a range of redshifts. We plot estimated distance against redshift, and find ....

Now, there is one good theory about the redshift of distant objects, and several ideas. The former is the Big Bang Theory, and it accounts for the observations I briefly summarised above very well. Then there is the plasma redshift and CREIL, which (AFAIK) cannot account for these observations at all.

We can go through the same exercise, with galaxies and quasars. IMHO, each time the result is the same ... alternative ideas have a very tough time accounting for ALL the good observational results (what you read in material by their proponents is carefully selected sub-sets of data, never the full set); the BBT no such difficulty (of course there are many details still being worked out).

Nevyn
2005-Jan-04, 11:32 PM
Thankyou. Seeing that spectrum shows a lot more than most books tell you. I think the problem here is that physics books, even when aimed at the layman, use terms without thoroughly explaining them. You get an idea, usually from researching other sources, but can sometimes miss the little things that they take for granted. But then again, that is why I was asking.

ngeo
2005-Jan-10, 07:15 PM
My question is the relation between red shift in absorption patterns from distant galaxies and the microwave radiation. We interpret red shift as absorption patterns of bodies receding from us at ever greater rates relative to distance. The BB theorists interpret CMB as &#39;leftover radiation&#39; in a blackbody pattern corresponding to a very low temperature. This radiation, which reaches us today, is supposed to have occurred at a specific point in universal expansion at which photons were no longer entirely absorbed by ionized hydrogen (am I right?). However this &#39;era&#39; is called the &#39;surface of last scattering&#39; or the &#39;cosmic photosphere&#39;. This is a spatial description. The universe at that &#39;point&#39; had a certain volume. At the &#39;time&#39; of &#39;last scattering&#39; did the decoupling of photons not occur throughout the entire volume of the universe? If that is so, what is the meaning of the &#39;surface&#39;, or &#39;cosmic photosphere&#39;? I see a drawing of the universe in which there is outer layer (labelled delta t) from which the CMB presumably comes. Where does this layer come from? In other words, how &#39;thick&#39; is this &#39;cosmic photosphere&#39; and for how long did it radiate photons? If the &#39;cosmic photosphere&#39; stopped emanating at a particular point in spacetime, are we just lucky that we see it? Aside from the confusing interpretation of a surface with a volume, it seems to me that there is an equally valide interpretation of the CMB which is that blackbody radiation of a very high frequency emitted from the event horizon of the universe is constantly received at a very low frequency, indicating a source receding from us at close to the speed of light. I believe a calculated redshift relation between blackbody gamma radiation and blackbody microwave radiation will bear this out. Could it be that we do not see any high redshifted galaxies between z=9 and the CMB because hydrogen plasma is absorbing all photons in that region, that the evolution of hydrogen plasma into atomic hydrogen takes place due to the absorption of energy from an energetic field which causes the expansion of the universe in the first place, and that at this point of evolution atomic hydrogen emits blackbody radiation as gamma rays, received by us as microwave radiation?

Nereid
2005-Jan-10, 08:43 PM
Excellent questions ngeo&#33;

I&#39;ve read one rather good analogy for the &#39;surface of last scattering&#39;; it goes something like this: imagine you and 10 million (or some other extremely large number) other people are on a plain, and you are all shouting. Then everyone stops shouting, at the same time. What will you hear? A &#39;ring&#39; of last shouting ... which gets further and further away as time goes on. Furthermore, everyone else experiences the same thing&#33; Now, switch from 2D (the plain) and 1D (the ring) and shouting, to 3D and 2D and scattering ... the &#39;ring of last shouting&#39; becomes the &#39;surface of last scattering&#39;.

The decoupling happened pretty much at the same time, but not the same instant ... the WMAP team&#39;s analysis (http://arxiv.org/abs/astro-ph/0302207) of the &#39;best fit&#39; cosmological parameters gives the z of the decoupling as 1089 +/- 1, and thickness dz 195 +/- 2.

We&#39;re not &#39;just lucky&#39; to see the CBR; at all times since the beginning of the era of re-ionization, the surface of last scattering has been visible, to all, everywhere in the Universe (well, not deep underground, etc&#33;). As the universe got older, the CBR got cooler, eventually becoming the CMBR.

There are many, many different things which could be the cause of the CMBR ... however, AFAIK, the only theory which accounts for its well-observed features is the cosmological one (surface of last scattering).

Have you heard of the Dark Age? It&#39;s the time between when H atoms formed (at the time of last scattering) and when most remaining dilute H was re-ionised. It&#39;s a fascinating period in the Universe&#39;s history, but extremely hard to study. During this time H was not ionised (or only weakly), so the only plasma around would have been in the newly formed massive stars (or whatever). It&#39;s call dark because EM short of ~120 nm would have been absorbed (by the H gas), and such wavelengths would be now observed in the IR (or longer).

ngeo
2005-Jan-11, 02:10 AM
Hi Nereid,

I read the WMAP abstract - I don&#39;t know the terms they use (my fault, not theirs), but I saw the thickness of the decoupling surface as you said. I wonder what it means in miles, or meters (something I can understand). Still I am uncomfortable with the description of a &#39;surface&#39; and a &#39;thickness&#39;. This implies that there is a shell which emits to an empty interior. But why would the shell remain intact with an &#39;empty space&#39; in the expanding interior? As the volume increased, would it not be reasonable for all the occupants of the expanding space to remain approximately where they were, becoming more widely spaced? This is why I am proposing an alternative scenario, in which the universe is an expanding field which creates pressure in its interior (within a limited volume) and matter in the form of spinning regions to absorb the pressure (energy). Absorption of the field&#39;s energy by matter reduces the expansion of the field in the regions of matter (gravitational fields). This is a continual, and periodic, process. Just inside its outer limit the field creates new matter. I believe this is the source of the CMB. The first matter created is in the form of protons and electrons (does this correspond to a plasma?). As they combine into more efficient spin systems (hydrogen atoms), they emit energy back out into the field in the form of radiation. This is what we see as CMB: redshifted blackbody radiation not from a specific period in history but from a continuing creative process. It is hard for me to swallow that a &#39;surface&#39; of a certain thickness that has been radiating out into the universe for 13 billion years without running out of stuff to radiate.

I have a larger problem with the BB theory, and the WMAP abstract includes it: that is that there is a finite &#39;amount&#39; of mass-energy in the universe. The WMAP abstract says, "... the total mass-energy of the universe is Omega_tot = 1.02 +/- 0.02." Is this in fact a finite number, or is it a relative number? And what exactly does &#39;mass-energy&#39; refer to? Is it the total of matter (or its energy equivalent) and &#39;dark energy&#39;? There seem to be many different measuring units used to measure &#39;energy&#39;. Today it appears no one knows how to deal with &#39;dark energy&#39;. I believe &#39;energy&#39; is a cause which is being defined by its measured effect.

I have heard of the &#39;dark age&#39;, but I don&#39;t know what it really means. I believe it is supposed to take place after the &#39;photon decoupling&#39; era. Does it have anything to do with the absence of sources between z=9 and z=1000?

Nereid
2005-Jan-16, 11:26 AM
ngeo,

Have you spent some time on Ned Wright&#39;s Cosmology tutorial (http://www.astro.ucla.edu/~wright/cosmolog.htm)? I think you&#39;ll find most of your questions are answered well there.

... the thickness of the decoupling surface as you said. I wonder what it means in miles, or meters (something I can understand).
Ned also has a cosmology calculator (http://www.astro.ucla.edu/~wright/CosmoCalc.html), which you can use to get the answer, in metres, to the thickness of the surface of last scattering. For example, taking the standard values for H0, OmegaM, and Omegavac, a z of 1089 gives an age of 378 kyears, and a comoving radial distance of 45.648 Gly; with a z of 894 (= 1089 - 195), the calculator gives 526 kyears and 45.504 Gly. Can you now work out the &#39;thickness&#39;, in metres?

Still I am uncomfortable with the description of a &#39;surface&#39; and a &#39;thickness&#39;. This implies that there is a shell which emits to an empty interior. But why would the shell remain intact with an &#39;empty space&#39; in the expanding interior? As the volume increased, would it not be reasonable for all the occupants of the expanding space to remain approximately where they were, becoming more widely spaced? This is why I am proposing an alternative scenario, in which the universe is an expanding field which creates pressure in its interior (within a limited volume) and matter in the form of spinning regions to absorb the pressure (energy). Absorption of the field&#39;s energy by matter reduces the expansion of the field in the regions of matter (gravitational fields). This is a continual, and periodic, process. Just inside its outer limit the field creates new matter. I believe this is the source of the CMB. The first matter created is in the form of protons and electrons (does this correspond to a plasma?).
Perhaps the best way to proceed is to drop back a dimension ... in the analogy I used (&#39;surface&#39; of last shouting), the ring (equivalent to the shell, in 3D) remains &#39;intact&#39; because there are shouts which haven&#39;t reached you yet (from people a very long way away) ... and this ring gets further and further away; the &#39;empty space&#39; is simply all the people who have stopped shouting AND whose last shout reached you some time ago.

Perhaps you could re-cast your alternative scenario into 2D? It might be easier to discuss.

I have a larger problem with the BB theory, and the WMAP abstract includes it: that is that there is a finite &#39;amount&#39; of mass-energy in the universe. The WMAP abstract says, "... the total mass-energy of the universe is Omega_tot = 1.02 +/- 0.02." Is this in fact a finite number, or is it a relative number? And what exactly does &#39;mass-energy&#39; refer to? Is it the total of matter (or its energy equivalent) and &#39;dark energy&#39;? There seem to be many different measuring units used to measure &#39;energy&#39;.
Ned&#39;s Relativity tutorial (http://www.astro.ucla.edu/~wright/relatvty.htm) is a good place to start (it&#39;s part of the cosmology tutorial) ... leave aside &#39;dark energy&#39; for the moment; if you need to dig deeper, click on some of the links at the bottom of page; GR isn&#39;t very easy to get your mind around.

Today it appears no one knows how to deal with &#39;dark energy&#39;.
And what an exciting time it is&#33; Please bear in mind that the typical timescale for major developments is about 30 years - in physics and astrophysics at least, but I suspect in most sciences.

ngeo
2005-Jan-16, 10:02 PM
Hi Nereid

I went to the pages you referred to but the problems I have with this BB-Inflation scenario still remain. The figures appear to show that the universe was a certain size at the &#39;time of last shouting&#39;, and it seems that the entire universe is included in the &#39;surface&#39; (&#39;volume&#39; as &#39;surface area&#39;). So to keep to your analogy, the people in the crowd would all be moving away from each other, those farthest away from the center of the crowd would be receding at close to the speed of sound, and their last &#39;shout&#39; would arrive red-shifted in various places. The size of the universe at the &#39;time of last shouting&#39; would appear to allow plenty of time for many more last &#39;shouts&#39; to be heard. This seems reasonable. However, in order for the Earth-received CMB to be almost identical from all regions, the people farthest away from the center of the crowd would have to be receding from the center at a speed greater than the speed of sound (unless we on Earth are in the exact center of the crowd), in which case it seems impossible to calculate the size of the universe at the &#39;time of last shouting&#39;, only the size of the universe from which we can receive the shout. And we receive the CMB as a specific blackbody pattern in a certain specific set of wavelengths, implying it was emitted by a certain specific number of &#39;people&#39; receding at a specific rate. This leads to the problem, how many people are there, even in the &#39;known&#39; universe? It seems to me that the BB-Inflation scenario is contradictory here. The omega factor appears to deal with whether the &#39;density&#39; of the universe will result in its recollapse, its continual acceleration, or its gradual slowing down without ever stopping. Density of what is not defined, and it appears that the &#39;density&#39; must be a relative number since if the density is close to 1 and the universe is expanding, you would always have to increase whatever is defined in order to keep up with the expansion. I have to assume the &#39;density&#39; is of something called &#39;mass-energy&#39; which I don&#39;t understand - correct me if I am wrong. (And in the BB-I scenario the closeness of omega to 1 is always treated as a miraculous - but chance - event. &#39;How did the universe ever manage to start off so close to 1?&#39;). But at the same time the BB-I scenario assumes there is a finite amount of mass-energy in the universe which was released in a large-scale quantum fluctuation over a specific period of time. Aside from the question of why the inflation stopped, given that only some of the shouting people are known, how does anyone know how much mass-energy was released? The BB scenario, which apparently doesn&#39;t work without inflation, also assumes that there was a finite amount of mass-energy infinitely bound at the time of the BB. Presumably this &#39;amount&#39; is &#39;all the known universe&#39;. I believe this assumption leads to a long period of confusion in physics and cosmology (longer than 30 years and counting). You have to create very complicated scenarios involving &#39;real&#39; and &#39;virtual&#39; particles, treating the results of relativistic collisions as revealing a very complex system requiring virtual &#39;fundamental&#39; particles that somehow ended up much simpler in the &#39;real&#39; world. Although I don&#39;t subscribe to the &#39;plasma&#39; non-BB or steady state, it seems to me that particle physics and cosmology have created a dogma based on circular arguments on which both depend. The attempt to unify all the forces of nature has not succeeded yet, and if a &#39;Higgs boson&#39; is &#39;found&#39; it will be as the interpretation of a mathematical formula created to &#39;find&#39; it. (I have to admit I don&#39;t speak Mathematese so I am only going by the English descriptions I have read.) A world in which most transactions take place in the &#39;virtual&#39; realm of the vacuum doesn&#39;t seem to &#39;real&#39; to me. When I started reading about the unification problems with BB-I (and particle physics) I wondered why someone wasn&#39;t taking an approach that asks what a universe driven by a single force would look like. It seemed that people were assigning &#39;forces&#39; to certain &#39;particles&#39; - for example, the &#39;force&#39; of gravity is a &#39;property&#39; of matter. But what if you turn that around as say &#39;matter&#39; is a manifestation of &#39;gravity&#39;? If it is clear that &#39;matter&#39; and &#39;energy&#39; are equivalent and indeed interchangeable, why does the universe have to begin with &#39;matter&#39; (or &#39;mass&#39;). Which leads to the question of just what &#39;energy&#39; is. Again it seems that energy is defined by its effect rather than its cause. A body has a certain quantity of &#39;energy&#39; - well, we could also say that a certain quantity of energy in a gravitational field is manifested as a &#39;body&#39;. Which comes first? So I tried to figure out a scenario in which &#39;matter&#39; arises from an &#39;energy&#39; field. Taking the various clues that the universe gives us - for example, that it appears to be expanding at least at the speed of light, that a &#39;gravitational field&#39; is a field in which rays of light are propagated curvilinearly, curving space-time, etc. - I came to the conclusion that energy is simply the ability to move - or to act. In the absence of anything to stop it, energy &#39;acts&#39; in all directions at the speed of light. Taking the Planck speed, and the Planck length as a radius, a &#39;Planck volume&#39; and a &#39;Planck surface area&#39; arise along with a &#39;Planck clock&#39;. After one tick of the &#39;Planck clock&#39; you have a volume equivalent to eight &#39;Planck volumes&#39; and four &#39;Planck surface areas&#39;. This seems to indicate that a &#39;Planck volume&#39; of energy has the ability to create eight copies of itself, and that every tick of the clock will increase the number of Planck copies by a power of 8. So after two ticks you would have 64, then 512, etc. It quickly becomes atronomically high. However, after two ticks you actually find only 27 &#39;Planck volume&#39; equivalents. So clearly something is going on. (What is it? I would like to know.) I wondered how the universe could absorb what to me seems to be a vast and increasing amount of &#39;surplus&#39; energy (even given that volume already increases in an acceleration). How could this energy be absorbed? Consider that no matter where you are in the universe, the universe is trying to expand into your location from every direction. How do you absorb this energy? I wondered whether spinning would absorb energy. The spin would have to be on the equivalent of three axes in order to absorb energy from every direction. What is strange (I laboriously drew these diagrams a few years ago) is that a point, on the surface of a sphere which is rotated simultaneously on the equivalent of three axes, never completes a &#39;full&#39; rotation even though it ends up where it started. There are eight possible combinations of spin but four are mirror images of the other four. There are only two patterns of motion, quite different, and each only completes a half rotation. So a point (of energy) arriving at the surface of a sphere rotating three-axially simultaneously at the same speed will take a path which leads it back to where it started from but without ever completing a full rotation. That to me is strange. It is like a &#39;half-spin&#39;. Curiously an electron has an &#39;intrinsic&#39; angular momentum (where did this &#39;intrinsic&#39; angular momentum come from) which is known as spin of 1/2. Somewhere along the line this all ties in to the electric and magnetic fields and I believe ties in to the nuclear force as well (are quarks really &#39;fundamental&#39; or simply relativistic creations?). &#39;Spin&#39; aside, as an energy-absorbing device a spinning sphere would make an energetic space &#39;stand still&#39;. An energetic &#39;particle&#39; (either external or internal) arriving at the surface of the sphere would find itself after one tick of the Planck clock back where it started. So in the spinning region space would not expand. A number of &#39;spin-points&#39; arising at specific intervals in the &#39;Planck evolution&#39; would each absorb the energy of the &#39;Planck volumes&#39; around them, space would not expand in their region, and if they were to transfer energy back and forth between them, they would be permanently bonded. Within the context of universal expansion, a non-expansionary field would be perceived as an inwardly attractive field - a &#39;gravitational field&#39;. The scenario becomes idle speculation at this point. How would various gravitational fields come into contact with other gravitational fields? I think that has something to do with the universe not being perfectly symmetrical, which is inherent in the universe.
The point is that the &#39;quantity&#39; of &#39;mass-energy- is not a finite quantity but a continually created phenomenon, leading to the miraculous omega factor, the expanding universe, and CMB from new matter constantly created at the edge of the &#39;known universe&#39;. There doesn&#39;t have to be a BB-I at all.

I should note that a theory called &#39;loop quantum gravity&#39; does in fact deal with an &#39;energized medium&#39;. Following a query I was sent an email from a LQG mathematical physicist which said:

"Fundamentally the dual role of space-time is as both "stage and actor." It is the "stage" on which everything else happens, but at the same time it is dynamical and hence "actor." This dual role was present even in classical general relativity: indeed it was *the* insight behind classical general relativity. Loop quantum gravity is faithful to this insight.

"In addition, there are speculations that loop quantum gravity, in addition to being a quantum theory of space-time, might also "automatically" include a theory of matter, so that matter arises from the quantum geometry of space-time itself. This
is only at the level of speculation. Nevertheless, it is in fact similar to your idea that space-time "is itself a kind of energized medium, which not only acts as a medium but also creates the phenomena that arise within it."

I think there have been recent breakthroughs regarding LQG, even to the point of creating the basis for a &#39;new quantum mechanics&#39;. I think it is worth studying if you understand Mathematese. My interest in it is that it bypasses the increasingly complex problems that particle physics and BB-I cosmology create, such as the &#39;dark energy&#39; problem.

Nereid
2005-Jan-20, 06:43 AM
That&#39;s an extremely long paragraph ngeo&#33; There are quite a number of different things all mixed up in it (assuming I understood it); to address it decently I&#39;ll have to take several passes.

So to keep to your analogy, the people in the crowd would all be moving away from each other, those farthest away from the center of the crowd would be receding at close to the speed of sound, and their last &#39;shout&#39; would arrive red-shifted in various places.
Yes; and the analogy breaks down rather quickly if you try to use it to understand all aspects of the CMBR.

Let&#39;s go back to what I introduced it for ... it was to show that the CMBR pervades the universe; at the same &#39;co-moving time&#39;, it will appear to be the same to all observers (just the main component, not the dipole or micro-K fluctuations).

If you apply the analogy to a universe (in 2D, not 3D), it breaks down in many ways. As you say, the further away the people are, the faster they are moving away from you (or so it seems; the &#39;raisin bread&#39; analogy helps get your mind around how all observers have the same perception). However, sound is not light; the &#39;speed of light&#39; is the same to ALL observers (Special Relativity). Worse, the &#39;moving away&#39; is an expansion of the universe, and if you crunch the numbers, you&#39;ll see that distant galaxies (say z ~3) are &#39;actually&#39; moving away from us &#39;now&#39; at several times the speed of light&#33; (IIRC, Ned Wright&#39;s website has a calculator that you can use to see how this &#39;speed&#39; relates to z and various cosmological parameters).

ngeo
2005-Jan-20, 03:47 PM
Hi Nereid,

I always find after I read what I write that it appears to be a jumbled mess. I usually take maybe five or six drafts to make something that follows. Anyway I will persevere.

You wrote that the CMBR "pervades" the universe. What do you mean by &#39;pervades&#39;? It seems to me the photons reaching Earth came from a specific source or combination of sources forming a blackbody radiator. If I understand the BB-Inflation scenario correctly, the source is the &#39;cosmic photosphere&#39; or &#39;surface of last scattering&#39;, the entire universe at a particular point in spacetime.

As I understand it, this particular point in spacetime did not last forever. It was a &#39;phase transition&#39; at a certain temperature when all emitted photons were no longer immediately absorbed by matter particles. This transition would take place at a specific point and would then be over. One minute, photons were all absorbed; the next minute, photons were free. They then moved through the universe being absorbed, re-emitted, etc. It is hard to believe that of all the photons continually reaching Earth, none has ever come into contact with another body, that they all arrive in pristine yet pervasive shape, representing the blackbody of the past universe. It seems more likely that they are the blackbody form of photons repeatedly absorbed and emitted in Compton scattering by every intervening body in the universe. Must there not have been some matter in the universe when the photons were freed? And ever since the alleged &#39;decoupling&#39;, photons have been emitted and absorbed everywhere in the universe, all the time, galaxies have been forming, etc. So the idea of the CMB representing a particular event at a particular point in spacetime sounds a little hazy to me.

You wrote, "distant galaxies (say z ~3) are &#39;actually&#39; moving away from us &#39;now&#39; at several times the speed of light&#33;" As I understand it, the only &#39;now&#39; in the universe is the &#39;now&#39; of the observer. I somewhat understand the spacetime expansion of the universe - this is what accounts for observed redshift of absorption lines, right? The pattern of photons emitted at high frequency, and absorbed at high frequency, are seen in a low frequency region of the spectrum. So a photon absorbed &#39;there&#39; at (e.g.) ten pulses per second is seen here as one pulse per second. So (e.g.) seconds &#39;here&#39; are ten times slower than seconds &#39;there&#39;. As I read Ned Wright&#39;s tutorial, he is saying that to travel the distance to &#39;there&#39; would take a speed several times the speed of light, not necessarily that the distant galaxies are actually &#39;moving away&#39; (which is your point, that the universe is expanding - but the universal expansion is a spacetime expansion, not just a spatial expansion. As I understand it, space without time doesn&#39;t mean much). Neither he nor anyone else knows how far away in space &#39;there&#39; is, because the &#39;time&#39; to get to &#39;there&#39; changes between &#39;here&#39; and &#39;there&#39;. He and everyone else is only extrapolating a distance from the apparent slowdown of frequency of absorption, which more accurately indicates the difference in &#39;time&#39; between &#39;here&#39; and &#39;there&#39;, not the distance. The distant galaxies are far away in &#39;time&#39;, but like us, in their &#39;time&#39; they are hardly moving at all. I note that there are many parameters pre-inserted in Ned&#39;s calculator.

In the tutorial, Ned says, for example, "This distance is much greater than the speed of light times the light travel time because the Universe has expanded by factors between 1 and 1+z=11 since the light did its traveling." When did the light &#39;do its travelling&#39;? Didn&#39;t it always do its travelling, ever since it was emitted? Doesn&#39;t he mean &#39;while the light has been travelling&#39;, or &#39;since the light was emitted&#39;? In which case, if the universe is expanding at different &#39;speeds&#39; in different regions, the light must have been travelling through regions that were expanding at different speeds, and the redshift we see is a cumulative redshift; or else the expansion&#39; of the regions through which the light was travelling is spacetime expansion, in which case time co-ordinates are &#39;expanding&#39; along with spatial co-ordinates, and we have no idea &#39;where&#39; the high redshift source is, nor how long it would take to get there.

Now I am really confused.

antoniseb
2005-Jan-20, 04:24 PM
Originally posted by ngeo@Jan 20 2005, 03:47 PM
You wrote that the CMBR "pervades" the universe. What do you mean by &#39;pervades&#39;? It seems to me the photons reaching Earth came from a specific source or combination of sources forming a blackbody radiator. If I understand the BB-Inflation scenario correctly, the source is the &#39;cosmic photosphere&#39; or &#39;surface of last scattering&#39;, the entire universe at a particular point in spacetime.
Hi ngeo,

Here&#39;s a way to think about it. The space where we are now, shortly after the "last scattering" was bathed in the ultra-violet light from the nearby surface of last scattering. If this was a hundred thousand years after the last scattering, that surface was a hundred thousand light years away.

As time went along, the place that we see as the surface of last scattering is increasingly far away, with all the space in between having already cooled off and ceased with the scattering. The longer we wait, the further away, and the faster the scattering wall is moving away from us, leading to increased redshifting of the CMBR, such that today, what we see is redshifted from the UV all the way down to microwaves.

In this way, there is no place in the universe which does not have CMBR photons flying through it. You ask whether all of those photons are untainted by interactions? No of course not, a small fraction have been repolarized, indicating that some have had interactions.

ngeo
2005-Jan-21, 03:49 AM
hi antoniseb,

You wrote of a surface &#39;nearby&#39; our region, which seems to mean an interior surface of a sphere. But as I read it, the photon decoupling supposedly took place throughout the whole volume of the universe, as the temperature dropped, so photons were scattered from all bodies of matter. That is why I have a problem with the word &#39;surface&#39; (and with the inflationary CMB interpretation). Why would there be a specific spherical interior surface from which photons scattered?

However if the photon decoupling did occur at a surface while the universe was expanding at a very high rate (inflation rate?) then you might see the high redshift, and the very high recessional rate would also reduce the emission spacetime by a huge factor, i.e. an emission in a relatively short time at the spacetime of emission would become a long time at our spacetime and wouldn&#39;t need such a thick surface. But still wouldn&#39;t that produce a constant redshift? Then the &#39;temperature&#39; idea would not be right - i.e. the idea that the &#39;temperature&#39; of the universe is constantly dropping.

But why would there be one specific &#39;surface&#39;, and why would that &#39;surface&#39; leave the rest of the universe behind? And - the inflationary question seems to be - how did the inflation stop? Would a drop in temperature cause inflation to come to a sudden end, according to the theory?

antoniseb
2005-Jan-21, 04:16 AM
Originally posted by ngeo@Jan 21 2005, 03:49 AM
as I read it, the photon decoupling supposedly took place throughout the whole volume of the universe, as the temperature dropped, so photons were scattered from all bodies of matter. That is why I have a problem with the word &#39;surface&#39; (and with the inflationary CMB interpretation). Why would there be a specific spherical interior surface from which photons scattered?
Hi ngeo,

I do not know what level of education you have, so perhaps I&#39;m aiming at the wrong level... but I will try again.

If the entire universe managed to cool off at exactly the same time in some Newtonian sense of what the same time is, at some point everything is cool enough to be transparent. But when we look in the distance, we are seeing things NOT as they are now, but as they were some time ago. Things one light year away, we see as they were a year ago. So, one year after the universe got transparent where we are, we can see one light year before we are stuck seeing the fog of hot plasma. After a thousand years, we see transparent space for a thousand lightyears before we see stuff so old that it is that plasma. At no actual time is there a wall. The appearance of the wall is because of time-of-flight of the photons coming from that distance. Now we see 13.7 billion light years to "the wall".

The above is something of a simplification of the actual story, since the universe did not cool identically all at once, but the idea is still valid.

Concerning why inflation ended, that&#39;s a completely different question for which there is no certain answer yet.

ngeo
2005-Jan-21, 06:43 AM
Thank you Antoniseb, that is a very clear description to me, lots to ponder. I have no formal scientific training, I am a writer and can only read English. I have been reading about relativity and quantum theories for about ten years, all with little understanding of the mathematical symbols.

Now I am wondering what part, if any, the decoupling might play in ending the inflation. Also how the universe clumped together instead of flying apart in the context of expansion, and whether this would cause reheating.

antoniseb
2005-Jan-21, 02:21 PM
Originally posted by ngeo@Jan 21 2005, 06:43 AM
Now I am wondering what part, if any, the decoupling might play in ending the inflation. Also how the universe clumped together instead of flying apart in the context of expansion, and whether this would cause reheating.
My understandin is that the main era of inflation was over in the first second, and the temperature cooled to free the CMBR at 380,000 years. I wouldn&#39;t think the two are related. It is possible that there was some "temperature" connection, in that there may be some nature of physics that allows inertia and the speed of light limit that only applies at temperatures below quadrillions of degrees. This is wild speculation, not closely connected to any current theory.

Things in the universe clumped together because they were co-moving, and gravity drew them together, and yes it caused an era of re-ionization which hasn&#39;t ended.

Nereid
2005-Jan-21, 02:26 PM
Originally posted by ngeo@Jan 21 2005, 06:43 AM
Now I am wondering what part, if any, the decoupling might play in ending the inflation. Also how the universe clumped together instead of flying apart in the context of expansion, and whether this would cause reheating.
Thanks for the clarification ngeo; it helps to know how comfortable you are (or not) with the math&#33;

There are a number of popular books on cosmology, many of which (deliberately) have no math in them. Also, being written by &#39;gurus&#39;, they &#39;get the physics right&#39; (at least at the time the books were written). You may have already read several of these, but from your questions I gather that they weren&#39;t entirely satisfactory in terms of helping you understand.

Would you mind letting us know which ones you&#39;ve read, which you found the most helpful, and what you found most difficult?

[Note to moderators: I suspect quite a few UT readers are in the same boat as ngeo; as the nature of their questions isn&#39;t &#39;alternatives to mainstream explanations of redshifts&#39;, rather &#39;Q&A&#39;, perhaps key posts here could be cut&pasted into a (new) thread in the Q&A section?]

Nereid
2005-Jan-21, 02:34 PM
Oops, didn&#39;t answer the question&#33;

There are many different &#39;inflation theories&#39; (hardly surprising, we have no direct &#39;channel&#39; to that era ... and even if we ever become able to detect the relict neutrinos, it won&#39;t improve things much), but as far as I know (AFAIK) in all of them, the inflationary era is long over by the time of photon-matter decoupling.

Clumping is due to gravity; some local &#39;over-densities&#39; were dense enough for (self-) gravity to be &#39;stronger&#39; than the &#39;expansion force&#39; (I&#39;m distorting things by writing this way, but my aim is to give you some kind of intuitive feel, not be 100% accurate).

ngeo
2005-Jan-21, 04:45 PM
Thanks again Antoniseb and Nereid,

I started reading &#39;physics&#39; about ten years ago mainly to find out whether there could be a scientific basis for morality (i.e. guidance in finding a good way to go). I read the Theory of Relativity by Einstein (the one published in 1927 I think), In Search of the Big Bang, and A Brief History of Time. I could understand the main points, both the Einstein and the Hawking books made sense in plain English, the Big Bang book lost me in speculative territory. I had problems accepting some of the concepts. Now having access to the internet I find many concepts are not written in stone. New evidence keeps pouring out of space. I realize &#39;physics&#39; as a field has grown so immense that it is literally all over the map, all fields come down to physics, and it seems impossible for anyone, even a dedicated expert, to cover all the ground. But I believe the universe can be understood, as its name implies, as a single unified system. I have hope because I believe eventually everything has to pass the test of mathematics (?). Now there is a forum for &#39;skeptics&#39; of &#39;mainstream&#39; theories, I wrote some of the problems I see and will keep looking there. One big problem is in the wide (and, I fear, political) dissemination of new hypotheses as new &#39;absolute truth&#39;, for example a Time magazine cover article (in 1999 I think, or around that time) "How the Universe will End". Doom by Big Crunch was replaced with Doom by Heat Death. Ouch. That will put a crimp in your sense of purpose.