Cmb Definition and 252 Threads

Hello i have a question about cmb radiation.Cmb was release about 13.7 billion years ago and reach us from a point about 42 million light years.At the past were the age of the universe was smaller and the time that cmb release was smaller too,we were able to detect the cmb?I mean the cmb was...

Hi, CMB photons reaching our telescopes have traveled for over 13 billion years without interacting with anything. If I understand correctly, from the event of the photon emission, its wavefunction gradually spreads, encompassing more and more possible states for the photon, coexisting in...

This might be a silly question. But recently I got to know about CMB(cosmic microwave background) and this question is nagging me. During CMB , the universe was pretty small compared to now, so our current point of existence in space would have been very near the CMB, 13.7 bill yrs ago. So the...

I fully understand the representation of the set of waves that are either at full compression or full rarefaction at recombination, thus, yielding a CMB map. But at this time are there no waves that are intermediate, e.g. 50% of the way to full compression or full rarefaction. Why don't these...

The cosmic microwave background was a single event that happened literally everywhere in pretty much a single instance. That moment was in the past and is unchanging. What does change is the wavelength of the radiation as it travels through the expanding universe causing the wavelength to grow...

An interesting discussion at this conference here: http://physics.princeton.edu/cmb50/videos/20150612_session6_2.mp4 David Spergel said the next project should be to look for something called f and L or is is FNL? Can someone explain what this is and what its significance is? What did you guys...

I know that in physics we can change referance frame.The Newtonian Friedmann equation is ##H^2-{8πGp /3}={-k/a^2}## I know that this equation derived from CMB referance frame.Now can we change this referance frame ? (And If you can give me an article about this issue I will be very happy,I...

Homework Statement Energy density of radiation ##\rho_r = 8 \times 10^{-14} J m^{-3}## and energy density of matter ##\rho_m = 2.63 \times 10^{-10} J m^{-3}##. Baryon density parameter is ##\Omega_b = 0.04##. Temperature of CMB today is ##2.73 K##. Ionization energy of Hydrogen is ##13.6 eV##...

10 billion years ago, photons emitted at the surface of last scattering were being absorbed by whatever stuff was around. Those atoms would absorb those photons and release other photons, but these would not be primordial photons from the CMB anymore but photons emitted at a later time by the...

In Dodelson's "Modern Cosmology" on p.241 he states that the ##a_{lm}##-s -- for a given ##l##-- corresponding to a spherical harmonic expansion of the photon-temperature fluctuations, are drawn from the same probability distribution regardless of the value of ##m##. Dodelson does not explain...

Alan Guth mentioned in his lectures that to get the accurate linear relationship of Hubble's law, we need to subtract the velocity of the Earth with respect to the cosmic microwave background (CMB) when calculating the velocity of galaxies. Question 1: If space is expanding uniformly...

Hello everyone, As you can see, I am new on this forum. In my first thread, I decided to ask one very interesting question, maybe one of the most shocking questions which exist at this moment. We all know the data which have been provided of WMAP and Planck satellites, and what this data shows...

If particle horizon is the maximum distance we can see presently in the universe, how come we are able to see CMB? CMB is radiation from surface of last scattering happened at t~380k years. Suppose universe is expanding at a constant rate ( i.e. no acceleration), will we be able to see CMB...

According to the hot Big Bang model, about 380000 years after that violent explosion, the universe was transparent to radiation but before that moment photons were trapped in the soup of ionized plasma. And my question is how does the matter distribute in space before the photons decouple from...

Dealing with CMB, people sometimes refer to the shift parameter; R = \sqrt{\frac{\Omega^0_m}{\Omega^0_k}}sinh(\sqrt{\Omega^0_k}\int^{z_{dec}}_{0}{\frac{dz}{E(z)}}) I know that it is related to the position of the first acoustic peak, however, the amount is around 1.7. What does this mean?! does...

This paper, http://arxiv.org/abs/1503.03859, suggests a possible explanation for hemispherical anisotropy in the CMB based on non-commutative space time.

According to Wayne Hu here, http://background.uchicago.edu/~whu/intermediate/intermediate.html, the universe started hot and dense and then expanded and cooled. In the hot, dense conditions of the early universe, photons were tightly glued to matter. When the universe was about 300,000 years...

http://pdg.lbl.gov/2013/reviews/rpp2013-rev-cosmic-microwave-background.pdf Here one reads in sec. 26.2.4 that: However it states that a single Y_{lm} corresponds to angular variations of \theta \sim \pi /l. I am not getting these statements. Also I find it difficult to understand, since...

Don't kill me, but I have a problem understanding and answering a question of what it means to be moving towards/away from CMB rest frame. The CMB is a sphere around earth, and corresponds to the last scattering surface of the Universe. If we are moving with respect to it, doesn't that mean we...

Can someone help me understand what information we extract from such kind of figure? In fact the C_l^{TT} parameter gives us information on the amplitude of the temperature fluctuations \Delta T/T... However I don't understand why there is such a peak formation (1 very large, 2 smaller and 2...

Recently I watched a lecture on Anti-matter and the Standard Model... ...At one point Dr. Quinn, makes the statement that the CMB is the resulting energy left over from the annihilation of the matter and anti-matter which arose during cosmic inflation (leaving behind only one part in 30 million...

It is known that the dipole anisotropies of the CMB radiation, can give the relative velocity of the Earth with respect to the CMB "rest" frame... In first order, this is given by \beta \approx 1.2 \times 10^{-3} or u_{CMB} \approx 360 km/s . I have one question here: Why is the velocity given...

I'm having some trouble understand this correctly, so I was hoping someone could enlighten me a bit :) Okay, so in the early Universe most of the hydrogen and helium was formed, and then kept in equilibrium, and ionized via photons. So we have a plasma of baryonic matter, including dark matter...

I've been trying to understand the whole BICEP story. Here's what I think I understand so far: Inflation produces primordial gravitational waves. During recombination, photons decouple from matter and the CMB is formed. Propagating gravity waves stretch space in one direction and squeeze it in...

One of my friends majoring in physics with me was telling me that the CMB radiation was not "predicted," by the big bang cosmology, but was in fact a "post-diction," and that the range of values for temp. obtained by Penzias were in fact way off, 5K to 50K and that other "cosmologies," can more...

Do you think we will ever be able to create a simplified computer simulation of the universe using the cosmic microwave background as the initial state that would generate the true locations of galaxies or at least galaxy clusters, and then be able to find our own galaxy or galaxy cluster within...

Joe Silk is one of the co-authors. One expects large voids in the distribution of galaxies because of the cobwebby way dark and ordinary matter have condensed. A large void comparatively close by (within a few billion LY of us) could cool ancient background light passing thru on its way to us...

I hope that this will be a simple question, but I had difficulty finding an answer by searching. If the Cosmic Microwave Background radiation was radiated over 13 billion years ago, and we are able to see it now, then does this mean that the radius of the universe at that time must have been...

Hi, I have been doing a coarse lately and am currently studying refraction. And it got me thinking about refractions effects on the Cosmic Microwave Background. If the cmb is light from the early universe then I think it would be ridiculous to assume that this light has traveled through nothing...

A very basic question that is stalking me for more than 20 years. Every popular science cosmology book states: A variation in temperature in the CMB of 1 part in 100.000, and then, from place to place or even from point to point. And then the WMAP picture. Everywhere hot en cold spots...

Two papers went up today regarding infrared all sky surveys by WISE and 2MASS that affirm the CMB cold spot - http://arxiv.org/abs/1405.1555, A Supervoid Imprinting the Cold Spot in the Cosmic Microwave Background; http://arxiv.org/abs/1405.1566, Detection of a Supervoid Aligned with the Cold...

Hi guys, As you can probably tell this is my first post, so I thought I ask a question that I've had trouble getting my head round. I think I know the reason but I'm not a 100% certain. Why is it that we see the CMB radiation from every direction we look? I would really appreciate if...

Hi guys. Consider the mean occupation number and specific intensity of the CMB photons in the CMB frame as given by the blackbody formulas: ##\eta = \frac{1}{e^{h\nu/k_{B}T_0} - 1}## and ##I_{\nu} =\frac{2h\nu^3}{e^{h\nu/k_{B}T_0} - 1}## with ##T_0## the thermal bath temperature in the CMB...

Ok so I'm a bit confused as to how to attempt to answer this question? Describing its significance vs explaining its significance? Here is my attempt, please be ruthless when correcting me as I feel like there are some gaps in my knowledge and misconceptions I have: Where I put '/' I...

Thanks to GJ for pointing out these three links: http://backreaction.blogspot.ca/2013/10/quantum-gravity-in-cosmic-microwave.html Quantum Gravity in the Cosmic Microwave Background? http://www.nature.com/news/how-to-see-quantum-gravity-in-big-bang-traces-1.13834 How to see quantum...

I have been searching through some of the literature, as well as this forum - but I have not found a clear explanation on how exactly the B-modes in the CMB polarization pattern are caused by gravitational waves. I have seen Wayne Hu's pages ( see for instance...

The data points of the polarization of the CMB are a magnitude and an orientation that varies between 0° and 180°. What kind of mathematical field is that, not quite a vector field? Thanks for any help!

Consider any of the latest maps of the temperature fluctuations of the CMB. Such a map can be considered a 2 dimensional topographical map of the surface of a sphere, high points hotter, low points cooler. Consider the contours that divide such a map into the two regions, fluctuations hotter...

I had this question pop up while watching something: Was early CMBR still CMBR or was the M something else, possibly even visible light? Scouring wiki yielded the following: Since decoupling, the temperature of the background radiation has dropped by a factor of roughly 1,100 due to the...

Two papers on arxiv today, http://arxiv.org/abs/1312.0025 and http://arxiv.org/abs/1312.0275, propose to resolve a large part of the CMB anisotropies suggested by WMAP and Planck based on the Integrated Sachs-Wolfe effect. The authorship appears independent, the former group is from India, and...

So for my physics class, we are trying to find modern applications for different areas of research. I know the HST had a lot of help in the areas of breast cancer research and eye surgery but what are some applications for modern technology that have stemmed from cosmic microwave background...

Hi all! In Ruth Durrer's book "The Cosmic Microwave Background" there is this picture (Fig. 5.2 page 193) about the E and B mode of the CMB polarization: http://imageshack.us/photo/my-images/11/s7o6.png/ http://imageshack.us/photo/my-images/11/s7o6.png/ They represent the E and B...

What is the observed DM ratio in CMB ? Is there observational evidence for the DM ratio in the CMB? Other then the info-graph from Wikipedia which I was explained is based on the assumption of DM being the same total amount back then but the mass of relativistic particles was higher. Would...

Meissner et al just posted a paper where they see those circles in the high res. microwave sky of Planck. Who knows if this is real, or what it would mean if it were confirmed? Meissner has a followup paper in preparation with Penrose and others. Either way I think it's pretty interesting...

Hi all, I'd like to apologise in advance for the layman's terminology in the idea below. I'd be delighted to get any feedback/thoughts on whether CMB observations could be explained in this way. Could the universe have started as a giant black hole that reached a critical mass and collapsed...

The furthest away (back in time) we can see is the CMB. This was the surface of last scatter, the surface of a hot gas bubble which due to redshift appears today as CMB. The actual temperature of that surface was around 3000 K. Moving from the CMB towards us, the next thing we can observe are...

Dear all, many people refer to the CMB anisotropy picture by WMAP or Plack and call it acoustic waves. I thought there is the anisotropy of the CMB radiation plotted, what exactly can I imagine to be the acoustic wave of it? Secondly, what exactly is plotted n the famous plot where the...

This paper critically examines the 'hemisphere of evil' CMB asymmetry reported by Planck - CMB Aberration and Doppler Effects as a Source of Hemispherical Asymmetries, http://arxiv.org/abs/1304.3506. Its worth a look if you find this aspect of Planck vaguely disturbing [as I did].

These days have been full of news of the Planck Telescope. The most popular is the actualization of the CMB picture (the ellipse with dots red and blue). I know the idea of it. Each dot represents the "temperature" in some direction (from the earth) in some sort of (θ;ψ) chart -0≤(θ;ψ)≤2\pi ...

The cosmic microwave background is anisotropic: the temperature is distributed as a dipole with the temperature at the poles differing by ±0.00335 K from the mean. This defines a Lorentz frame: we can boost by several hundred km/s to make the dipole vanish, on average. This new frame could...