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Static Universe
On Apr 5, 7:03*am, Eric Gisse wrote:
On Apr 4, 12:12 pm, Thomas Smid wrote: Actual plasma physics can not explain the effect. I am suggesting that the redshift in an electric field is a new effect which only has not been discovered so far because it is so small that it would require electric field strengths of the order of the inner-atomic field to be observed in the lab. Electric field strengths on the order of what is inside an atom are responsible for the optical properties of matter. The simultaneous argument they are responsible for galactic redshift is... not credible. Charges in intergalactic space are distanced maybe about 1m i.e. 10^10 times further apart than in matter, so the electric field strength is a factor 10^-20 smaller. The point is that (as illustrated on my page http://www.plasmaphysics.org.uk/research/redshift.htm ) a typical photon length (as defined by the coherence time of the light wave) is much smaller than the distance between two charges in intergalactic space (about 10^-2 cm for starlight), so the 'photon' is more or less constantly immersed in an electric field for a very long time (whereas in matter the electric field is practically zero over the full length of the photon as all the charges cancel out at any time). Ok. How does it explain the Tolman surface brightness test (direct test of expansion vs other possibilities) As mentioned already, if the redshift not only increases the wavelength of the electromagnetic waves but also reduces their amplitude inversely proportionally (as suggested on page http://www.physicsmyths.org.uk/redshift.htm ), then this leads already to a decrease of the intensity proportional to z^-2 . If you furthermore take my theory for the photoelectric effect ( http://www.plasmaphysics.org.uk/photoionization.htm ) then there adds another factor z^-2 due to the fact that the photoionization efficiency is proportional to the square of the field strength (Eq. (8)), i.e. overall it is proportional to z^-4. So no expanding universe is needed to explain the observed surface brightnesses. and the multiple indirect observations of the CMB temperature at various redshifts? As far as I am concerned, the CMB temperature results are too uncertain to be conclusive. I mentioned this already in this group a couple of years ago (see the last entry in the thread https://groups.google.com/group/sci....f1fe05a8b80d4/ ). I just repeat this he I would consider the results presented in these papers as anything but accurate. Most of the measurements presented in the first paper (Srianand et al.) represent anyway only upper limits, and in addition they use the COBE measurement of the present temperature to constrain the data. Without the latter, one could fit the data virtually by any z-dependence, e.g. with a constant temperature of about 8 K. See for instance my adaption of the corresponding result from an earlier paper by Srianand et al. at http://www.plasmaphysics.org.uk/imgs/srianand.gif (where I have also added the actual error bars to the upper limits). The new publication merely adds two more data points which hardly manage to constrain the data any further (as they would both be consistent with a constant temperature at 8K as well (as are the results of the other reference)). So although the data don't rule out an increase of the excitation temperature with z, they can't confirm it either. This means the observed excitation might probably not be due to the CMB radiation field at all but due to other processes (e.g. collisional excitation by electrons) which simply may have been mis-modelled here. Thomas |
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Static Universe
On Apr 7, 9:06*am, Thomas Smid wrote:
On Apr 5, 7:03*am, Eric Gisse wrote: ... Ok. How does it explain the Tolman surface brightness test (direct test of expansion vs other possibilities) As mentioned already, if the redshift not only increases the wavelength of the electromagnetic waves but also reduces their amplitude inversely proportionally (as suggested on pagehttp://www.physicsmyths.org.uk/redshift.htm), then this leads already to a decrease of the intensity proportional to z^-2 . If you furthermore take my theory for the photoelectric effect (http://www.plasmaphysics.org.uk/photoionization.htm) then there adds another factor z^-2 due to the fact that the photoionization efficiency is proportional to the square of the field strength (Eq. (8)), i.e. overall it is proportional to z^-4. So no expanding universe is needed to explain the observed surface brightnesses. Actually, I noticed that my argument was not quite correct, as I did not take into account that the ionization time (Eq.(8) on that page) also contains the frequency nu which obviously will be inversely proportional to the redshift. Thus the intensity (which according to my theory is the inverse of the ionization time) would only go like z^-3 (or rather (z+1)^-3). Even though this is actually more consistent with observations than a (z+1)^-4 decrease (see http://en.wikipedia.org/wiki/Tolman_...rightness_test ) my equation also additionally contains the coherence time tau_c, and I can't find a stringent argument at the moment how this would be affected by the redshift. Bear with me until I have thought this issue through.again. Thomas |
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On Apr 7, 2:06*am, Thomas Smid wrote:
On Apr 5, 7:03*am, Eric Gisse wrote: On Apr 4, 12:12 pm, Thomas Smid wrote: Actual plasma physics can not explain the effect. I am suggesting that the redshift in an electric field is a new effect which only has not been discovered so far because it is so small that it would require electric field strengths of the order of the inner-atomic field to be observed in the lab. Electric field strengths on the order of what is inside an atom are responsible for the optical properties of matter. The simultaneous argument they are responsible for galactic redshift is... not credible. Charges in intergalactic space are distanced maybe about 1m *i.e. 10^10 times further apart than in matter, so the electric field strength is a factor 10^-20 smaller. Wow, you moved the goalpost 10^20 times further than I expected. You are aware that effects are not inversely proportional to field strengths, right? A weak electric field means the effects are weak, not strong. The point is that (as illustrated on my pagehttp://www.plasmaphysics.org.uk/research/redshift.htm) a typical photon length (as defined by the coherence time of the light wave) is much smaller than the distance between two charges in intergalactic space (about 10^-2 cm for starlight), so the 'photon' is more or less constantly immersed in an electric field for a very long time (whereas in matter the electric field is practically zero over the full length of the photon as all the charges cancel out at any time). That's now how it works, Thomas. Photons do not scatter or even interact with the fields, but rather the charges themselves. Further, effects do not 'cancel out' like you say. Example: literally any medium with optical properties. Ok. How does it explain the Tolman surface brightness test (direct test of expansion vs other possibilities) As mentioned already, if the redshift not only increases the wavelength of the electromagnetic waves but also reduces their amplitude inversely proportionally (as suggested on pagehttp://www.physicsmyths.org.uk/redshift.htm), then this leads already No. You have no theory that supports this, you are literally making it up as you go. to a decrease of the intensity proportional to z^-2 . If you furthermore take my theory for the photoelectric effect (http://www.plasmaphysics.org.uk/photoionization.htm) then there adds You do know that photons are quantum objects, and that semiclassical descriptions simply fail, right? another factor z^-2 due to the fact that the photoionization efficiency is proportional to the square of the field strength (Eq. (8)), i.e. overall it is proportional to z^-4. So no expanding universe is needed to explain the observed surface brightnesses. Except plasma scatters, it doesn't redshift light at every wavelength. There's nothing in the behavior of plasmas that justifies your claims. and the multiple indirect observations of the CMB temperature at various redshifts? As far as I am concerned, the CMB temperature results are too uncertain to be conclusive. Not going to mince here. Either you are lying or you do not know what you are talking about. The CMB was measured [Mularo, P. et. al, A&A 381, L64] to be T = 12.6 +1.7/-3.2 K via CII emissions in the quasar Q0347-3819, which has a redshift of z = 3.025. The uncertainty on that particular measurement is rather clear. Johnathan Thornburg gave you another reference, which you dismissed as you'll probably dismiss this one. I mentioned this already in this group a couple of years ago (see the last entry in the threadhttps://groups.google.com/group/sci.astro.research/browse_thread/thre... ). I just repeat this he I would consider the results presented in these papers as anything but accurate. Most of the measurements presented in the first paper (Srianand et al.) represent anyway only upper limits, and in addition http://www.astro.wisc.edu/~ewilcots/...6/srianand.pdf Temperature is between 6 and 14K, not an 'upper limit'. I know how to do a literature search, Thomas. Lying about the contents of the paper, or being so mistaken that you don't even know what they are, is a bad sign. they use the COBE measurement of the present temperature to constrain the data. Without the latter, one could fit the data virtually by any z-dependence, e.g. with a constant temperature of about 8 K. See for You don't know what you are talking about. The only COBE result used was the local temperature of the CMBR which has not changed meaningfully with the subsequent deployment of WMAP (and now Planck) along with its' 7 years of data releases. The errors in the measurement are primarily from the observations of the singly ionized Carbon lines rather than the local CMB temperature itself. Feel free to propagate the sources of error yourself. I'll hold your hand through the addition via quadrature if you need the help. instance my adaption of the corresponding result from an earlier paper by Srianand et al. athttp://www.plasmaphysics.org.uk/imgs/srianand.gif (where I have also added the actual error bars to the upper limits). The new publication merely adds two more data points which hardly manage to constrain the data any further (as they would both be consistent with a constant temperature at 8K as well (as are the results of the other reference)). This makes me question your ability to read scientific papers for comprehension. The figure you are looking at is irrelevant, as it is nothing more than a then-current sampling of efforts to determine the CMB at higher redshifts. They even explain this for those with reading disabilities: "Upper limits are previous measurements [3,8-10] using the same techniques as we did." The one result in there that has an upper and lower bound is the one DETERMINED WITHIN THAT PAPER. And given that the bound is relatively wide, it isn't a huge shocker that the data is consistent with 8K, that's what the bound 6K T_CMBR 14K *MEANS*. It is also consistent with 9.1K and 10K and everything else between 6 and 14K. Which, no matter how you slice it, means the CMB was warmer in the past. There's another two papers citing much tighter measurements of the CMB within *THIS VERY THREAD*, why don't you go read them? So although the data don't rule out an increase of the excitation temperature with z, they can't confirm it either. This means the observed excitation might probably not be due to the CMB radiation field at all but due to other processes (e.g. collisional excitation by electrons) which simply may have been mis-modelled here. Thomas Nobody has performed that modeling, nor has anybody raised a convincing argument as to why these results should not be believed. You are simply wishing and hoping, then arguing based on that. |
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On Apr 8, 8:47 am, Eric Gisse wrote:
On Apr 7, 2:06 am, Thomas Smid wrote: Charges in intergalactic space are distanced maybe about 1m i.e. 10^10 times further apart than in matter, so the electric field strength is a factor 10^-20 smaller. Wow, you moved the goalpost 10^20 times further than I expected. You are aware that effects are not inversely proportional to field strengths, right? A weak electric field means the effects are weak, not strong. You should read the second half of an argument as well (or better even the whole post) before you reply to it. The point is that (as illustrated on my pagehttp://www.plasmaphysics.org.uk/research/redshift.htm) a typical photon length (as defined by the coherence time of the light wave) is much smaller than the distance between two charges in intergalactic space (about 10^-2 cm for starlight), so the 'photon' is more or less constantly immersed in an electric field for a very long time (whereas in matter the electric field is practically zero over the full length of the photon as all the charges cancel out at any time). That's now how it works, Thomas. Photons do not scatter or even interact with the fields, but rather the charges themselves. How would you know? Are you omniscient? There is no physical law that would forbid this to happen. If particle physicists can propose photon- photon interactions, then I can propose photon-electric field interactions. Also, it would be strange if photons can interact with a gravitational field but not electromagnetic fields. Except plasma scatters, it doesn't redshift light at every wavelength. There's nothing in the behavior of plasmas that justifies your claims. The intergalactic plasma is not a normal plasma, but one where not only the wavelength but even the coherence length is much smaller than the distance between two charges in the plasma. This could lead to completely knew effects (e.g the redshift as suggested) The CMB was measured [Mularo, P. et. al, A&A 381, L64] to be T = 12.6 +1.7/-3.2 K via CII emissions in the quasar Q0347-3819, which has a redshift of z = 3.025. The uncertainty on that particular measurement is rather clear. Johnathan Thornburg gave you another reference, which you dismissed as you'll probably dismiss this one. Indeed, all these papers are based on very dubious if not non-sensical assumptions for the excitation processes. I dealt with this already a couple of years ago in a thread in the sci.astro group and I repeat it he QUOTE: The physical assumptions made in these papers are very much inappropriate and thus effectively invalidate the analysis: 1) There is no way that photoelectrons of around 10 eV could lose sufficient energy such as to end up with a kinetic temperature of around 10^-2 eV (100K) (as assumed in these papers). Due to the mass ratio of the electrons and neutrals, this would take more than 10^4 collisions, but in the meanwhile the electrons will have long recombined. To a certain extent this may be offset if the neutral density is several orders of magnitudes higher than the plasma density (which it is in many cases and presumably also here), but the point is that the recombination probability increases towards smaller energies like E^-1.2 (E^-1.7 for the recombination cross section (see http://www.plasmaphysics.org.uk/research/recrsect.htm ) and E^0.5 for the velocity; for more details see Eq.(A.2.17) in http://www.plasmaphysics.org.uk/papers/radscat2.htm ). So the recombination probability will steadily increase as the electron energy degrades, and the electrons will recombine way before the energy has decreased to 10^-2 eV. 2.) It is assumed in these papers that the fine-structure levels are populated according to a Boltzmann distribution. This would require that elastic collision time scales are shorter than the life time of the levels. Taking the values assumed here, the elastic collision time scale with neutrals would be about 10^10 sec. I am not familiar with the details of the transitions involved here, but it seems unlikely to me that the lifetime of the levels is any longer than this, even if the transitions are dipole-forbidden (in case of the Carbon transitions, which are electronic transitions, it would anyway only be electrons that could lead to an energy exchange as neutrals could not transfer enough energy due to the mass difference; this would make the collisional time scale even longer due to the smaller density of electrons). 3.) The figures used in the papers do in fact not add up at all: in Ge,J., Bechtold,J. and Black,J.H. , Ap.J. 474, 72 (1997) for instance, the H-ionization photon flux appropriate for the observation is given as about F= 10^8 ph/cm^2/sec . On the other hand, the neutral density is taken as N=10 cm^-3 and the electron density as n=10^-2 cm^-3. Over the ionization-recombination equilibrium condition F*Q(ion)*N = alpha*n^2 , one would thus obtain (using a photoionization cross section Q(ion)=10^-17 cm^2) a value for the recombination coefficient of alpha=10^-4 cm^3/sec which is a completely unfounded value (usually it is between 10^-8 - 10^-12 cm^3/ sec depending on the assumptions). END QUOTE I would consider the results presented in these papers as anything but accurate. Most of the measurements presented in the first paper (Srianand et al.) represent anyway only upper limits, and in addition http://www.astro.wisc.edu/~ewilcots/...6/srianand.pdf Temperature is between 6 and 14K, not an 'upper limit'. I know how to do a literature search, Thomas. Lying about the contents of the paper, or being so mistaken that you don't even know what they are, is a bad sign. Huh? Do you have a special 'Eric Gisse' version of the paper? Read again what I said and what is stated in the paper. Srianand has also a new publication http://adsabs.harvard.edu/abs/2008A%26A...482L..39S adding two points to the already mentioned z,T diagram, and, not surprisingly, these are also consistent with a constant temperature of 8K. they use the COBE measurement of the present temperature to constrain the data. Without the latter, one could fit the data virtually by any z-dependence, e.g. with a constant temperature of about 8 K. See for You don't know what you are talking about. The only COBE result used was the local temperature of the CMBR which has not changed meaningfully with the subsequent deployment of WMAP (and now Planck) along with its' 7 years of data releases. The errors in the measurement are primarily from the observations of the singly ionized Carbon lines rather than the local CMB temperature itself. Why did the authors not use the same technique to determine the local CMB temperature they used for the higher z-values? Did they fear it might be 8K as well? It is at least a scientifically very dubious method to add a data point obtained by different method to constrain other data that inconclusive on their own regarding the z-dependence. The one result in there that has an upper and lower bound is the one DETERMINED WITHIN THAT PAPER. One data point can't define a z-dependence. Neither can a number of data points with huge error bars. And given that the bound is relatively wide, it isn't a huge shocker that the data is consistent with 8K, that's what the bound 6K T_CMBR 14K *MEANS*. It is also consistent with 9.1K and 10K and everything else between 6 and 14K. Which, no matter how you slice it, means the CMB was warmer in the past. Or it means (more likely) that, as indicated above, the higher observed temperatures in the past have nothing to do with the CMB at all. In any case, it would be fraudulent to claim that they confirm a linear dependence with (z+1) (or any z-dependence for that matter). Thomas |
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On Apr 10, 11:33 am, Thomas Smid wrote:
On Apr 8, 8:47 am, Eric Gisse wrote: On Apr 7, 2:06 am, Thomas Smid wrote: Charges in intergalactic space are distanced maybe about 1m i.e. 10^10 times further apart than in matter, so the electric field strength is a factor 10^-20 smaller. Wow, you moved the goalpost 10^20 times further than I expected. You are aware that effects are not inversely proportional to field strengths, right? A weak electric field means the effects are weak, not strong. You should read the second half of an argument as well (or better even the whole post) before you reply to it. The point is that (as illustrated on my pagehttp://www.plasmaphysics.org.uk/research/redshift.htm) a typical photon length (as defined by the coherence time of the light wave) is much smaller than the distance between two charges in intergalactic space (about 10^-2 cm for starlight), so the 'photon' is more or less constantly immersed in an electric field for a very long time (whereas in matter the electric field is practically zero over the full length of the photon as all the charges cancel out at any time). That's now how it works, Thomas. Photons do not scatter or even interact with the fields, but rather the charges themselves. How would you know? Are you omniscient? There is no physical law that would forbid this to happen. If particle physicists can propose photon- photon interactions, then I can propose photon-electric field interactions. Also, it would be strange if photons can interact with a gravitational field but not electromagnetic fields. Contrary to the belief of many people on USENET, apparently including yourself, you can't just snap your fingers and have well established phenomena suddenly decide to do things it has never done before. Sure, photon-photon scattering has been observed. But the intensities required for that little move were a fair bit higher than the emptiness that is space. Plus photons are actual particles. Plus, photons are not observed to interact gravitationally. Making stuff up won't fly. Except plasma scatters, it doesn't redshift light at every wavelength. There's nothing in the behavior of plasmas that justifies your claims. The intergalactic plasma is not a normal plasma, but one where not Yes, it is magical plasma. only the wavelength but even the coherence length is much smaller than the distance between two charges in the plasma. This could lead to completely knew effects (e.g the redshift as suggested) Again - you can't just snap your fingers and have well studied phenomena start doing bizarre things. The CMB was measured [Mularo, P. et. al, A&A 381, L64] to be T = 12.6 +1.7/-3.2 K via CII emissions in the quasar Q0347-3819, which has a redshift of z = 3.025. The uncertainty on that particular measurement is rather clear. Johnathan Thornburg gave you another reference, which you dismissed as you'll probably dismiss this one. Indeed, all these papers are based on very dubious if not non-sensical assumptions for the excitation processes. Or, more likely, you don't like the result and don't understand the paper so you reject the result. I dealt with this already a couple of years ago in a thread in the sci.astro group and I repeat it he QUOTE: The physical assumptions made in these papers are very much inappropriate and thus effectively invalidate the analysis: 1) There is no way that photoelectrons of around 10 eV could lose sufficient energy such as to end up with a kinetic temperature of around 10^-2 eV (100K) (as assumed in these papers). Except electrons aren't the ones doing the work here. Read the paper. Due to the mass ratio of the electrons and neutrals, this would take more than 10^4 collisions, but in the meanwhile the electrons will have long recombined. Your point? Read the paper. The spectral lines are from absorption lines from neutral carbon. To a certain extent this may be offset if the neutral density is several orders of magnitudes higher than the plasma density Read the paper. That's specifically assumed. (which it is in many cases and presumably also here), but the point is that the recombination probability increases towards smaller energies like E^-1.2 (E^-1.7 for the recombination cross section (seehttp://www.plasmaphysics.org.uk/research/recrsect.htm) and E^0.5 for the velocity; for more details see Eq.(A.2.17) inhttp://www.plasmaphysics.org.uk/papers/radscat2.htm). So the recombination probability will steadily increase as the electron energy degrades, and the electrons will recombine way before the energy has decreased to 10^-2 eV. Since the primary assumption is that the field of carbon is overall neutral, I don't see what point you are making beyond that 'yes, the carbon gas WILL be neutral as the paper assumes'. 2.) It is assumed in these papers that the fine-structure levels are populated according to a Boltzmann distribution. This would require that elastic collision time scales are shorter than the life time of the levels. No such requirement exists. Do you have a short proof or a reference that justifies this? Taking the values assumed here, the elastic collision time scale with neutrals would be about 10^10 sec. I am not familiar with I'm rather curious to know how you pulled 10^10 sec for a characteristic collision time out of the air. the details of the transitions involved here, but it seems unlikely to me that the lifetime of the levels is any longer than this, even if the transitions are dipole-forbidden (in case of the Carbon transitions, which are electronic transitions, it would anyway only be electrons that could lead to an energy exchange as neutrals could not transfer enough energy due to the mass difference; this would make the collisional time scale even longer due to the smaller density of electrons). Read the paper. The fine structure of the ground state are not only spelled out for you, but are rather obviously not forbidden transitions. 3.) The figures used in the papers do in fact not add up at all: in Ge,J., Bechtold,J. and Black,J.H. , Ap.J. 474, 72 (1997) for instance, the H-ionization photon flux appropriate for the observation is given as about F= 10^8 ph/cm^2/sec . On the other hand, the neutral density is taken as N=10 cm^-3 and the electron density as n=10^-2 cm^-3. Over the ionization-recombination equilibrium condition F*Q(ion)*N = alpha*n^2 , one would thus obtain (using a photoionization cross section Q(ion)=10^-17 cm^2) a value for the recombination coefficient of alpha=10^-4 cm^3/sec which is a completely unfounded value (usually it is between 10^-8 - 10^-12 cm^3/ sec depending on the assumptions). What's your point? The citation's only relevance was an upper limit data point which you yourself argued wasn't all that useful. The quasar is a full 1 redshift unit away and is obviously not the same one, so I don't see the relevance. So I'm not going to sit and work through whether or notyour argument is even correct because it does no matter. END QUOTE I would consider the results presented in these papers as anything but accurate. Most of the measurements presented in the first paper (Srianand et al.) represent anyway only upper limits, and in addition http://www.astro.wisc.edu/~ewilcots/...6/srianand.pdf Temperature is between 6 and 14K, not an 'upper limit'. I know how to do a literature search, Thomas. Lying about the contents of the paper, or being so mistaken that you don't even know what they are, is a bad sign. Huh? Do you have a special 'Eric Gisse' version of the paper? Apparently the lens of 'reading for comprehension' colors mine differently than from what you see without that lens. You: "Most of the measurements presented in the first paper (Srianand et al.) represent anyway only upper limits" The actual paper: "...we find that T_CMBR (…z= 2.3371) is between 6.0 and 14 K. This is in accord with the temperature of 9.1 K predicted by hot Big Bang cosmology." Read again what I said and what is stated in the paper. Srianand has also a new publicationhttp://adsabs.harvard.edu/abs/2008A%26A...482L..39S adding two points to the already mentioned z,T diagram, and, not surprisingly, these are also consistent with a constant temperature of 8K. The (z,T) diagram compares observations of the CMB at DIFFERENT redshifts. Go ahead - draw a straight line of T = 8K through it. Doesn't fit anything except (Srianand et al.), and most certainly not the paper you just cited. You might note the much smaller error bars - things have come a good way in 11 years. So from what oriface, I find myself asking, are you continually pulling that 8 degree number? they use the COBE measurement of the present temperature to constrain the data. Without the latter, one could fit the data virtually by any z-dependence, e.g. with a constant temperature of about 8 K. See for You don't know what you are talking about. The only COBE result used was the local temperature of the CMBR which has not changed meaningfully with the subsequent deployment of WMAP (and now Planck) along with its' 7 years of data releases. The errors in the measurement are primarily from the observations of the singly ionized Carbon lines rather than the local CMB temperature itself. Why did the authors not use the same technique to determine the local CMB temperature they used for the higher z-values? Because there's no reason to. Did they fear it might be 8K as well? Yes, Thomas, that's exactly it. "They", whoever "they" are, are TERRIFIED that the true answer is a number you picked out of your ear. It is at least a scientifically very dubious method to add a data point obtained by different method to constrain other data that inconclusive on their own regarding the z-dependence. Fine, let's indulge your moment of idiocy. Pull off the z=0 data point. The remote CMB measurements are still in accord with theory - the only thing you don't have is a local anchoring data point for CMB fit for multiple redshifts. Which does absolutely nothing towards discrediting the result, but plenty for marginalizing your opinion on the matter. The one result in there that has an upper and lower bound is the one DETERMINED WITHIN THAT PAPER. One data point can't define a z-dependence. Neither can a number of data points with huge error bars. The 2000 version of Srianand has 9 data points, 8 of them being upper limits with 1 of them having a firm range which matches the predictions of the big bang theory. It'd help if you understood that the paper's primary scientific result was the measurement of the CMB, not an ancillary figure that had no other purpose than shine a light on contemporary results. Now 11 years later you can add at least two more data points from myself and Jonathan Thornburg which correspond to theory as well. Plus the one you threw in today. And given that the bound is relatively wide, it isn't a huge shocker that the data is consistent with 8K, that's what the bound 6K T_CMBR 14K *MEANS*. It is also consistent with 9.1K and 10K and everything else between 6 and 14K. Which, no matter how you slice it, means the CMB was warmer in the past. Or it means (more likely) that, as indicated above, the higher observed temperatures in the past have nothing to do with the CMB at all. In any case, it would be fraudulent to claim that they confirm a linear dependence with (z+1) (or any z-dependence for that matter). Thomas Why are you whining about this? The measurement of the CMB was the principle objective of the paper, and here you are STILL whining about some upper limits that are - quite frankly - irrelevant in 2011 given the multitude of other observations. |
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In article , Eric Gisse
writes: photons are not observed to interact gravitationally. Do you mean with each other or with external gravitational fields? If the latter, then of course they do---there is a whole field of astrophysics known as gravitational lensing. Of course, since photons are energy, they produce a gravitational field given by E=mc^2 and so photons can interact gravitationally with each other, though the effect is minute. Also, have a look at http://en.wikipedia.org/wiki/Geon_(physics) |
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On Apr 12, 12:24*am, Phillip Helbig---undress to reply
wrote: In article , Eric Gisse writes: photons are not observed to interact gravitationally. Do you mean with each other or with external gravitational fields? *If the latter, then of course they do---there is a whole field of astrophysics known as gravitational lensing. *Of course, since photons are energy, they produce a gravitational field given by E=mc^2 and so photons can interact gravitationally with each other, though the effect is minute. Also, have a look at * *http://en.wikipedia.org/wiki/Geon_(physics) None of this is new information to me. Except the E=mc^2 thing - that's just wrong, as photons are massless. Within the context of relativity (which is my default position) photons, to excellent approximation, merely travel along null geodesics which do not depend on the nature of the object traversing it. Remember our old friend the equivalence principle! Gravitational waves, for example, travel along null geodesics. As do photons. There's no interaction between the particles and the overall structure of spacetime. |
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On Tue, 12 Apr 11 07:24:49 GMT, Phillip Helbig wrote:
Eric Gisse writes: photons are not observed to interact gravitationally. Do you mean with each other or with external gravitational fields? If the latter, then of course they do---there is a whole field of astrophysics known as gravitational lensing. This just refers to their paths following null geodesics. Since the geodesics define local space, no interaction is required from the photon for it to follow the geodesics. Of course, since photons are energy, they produce a gravitational field given by E=mc^2 and so photons can interact gravitationally with each other, though the effect is minute. Not shown. No interaction with an in-flight photon has ever been demonstrated. Experiments like Wheeler's delayed choice, in fact show that the premise of in-flight photons is likely to be wrong. Even if it is true that energy produces a gravity field, there is no evidence that light manifests any energy in flight -- only at registration does it do so. Eric Flesch |
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Static Universe
On Apr 12, 6:09*am, Eric Flesch wrote:
On Tue, 12 Apr 11 07:24:49 GMT, Phillip Helbig wrote: Eric Gisse writes: photons are not observed to interact gravitationally. Do you mean with each other or with external gravitational fields? *If the latter, then of course they do---there is a whole field of astrophysics known as gravitational lensing. This just refers to their paths following null geodesics. *Since the geodesics define local space, no interaction is required from the photon for it to follow the geodesics. Of course, since photons are energy, they produce a gravitational field given by E=mc^2 and so photons can interact gravitationally with each other, though the effect is minute. Not shown. *No interaction with an in-flight photon has ever been demonstrated. *Experiments like Wheeler's delayed choice, in fact show that the premise of in-flight photons is likely to be wrong. *Even if it is true that energy produces a gravity field, there is no evidence that light manifests any energy in flight -- only at registration does it do so. Eric Flesch Not quite! http://www.slac.stanford.edu/exp/e144/e144.html Not that it is at all relevant to the thread or the concept of gravitation, but in-flight interactions have been seen. |
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Static Universe
In article , Eric Gisse
writes: On Apr 12, 12:24 am, Phillip Helbig---undress to reply wrote: In article , Eric Gisse writes: photons are not observed to interact gravitationally. Do you mean with each other or with external gravitational fields? If the latter, then of course they do---there is a whole field of astrophysics known as gravitational lensing. Of course, since photons are energy, they produce a gravitational field given by E=mc^2 and so photons can interact gravitationally with each other, though the effect is minute. Also, have a look at http://en.wikipedia.org/wiki/Geon_(physics) None of this is new information to me. Except the E=mc^2 thing - that's just wrong, as photons are massless. OK, but they do have energy and hence are the source of gravitational fields. Imagine a cavity with perfect mirrors on the inside. It contains more energy, has more inertia, creates a larger gravitational field if there are photons bouncing around inside. Within the context of relativity (which is my default position) photons, to excellent approximation, merely travel along null geodesics which do not depend on the nature of the object traversing it. Remember our old friend the equivalence principle! Gravitational waves, for example, travel along null geodesics. As do photons. There's no interaction between the particles and the overall structure of spacetime. Perhaps it is a question of definition, but the fact that the trajectory followed by a photon is the same as that of a massive particle (in the limit of small mass, so that its own gravitational field can be neglected) shows that they interact much as ordinary matter does. |
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