Cmb Definition and 252 Threads

Hi What was the distance between our point in space and the points from which the Cosmic Microwave Background radiation emanated that we detect today at the moment that that radiation was created. Or similarly, what was the diameter of the sphere, the surface of which we detect today as CMB.

Hi all. I relish hearing from our great cosmological explainers like Neil DeGrasse Tyson and Brian Greene and watch whenever I find something new on youtube, but one thing that I don't understand and haven't heard anyone specifically address is that, if the part of the universe we are able to...

The balloon-borne EBEX microwave background mapper was let fly today. Andrew Jaffe's blog has a video of the launch, down in the Antarctic. video made by Aboobaker: http://www.youtube.com/watch?v=f-_2ESkCf94&...

CMB Maximum Temperature Asymmetry Axis: Alignment with Other Cosmic Asymmetries, http://arxiv.org/abs/1211.5915, raises some interesting questions so I spent most of the day reading more papers [I need a hobby]. It is certainly curious that the dark flow, alpha gradient, and dark energy dipoles...

hello I have a question: i am trying to understand how we find out that the curvature of the universe is zero using the angular size of the hot spots of the d microwave background radiation. http://scienceblogs.com/startswithabang/2012/07/18/how-big-is-the-entire-universe/ there is a...

A hypothetical question relating to 1) moving a physical object at a significant % of c. 2) interaction with the cosmic microwave background radiation Is it the case that doppler effect and time dilation means that the CMB is going to be physically damaging to the object? Further...

I'm reasonably convinced that physicists know what happened in the universe at certain temperatures: just find out what happens when you reach those temperatures in a particle accelerator. I still have yet to come across the equation that measures the time before the CMB and what the universe's...

Hello everybody, (sorry for the eventual Engrish) I can't find any convincing answer for the following question : Why do we always (or often) plot the CMB power spectrum in this way : jb.man.ac.uk/research/cosmos/vsa/images/CMB_power_spectrum.gif I mean the y-axis is $$C_\ell \ell...

There is a video on youtube called how do we know the universe is flat. (put those keyword in youtube and you should find it, I can't post links to videos until I have 10 posts) It has something to do with using the Earth as an apex of a triangle then measuring two points on the cosmic...

The earlier thread was closed for some reason. It prompted this question: Given the formula for CMB temperature Tobs = Tem/(1+z) (analogous to the formula for z) it seems the age of the universe at the emission of the CMB would have been about 12.5 Myr (if 13.75 Gyr presently), not 380,000...

wikipedia says: "The CMBR has a thermal black body spectrum at a temperature of 2.725 K, which peaks at the microwave range frequency of 160.2 GHz, corresponding to a 1.873 mm wavelength. This holds if measured per unit frequency, as in Planck's law. If measured instead per...

The radiation we see today as the CMBR - was this originally released as a pulse or was it continuous for some length of time ?

If the CMB is quantum fluctuations of the primordial universe, I would expect it to move, not be static like a photograph. Quantum fluctuations do not hold still, nor has time itself seem to have dilated to the point where it would look constant. Can somebody take a movie of it and see? All...

How does CMB support the predictions of "inflation"? Could explain to the novice I am, how does the CMB observation support the predictions of "inflation"?

When one says they are at rest relative to the cosmic microwave background, does this mean that they are in a frame where the same frequency is measureed in all directions? Because, I could imagine if I boosted in one direction, then the spectrum behind me would be redshifted, and the spectrum...

Can anyone point me to some articles or book giving details of how the CMB data is processed to calculate the average density of the universe (or equivalently the average spatial curvature)? Thanks, Skippy

Hello, friends. I read that polar anisotropy of the CMB shows that the solar sistem is moving towards the Virgin constellation. This polar anisotropy is not something which is not going to cause some problems... First question: Isn't this a sort of ABSOLUTE MOTION? i.e. we have found out...

Is there a known quantity of CMb phtons? Presumably we can only receive a finite amount in our detectors, but is that due to the fininite distance to our comsic horizon? But if the universe were infinite would it have emitted an infinite amount of photons from the CMb/ Would everyplace in the...

I'm having trouble resolving the contradiction between theories of the Cosmic Microwave Background, and Special Relativity. Einstein denied the existence of any absolute standard of rest. As einstein-online.info paraphrases: "In the real world, there exists no such state of absolute rest...

How can we still receive photons from last scattering, i.e. the CMB? Does our receiving the photons (not other evidence from CMB) require a constraint on the curvature of the universe or the speed of expansion? I can see how a curvature that described a closed universe would have CMB around...

Whats this all about the cold spot found on the WMAP satellite's photo of cosmic microwave background radiation? To explain this there's even been a possibility of a parallel universe's gravitational effect causing this cold spot?

From an entropy argument it is concluded that the CMB neutrino temperature is (4/11)1/3 of the CMB photon temperature. This assumes massless neutrinos. Although neutrino contribution to the present energy density is therefore very small, it was significant must earlier, such as at the time of...

I have a question sort of related the size of the observable universe. I know that we are limited by the speed of light in how far we can see, but what I am wondering is... In the early universe when the first light could finally break free and travel in straight lines did it travel in...

This article http://www.physorg.com/news/2011-06-big-edge-solar.html" tells about discovery of magnetic bubbles at the edge of solar system. As I understand they are around 100AU from Sun and around the size of 1AU. That makes them roughly 3.6° angular size. Shouldn't these bubbles cause...

What is CMB rest? The Cosmic Microwave Background is remarkably uniform -- the temperature of the light is the same from all directions in the sky to within about one thousandth of one percent! That is, if you first adjust for the effects of solar system/orbital motion. Solar system motion...

just to interesting not to share. http://bit.ly/g6sFMh i posted a question there which i wish to post also here, and get some insight. why is this CMB uniform and dark energy and/or dark matter so uniformly spread and are not directly related? i.e. why aren't we saying that the CMB is emitted...

If I'm correct Planck will publish its all-sky CMB map (foreground deducted) this year. What's to be expected from this? Is another revolution coming?

Not that it has become so small it is undetectable; but the point from which it was emitted is such a distance away that the expansion of space between Earth and that point is greater than the speed of light (like swimming upstream in a river going faster than you can swim).

Can someone give a clear definition of what we mean when we say the CMb spectrum is adiabatic and what it means for simple infaltionary models?

http://map.gsfc.nasa.gov/media/070950/070950b.jpg So the x-axis is multipole moment, which I remember from 2nd-quarter electromagnetism. Anyways, it surprises me that 1000-order multipole moments can even be physically significant.

Dear all, Searching proofs for Dark energy, people always mention "the first acoustic peak in CMB". can anyone tell me what exactly is that? how long did we expect it to be and now -having Dark energy- how long do we see it? can anyone help me please?

Can anyone give a good explnanation of red tilt in comsology? why inflation predicts this and how its measured in the CMb? Many thanks.

I wanted to ask if there are any tests that CMB primary anisotropies are ancient? Or to put it differently can we exclude possibility that they are forming somewhere not far from Solar system say on some spherical horizon? Just thought that black body spectrum is what you would expect from...

http://arxiv.org/abs/1012.1268 http://arxiv.org/abs/1012.1305 These papers seem to claim that the circles found by Penrose and Gurzadyan in the WMAP data, which were presented as evidence of pre-big bang activity, are entirely consistent with what we would expect the CMB to look like from...

Hello, i wrote a Matlab program which calculate the apparent angle of an anisotropy with a size equal to "380.000 light-years" , i.e "0.1166 Mpc". For this, i have used the following equation defining the apparent angle ( in arcminute unit) as a function of the redshift "z" with...

I came across this http://scienceblogs.com/startswithabang/2010/11/the_simplest_argument_for_dark.php cutesy pop-sci-ish explanation of how we know there's dark matter. If you scroll about 1/3 of the way down, it shows plots of the CMB's power spectrum as a function of multipole moment, l...

Does anyone know how is the direction of motion from the CMB dipole determined? Do Earth's motion around the sun affect the direction and magnitude of the velocity as seen on observations made over many months?

General relativity predicts that electromagnetic fields contribute to the stress-energy tensor, and that they therefore have gravitational fields. Kreuzer (1968) did laboratory experiments that were interpreted by Will (1976) as confirmation of this prediction in the case of the static electric...

Hello, I'm new here and have joined to ask the following two questions: 1 - The distance to the CMB has been measured at approximately 14 billion light years. How was this achieved, what is the error and is it the same in all directions? 2 - WMAP data clearly shows that the CMB has a plane...

Hi. How does the number 605km/s come from the observed CMB wavelength of 1.9mm? (http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation) Please only reply in 'English' and not a bunch of calculations because Google already provides lots of calculations. I am trying to get a...

...residual signals of CMB radiation from the Big Bang? I've heard and read this before but I'm not too sure how credible this is. Are TV antennas really that strong to pick up CMB?:confused: Just wana get this cleared up by an expert. Thanks.

Anyone knows if the CMB map of anisotropies from WMAP is used to implement the angular power spectrum plot(acoustic peaks)? I'm not sure, but I tend to think it is not.

As noted in the thread "Dark Matter, On the Ropes?" there is disagreement with the observed velocity profile of spiral galaxies, the size of spiral galaxies' bulge, and the spiral galaxies' halo when compared to what theory predicts and what simulations with dark matter indicate...

I'm doing OCR A-Level Physics, and in my textbook it states "They (Penzias and Wilson) made a calculation to find the temperature of the source of the radio waves, which had a maximum intensity at wavelength 1.1 cm, and found it to be 2.7K". This was all good and well, until I answered a...

Can't we simply assume that the initial condition for the universe is perfectly spherically symmetric, and the problem is solved? In other words, can't we make the CMB homogeneous just by imposing homogeneous initial conditions? The fluctuations can be explained by quantum effects. Of course...

Seems like the universe was opaque for 380k years, and then suddenly nuclei capture electrons and there's an almighty flash, in all directions. By this time the universe is what, a million light-years in diameter, or less? Seems like the light from the last scattering surface would have gone by...

The CMB is believed to have started [or ended] 13.7 billion years ago. Recent estimates of Hubble constant are around 70 km/s/Mpc, or 228 km/s/Mlyr. When we look at CMB we are looking back 13700 million years into the past. Multiplying 228 by 13700 gives us 1.04 times the speed of light as...

In other words, when did the big bang cool down to 3 degrees? Like 13.7 billion years ago, or in recent millenia? If it only cooled that much near current time - which is what I understood - then the CMB must be "coming from" the space right around the Milky way - which is not what I understood.

Here is my understanding of how the anisotropies of the CMB are used to determine the geometry of the universe: The fluctuations represent fluctuations in temperature just at the moment of last scattering, and therefore are a 'fingerprint' for the fluctuations in density of particles. We can...

Not sure if this is an easy question or not. The Wikipedia entry on the Big Bang, in its section on "Abundance of primordial elements," cites the 1988 book by Kolb and Turner (The Early Universe), in saying that the ratio of photons to baryons "can be calculated independently from the...