Astronomy Stack Exchange
Astronomy Stack Exchange

Questions tagged [cosmic-microwave-background]

Questions about is the electromagnetic radiation remnant from the early stage of the universe, also known as "relic radiation".

Cosmic microwave background radiation (short: CMB radiation) is radiation in the microwave part of the electromagnetic spectrum, which comes from all directions in outer space. Since the universe is very large, and the speed of light is constant, we know that when the CMB light arrives from the infant universe, it arrives as the oldest signal that we can detect.

During the Big Bang, a lot of high-energy radiation was created. Then, the universe became bigger and colder. Therefore, the high-energy photons lost most of their original energy. Now, as a result, that radiation is in the microwave part of the electromagnetic spectrum (the microwave part has quite low energy).

References

136 questions
25
votes
1 answer

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 in relation to the CMB? If you subtract the various…
cuckoo
  • 690
  • 5
  • 9
14
votes
1 answer

How long after the Big Bang would CMB radiation have been between 273 and 373 K?

Cosmic microwave background radiation is 2.7 K today. When would it have been between 0 and 100 C?
user332336
  • 143
  • 5
11
votes
1 answer

How did astronomers get rid of microwave radiation from stars and galaxies in picures of the CMB?

Images of the CMB show no sign of stars or galaxies. If they did, shouldn't the Milky Way be a bright band dividing the CMB into hemispheres? Black body radiation in a given wavelength/frequency range gets more intense as the object in question gets…
zucculent
  • 1,748
  • 3
  • 20
10
votes
1 answer

Where's the matter that created the CMB?

I know that the CMB was created at the recombination, when photons could finally travel freely. But each of those photons was deflected one last time before this happened. Where's the matter that deflected the photons? Has it become the baryonic…
zucculent
  • 1,748
  • 3
  • 20
9
votes
4 answers

How is the Cosmic Microwave Background so big?

If the CMB is an image of the universe when it was 379,000 years old, how is it so large? Since the light is 13.8 billion years old, the image represents the surface of a sphere with a radius of 13.8 billion light years, and I don't think the…
Proxima Ace
  • 101
  • 1
  • 4
9
votes
2 answers

Why can we still 'see' the CMB

I read that the CMB were all the photons left free when the universe was cold enough for electrons got bound with protons (recombination) and the photons free in that moment continued traveling in the directions they were. So I imagine: the CMB as…
jisuskraist
  • 191
  • 1
  • 2
8
votes
1 answer

How do CMB photons 'gain energy when they pass through normal regions of space with matter' and 'lose energy when they pass through voids'?

The Space.com article Huge Hole Found in the Universe says: The gargantuan hole was found by examining observations made using the Very Large Array (VLA) radio telescope, funded by the National Science Foundation. There is a "remarkable drop in the…
uhoh
  • 31,151
  • 9
  • 89
  • 293
7
votes
1 answer

Is CMB Polarization simply the temperature gradient of the CMB?

Firstly, I have to admit that I don't fully comprehend the concept of "CMB Polarization". When I think of "Polarization", I normally think of the optical definition of polarization, as defined by the electric field. What I currently think is that…
krismath
  • 328
  • 1
  • 6
5
votes
3 answers

Are we moving faster than the Cosmic microwave background radiation?

if the Cosmic microwave background radiation is coming towards us in the speed of light and all matter and energy was singular at the big bang, doesn't that mean we somehow moved faster than the speed of light (otherwise the CMBR would have already…
Tiktinsky Moshe
  • 61
  • 2
2
votes
1 answer

Understanding the angular peaks in the CMB power spectrum

I have read up quite a bit on the CMB power spectrum, but one feature evades my understanding. The first peak is often referred to as the "first compression peak", meaning that the plasma had time to compress exactly once. The way I imagine this is…
Kristian
  • 305
  • 1
  • 5
2
votes
0 answers

How large part of the energy of the electromagnetic radiation in the universe is primordial

As I understand it there can be said to be two "kinds" of electromagnetic radiation filling up the universe. First you have the primordial radiation from a time soon after Big Bang. Then you have "newer" radiation from the fact that you start up…
Agerhell
  • 457
  • 2
  • 15
2
votes
1 answer

Is the total energy of the CMBR diminishing with time?

Is the total energy of the CMBR diminishing with time? Since it's existence the volume of the Universe (at least the visible part) has grown by a factor three, which is to say, the number of photons per unit volume is diminished by a factor 27. But…
Deschele Schilder
  • 1
  • 11
  • 26
2
votes
1 answer

How do we know background radiation does not come from undiscovered galaxies?

Each year while observing voids, astronomers discover more and more unexpected galaxies within them. How do we know the cosmic microwave background radiation is not the weak light from distant galaxies? How do we know cosmic microwave background…
Waldemar Gałęzinowski
  • 351
  • 1
  • 4
1
vote
0 answers

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 the night sky will be increasingly bright…
user31880
0
votes
1 answer

How much data are with cosmologist from JWST about CMB?

I need to know about the data, which scientist have already received from JWST about the CMB.
Jahid Hossain
  • 17
  • 1
1
2