The cosmic microwave background (CMB) is the electromagnetic radiation in the microwave band which can be observed throughout the whole universe, not connected to any astronomical object. Its spectrum follows a very precise black-body radiation with a temperature of about 2.7 K.

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How do quantum fluctuations lead to overdense regions in the CMB?

I've read a lot of work about Inflation but yet to find a cogent description where someone explains exactly what 'quantum fluctuations' are and how they led to overdense regions in the CMB. I get the ...
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268 views

Has the cosmic alignment of Earth and the Solar System been explained (CMB anisotropy)

The Cosmic Microwave Background anisotropy is currently aligning Earth and the Solar System with the largest and earliest structure of the universe. Has this been explained yet? Or are the theories ...
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What are the latest findings on the topology and size of the universe?

The paper G. Aslanyan & A.V. Manohar, The Topology and Size of the Universe from the Cosmic Microwave Background, JCAP 06 (2012) 003, arXiv:1104.0015, uses the 7-year WMAP data. Has any ...
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Cosmological fluctuations: what is gaussian?

When we are speaking about gaussianity and non-gaussianity in a cosmological context, what is gaussian or non-gaussian in the CMB? What would a non gaussian CMB look like compared to a gaussian one? ...
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132 views

The CMB and the Hubble comoving radius

I have been thinking on this for a while and i don't get it. My point is, the comoving Hubble radius $(aH)^{-1}$ is the distance at wich the universe expansion begins to be superluminical. In an ...
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Is the fluctuation pattern of the Cosmic Microwave Background (CMB) identical in every location of the universe?

I know that the Cosmic Microwave Background (CMB) is the leftover radiation from the "surface of last scattering". Let's say an alien civilisation lives on andromeda or further away. Would they see ...
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Radiative equilibrium in orbit of a black hole

According to Life under a black sun, Miller's planet from Interstellar, with a time dilation factor of 60,000, should be heated to around 890C by blue-shifted cosmic background radiation. How they ...
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What would we observe as background on the sky if the big bang had never occurred?

The data we've received so far from satellites such as WMAP paints a near uniform distribution in intensity of the background radiation that we take as evidence that our universe had an origin, and ...
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Thomson scattering on the elections does not produce any circular polarization?

All references on CMB polarization has this statement as if it is a trivial fact. But I have to admit that I completely don't understand what this sentence is telling us.
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176 views

What does BICEP2's results tell us about gravitation waves and quantum gravity?

The BICEP2 results, unless I am mistaken, are a measurement of CMB polarization, i.e. photon polarization. That is, taken at face value they say nothing about gravity directly. Now, we can start to ...
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159 views

Connection between BAO und CMB Spectrum

I have a problem understanding the connection between the accoustic peaks in the CMB spectrum and the baryon oscillation picture. On the one hand it is stated, that the odd accoustic peaks (1,3,5..) ...
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Did Penzias and Wilson need such a large horn antenna to discover the CMB?

Penzias and Wilson discovered the 2.7K Cosmic Microwave Background (CMB) Radiation using a 6 meter horn antenna, along with a cryogenic low-noise detector measuring at 4 GHz: ...
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what is the radial extent of the last scattering “shell”?

At CMB recombination (z=1090), what is the radial extent of the last scattering "shell"? a) Delta(z) = .... b) Delta(comoving angular distance)= ....Mpc The WMAP first-year parameters give Delta(z) ...
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What do the $T, E, B$ in polarization spectra mean?

I was reading about CMB Polarization here. I know that $E$ and $B$ stand for E-mode and B-mode, but what does the $T$ mean? The author states that there are 3 observables: $T, E, B$ and six spectra: ...
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59 views

Are Cosmic Microwave Background (CMB) photons entangled?

Suppose we'd like to know whether two cosmic microwave background photons emitted from different parts of the sky have any quantum correlation with each other. We could measure polarization of two ...
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82 views

How do we get the power spectrum through the CMB?

How do we get the power spectrum through observing the CMB?
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376 views

BICEP2 and string theory

Can anybody elaborate on the implications of the BICEP2 result for string theory? The discussion here What experiment would disprove string theory? suggests that refuting string theory is rather ...
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83 views

Angles in cosmology

We have several definitions of distances in cosmology. Take angular diameter distance. $$d_A = a(t)\int \frac{dt}{a(t)}\;.$$ If an object has proper length $L$ then the angle $\theta$ it is seen at ...
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What speed should have an alone planet to have a habitable zone due to relic radiation?

What speed should have an alone planet to have a habitable zone due to relic radiation, without any star involvement? How much time the planet will be able to remain in the habitable zone before the ...
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calculation of mean energy value of CMB photons for recombination

I am interested in the calculation of the mean energy value of CMB (Cosmic Microwave Background) photons from which the recombination is performed. The subject on French Wikipedia says : ...
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Is there a direct/indirect detection for the homogeneity of the Universe?

I know that for mathematical simplicity the Universe is assumed to be isotropic and homogeneous (the cosmological principle). The isotropy of the universe, and correct me if I'm wrong, is confirmed ...
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35 views

Is the CMB Cold spot growing or shrinking?

What do we know about the nature of this region of the sky? is that region entirely devoid of galaxies? Could it be a bubble void, and we are simply unable to see the galaxies that are on the ...
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54 views

How will TV Noise look like If we remove the Cosmic Microwave Background?

People have been saying that a small amount of noises you see in the Analog TV is from the CMB and other devices. What if the CMB never existed and the TV never got affected by devices? (Maybe in ...
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The steady state theory, can it now be falsified on particle physics grounds, in addition to CMB data?

The steady state theory is no longer taken seriously by most physicists and the Big Bang theory is supported by an enormous amount of evidence, especially the CMB data. But from a quick scan through ...
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56 views

Units of angular power spectrum

I am not sure whether this question might be better suited for crossvalidated or stackoverflow, but I will give it a try here: I have a map of the full sky in in the healpix format, units are $\rm ...
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52 views

A physical understanding of the 2/3 in the Sachs-Wolfe effect

I am trying to develop an intuitive but quantitative understanding of the factor of 2/3 in the Sachs-Wolfe effect. I believe I have a picture that makes sense but it relies on one assumption I don't ...
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68 views

Meaning of $k$ in Sachs-Wolfe formula for angular power spectrum

I've seen the formula for the angular power spectrum of the CMB written as $$C_\ell = \frac2\pi \int\left|\Theta_\ell(k) \right|^2 k^2dk, $$ where $\Theta_\ell(k)$ is the temperature contrast at a ...
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CMB radiation and holography

If in principle someone have the exact data of the CMB of our universe and unlimited computability power, to what extent it is possible to determine how the universe should look like? Does it fully ...
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79 views

Weak gravitational lensing multispectral, multibackground correlations

My understanding of weak gravitational lensing is that it assumes random alignment distribution of galaxies in order to estimate statistical shear and convergences, which are used to estimate matter ...
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268 views

superhorizon mode and cmb

During the period of inflation, perturbations went out of the Hubble horizon (Hubble radius, R = 1/aH) because the Hubble radius was decreasing during that time. After inflation, the Hubble radius ...
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What is the relationship between the E mode polarisation of the CMB and the velocity of the primordial plasma precisely?

I understand that the CMB is polarised into E and B modes due to Thompson scattering in the primordial plasma of the early universe. Also, I understand that this polarisation is directly related to ...
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13 views

Scales In Inflationary Cosmology

In inflationary cosmology terminologies, what do the scale, scale invariance and scale dependence really mean? This is an excerpt from http://arxiv.org/pdf/astro-ph/0702170v3.pdf "In presenting ...
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23 views

Will CMB images change as technology progresses?

Will cosmic background radiation images change as technology progresses? Will they become more precise, so to speak? I am asking because the images gotten by Planck and WAMP differ greatly. Will the ...
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37 views

I need Resources on CMB Neutrinos

I am doing a research paper for upper level undergrad class on CMB neutrinos (C$\nu$B). I need papers that explain CMB Neutrinos from the ground up like the main theory behind the CMB Neutrinos and ...
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61 views

Size of the universe from CMB?

The CMB is almost 13.8 billion light years away in every direction so the diameter of the visible universe as we actually observe it is 27.6 billion light years, twice the distance light traveled over ...
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58 views

How is the first acoustic peak calculated in CMB?

I'm trying to work out the rudiments of the CMB power curve. Looking at the Plank results, we're given the sound horizon at recombination as $\theta = 1.04147\times 10^{-2}$ (radians). So the first ...
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42 views

CMB and Gibbs free energy

I was doing my homework and I have a doubt. I proved that if I have the radiation energy density $$u = \frac{U}{V} $$ and $$P = \frac{1}{3}u $$ Then the Gibbs free energy is 0. But, how can I to ...
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Implications of dark matter imprints on Cosmic Microwave Background Radiation?

Looking at this link, CMB Anisotropy, I have two questions regarding the possible creation and properties of dark matter: If dark matter has left it's imprint on the CMB, that to me, would imply ...
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Assuming the universe is finite, at some point, CMB should go away, right?

I'm not talking about gradual red-shifting, that happens slowly anyway, but with a universe of finite size, we should actually see Cosmic Background Radiation turn off in a sense, first at a point, ...
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Direction of CMB and magnetic fields?

Measurements show the CMB is warmer to the North. Could more photons coming from that direction of the sky, cause metals in the Earth to move in that particular direction? As the Earth orbits the ...
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What are the implications of the possibility that the BICEP2 results are caused by a self ordering scalar field transition?

I've found this interesting paper that mentions another possible way to interpret the recent BICEP2 results, and that hadn't been ruled out yet 1. As interesting as the possibility that the BICEP2 ...
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Is it reasonable to assume that de Sitter temperature will stop growing when it reaches equilibrium with the temperature of CMB?

Is it reasonable to assume that de Sitter temperature will stop growing when it reaches equilibrium with the temperature of CMB? Currently the de Sitter temperature (the temperature of the Universe's ...