Questions tagged [cosmic-microwave-background]
Questions about is the electromagnetic radiation remnant from the early stage of the universe, also known as "relic radiation".
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Why was the Cosmic Microwave Background (CMB) released at a blackbody temperature of 3000K rather than 30,000K?
If the ionization (or reionization, or Recombination) energy of atomic hydrogen is 13.6 EV, which corresponds to a black body temperature of 30,000K, why did the CMB not begin to appear then?
Why did ...
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How can scientists deduce the number of types of neutrinos, or 'effective number', from Planck satellite data?
Is it related to the way they deduce the Hubble constant from Planck data?
Would more types of oscillating and mixing neutrinos mean faster or slower expansion of the universe?
Would a fourth mass ...
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Why does the 'Big Bang Nucleosynthesis' theory require that neutrinos, or at least sterile neutrinos, have a LARGE mass rather than a tiny one?
From Wikipedia, Sterile neutrino
Particles that possess the quantum numbers of sterile neutrinos and masses great enough such that they do not interfere with the current theory of Big Bang ...
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Explain as simply as possible how the Sunyaev-Zeldovich (SZ) effect is used to estimate the Hubble constant
The Sunyaev–Zeldovich effect (SZ effect) is useful in determining the Hubble constant because it is independent of the cosmic distance ladder. This effect occurs when CMB (cosmic microwave background) ...
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Is it Possible to Calculate The Centre of Mass of the Visible Universe?
It is easy to deduce that we appear to be at the centre of the visible universe, assuming the visible universe is approximately isotropic and homogeneous in all its properties, including expansion ...
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Are features in the CMB correlated with features in the SDSS map of the most distant galaxies?
This is a follow up to an earlier question to which @pela gave an excellent answer. Apparently the statistics of the length-scales of the CMB fluctuations are similar to those obtained from other ...
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Is there any correlation between the Cosmic Microwave Background (CMB) and the distribution of distant galaxies?
The Cosmic Microwave Background (CMB) is remarkably isotropic but does exhibit a distinct dipolar Doppler shift and also much smaller but measurable fluctuations in intensity and polarization. ...
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How can the CMB have a "monopole anisotropy"?
Wikipedia's Cosmic Microwave Background (CMBR) radiation monopole anisotropy (ℓ = 0) says
When ℓ = 0, the ${\displaystyle Y(\theta ,\varphi )}{\displaystyle Y(\theta ,\varphi )}$ term reduced to 1, ...
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Objects beyond 13.3 billion light-years away are (apparently) moving away from us at faster-than-light speeds? [duplicate]
That is, if you use the cosmic distance ladder method, and a value of about 73.5 for the Hubble constant....
But, if you plug in the Planck CMB value of about 67.5, you get a distance of about 14.5 ...
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How is the density parameter estimated via cosmic microwave background anisotropies?
In 2003 and again in 2018, the density parameter was estimated based on measurements of the cosmic microwave background anisotropies. Can someone please explain how that works? Why do the anisotropies ...
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Can Gravitational astronomy look beyond the CMB?
In another question dealing with the earliest explored phenomenon in the Universe the observing limit of the CMB was mentioned. Prior to CMB the Universe was opaque to photons, I believe. I'm ...
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How did we determine the distance of the CMB?
The cosmological microwave background (CMB) is the oldest electromagnetic radiation in the universe. How do we know how far away the CMB is?
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How, exactly, does the precise measurement of the CMB's polarization modes and temperature fluctuations tell us the value of Hubble's 'constant'?
Amidst all the talk a year and change ago about the value of the Hubble parameter reached by the Planck satellite team, and how it's value differed from the value reached by the 'distance-ladder' team(...
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817 views
Confused about rubber sheet analogy!
How to resolve confusions on the rubber sheet analogy of the spacetime curvatures?
I am a newbie to spacetime curvature. I have watched several youtube videos on Einsteins GR and spacetime curvature ...
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1answer
352 views
Why is the Cosmic Microwave Background at the same distance no matter the direction we look?
I've read from different sources that:
The CMB is visible at a distance of 13.8 billion light years in all
directions from Earth, leading scientists to determine that this is
the true age of the ...
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Why is the peak value(s) of the spectral radiance of the CMB different if you calculate with freq. instead of wavelength?
On Wikipedia, the calculated value of the peak frequency of the cosmic microwave background is 160.23 GHz, but it says if you do the calculating with wavelengths, then convert to frequency, you get a ...
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What was the energy/wavelength/frequency of the CMB when first emitted/released?
Given the z redshift of 1089, and the temperature difference between then and now of about 1089, I tried scaling the ev, freq. and wavelength by 1089....
Is that right?
I get a freq. of about 240 ...
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243 views
Highest frequency that's been imaged by a radio telescope?
In this answer to Should we update definitions and remove the 100 GHz hard limits on radio astronomy related tags? I wrote the following partial answer:
Yes, there are plenty of dishes that focus ...
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Cosmic Microwave Background Map
When a satellite takes measurements of the radiation from different patches of the sky to construct a map of the thermal radiation of the universe on the surface of a sphere, it would also contain ...
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Does the image of the cosmic microwave background radiation show us what the universe used to look like?
Is it possible to interpolate using the cosmic microwave background radiation and currently what we can see in the sky at night to predict what the night sky will look like in the future? I’m guessing ...
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Why is the Cosmic Microwave Background evidence of for a hotter, denser early Universe?
In his book Gravitation and cosmology, Steven Weinberg says that CMB makes it "difficult to doubt that the universe has evolved from a hotter, denser early stage".
In my understanding, the ...
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When do radio and tv signals become indistinguishable from background noise of the universe?
I understand the rate an EM signal broadcast uniformly from the Earth will decrease in its power is governed by the inverse square law. How far from Earth will radio and tv signals become ...
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Understanding The Fluctuations In The CMB Maps
If I'm understanding this correctly the fluctuations in CMB are a result of the "last scatter" of photons when electrons joined together with nuclei that before this formed plasma. CMB is among other ...
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How fast are we moving relative to the CMB?
The cosmic microwave background radiation should provide kind of a global reference frame, because you can determine your speed relative to it using the redshift.
Is it known how fast we are moving ...
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3answers
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Why do scientists assume they can measure the shape of the universe if it is also widely believed to be infinite?
The shape of the universe is the question of whether the universe is flat, has a positive curvature or a negative one. More recently astronomers have compared radiation coming from extremely distant ...
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Is the universe older than 13.7 Billion years?
I came to know that the cosmic horizon is the part of universe beyond which we cannot see. So if the light from 13.7 billion years ago is what we can observe, does that mean the universe is older than ...
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cosmic-microwave-background - 2.7 degrees but does the Big Bang care?
The Big Bang is a proposed answer to the beginning of the universe, and the Cosmic Microwave Background or CMB is a central part of the evidence for it.
Now suppose the measurement returned a ...
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Can we track matter through time by looking at different depths in space?
If we look back far enough we can see all the origins of the universe, so is it possible, even if not feasible, that we could trace the history of some matter as it moves through space-time? I want to ...
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Deep space radiation distribution
What frequency distribution law applies to a random point in deep space that is assumed to be far away from any particular source of radiation.
Can it be expressed by some form of Plancks/Bose-...
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1answer
255 views
Scientific evidence against CMB originating from “Oort Soup”?
In this article (and references therein) the author claims that the Cosmic Background Radiation can be explained as black-body radiation originating from the cold bodies filling the interstellar space ...
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How much radiation would something need to output to sufficiently affect the CMB? [closed]
Let’s say that I had some device capable of outputting insane amounts of radiation, across the entire EM spectrum. If I wanted to affect the CMB to the point that, were Earth-based scientists to know ...
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How thick is the cosmic microwave background, including the part we cannot see within the observable universe?
What I want to know is how thick the observable universe is from the point of the cosmic microwave background and beyond.
It appears the thickness of the cosmic microwave background itself (the part ...
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Cosmic microwave background radiation
If the big bang is true, after the emission of light from the hydrogen plasma, the universe was still expanding. Why would we expect to see uniform radiation if earth very well could have formed ...
