Cosmic background radiation - alternative proposal

[zforgetaboutit]

I've had this idea for years but never had a forum.

How do we know we aren't merely measuring the energy emitted by our sun's http://science.nasa.gov/ssl/pad/solar/images/heliosph.gif ?

 

[russ_watters]

We see the background radiation in every direction - not just in the direction of the sun.

 

[zforgetaboutit]

The solar wind contents http://science.nasa.gov/ssl/pad/solar/images/heliosph.gif are also in every direction, relative to where we've been making CBR measurements.

The http://science.nasa.gov/ssl/pad/solar/heliosph.htm consists of particles, ionized atoms from the solar corona, and fields, in particular magnetic fields. (see web link for details - zforgetaboutit)

 

[russ_watters]

Solar wind and cosmological background radiation are completely unrelated concepts.

 

[Janus]

Originally posted by zforgetaboutit
The solar wind contents http://science.nasa.gov/ssl/pad/solar/images/heliosph.gif are also in every direction, relative to where we've been making CBR measurements.

But, the Solar wind becomes more concentrated as you near the Sun, so if it were the source of the CBR, then the radiation we measure would become stronger as we started pointing our detectors near the Sun. This doesn't happen.

 

[zforgetaboutit]

Originally posted by russ_watters
Solar wind and cosmological background radiation are completely unrelated concepts.

They are related inasmuch as they may both contribute to the perceived temperature of the night time sky.

If the dust of nebulas is illuminated by solar radiation, then the particles of the solar wind could also be lit up by radiation from our Sun. If the nebulas emit IR radiation then so could the solar wind, also consisting of particles, for the same reason.

 

[zforgetaboutit]

Originally posted by Janus
But, the Solar wind becomes more concentrated as you near the Sun, so if it were the source of the CBR, then the radiation we measure would become stronger as we started pointing our detectors near the Sun. This doesn't happen.

Fair enough. Do you happen to have a web link which mentions this lack of change when the detector is pointed closer to the Sun in a non-trivial way?

 

[Hurkyl]

Solar wind would also, I imagine, be much warmer than the CBR.

 

[UltraPi1]

The CBR could be the result of an ongoing process. I.E The universe is incomplete and new material is still being created.

 

[Nereid]

Originally posted by zforgetaboutit
*SNIP
If the dust of nebulas is illuminated by solar radiation, then the particles of the solar wind could also be lit up by radiation from our Sun. If the nebulas emit IR radiation then so could the solar wind, also consisting of particles, for the same reason.

Before the COBE, WMAP, ACBAR, BOOMERANG, etc teams present results of their observations of the CMB, they must remove 'foreground' contributions to the microwave signal. For satellite observatories, there are two primary sources of such contributions (after purely instrumental effects are accounted for), the IR from solar system dust (which is also responsible for the 'zodiacal light'), and dust in the Milky Way.

http://lambda.gsfc.nasa.gov/product/map/pub_papers/firstyear/foregrounds/wmap_galaxy.pdf.

Among the difficulties that zforgetaboutit's idea would have to deal with are:
- the CMB has a near-perfect black-body spectrum; as Hurkyl said, it's very difficult to see why 'solar wind particles' should be so cold (~2.73K)
- whatever solar wind particles are, they would have an emission spectrum that differed from a black-body; for example, silicate, carbon-compound, etc bands
- AFAIK, the 'solar wind particles' are ions, mostly atomic ions; how could they give rise to microwave radiation?
- quite a few other stars have 'solar winds' much stronger than the Sun's, yet AFAIK none have a spectrum resembling the CMB
- ditto zodiacal dust

 

[zforgetaboutit]

Originally posted by Nereid
- AFAIK, the 'solar wind particles' are ions, mostly atomic ions; how could they give rise to microwave radiation?

I didn't read about solar wind ions as a microwave source but I haven't finished the paper yet (~40 pages).

Reasonable replies, so far. The link is a good read (from what little I can grasp). I quote from it:

In addition to the thermal emission from dust, above, there are various other ways in which dust can radiate at microwave wavelengths. These include electric dipole emission from spinning dust grains and magnetic dipole emission from thermally fluctuating dust grains (Erickson 1957; Draine & Lazarian 1999, 1998a,b). Emission from spinning dust can produce   -2 from 20-40 GHz. The high-frequency cut-off of spinning dust emission is due to the limited speed at which a dust grain can spin.

So thermal emission from dust can emit microwaves. We already agree on a possible heat source (the Sun). As a source of dust, how about whatever ablates from comets as they are heated by the Sun? Comet dust may be spread about quite a bit from their orbital plane, due to eons of buffeting by the solar wind and may inhabit a spherical shell by now. We may be looking through this shell when making our measurements

 

[russ_watters]

Originally posted by zforgetaboutit
Fair enough. Do you happen to have a web link which mentions this lack of change when the detector is pointed closer to the Sun in a non-trivial way?

[?] [?] Thats basic - its the reason we care about the cmb. Any single paragraph description of the cmb mentions its homogeneity. HERE is a good description which includes a map of the sky.

A map of the sky at microwave frequencies, showing that the CMB is almost completely the same in all directions.

 

[Nereid]

There's no doubt that comets 'shed' dust! That's what meteor showers are, the dust streams in the orbits of comets, intersecting the Earth. There's also no doubt that this - and other - dust can be detected; http://dorothy.as.arizona.edu/DSN/IRAS/iras.html#i.3 may have given us the first 'all-sky' observation of this dust. As they journeyed out of the solar system, the Voyager (1 and 2) and Pioneer (10 and 11) spacecraft also measured dust.

IIRC, the IRAS etc results are all pretty clear - there's far too little dust in the outer reaches of the solar system to generate an 'undetected' zodiacal signal. Further, if there was enough dust to generate non-thermal microwaves at frequencies where the CMB is strong, a) it wouldn't have such a perfect black-body spectrum, b) the thermal signal from the dust - at considerably higher temperature than ~3K - would be very obvious, and c) there'd be significant anisotropy, near the shock-front of the heliosphere (and no, the CMB dipole is in quite a different direction from where the Sun is going).

 

[Loren Booda]

The CMB includes small changes in temperature: 2.735 [+/-] .0001 K across the sky. These fluctuations are thus some 20,000,000-fold less than the Sun's blackbody temperature at ~5800 K. The magnitude and variation of the Sun's radiation easily masks the CMB patterns; I believe this is the reason that COBE and similar explorers have been purposely hidden by the Earth from the Sun. The measured CMB has been used to calculate the age of the universe at 13.7 billion years, no solar artifact.

 

[zforgetaboutit]

As a lay person not trained in thermodynamics nor radio, my overall understanding of the paper's details is poor.

They performed an awful lot of statistical analysis and necessary (they claim) data smoothing to arrive at their results. Unfortunately I'm not qualified enough to referee this but am naturally wary of too much fudging.

However, you know how you can view some "microwave pictures" of this subject, and they purport to show the relative uniformity of the CMB?

Well I'm taken aback at the recent long exposure deep field Hubble pics that show a high number of galaxies having a non-trivial angular size inhabiting the picture. It's like increase the sensor exposure time enough and the entire frame would be occupied by pictorially visible galaxies.

What "background" would there then be ... the emissions from all these galaxies in our line of sight, barely leaving room for "empty black" space? By the time you removed all the pixels containing radiation from galaxies (the foreground anomalies) there might not be any pixels left!

I'm suggesting, without being educated in the subject, the temperature would not reasonably be ~3K. This is what I expect if COBE was to zoom in on, say, the Andromeda Galaxy as opposed to an empty piece of sky. I don't expect them to roughly be the same.

I'm thinking if COBE et al also had a much longer exposure time available, there might be no uniformity to its measurements.

Can anybody yet say COBE's uniformity results would not drastically change because its exposure times are already long enough to make final conclusions?

 

[Nereid]

Indeed, the WMAP team found ~200 point sources in their results, and they corresponded very closely with the ~200 that they expected to find, based on the known spectrum of (radio) galaxies, observed in different wavelength regions. Do other galaxies also emit microwaves? Certainly. Can at least some of these other galaxies also be detected in the wavelength bands at which WMAP (and later Planck) observes? Almost certainly. Is the combined contribution of all galaxies' microwave emission going to be detected any time soon? No; it's far, far too faint.

Interestingly there are other signatures which can be investigated, e.g. Sunyaev-Zel'dovich effect, Sachs-Wolfe effect.

Bottom line: COBE, WMAP, ACBAR, BOOMERANG, DASI, ... have observed the CMB. While there will always be fine tuning to be done, there's no evidence of 'local' contributions to the observed microwave sky, other than those already detected and analysed.

 

[kingofjazz]

how quickly is the Milky Way relative to the cosmic background radiation?

I mean not the rotation-speed !

thank you

 

[Nereid]

Welcome to Physics Forums kingofjazz!

This APOD has a good, if outdated, summary. Since this was written (in 2001), a lot of work has gone into understanding this ~600km/s motion; http://cow.physics.wisc.edu/~ogelman/guide/gr8a/ is the favourite fall guy.

 

[zforgetaboutit]

Next ideas ...

1) What if the CMB is emitted by some aspect, or possibly side-effect, of black holes situated in the center of galaxies?
Example: matter falling into the black hole, accelerates, emits radiation which is absorbed by something... which radiates to something else ... etc. which finally emits microwaves at CMB wavelength.

There are galaxies in every direction (observed) so that could account for the uniformity.​

2. What if the solar wind loses velocity the further out it gets, and the particles slow down, exist as a particle cloud, and THEN are able to emit CMB because of interaction with cosmic rays, radiation from the Sun, or some other effect?

COBE would still be at the relative center of this weakly emitting soup, assuming the soup has, in its multi-billion year lifetime, expanded further than the Oort Cloud. We may not yet be able to "see" past the soup because our probes haven't gotten far enough yet.

Like, if you were underwater and you had a water detector, it would detect water in all directions! Cool water, to be sure, but evidence nonetheless of the "Big Sauna" which existed billions of years ago. :-)

Or your local solar system was inside a bright nebula. Everywhere you looked, you'd measure the radiation effects of local stars heating up the gas. That civilization might assume they were inside an illuminated cosmic "room" because everywhere they looked they saw this visible background haze. Having never left the nebula, instrumentation-wise, how could somebody propose, as an alternative idea worth exploring, that the nebula might be a local entity? The same objection would exist: "It's everywhere we've looked so obviously there is a 'room'". There's even a blue shift in the direction we are going (see APOD, below).

I looked at the APOD link - maybe it's Milky Way scale soup. That could account for the red shifts. I'd name the APOD pic the Great Yin-Yang.

Perhaps researchers could state "The uniformity of CMB measurement exists within our solar system - we don't know about further out, yet."​

3) Sidebar: if a single "particle" (of the class attributed to CMB) was heated to "big bang" temperatures, how long would it take for it to cool down to < CMB temperature, without outside interference?​

4) Sidebar: if the smallest collection of entities responsible for emitting the observed CMB were ideally contained in an isolation box, what does the current model predict about the long term (cosmological time scale, if necessary) observation of their emitted radiation? Asymptotically approaching some state, perhaps, but at what rate?​

5. Sidebar: maybe the CMB comes from radiation emitted when small-enough particles (or whatever) decay, after enough time has passed. Why uniform CMB? Because very old stuff really really far away is decaying all over the place.

I've read here, for example, about a proposed, natural, proton decay mode of 10^31 years, which is somewhat older than current models of the universe's age.​

We have the same chance of understanding the universe's origins as cartoon characters having the understanding that they were drawn by an artist.

But it's still interesting to try, and see how far we can get. Plus there's a lot of useful things we will discover on the way.

 

[jcsd]

The source of the CMBR must be very, very faraway (due to it's isotropy), certainly extragalactic; it also must be a single source of reasonably small size (due to it's homogenity), add to this the fact that ot is coming from all directions and the conventional big bang theory is really the only theory that can offer a reasonable explanation.

 

[Nereid]

Next ideas ...

1) What if the CMB is emitted by some aspect, or possibly side-effect, of black holes situated in the center of galaxies?
Example: matter falling into the black hole, accelerates, emits radiation which is absorbed by something... which radiates to something else ... etc. which finally emits microwaves at CMB wavelength.

There are galaxies in every direction (observed) so that could account for the uniformity.​

Wouldn't we then see much more of the CMB in the direction of the nearest BHs then (other than that at the centre of the Milky Way - too many other sources)? For example, a big increase towards the Andromeda nucleus, M87 and other big ellipticals in the Virgo cluster, ...

You would also have the problem of its spectrum - as I said earlier, it's a near-perfect black-body spectrum - how would something which gets emitted by galaxy nuclei at a wide range of distances make such a spectrum?

2. What if the solar wind loses velocity the further out it gets, and the particles slow down, exist as a particle cloud, and THEN are able to emit CMB because of interaction with cosmic rays, radiation from the Sun, or some other effect?​

Yes, indeed ... can you describe such an effect? Can you show that it will have a 2.73 K black-body spectrum? That it will not show variation related to the solar cycle and known CMEs? (AFAIK, the CMBR does NOT show an 11-year cycle, nor the echos of past giant flares and CMEs; so, any alternative explanation involving the Sun would have to show why well-observed solar variability doesn't show up in the CMBR).

COBE would still be at the relative center of this weakly emitting soup, assuming the soup has, in its multi-billion year lifetime, expanded further than the Oort Cloud. We may not yet be able to "see" past the soup because our probes haven't gotten far enough yet.

Like, if you were underwater and you had a water detector, it would detect water in all directions! Cool water, to be sure, but evidence nonetheless of the "Big Sauna" which existed billions of years ago. :-)

If that were the case, then the obvious Milky Way emissions would surely be masked! Alternatively, since we know lots of stars have far, far more powerful 'stellar' winds than the Sun's, wouldn't we see lots of CMBR-like point sources at the positions of these active stars? If you propose the CMBR orginates beyond the Oort cloud, then the equivalent for Alpha Cen would be clearly visible (AFAIK, there's no enhancement of the CMBR in that direction).

Or your local solar system was inside a bright nebula. Everywhere you looked, you'd measure the radiation effects of local stars heating up the gas. That civilization might assume they were inside an illuminated cosmic "room" because everywhere they looked they saw this visible background haze. Having never left the nebula, instrumentation-wise, how could somebody propose, as an alternative idea worth exploring, that the nebula might be a local entity? The same objection would exist: "It's everywhere we've looked so obviously there is a 'room'". There's even a blue shift in the direction we are going (see APOD, below).

Well, we are near the edge of an interstellar bubble, and we can measure the density of all kinds of things between ourselves and the edge of the Milky Way halo. So, if we're inside and can't see out, what are all the objects that we *do* see in the same microwave bands as the CMBR? If we can see out of the room (and the CMBR is like a translucent curtain around us), why can't we see the equivalents around other stars?

I looked at the APOD link - maybe it's Milky Way scale soup. That could account for the red shifts. I'd name the APOD pic the Great Yin-Yang.

You would have the small problem of explaining the apparent motion of the solar system wrt this MW 'soup' ... no, perhaps it's a big problem, because you then have to 'un-explain' all the high quality proper motion and radial velocity observations of the hundreds of thousands of MW stars!

Perhaps researchers could state "The uniformity of CMB measurement exists within our solar system - we don't know about further out, yet."

3) Sidebar: if a single "particle" (of the class attributed to CMB) was heated to "big bang" temperatures, how long would it take for it to cool down to < CMB temperature, without outside interference?​

Can you clarify? what is the 'BB temperature'? what do you mean by 'without outside interference'?

4) Sidebar: if the smallest collection of entities responsible for emitting the observed CMB were ideally contained in an isolation box, what does the current model predict about the long term (cosmological time scale, if necessary) observation of their emitted radiation? Asymptotically approaching some state, perhaps, but at what rate?​

The CMBR, in today's concordance cosmological models, is the surface of last scattering - photons that decoupled from matter when hydrogen atoms formed. In a sense, it's like the photosphere of the Sun. Since the radiation has decoupled, it is moving through the universe essentially unhindered, and in the future we will see that it has become colder.

BTW, did you know there was a very good observation a year or so ago which showed that the CMBR was hotter in the past? While the observational constraints weren't all that tight (it was a pretty difficult observation), the inferred ancient temperature was just what the concordance model predicts!

5. Sidebar: maybe the CMB comes from radiation emitted when small-enough particles (or whatever) decay, after enough time has passed. Why uniform CMB? Because very old stuff really really far away is decaying all over the place.​

Then why is the CMBR a black-body of temp ~2.73K? How do you explain the observed polarisation in the CMBR under this idea?

I've read here, for example, about a proposed, natural, proton decay mode of 10^31 years, which is somewhat older than current models of the universe's age.

IIRC, the current upper limit, from recent experiments, is ~10³⁵ years, for a variety of proposed decay modes. Again, your challenge is to show that such decays can produce EM with the observed characteristics of the CMBR.

We have the same chance of understanding the universe's origins as cartoon characters having the understanding that they were drawn by an artist.

This may be so, but such speculation has nothing whatever to do with science

 

[zforgetaboutit]

Wouldn't we then see much more of the CMB in the direction of the nearest BHs then (other than that at the centre of the Milky Way - too many other sources)? For example, a big increase towards the Andromeda nucleus, M87 and other big ellipticals in the Virgo cluster, ...

Let me address one rebuttal at a time.

As a result of your posting I just skimmed http://ernie.ecs.soton.ac.uk/opcit/cgi-bin/pdf?id=oai%3AarXiv%2Eorg%3Aastro%2Dph%2F9905257 as best I could and finally arrived at the Conclusions on page 27 where the authors state

With these handles on the cosmic signal, we find that the error bars on most cosmological parameters are degraded by less than a factor of two for our best-guess foreground model and by less than a factor of five in our most pessimistic scenario. (boldened characters by zforgetaboutit)[/color]

I was impressed with the paper's details, and the very difficult attempts to make sense of the apparently noisy data via COBE et al.

The sheer number of analytical assumptions that permit further progress is amazing, but you have to start some where.

So, as I (mis?)understand it, the results could be off by 2X or 5X, due to the complexities of foreground signal artifact removal. I realize the scope is cosmological here, but still - that's a lot of fudge factor, so far.

At the end of the parer they state

A large number of papers have now painted a rosy picture of the future of cosmology, with CMB experiments measuring cosmological parameters to unprecedented accuracy over the next decade. In this paper, we have tried quite hard to spoil this picture, using foreground models with hundreds of harmful parameters and pushing them to limits of physical plausibility and current constraints.

Although we have found that great care needs to be taken in the foreground removal phase of the data analysis to avoid potentially perilous pitfalls, we have failed to tarnish the overall picture with more than a few minor blemishes, degrading the accuracy on certain measurements by small factors. Although much work certainly remains to be done on the foreground problem, this is cause for cautious optimism.

Some other scientists think we should wait a little longer.

I'm prepared to accept I misunderstood this paper. Did I?

 

[zforgetaboutit]

AFAIK, the CMBR does NOT show an 11-year cycle, nor the echos of past giant flares and CMEs; so, any alternative explanation involving the Sun would have to show why well-observed solar variability doesn't show up in the CMBR

Maybe there is no correlation.

As for CME's (coronal mass ejections?) - maybe COBE et al weren't looking downwind at the CME's path, so there's no measurement one way or another? Did somebody actually try to do this during a CME?

There would be so much interference from the CME (as I understand from the aforementioned paper) that it would be a messy undertaking to subtract other CME artifacts from the observations.

 

[zforgetaboutit]

If we can see out of the room (and the CMBR is like a translucent curtain around us), why can't we see the equivalents around other stars?

Our local haze may prevent us from seeing more distant, and therefore less distinct, neighbor extrasolar hazes.

(speaking underwater) "Can you see any water over there a couple of Km away?"

"No, there's too much intervening water to know for sure."​

 

[zforgetaboutit]

You would have the small problem of explaining the apparent motion of the solar system wrt this MW 'soup' ... no, perhaps it's a big problem, because you then have to 'un-explain' all the high quality proper motion and radial velocity observations of the hundreds of thousands of MW stars!

In my proposals, there could still be red shifts in the indicated directions; they would be from different causes (BH's, soups, etc.), not necessarily restricted to Big Bang theories.

 

[zforgetaboutit]

Can you clarify? what is the 'BB temperature'? what do you mean by 'without outside interference'?

What "BB" are you referring to? I meant the 2.72K temperature.

By interference I mean the ideal container has no effect on the CMB emitters we are studying (apologies to Heisenberg), and additionally shields them from perturbation by the rest of the universe.

 

[zforgetaboutit]

While the observational constraints weren't all that tight (it was a pretty difficult observation), the inferred ancient temperature was just what the concordance model predicts!

Inferred is the operational word here. I'll bet it was fudged just enough to agree with the concordance model.

http://citebase.eprints.org/cgi-bin/citations?id=oai:arXiv.org:astro-ph/0306088 is an obvious example of concordance cosmological model fudging.

I'm not outright dismissing the results, but we have to be aware of the shadowy assumptions made to "make the data/theory fit".

I don't have a problem with this strategy, but I can't yet accept it as obvious fact either because of the fudging.

 

[zforgetaboutit]

Then why is the CMBR a black-body of temp ~2.73K? How do you explain the observed polarisation in the CMBR under this idea?

Help me here:

Black Body - An ideal body which would absorb all (and reflect none) of the radiation falling upon it. The spectral energy distribution of a black body is described by Planck's equation; the total rate of emission of radiant energy is proportional to the fourth power of the absolute temperature (Stefan-Boltzmann law).​

I don't understand the claim of the CMBR being a black body in the first place.

If we heat a black body and measure the total rate of emission radiation and it fits the law (as above), fine.

How does this relate to CMB being heated, and emission measurements being made in accordance with the law? Radiation being heated? By what? How? I don't understand what you mean. Dumb it down for me.

 

[zforgetaboutit]

Again, your challenge is to show that such decays can produce EM with the observed characteristics of the CMBR.

I'm unable to comply. Maybe I could also fudge it into concordance.

My points are just thought experiments by me, after all, emitted by my semi-plausible shotgun theory-generator.

 

[zforgetaboutit]

This may be so, but such speculation has nothing whatever to do with science

Yes it does, because it's a statement made by me based on my study of the physical world and its manifestations. Maybe not so with your science, Horatio.

When was the last time you created a Big Bang in the lab and witnessed/published the resulting isotropic CBR? Where's your fudge-free experimental data?

I think mathematical theorems are fudge-free, as long as you accept the total set of axioms.

You, and everybody else, don't have any such experiments to relate, and that's why these grand concepts are in the realm of cosmology - nobody can and ever will know why these things are the way they are, because there will never be, and never can be, an experiment to prove them. It's too fundamental. I'm all for the continuation of observation/discussion about them, however, to improve upon their models.