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cmb has not proven to be evidence of a big bang... its hypothesized... and very far from proven. in fact its unlikely it is evidence of a big bang. in fact its unlikely the universe was ever created... it simply is. no beginning no end — Preceding unsigned comment added by Majorheadrush ( talk • contribs) 13:37, 30 August 2019 (UTC)
I think pictures like that would help improve the article, not to mention the readers' understanding of what is being described. -- TiagoTiago ( talk) 05:01, 27 September 2014 (UTC)
The lede states: "(Alternatively if spectral radiance is defined as dEλ/dλ then...". This is just wrong. That is, dE/dλ is NOT spectral radiance. The implied claim is also made that dE/dv can be called 'spectral radiance', which if I understand the terminology correctly is also wrong. It is technically correct, I think, to state "spectral radiance dE/dv peaks at ..." but dE/dv qualifies (clarifies) the term 'spectral radiance' - since it could be, for instance, photon count rather than energy which is 'peaking'. This is just slightly sloppy. Why not make it correct by describing the spectral radiance function which peaks? Alternatively, you could speak about the differential (or incremental) change in energy with frequency or wavelength having a maximum. Abitslow ( talk) 18:41, 30 December 2014 (UTC)
I would like to see a sentence on the flux in photons per second per area, and watts per square meter. 10 trillion photons per second per squared centimeter is stated at [1] but figure is rough. But most of what I look at so far are problems for students to solve and not a reliable source. Also is energy density more like 4.178×10-14? [2] Graeme Bartlett ( talk) 22:46, 18 January 2015 (UTC)
The American Physical Society says: June 1963: Discovery of the Cosmic Microwave Background, at http://www.aps.org/publications/apsnews/200207/history.cfm I assume the main article is correct. There are also claims that the discovery was made in 1965. It's obvious that there's widespread confusion about the date that the big bang theory was proposed (not on WP, but all over the web on "authoritative" sites), and when was, and by whom was, the expanding universe proposed: http://scitation.aip.org/content/aip/magazine/physicstoday/article/64/8/10.1063/PT.3.1194 But seems like the date of the discovery of the CMB should be more clear. In Wilson's Nobel lecture at http://www.nobelprize.org/nobel_prizes/physics/laureates/1978/wilson-lecture.pdf he gives dates of 1963 and 1965, and for 1964 only references the work of Doroshkevich and Novikov. So, is there a correct year of the discovery of the CMB? Bob Enyart, Denver KGOV radio host ( talk) 05:03, 26 February 2015 (UTC)
The first line of this article:
The cosmic microwave background (CMB) is the thermal radiation left over from the "Big Bang" of cosmology.
I think it's misleading. CMB is from the time of recombination, 300,000 years after the Big Bang, not from the Big Bang itself. How about changing it to "...thermal radiation left over from the time of recombination." 220.244.178.10 ( talk) 11:56, 6 April 2015 (UTC)
The graph of cosmic microwave background spectrum measured by the FIRAS instrument on the COBE labels the x-axis to be in terms of frequency, but it should be labeled in terms of wavenumber, since the units are 1/cm.
I edited the Image to reflect the changes as this also bothers me. In general I think it would be better to have a plot with the frequency but I don't have the data. I just have one question, how do I upload / reference correctly the changed image? — Preceding unsigned comment added by SourBitter ( talk • contribs) 07:14, 16 November 2022 (UTC)
These two edits by Wdanwatts [4], [5] suggest that galactic dust emission is responsible for large-scale features in the CMB. The second edit does have a more suitable source than the first edit did. However, the basic problem is that the article text and the sources are talking about two different things. The article is talking about the CMB temperature anisotropies, which have been measured to very high signal-to-noise on a wide range of angular scales and at many frequencies. The foreground (such as dust) contributions here are small away from the galactic plane, and are well understood. The temperature anisotropies are generated by primordial scalar density perturbations which evolve in a simple way to create the "acoustic peaks" in the CMB power spectrum. Where galactic dust becomes relevant is in looking for a different, much fainter signal in the CMB polarization. The pure-curl or "B-mode" component of the polarization is used to search for a possible signal of inflationary gravitational waves or "tensor perturbations". The very faint B-mode polarization signal has only recently been detected at all, and is now beginning to be measured with high signal to noise at multiple frequencies. It appears that dust does contribute most or all of the detected B-mode polarization signal, so there is no clear evidence for a detection of IGW. However, this simply isn't relevant to this section of the article, which is describing the much larger and very precisely measured temperature anisotropy signal. -- Amble ( talk) 01:57, 13 May 2015 (UTC)
The next-to-last paragraph of the lede begins with this: "Precise measurements of the CMB are critical to cosmology, since any proposed model of the universe must explain this radiation."
I would like to humbly point out that this is a subjective worldview claim. There's no such thing as a model which adequately "explains" every observed phenomenon; each model has its strengths and weaknesses. So the author is showing favoritism toward CMB and any model which explains it (at the expense of explaining certain other phenomena).
Admittedly this favoritism may reflect the Scientific Consensus on the subject, which is surely Wikipedia's intent. But at least we need not be dishonest that it's favoritism. The Scientific Consensus can be selective about which phenomena it says "must" be explained and which it does not.
QuartzMMN ( talk) 04:11, 29 June 2015 (UTC)
rare term but used among students
proto-photons has a second meaning - it is a theoretical not yet discovered particle supposedly contributing to gravity - this is a totally separate - not connected meaning— Preceding unsigned comment added by 2.84.220.197 ( talk • contribs)
[ask for more]
"tired light" is not lectically [as a word] the same as "tired photon" as you claimed, it would have been in Chinese: 累光子 - tired photon/not tired light. Also "tired" doesn't mean old, but yes Fritz Zwicky claimed that time plays a crucial role. By the way tired light is hypothetical, and the CMB - cosmic microwave background experimental fact.
旧 means old but also paleo-, a prefix in Japanese and Chinese - same character. Paleo- means that the photon was emitted in the past. Tired light means that hypothetically a photon emitted in the past, has been affected by the expansion of space-time. So these terms focus on different issues.
The timeline section appears to have been merged with this article by a single editor without discussion. To me it badly disrupts the flow of the article and should be moved back to the original location. What do you think? Praemonitus ( talk) 22:11, 1 April 2016 (UTC)
Someone has undone my edits twice today without adequately explaining why. Regarding the quote that they restored to the introduction, there were several problems with it. Firstly, it was not made clear that it was text taken from an external source. Second, that source is a non-free source. Third, it did not say anything that was not better expressed elsewhere in the introduction. Fourth, it did not fit in at all with the text surrounding it. Thus, it added nothing to the article, but was a copyright violation. This is supposed to be a free encyclopaedia, so using non-free text can only be done in certain situations. One key justification is that a free alternative is not available. That's clearly not the case here.
As for the other two edits the user objected to, they haven't yet indicated why. Perhaps they would do so here. 128.40.9.164 ( talk) 21:05, 29 November 2016 (UTC)
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The article currently states in the third paragraph of the introduction
"The photon energy of CMB photons is about 6.626534 × 10−4 eV."
Where does this value come from? I searched via both Google and Google Scholar but was unable to locate a source for this claim. -- Toshio Yamaguchi 10:13, 27 August 2017 (UTC)
The following Wikimedia Commons file used on this page has been nominated for speedy deletion:
You can see the reason for deletion at the file description page linked above. — Community Tech bot ( talk) 03:51, 7 August 2018 (UTC)
In the Cosmic microwave background#Microwave background observations this article mentions that the radiation is observed from satellites and telescopes in the Atacama desert in Chile and at the South Pole. However it does not explain to the reader why this is.
I think the section should have an intro paragraph briefly summarizing the reasons. I'm quoting here from the South Pole Telescope article - this text could be edited and trimmed down a little as an introductory motivational paragraph
It is easily adapted to include the reasons for observing in the dry Atacama desert and from above the atmosphere in satellites. If you have any thoughts do say - otherwise if there is no response after a few days, I will be WP:BOLD and add the para myself. Robert Walker ( talk) 16:09, 16 August 2018 (UTC)
References
The section -- 2600:1700:BFC2:A3E0:9DED:3F05:1D3E:333E ( talk) 15:37, 12 August 2019 (UTC)Relationship to the Big Bang has a sidebar that says it is ( or may be ) too technical for the average reader; It is nothing of the sort and I find it lacking some features of what may be correct only for an entire volume of work yet me — with no formal training in the subject — only what I can find on the internet — see only significant prior work by the reader is to be expected before it is an easy read; This subject is rapidly developing due to machines which have never here-to-fore existed yet archaic convention continues to rule and dominate efforts 2600:1700:BFC2:A3E0:9DED:3F05:1D3E:333E ( talk) 15:37, 12 August 2019 (UTC) there is nothing complex that needs to be kept from view as the work is not such that just anybody with no prior work raises their hand while professionals are working
nicholas_jordan456 ••• I am not familiar with how to do wikki; I believe I am on a talk page and not making any edits
The article already has this: "Since decoupling, the temperature of the background radiation has dropped by a factor of roughly 1100[52] due to the expansion of the universe. As the universe expands, the CMB photons are redshifted, causing them to decrease in energy. The temperature of this radiation stays inversely proportional to a parameter that describes the relative expansion of the universe over time, known as the scale length. The temperature Tr of the CMB as a function of redshift, z, can be shown to be proportional to the temperature of the CMB as observed in the present day (2.725 K or 0.2348 meV):[53] Tr = 2.725 ⋅ (1 + z) For details about the reasoning that the radiation is evidence for the Big Bang, see Cosmic background radiation of the Big Bang." So might it be helpful to add to the article a succinct statement, something to the effect of: "The cosmic microwave background has a redshift of z = 1089", or something like that? Thanks for your consideration! Bob Enyart, Denver KGOV radio host ( talk) 02:34, 27 December 2019 (UTC)
In my humble opinion, this is a very well written article. Chapeau! — Preceding unsigned comment added by Koitus~nlwiki ( talk • contribs) 13:10, 15 February 2020 (UTC)
I came to the article attempting to find the peak frequencies of the cosmic microwave background but have been unable to locate that information. I know that the peak frequency is 160.4 but do not know what the other three peak frequencies are. Does anyone here know?
CWatchman ( talk) 17:48, 16 September 2020 (UTC)
The main peak has a thermal 2.725 kelvin black body spectrum which peaks in the microwave range at a frequency of 160.4 GHz, corresponding to a wavelength of 1.9 mm.
CWatchman ( talk) 17:50, 16 September 2020 (UTC)
If the observer is close to the edge of the Universe, the CMB from that side should be blue shifted vs the CMB from the far side.
The graph of CMB we have puts the observer smack dab in the center of the Universe. It is more likely that all points in the Universe observe the same CMB. That means that CMB does not delineate the beginning of the Universe. GuildCompounder ( talk) 20:18, 31 October 2020 (UTC)
The article section titled "Timeline of prediction, discovery and interpretation" would seem to be somewhat redundant with the "History" section. I'm proposing that we merge it into the related Timeline of cosmological theories article where it likely would be more useful and relevant. Do you concur? Praemonitus ( talk) 16:49, 12 April 2021 (UTC)
The article should include an explanation of how high temperatures after the Big Bang due to quantum fluctuations resulted in higher mass densities of localities throughout the Universe. Something explaining that warmer areas are denser and cooler areas are more void-like would be good to include. ScientistBuilder ( talk) 19:21, 12 October 2021 (UTC)ScientistBuilder ScientistBuilder ( talk) 19:21, 12 October 2021 (UTC)
The maximum of the PVF (the time when it is most likely that a given CMB photon last scattered) is known quite precisely. The first-year WMAP results put the time at which P(t) has a maximum as 372,000 years.[58] This is often taken as the "time" at which the CMB formed. However, to figure out how long it took the photons and baryons to decouple, we need a measure of the width of the PVF. The WMAP team finds that the PVF is greater than half of its maximal value (the "full width at half maximum", or FWHM) over an interval of 115,000 years. By this measure, decoupling took place over roughly 115,000 years, and when it was complete, the universe was roughly 487,000 years old.
Perhaps my understanding is faulty, but wouldn't it be (mostly) complete after: 372,000 + (115,000/2) = 429,500 years? Praemonitus ( talk) 20:04, 22 October 2021 (UTC)
We are now at Keck/BICEP3, which is returning r < 0.036. The current section looks 7 years out of date.
Also, r is never defined.
2600:1700:C280:3FD0:F92F:79DA:1665:C1DF ( talk) 21:42, 6 December 2021 (UTC)
This article is missing a responses and criticism section 185.107.13.110 ( talk) 09:00, 24 April 2022 (UTC)
The map of the Cosmic Microwave Background from Planck was recently deleted from Commons due to "no permission". Is this image available under CC BY-SA (likely in a paper), or does it need to be uploaded locally as fair use? SevenSpheres ( talk) 23:02, 28 October 2022 (UTC)
The article mentions in the 1st line that the CMB "is" something in the Big Bang "Big Bang cosmology". While this is not technically wrong. It hides the fact that this is a theory. For a common reader, this is given as a fact. The citation made to support this, "Sunyaev, R. A. (1974)." uses the words "model" and "theory".
So I propose that the words "is theorized" be included in the 1st line of the article.
I understand that all of you have to "fight" flat-earthers all day trying to change significant articles. But this is not about that. I'm trying to explain to you, and the user, that you are over extending your theories to facts.
On the absolute, all understanding of reality is a theory. So the question is, when does the understanding stop being a "theory" and start being accepted as a fact.
I agree with:
And I even agree that the CMB characteristics correlate with the emissions at the 1st instances of the big bang.
Where I disagree with the most is that nothing else in the known or unknown universe can generate emissions that can correlate with the big bang. While the big bang existence is an objective truth, the idea that the entirety of the universe started with it is not an objective truth. It is a theory.
It is an objective truth that everything we can observe was created with the Big Bang. But we could just be "too small" to realize what is very far away. To my understanding, the idea that there was nothing "before" the Big Bang is the part that is not "objective truth". By all chance, It can be a localized thing in a very, very vast universe.
This idea that the CMB is a result of the Big Bang is a loop of self-supporting theories. For the CMB to be a result of the Big Bang, Space needs to be "limited" and fully created in the Big Bang. But then the CMB is used to prove that the Big bang created everything.
And again. I'm not saying that it's "probably" right. But it's not an objective truth on the same level of "the Big Bang happened".
As such, this is "theorized" and the user should read it on the 1st line in concordance with the 1st citation. Joao.cordeiro ( talk) 17:04, 7 January 2023 (UTC)
Complex, current, or controversial subjects may require many citations; others, few or none.There is no scientific controversy here. Moreover, the given source does support the sentence to which it is attached; it is not a reference full of speculation, but one that describes how predictions are made that agree with observations. XOR'easter ( talk) 13:20, 8 January 2023 (UTC)
Sorry but this is starting to read like a bunny trail argument. I think the main point should be that we're not 100% sure about what happened before the CMB appeared; but we're pretty certain that the CMB is there. At present, everything that happened beyond that apparent radiation shell is subject to modelling, whereas afterward we can observe it more directly. That's probably the main point we need to get across to most readers. The argument about what is theory and what is fact gets a bit circular. Praemonitus ( talk) 23:03, 9 January 2023 (UTC)
The Jasnky is a unit of spectral irradiance equivalent to 10−26 watts per square metre per Hertz. Thus the units MJy/sr on the vertical axis of the graph is a measure of spectral radiance, not intensity.
The article is suitably referenced, with inline citations. It has reliable sources, and any important or controversial material which is likely to be challenged is cited.At present the article does not meet the criteria for B-class assessment. -- Otr500 ( talk) 03:15, 28 February 2023 (UTC)
This is the
talk page for discussing improvements to the
Cosmic microwave background article. This is not a forum for general discussion of the article's subject. |
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Cosmic microwave background was one of the Natural sciences good articles, but it has been removed from the list. There are suggestions below for improving the article to meet the good article criteria. Once these issues have been addressed, the article can be renominated. Editors may also seek a reassessment of the decision if they believe there was a mistake. | |||||||||||||
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Current status: Delisted good article |
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A summary of this article appears in Big Bang. |
cmb has not proven to be evidence of a big bang... its hypothesized... and very far from proven. in fact its unlikely it is evidence of a big bang. in fact its unlikely the universe was ever created... it simply is. no beginning no end — Preceding unsigned comment added by Majorheadrush ( talk • contribs) 13:37, 30 August 2019 (UTC)
I think pictures like that would help improve the article, not to mention the readers' understanding of what is being described. -- TiagoTiago ( talk) 05:01, 27 September 2014 (UTC)
The lede states: "(Alternatively if spectral radiance is defined as dEλ/dλ then...". This is just wrong. That is, dE/dλ is NOT spectral radiance. The implied claim is also made that dE/dv can be called 'spectral radiance', which if I understand the terminology correctly is also wrong. It is technically correct, I think, to state "spectral radiance dE/dv peaks at ..." but dE/dv qualifies (clarifies) the term 'spectral radiance' - since it could be, for instance, photon count rather than energy which is 'peaking'. This is just slightly sloppy. Why not make it correct by describing the spectral radiance function which peaks? Alternatively, you could speak about the differential (or incremental) change in energy with frequency or wavelength having a maximum. Abitslow ( talk) 18:41, 30 December 2014 (UTC)
I would like to see a sentence on the flux in photons per second per area, and watts per square meter. 10 trillion photons per second per squared centimeter is stated at [1] but figure is rough. But most of what I look at so far are problems for students to solve and not a reliable source. Also is energy density more like 4.178×10-14? [2] Graeme Bartlett ( talk) 22:46, 18 January 2015 (UTC)
The American Physical Society says: June 1963: Discovery of the Cosmic Microwave Background, at http://www.aps.org/publications/apsnews/200207/history.cfm I assume the main article is correct. There are also claims that the discovery was made in 1965. It's obvious that there's widespread confusion about the date that the big bang theory was proposed (not on WP, but all over the web on "authoritative" sites), and when was, and by whom was, the expanding universe proposed: http://scitation.aip.org/content/aip/magazine/physicstoday/article/64/8/10.1063/PT.3.1194 But seems like the date of the discovery of the CMB should be more clear. In Wilson's Nobel lecture at http://www.nobelprize.org/nobel_prizes/physics/laureates/1978/wilson-lecture.pdf he gives dates of 1963 and 1965, and for 1964 only references the work of Doroshkevich and Novikov. So, is there a correct year of the discovery of the CMB? Bob Enyart, Denver KGOV radio host ( talk) 05:03, 26 February 2015 (UTC)
The first line of this article:
The cosmic microwave background (CMB) is the thermal radiation left over from the "Big Bang" of cosmology.
I think it's misleading. CMB is from the time of recombination, 300,000 years after the Big Bang, not from the Big Bang itself. How about changing it to "...thermal radiation left over from the time of recombination." 220.244.178.10 ( talk) 11:56, 6 April 2015 (UTC)
The graph of cosmic microwave background spectrum measured by the FIRAS instrument on the COBE labels the x-axis to be in terms of frequency, but it should be labeled in terms of wavenumber, since the units are 1/cm.
I edited the Image to reflect the changes as this also bothers me. In general I think it would be better to have a plot with the frequency but I don't have the data. I just have one question, how do I upload / reference correctly the changed image? — Preceding unsigned comment added by SourBitter ( talk • contribs) 07:14, 16 November 2022 (UTC)
These two edits by Wdanwatts [4], [5] suggest that galactic dust emission is responsible for large-scale features in the CMB. The second edit does have a more suitable source than the first edit did. However, the basic problem is that the article text and the sources are talking about two different things. The article is talking about the CMB temperature anisotropies, which have been measured to very high signal-to-noise on a wide range of angular scales and at many frequencies. The foreground (such as dust) contributions here are small away from the galactic plane, and are well understood. The temperature anisotropies are generated by primordial scalar density perturbations which evolve in a simple way to create the "acoustic peaks" in the CMB power spectrum. Where galactic dust becomes relevant is in looking for a different, much fainter signal in the CMB polarization. The pure-curl or "B-mode" component of the polarization is used to search for a possible signal of inflationary gravitational waves or "tensor perturbations". The very faint B-mode polarization signal has only recently been detected at all, and is now beginning to be measured with high signal to noise at multiple frequencies. It appears that dust does contribute most or all of the detected B-mode polarization signal, so there is no clear evidence for a detection of IGW. However, this simply isn't relevant to this section of the article, which is describing the much larger and very precisely measured temperature anisotropy signal. -- Amble ( talk) 01:57, 13 May 2015 (UTC)
The next-to-last paragraph of the lede begins with this: "Precise measurements of the CMB are critical to cosmology, since any proposed model of the universe must explain this radiation."
I would like to humbly point out that this is a subjective worldview claim. There's no such thing as a model which adequately "explains" every observed phenomenon; each model has its strengths and weaknesses. So the author is showing favoritism toward CMB and any model which explains it (at the expense of explaining certain other phenomena).
Admittedly this favoritism may reflect the Scientific Consensus on the subject, which is surely Wikipedia's intent. But at least we need not be dishonest that it's favoritism. The Scientific Consensus can be selective about which phenomena it says "must" be explained and which it does not.
QuartzMMN ( talk) 04:11, 29 June 2015 (UTC)
rare term but used among students
proto-photons has a second meaning - it is a theoretical not yet discovered particle supposedly contributing to gravity - this is a totally separate - not connected meaning— Preceding unsigned comment added by 2.84.220.197 ( talk • contribs)
[ask for more]
"tired light" is not lectically [as a word] the same as "tired photon" as you claimed, it would have been in Chinese: 累光子 - tired photon/not tired light. Also "tired" doesn't mean old, but yes Fritz Zwicky claimed that time plays a crucial role. By the way tired light is hypothetical, and the CMB - cosmic microwave background experimental fact.
旧 means old but also paleo-, a prefix in Japanese and Chinese - same character. Paleo- means that the photon was emitted in the past. Tired light means that hypothetically a photon emitted in the past, has been affected by the expansion of space-time. So these terms focus on different issues.
The timeline section appears to have been merged with this article by a single editor without discussion. To me it badly disrupts the flow of the article and should be moved back to the original location. What do you think? Praemonitus ( talk) 22:11, 1 April 2016 (UTC)
Someone has undone my edits twice today without adequately explaining why. Regarding the quote that they restored to the introduction, there were several problems with it. Firstly, it was not made clear that it was text taken from an external source. Second, that source is a non-free source. Third, it did not say anything that was not better expressed elsewhere in the introduction. Fourth, it did not fit in at all with the text surrounding it. Thus, it added nothing to the article, but was a copyright violation. This is supposed to be a free encyclopaedia, so using non-free text can only be done in certain situations. One key justification is that a free alternative is not available. That's clearly not the case here.
As for the other two edits the user objected to, they haven't yet indicated why. Perhaps they would do so here. 128.40.9.164 ( talk) 21:05, 29 November 2016 (UTC)
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The article currently states in the third paragraph of the introduction
"The photon energy of CMB photons is about 6.626534 × 10−4 eV."
Where does this value come from? I searched via both Google and Google Scholar but was unable to locate a source for this claim. -- Toshio Yamaguchi 10:13, 27 August 2017 (UTC)
The following Wikimedia Commons file used on this page has been nominated for speedy deletion:
You can see the reason for deletion at the file description page linked above. — Community Tech bot ( talk) 03:51, 7 August 2018 (UTC)
In the Cosmic microwave background#Microwave background observations this article mentions that the radiation is observed from satellites and telescopes in the Atacama desert in Chile and at the South Pole. However it does not explain to the reader why this is.
I think the section should have an intro paragraph briefly summarizing the reasons. I'm quoting here from the South Pole Telescope article - this text could be edited and trimmed down a little as an introductory motivational paragraph
It is easily adapted to include the reasons for observing in the dry Atacama desert and from above the atmosphere in satellites. If you have any thoughts do say - otherwise if there is no response after a few days, I will be WP:BOLD and add the para myself. Robert Walker ( talk) 16:09, 16 August 2018 (UTC)
References
The section -- 2600:1700:BFC2:A3E0:9DED:3F05:1D3E:333E ( talk) 15:37, 12 August 2019 (UTC)Relationship to the Big Bang has a sidebar that says it is ( or may be ) too technical for the average reader; It is nothing of the sort and I find it lacking some features of what may be correct only for an entire volume of work yet me — with no formal training in the subject — only what I can find on the internet — see only significant prior work by the reader is to be expected before it is an easy read; This subject is rapidly developing due to machines which have never here-to-fore existed yet archaic convention continues to rule and dominate efforts 2600:1700:BFC2:A3E0:9DED:3F05:1D3E:333E ( talk) 15:37, 12 August 2019 (UTC) there is nothing complex that needs to be kept from view as the work is not such that just anybody with no prior work raises their hand while professionals are working
nicholas_jordan456 ••• I am not familiar with how to do wikki; I believe I am on a talk page and not making any edits
The article already has this: "Since decoupling, the temperature of the background radiation has dropped by a factor of roughly 1100[52] due to the expansion of the universe. As the universe expands, the CMB photons are redshifted, causing them to decrease in energy. The temperature of this radiation stays inversely proportional to a parameter that describes the relative expansion of the universe over time, known as the scale length. The temperature Tr of the CMB as a function of redshift, z, can be shown to be proportional to the temperature of the CMB as observed in the present day (2.725 K or 0.2348 meV):[53] Tr = 2.725 ⋅ (1 + z) For details about the reasoning that the radiation is evidence for the Big Bang, see Cosmic background radiation of the Big Bang." So might it be helpful to add to the article a succinct statement, something to the effect of: "The cosmic microwave background has a redshift of z = 1089", or something like that? Thanks for your consideration! Bob Enyart, Denver KGOV radio host ( talk) 02:34, 27 December 2019 (UTC)
In my humble opinion, this is a very well written article. Chapeau! — Preceding unsigned comment added by Koitus~nlwiki ( talk • contribs) 13:10, 15 February 2020 (UTC)
I came to the article attempting to find the peak frequencies of the cosmic microwave background but have been unable to locate that information. I know that the peak frequency is 160.4 but do not know what the other three peak frequencies are. Does anyone here know?
CWatchman ( talk) 17:48, 16 September 2020 (UTC)
The main peak has a thermal 2.725 kelvin black body spectrum which peaks in the microwave range at a frequency of 160.4 GHz, corresponding to a wavelength of 1.9 mm.
CWatchman ( talk) 17:50, 16 September 2020 (UTC)
If the observer is close to the edge of the Universe, the CMB from that side should be blue shifted vs the CMB from the far side.
The graph of CMB we have puts the observer smack dab in the center of the Universe. It is more likely that all points in the Universe observe the same CMB. That means that CMB does not delineate the beginning of the Universe. GuildCompounder ( talk) 20:18, 31 October 2020 (UTC)
The article section titled "Timeline of prediction, discovery and interpretation" would seem to be somewhat redundant with the "History" section. I'm proposing that we merge it into the related Timeline of cosmological theories article where it likely would be more useful and relevant. Do you concur? Praemonitus ( talk) 16:49, 12 April 2021 (UTC)
The article should include an explanation of how high temperatures after the Big Bang due to quantum fluctuations resulted in higher mass densities of localities throughout the Universe. Something explaining that warmer areas are denser and cooler areas are more void-like would be good to include. ScientistBuilder ( talk) 19:21, 12 October 2021 (UTC)ScientistBuilder ScientistBuilder ( talk) 19:21, 12 October 2021 (UTC)
The maximum of the PVF (the time when it is most likely that a given CMB photon last scattered) is known quite precisely. The first-year WMAP results put the time at which P(t) has a maximum as 372,000 years.[58] This is often taken as the "time" at which the CMB formed. However, to figure out how long it took the photons and baryons to decouple, we need a measure of the width of the PVF. The WMAP team finds that the PVF is greater than half of its maximal value (the "full width at half maximum", or FWHM) over an interval of 115,000 years. By this measure, decoupling took place over roughly 115,000 years, and when it was complete, the universe was roughly 487,000 years old.
Perhaps my understanding is faulty, but wouldn't it be (mostly) complete after: 372,000 + (115,000/2) = 429,500 years? Praemonitus ( talk) 20:04, 22 October 2021 (UTC)
We are now at Keck/BICEP3, which is returning r < 0.036. The current section looks 7 years out of date.
Also, r is never defined.
2600:1700:C280:3FD0:F92F:79DA:1665:C1DF ( talk) 21:42, 6 December 2021 (UTC)
This article is missing a responses and criticism section 185.107.13.110 ( talk) 09:00, 24 April 2022 (UTC)
The map of the Cosmic Microwave Background from Planck was recently deleted from Commons due to "no permission". Is this image available under CC BY-SA (likely in a paper), or does it need to be uploaded locally as fair use? SevenSpheres ( talk) 23:02, 28 October 2022 (UTC)
The article mentions in the 1st line that the CMB "is" something in the Big Bang "Big Bang cosmology". While this is not technically wrong. It hides the fact that this is a theory. For a common reader, this is given as a fact. The citation made to support this, "Sunyaev, R. A. (1974)." uses the words "model" and "theory".
So I propose that the words "is theorized" be included in the 1st line of the article.
I understand that all of you have to "fight" flat-earthers all day trying to change significant articles. But this is not about that. I'm trying to explain to you, and the user, that you are over extending your theories to facts.
On the absolute, all understanding of reality is a theory. So the question is, when does the understanding stop being a "theory" and start being accepted as a fact.
I agree with:
And I even agree that the CMB characteristics correlate with the emissions at the 1st instances of the big bang.
Where I disagree with the most is that nothing else in the known or unknown universe can generate emissions that can correlate with the big bang. While the big bang existence is an objective truth, the idea that the entirety of the universe started with it is not an objective truth. It is a theory.
It is an objective truth that everything we can observe was created with the Big Bang. But we could just be "too small" to realize what is very far away. To my understanding, the idea that there was nothing "before" the Big Bang is the part that is not "objective truth". By all chance, It can be a localized thing in a very, very vast universe.
This idea that the CMB is a result of the Big Bang is a loop of self-supporting theories. For the CMB to be a result of the Big Bang, Space needs to be "limited" and fully created in the Big Bang. But then the CMB is used to prove that the Big bang created everything.
And again. I'm not saying that it's "probably" right. But it's not an objective truth on the same level of "the Big Bang happened".
As such, this is "theorized" and the user should read it on the 1st line in concordance with the 1st citation. Joao.cordeiro ( talk) 17:04, 7 January 2023 (UTC)
Complex, current, or controversial subjects may require many citations; others, few or none.There is no scientific controversy here. Moreover, the given source does support the sentence to which it is attached; it is not a reference full of speculation, but one that describes how predictions are made that agree with observations. XOR'easter ( talk) 13:20, 8 January 2023 (UTC)
Sorry but this is starting to read like a bunny trail argument. I think the main point should be that we're not 100% sure about what happened before the CMB appeared; but we're pretty certain that the CMB is there. At present, everything that happened beyond that apparent radiation shell is subject to modelling, whereas afterward we can observe it more directly. That's probably the main point we need to get across to most readers. The argument about what is theory and what is fact gets a bit circular. Praemonitus ( talk) 23:03, 9 January 2023 (UTC)
The Jasnky is a unit of spectral irradiance equivalent to 10−26 watts per square metre per Hertz. Thus the units MJy/sr on the vertical axis of the graph is a measure of spectral radiance, not intensity.
The article is suitably referenced, with inline citations. It has reliable sources, and any important or controversial material which is likely to be challenged is cited.At present the article does not meet the criteria for B-class assessment. -- Otr500 ( talk) 03:15, 28 February 2023 (UTC)