How can we see the cosmic background radiation?

In summary: So, essentially, the CMB we see is just a remnant of the early stages of the universe, and not necessarily the same particles we are made of. In summary, the Cosmic Microwave Background radiation that we see today is a remnant from the early stages of the universe and is not necessarily made up of the same particles that we are made of.
  • #1
FizX
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I am wondering how it is possible that we see CBR. Here's why:
When the big bang occured, there was a sea of particles that gave off radiation. Now, if we are now made out of those particles, then how are we seeing their radiation now?
The only way I see this happening is if matter traveled faster than light at some point. How else would we be seeing the radiation from the same particles we are made out of? It would be violating the light-cone rules. Can someone clarify this for me? Thanks
-Chax
 
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  • #2
I think you need look no further than a static (one with no reception) channel on your T.V.
 
  • #3
What's more, we are looking into the past with CBR. So, we have a long time to separate from those particles, but we are seeing them back in their primitive form much as our particles were.

Funny: So, those particles may some day very well become part of an ET fixing to hunt us down and exterminate us for unwittingly insulting them with our messages to outer space.
Indeed, what if those SOS signals you made as a kid playing with your Dad's flashlight actually translate into something insulting enough for ET to start an intergalactic war once ET sees it?

Oh no... What have you done??
 
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  • #4
FizX said:
I am wondering how it is possible that we see CBR. Here's why:
When the big bang occured, there was a sea of particles that gave off radiation. Now, if we are now made out of those particles, then how are we seeing their radiation now?
The only way I see this happening is if matter traveled faster than light at some point. How else would we be seeing the radiation from the same particles we are made out of? It would be violating the light-cone rules. Can someone clarify this for me? Thanks
-Chax

This is indeed a good question, which luckily has a solution!
The point here is that when the CMB (Cosmic Microwave Background) raditation was released, the universe was in fact much bigger than what one naively would think if one just let's it expand from a single point with the speed of light.
First of all, the initial singularity of the Big Bang need not be equivalent with that the universe started out from a single point. Somewhat loosley speaking the singularity just means that the density goes to infinity, not that the volume has to go to zero.
Secondly, even if the universe is finite in size (a closed universe) and once was much smaller, the period of http://en.wikipedia.org/wiki/Cosmic_inflation" [Broken] saves the day, since during this epoch space expanded much faster than the speed of light (which does not contradict General Relativity). When the CMBR finally was released the space was already huge.
 
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  • #5
The more fundamental thing to point out (apologies if I'm being too obvious here) is that was are not 'made out of those particles' that gave off the CMB photons that we see today. The stuff we are made of did give off CMB photons, but those photons are now a very very long way away from us. The material that gave of the particular CMB photons is by the same token a very long way away from us.
 
  • #6
Thanks guys, that really helped.
 

1. What is cosmic background radiation?

Cosmic background radiation, also known as the cosmic microwave background (CMB), is a faint glow of electromagnetic radiation that fills the entire universe. It is a remnant of the Big Bang and is the oldest light in the universe, dating back to about 380,000 years after the Big Bang.

2. How can we detect cosmic background radiation?

Cosmic background radiation can be detected using specialized instruments called radiometers or radiotelescopes. These instruments are able to detect the faint microwave radiation emitted from all directions in the universe.

3. What is the significance of studying cosmic background radiation?

Studying cosmic background radiation allows scientists to gather information about the early universe and the processes that led to the formation of galaxies and structures we see today. It also provides evidence for the Big Bang theory and helps us understand the composition of the universe.

4. How is cosmic background radiation related to the expansion of the universe?

Cosmic background radiation is related to the expansion of the universe because it is a direct result of the Big Bang. As the universe expanded and cooled, the radiation from the Big Bang became stretched out and shifted towards the microwave region of the electromagnetic spectrum.

5. Are there any current projects or missions studying cosmic background radiation?

Yes, there are several projects and missions dedicated to studying cosmic background radiation, such as the Planck satellite mission and the South Pole Telescope. These projects aim to gather more precise data and images of the CMB to further our understanding of the early universe.

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