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Quasar found 13 billion years away
[[Mod. note -- I apologise to the author and the s.a.r readership
for the week-long delay in posting this article, which arrived at my institution's mail system on Thu, 14 Jun 2007 13:59:45 +0200 but was mistakenly categorized as spam by an over-eager (and *not* user-configurable) spam filter. I just now discovered it when cleaning out the spam folder. I will try to do this more frequently in the future. If it's any consolation, computer support just sent around a message today that they're preparing to switch to a new spam filter... -- jt]] Kent Paul Dolan wrote: I don't see anything useful to be accomplished by trying to twist every new find at the limits of our current vision into some "counter-argument" to the Big Bang, though, as the OP persists in doing, despite the twisting given to each piece of evidence being promptly debunked. "Debunked" is an emotionally laden word. It is not unreasonable to point to a quasar in just 500 million years being too fast to believe. I quoted the original researcher saying the same. This is the obsessive behavior typical of those trying to square the circle or trisect the angle for lifetimes after it is proved impossible with standard tools of Euclidean geometry constructions. This is just polemic. Trying to obsessively establish what I consider the truth is a behavior I consider correct. I could argue that you compulsively try to establish the BB as the truth, but that would not lead the discussion anywhere. I think that a calm discussion without any emotional undertones is the best for exchanging points of view. So long as the cosmic microwave background radiation continues to shine, and it shows no sign of going away, the universe keeps testifying for all to understand: "I had a beginning, and in that beginning, things were different from today". Taking out that "beginning" words (In the beginning was the bang, and the bang cooled and created light... That sounds familiar and it is maybe the deep reason for my distaste of the BB theory) I asked a question concerning this, but apparently it got lost. It was basically this: What physical evidence we have that the CMB is not just radiation coming from a diluted hydrogen cloud whose mean temperature is 2.7K and whose radius is (say) 20 billion years? And if we were in the middle of such a HUGE cloud? And that would be just *one* of the explanations for the CMB that doesn't require a big bang or a "beginning". Why is this so hard for some people to accept? xanthian. Yes, why would that be so difficult to accept? jacob |
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Quasar found 13 billion years away
"jacob navia" wrote in message
... ..... Taking out that "beginning" words (In the beginning was the bang, and the bang cooled and created light... That sounds familiar and it is maybe the deep reason for my distaste of the BB theory) I asked a question concerning this, but apparently it got lost. It was basically this: What physical evidence we have that the CMB is not just radiation coming from a diluted hydrogen cloud whose mean temperature is 2.7K and whose radius is (say) 20 billion years? The evidence is the observed Hubble red shift. Take the cloud and divide it into thin spherical shells. We see some light from each shell but more distant shells are red shifted to a greater degree. If the cloud is at a uniform temperature, we should see the integral of the redshifted curves. Ned Wright produced a similar curve based on the CMBR being red shifted starlight to illustrate the problem: http://www.astro.ucla.edu/~wright/Stolmar_Errors.html And if we were in the middle of such a HUGE cloud? Yes, we would have to be at the centre, but the model only works if the temperature is proportional to the radius from us so that the redshifted temperature is 2.7K for all shells. The cloud has to have a spherically symmetric temperature profile with the lowest temperature of 0K at the centre, exactly where our galaxy is situated, but the temperature 13.7 billion light years away is 3000K. And that would be just *one* of the explanations for the CMB that doesn't require a big bang or a "beginning". Why is this so hard for some people to accept? xanthian. Yes, why would that be so difficult to accept? It is difficult to accept because there is no good explanation for how a cloud could maintain such a strange temperature profile without the gas at the centre being warmed to equilibrium, and personally I find the idea that the universe is centred on the Earth even more distasteful than a beginning with a homogenous and isotropic universe. On the other hand, the cooling of a dense cloud to the point where it becomes transparent at around 3000K is not unlike looking at the surface of the Sun where we see the outer surface of the opaque layers. That, the evolution of galaxy structures, the ages of stars, elemental abundances and the red shift itself all point to the same conclusion, the matter in the universe was denser and hotter in the past. Whether that implies a "beginning" in the classical sense is another matter until we can reconcile GR and QM but whether you find the idea distasteful or not will not change the nature of the universe, either it did or it didn't regardless of our opinions. George |
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Quasar found 13 billion years away
On Jun 23, 9:17 am, George Dishman wrote:
"jacob navia" wrote in message ... What physical evidence we have that the CMB is not just radiation coming from a diluted hydrogen cloud whose mean temperature is 2.7K I assume here the implied qualification: "post redshift" and whose radius is (say) 20 billion years? The evidence is the observed Hubble red shift. Take the cloud and divide it into thin spherical shells. We see some light from each shell but more distant shells are red shifted to a greater degree. If the cloud is at a uniform temperature, we should see the integral of the redshifted curves. Ned Wright produced a similar curve based on the CMBR being red shifted starlight to illustrate the problem: http://www.astro.ucla.edu/~wright/Stolmar_Errors.html And if we were in the middle of such a HUGE cloud? Yes, we would have to be at the centre, but the model only works if the temperature is proportional to the radius from us so that the redshifted temperature is 2.7K for all shells. Absolutely. This is the crux of the matter. The cloud has to have a spherically symmetric temperature profile And what is wrong with that? The same is true, in essence, within classical BB theory, for increasing z, no matter what cosmological parameters you choose. with the lowest temperature of 0K at the centre, Why? exactly where our galaxy is situated, but the temperature 13.7 billion light years away is 3000K. And that would be just *one* of the explanations for the CMB that doesn't require a big bang or a "beginning". Why is this so hard for some people to accept? xanthian. Yes, why would that be so difficult to accept? It is difficult to accept because there is no good explanation for how a cloud could maintain such a strange temperature profile without the gas at the centre being warmed to equilibrium, Expansion and accelerating expansion potentially account for that. Otherwise you are essentially re-introducing Olber's paradox at a lower EM frequency range. Incidentally, what, precisely, is the z/T relationship predicted by EFE? (I honestly don't remember) and personally I find the idea that the universe is centred on the Earth even more distasteful than a beginning with a homogenous and isotropic universe. AHA! Back to the foundations of natural philosophy, I am pleased to see! It has been pointed out (by prior authors) that Einstein's general principle (also attributed {by some} to Galileo), puts the cat amongst the pigeons in this respect. Stated pregeometrically, all bodies of ref. are equiv. for formulating general laws of nature. Hence coordinates centred around the observer are as good as any other. Thus, the pre-Copernican and Copernican approaches are equivalently valid in this relativistic respect. This is the "sting in the tail" of GR theory, and greater authors than me have made this point before. On the other hand, the cooling of a dense cloud to the point where it becomes transparent at around 3000K is not unlike looking at the surface of the Sun where we see the outer surface of the opaque layers. Agreed [snip] George Touchee, Chalky. |
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Quasar found 13 billion years away
Chalky wrote:
George Dishman wrote: The cloud has to have a spherically symmetric temperature profile And what is wrong with that? The same is true, in essence, within classical BB theory, for increasing z, no matter what cosmological parameters you choose. Because the diameter of the observable universe is larger than the radius of the observable universe, so unless they were once nearby one another [and inflation makes the math work that puts them "nearby enough"], the part in front of us hasn't yet had enough time (by half) to communicate to the part in back of us, "hey, let's all be _this_ temperature". That leaves sheer coincidence as the remaining mechanism for the observed smoothness of the CMBR, if past propinquity is denied, and scientists pretty much universally distrust coincidences of that ubiquity. xanthian. |
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Quasar found 13 billion years away
Thus spake Kent Paul Dolan
Chalky wrote: George Dishman wrote: The cloud has to have a spherically symmetric temperature profile And what is wrong with that? The same is true, in essence, within classical BB theory, for increasing z, no matter what cosmological parameters you choose. Because the diameter of the observable universe is larger than the radius of the observable universe, so unless they were once nearby one another [and inflation makes the math work that puts them "nearby enough"], the part in front of us hasn't yet had enough time (by half) to communicate to the part in back of us, "hey, let's all be _this_ temperature". That leaves sheer coincidence as the remaining mechanism for the observed smoothness of the CMBR, if past propinquity is denied, and scientists pretty much universally distrust coincidences of that ubiquity. One cannot draw definite conclusions about the predictions of a model of quantum gravity which we do not yet have. Regards -- Charles Francis moderator sci.physics.foundations. substitute charles for NotI to email |
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Quasar found 13 billion years away
On Jun 25, 2:05 pm, Chalky wrote:
On Jun 23, 9:17 am, George Dishman wrote: "jacob navia" wrote in message ... What physical evidence we have that the CMB is not just radiation coming from a diluted hydrogen cloud whose mean temperature is 2.7K I assume here the implied qualification: "post redshift" and whose radius is (say) 20 billion years? The evidence is the observed Hubble red shift. Take the cloud and divide it into thin spherical shells. We see some light from each shell but more distant shells are red shifted to a greater degree. If the cloud is at a uniform temperature, we should see the integral of the redshifted curves. Ned Wright produced a similar curve based on the CMBR being red shifted starlight to illustrate the problem: http://www.astro.ucla.edu/~wright/Stolmar_Errors.html And if we were in the middle of such a HUGE cloud? Yes, we would have to be at the centre, but the model only works if the temperature is proportional to the radius from us so that the redshifted temperature is 2.7K for all shells. Absolutely. This is the crux of the matter. The cloud has to have a spherically symmetric temperature profile And what is wrong with that? The same is true, in essence, within classical BB theory, for increasing z, no matter what cosmological parameters you choose. Hmmm.... Looked at simply, F is proportional to 1/r*r P=F/A (definition of pressure) hence P is proportional to 1/r*r*r*r but V is proportional to r*r*r, and PV=nRT (ideal gas law). Thus 1/r is proportional to T so, if r is proportional 1/(1+z), T is proportional to redshift. When 1+z~1000, T~3000 When 1+z~1, T~3 So, why wouldn't the thermal radiation from this known expanding cloud of hot transparent gas, after the surface of last scattering, produce, or, at least, contribute to, the observed CMB spectrum? If something re-absorbs that thermal radiation, why does it not simultaneously re-absorb the classically predicted CMBR, which we are taught was only released at this surface of last scattering? |
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Quasar found 13 billion years away
Chalky wrote:
So, why wouldn't the thermal radiation from this known expanding cloud of hot transparent gas, after the surface of last scattering, produce, or, at least, contribute to, the observed CMB spectrum? If something re-absorbs that thermal radiation, why does it not simultaneously re-absorb the classically predicted CMBR, which we are taught was only released at this surface of last scattering? Possibly because most of the universe mass/energy at 1+z~1000, T~3000 was 'dark matter/energy' at temperature Td in equilibrium ~T/Td with CMBR at that time just as it is now ~T/Td at 1+z~1, T~3 Richard [Mod. note: four generations of quoted articles snipped -- please do this yourself -- mjh] |
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Quasar found 13 billion years away
On Jun 26, 9:06 am, Kent Paul Dolan wrote:
Chalky wrote: George Dishman wrote: The cloud has to have a spherically symmetric temperature profile And what is wrong with that? The same is true, in essence, within classical BB theory, for increasing z, no matter what cosmological parameters you choose. Because the diameter of the observable universe is larger than the radius of the observable universe, This is a semantic argument not a physical one. It is true that the distance to the big bang is ~13.7 billion lyr in all directions, but this does not mean that the bb had a diameter of ~37.4 billion lyr, 13.7 billion yr ago. You have thus missed my real point, which is as follows: Closer to us than the surface of last scattering, we should 'see' successively closer shells of successively cooler gas, which should emit thermal radiation, according to temperature. However, if the temperature increases with redshift, and that radiation is, by definition, redshifted by that redshift, all successive shells should reinforce a black body 2.7K spectrum, when measured in the here and now. If we don't see that spectrum, why, not? And, since we do see that spectrum, why do we assume that it all came from z=1069 Chalky |
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Quasar found 13 billion years away
In article ,
Chalky wrote: Closer to us than the surface of last scattering, we should 'see' successively closer shells of successively cooler gas, which should emit thermal radiation, according to temperature. I don't really want to get involved in this argument, since I have to moderate it, but here's a hint: since this 'cooler gas', after the epoch of recombination, will be neutral atomic hydrogen, by what emission process will it 'emit thermal radiation'? At what rest-frame wavelength will the radiation appear? At what wavelength would we see it now? Martin -- Martin Hardcastle School of Physics, Astronomy and Mathematics, University of Hertfordshire, UK Please replace the xxx.xxx.xxx in the header with herts.ac.uk to mail me |
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Smoothing the Universe (was: Quasar found 13 billion years away)
Chalky wrote:
This is a semantic argument not a physical one. No, it's not. The argument is entirely a physical one. You don't see it because you are using a failing intuition for the problem. It is true that the distance to the big bang is ~13.7 billion lyr in all directions, but this does not mean that the bb had a diameter of ~37.4 billion lyr, 13.7 billion yr ago. That's not a useful argument, nor is it required. Try to be a bit more alert to the sheer simplicity of the situation. The light (and _any other_ form of signal) from the farthest observable universe, _by definition_, just reached _us_. The problem is spherically symmetrical. Thus, regardless of _anything_ happening in between, by sheer symmetry, the light from the farthest observable universe "in front of us" has _not_ yet had time to reach the farthest observable universe "in back of us". Elsewhere, you make arguments in terms of the ideal gas law, but those arguments fail for exactly the same reason: no mechanism exists, absent initial propinquity, for communicating to the farthest observable universe along one radius of the diameter "from here" the _gas pressure_ of the farthest observable universe along the opposite radius, so there is no reason for the two pressures to resemble one another _at all_, so any argument based on them being spherically symmetrical fails from the outset. The problem is perfectly general, for _any_ physical constant: you can't get the information that makes things smooth from one end of that diameter to the other end of that diameter in the existing lifetime of the observable (and thus from our point of view "communicating with us") universe, absent arguments that said diameter was at one time small enough that considerations of propinquity allowed that communication to occur and the observed smoothness of the resulting CMBR (or of anything _else_ you claim to be spherically symmetrical like the CMBR is) to be other than coincidental. Occam's razor then dismisses such claims of the CMBR being spherically symmetrical and smooth "by coincidence". Quantum valeat. xanthian. |
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