Cmb Definition and 252 Threads

I could not find an answer by checking the web. Could these perturbations originate from primordial black holes? What else?

JWST is detecting objects that would have been emitting light BEFORE the CMB. If so, their light has already passed us for eons, and we are now accelerating into their ancient photon-stream in the opposite direction of the original object, revealing faint and blurry images like the 'ultra-faint...

To be clear, I'm looking for the speed at which points in space were moving apart from one another in the universe as it existed 370000 years after the big bang, not the Hubble parameter (expansion rate) derived from our current distance within our current time. Thanks in advance!

I'm coming upon multiple definitions of what the universe size was at around 378 000 years after the big bang. Some say it was around 42 million ly across, some say it was much larger. Why am I asking this? I was thinking about the cosmic microwave background. If the universe was only 42...

A collaborative effort is yielding a Dark Matter picture of the universe from microwave (CMB) data collected by the Atacama Cosmology Telescope. Major sections of the sky have already been imaged. Those are shown in the image below as the red/blue speckled regions (from a University of Toronto...

Hello. I was wondering if there have been any further developments on the topic of B-modes in the CMB polarization since this 2015 paper? https://arxiv.org/abs/1502.00612 A Joint Analysis of BICEP2/Keck Array and Planck Data The above paper declares that... 'We find strong evidence for dust...

Does the polarization spectrum TE measured by the Planck and WMAP satellites show evidence for superhorizon fluctuations at low multipoles and are these evidence for pre-bigbang inflation?

Is it possible to estimate the number of hot and cold spots of average diameter of 1° in a full-sky map of the CMB?

The Wilkinson Microwave Anisotropy Probe (WMAP) measured temperature differences across the sky in the cosmic microwave background (CMB). See --->(Wikipedia: https://en.wikipedia.org/wiki/Wilkinson_Microwave_Anisotropy_Probe#Main_result) From these observations researchers concluded that the...

https://en.wikipedia.org/wiki/Wien's_displacement_law "Maxima differ according to parameterization ... Using the value 4 to solve the implicit equation yields the peak in the spectral radiance density function expressed in the parameter radiance per proportional bandwidth. (That is, the density...

Another noob relativity / cosmology question (although at least this time won't turn out to be a coding bug, as no code is involved...) AIUI, according to relativity, there is no privileged reference frame, and any inertial reference frame is as "correct" as any other. But... In practice, in...

I know for sure PICO will be measuring polarization anisotropies with high fidelity. In addition, the PICO science paper shows that it will make full-sky Compton-y maps but the plots are mostly limited to l=1000. Will PICO be able to measure kSZ temperature anisotropy at l=3000?

Hi,this one as my new guy post! Any news on the next generation satellite?NASA?

Hi. Could the original temperature of the cosmic microwave background be deduced without a theory of a cooling universe? I.e. if we didn't know that the universe started hotter than 3000K and cooled to below 3000K, would we be able to look at the CMB and say, "Yep, that was definitely...

Significance of https://arxiv.org/abs/2110.00120 ,also https://arxiv.org/abs/2109.11092 on CMB anomaly and holographic models? Support?Confirmation?Interpretation? Not my field,but striking!

An object moving through a fluid, such as the air, experiences a pressure drag caused by the difference in fluid pressure between the front and back surfaces of the object. Similarly, an object moving through a thermalized photon gas, such as the CMB, also experiences a drag. The cause in this...

I am still so totally confused about the ultimate source of the photons of the CMB. I am getting really confused by online sources, who are either not very clear, or seem to contradict each other. I feel like I have narrowed it down to two sources; 1. The early universe was full of high...

A photon often travels billions of years (Gyr) through the CMB photon gas (410 photons per cubic centimeter) to reach us. Does it travel freely? Let’s share our thoughts about this. For discussion purpose, let’s assume the photon has a wavelength of 500 nm, close to the peak of the solar...

Studies of the Cosmic Microwave Background shows that the Earth is moving roughly 380 km/s with respect to it towards the constellation Leo I think. Yet (I think) the Cosmological Principle and the Michelson-Morely experiments suggest there is no preferred reference frame in the universe --...

About 0.38 Myr after the Big Bang, the universe cooled to about 3,000 K and went through the recombination era. Electrons and protons combined to form neutral hydrogen atoms and the photons became free to travel through space. The freed photons can be considered as photon sources of a small...

Did some searches through these forums but didn't find this exact question. I'm sure it's already been asked, but I just missed it, my apologies. Please link. I’ll try and ask this question in 3 different ways, and maybe the idea behind it will become apparent. I know that semantics can really...

In cosmology, CMB tells a lot about which cosmological model can be acceptable or not. For instance we know that, whatever the cosmological model we use ##\theta_*## parameter will be always the same. Is there any other parameters that is listed in this picture is **model-independent** ?(i.e...

So as the hot plasma of a universe expanded it grew colder and at "recombination" it reached a state where it isn't opaque to em radiation any more unlike dense plasma which is. So we say this is the moment the CMB started. But this got me thinking, after recombination the matter was still some...

So, as I understand it, the photons from the microwave background were the result of photon decoupling. Now, if I remember correctly, because of the accelerated expansion of the universe, the diameter of the universe is not about 28 Gyr, but about 90 Gyr, the consequence of which is that there...

How do we know it;s redshift for certain? because unlike with stars the CMB doesn't have spectral lines nor other "similar" objects to compare to as it is everywhere and the same. From what I understand first came the theory and model of the Big bang, then Hubble saw that distant galaxies are...

Here is something that struck a note to me, they give the CMB radiation in it's frequency which is in Ghz as the name "microwave" implies and then they also give a temperature in Kelvin. But how can light aka EM radiation have a temperature? I thought only matter with mass can have a temperature...

From the density and the mass we can find the volume using d=m/v <=> v=0.06 m^3. Since we consider the astronaut a sphere we find his radius using V(sphere)=4/3*π*R^3 =>R=0.242m. Now we can calculate the surface area with the formula A=4πR^2=0.735m^2. The energy absorbed will be i suppose equal...

I have heard that results form CMB experiments show a suppression of power at large angular scales. Can someone explain what "suppression of power" means in laymen terms in this context?

This paper just came out with a new measurement of the Hubble constant based on the technique of gamma ray attenuation. The result is consistent with the lower (CMB-based) value. Interestingly, they also do a joint analysis of several non-CMB techniques (BAO+BBN+SN+γ-ray attenuation), and find...

As I understand it the fact the COBE measured the CMB to be a perfect black body implies strong evidence for the hot big bang. However, I am wondering what was the earliest prediction that this must be so from big bang cosmology? Does it go all the way back to Gamov and Alpher? is it older ...

Hello. http://www.jb.man.ac.uk/distance/frontiers/cmb/node10.htm The above article refers to the CMB "wall" in sections 2.4.2 and 2.4.2.1. It's my current understanding that this wall prevents observation of the very early universe; i.e, earlier than 380,000 years after the Big Bang. I also...

The formula for the Damping Tail in the CMB BAO analysis generally has the form: $$\mathcal{D} (k)=\int_{0}^{\eta_0}\dot\tau e^{-\left[\frac {k}{k_D(\eta)} \right]^2}d\eta $$I can’t make sense of this. ##\dot\tau## is the Thompson (Differential) Opacity; the product of electron density, cross...

Recently, the origin of the cosmic microwave background as a relic radiation of the Big Bang was questioned and an idea of the CMB as thermal radiation of cosmic dust was revived and revisited. Under this theory, the temperature of the cosmic dust is predicted to be 2.776 K which differs from...

Hello, I often read that hot dark matter is constrained by structure formation issues. But I'm now wondering why it is not constrained by the CMB data itself because such hot dark matter should belong to radiation (with density evolving as 1/a^4 rather than 1/a^3) so for instance when we...

- The wavelength of light doesn't change at all in the galaxies because the space of the galaxies doesn't expand. - The wavelength of light should be different when it passes through the galaxy or not. However, this is contradictory to the observed result. So, the big bang theory is wrong.

Homework Statement What is the average energy of the CMB photons, in electronvolts, for ##T=2.73K##? Homework EquationsThe Attempt at a Solution I used the grand canonical ensemble for photons and after several calculations I get $$<E>=\frac{8\pi V}{c^3}\int_0^\infty \frac{h\nu^3}{e^{\beta h...

I am looking for a way to get, by a simple numerical computation, the 3 curves on the following figure: For this, I don't know what considering as abcissa (comoving distance ?, i.e ##D_{comoving} = R(t)r## with ##R(t)## scale factor and ##r## the coordinate which appears into FLRW...

This paper seems to claim, that there is found powerful observational evidence for some anomalies in the CMB that seems to suggest a conformal cyclic cosmology and so called Hawking points. As I understand it, it also claims, that these points, were present in the very early universe and that...

Very recently, Roger Penrose, along with Daniel An and Krzystztof Meissner, have submitted a new paper to PRL. In the new paper they present new empirical findings which support CCC. It doesn't seem to be out yet though, I can't find it anywhere, but I will place the link here when it is out...

This may seem like a naive or obvious question, which is why I posted it here. How do we know the cosmic microwave background came from the Big Bang? How can we tell how old radiation is?

Per Wikipedia (Outer Space) referencing Davies, P. C. W. (1977), "...the mean free path of a photon in intergalactic space is about 10E23 km, or 10 billion light years." Per Lawrence Krauss (1999), it is longer than the size of the visible universe. What is the current thinking about this?

Why is the vertical axis in the CMB power spectrum usually chosen as ##l(l+1)C_l/2\pi## instead of simply ##C_l## ? The only answer I found come from this post on stackexchange, but the answer doesn't seem very complete. Anyone knows ?

The CMB has already stretched from some 3000K to 3K, so 99.9% of all the possible stretching until asymptotically approaching absolute zero. Even if our telescope technology continues improving, with the ongoing expansion there may come a time in the future when the CMB temperature will be so...

I have been trying to understand some trechnical aspects of the Holmdel Horn Antenna used to first confirm CMB. My references are: (1) https://en.wikipedia.org/wiki/Antenna_gain (2) https://en.wikipedia.org/wiki/Isotropic_radiator (3)...

Is the pattern of temperature variation of the cosmic microwave background static, or does it vary over time?

Hi, I'm hoping someone can point me in the right direction please. I'm using the Planck 2015 CMB temperature (intensity) SMICA pipeline maps (Nside = 2048) and am trying to determine the temperature variance of each individual pixel. Variance and hit-count were provided with the 2013 CMB maps...

It may sound stupid but something bothers me and I want to ask This question come to my mind due to another thread, https://www.physicsforums.com/threads/entropy-and-derivations-is-my-logic-faulty.935533/page-2#post-5910474 In Friedmann Equation we are assuming that universe is homogeneous and...

From the basic definition of vacuum energy as being tied in with the Uncertainty principle, I would expect this not to include the Cosmic Background Radiation. Right? On the other hand, in figuring out (a) the Casimir effect, one attributes the force to the field between the plates carrying...

bapowell submitted a new PF Insights post A Poor Man's CMB Primer. Part 5: Quantum Seeds Continue reading the Original PF Insights Post.

Is there more to our universe than what we can observe? If so, does that mean that photons from the CMB are traveling towards us from beyond our cosmological horizon?