If I understood correctly, the CMB originated at a time when the universe was much hotter and denser than today, and originally consisted of photons of much shorter wavelength than today. As the universe expanded and cooled, the photons comprising this background radiation did too, and at present it appears to us in the microwave range of wavelengths.
I don't understand how the law of conservation of energy holds for the total amount of energy carried by the CMB. The number of photons comprising the CMB can't increase. It can only remain the same or decrease (some photons will get absorbed by matter), and their wavelength is continually increasing. The total amount of energy carried by the CMB should therefore decrease (photons will longer wavelengths have less energy). If energy is conserved, where did this energy go?
I guess I'm just asking because I have no sense of scale when looking at the CMB. Like how large is the average clump? Galaxy-size? Yellow dwarf-size? Great Wall-size? Bigger? I know none of these things existed yet, but I'm just asking about sheer scale here. If all that light was once radiated toward us as the center of our arbitrarily-located observable sphere of the cosmos, how big was that sphere at the time its light was emitted? About 13.7 billion years ago I believe.
If i'm not mistaken, earth's magnetic field deflect charged particles, and pushes them to the poles, creating the Auroras. Also if i'm not wrong, the background radiation can vary really highly from place to place, because it's affected by many variants. But is there any increase in the background radiation, if you stand right under the northern lights or the cosmic radiation level stay consistent?
I am given to understand that background radiation from the big bang has shifted wavelength into the microwave region of the EM spectrum over time due to the expansion of space. This implies that in the past, the frequency of this radiation must have been much greater and will have gradually shifted through the EM spectrum. I understand that there is nothing particularly special about the visible range of light other than the fact that human eyes are sensitive to it, but since the background radiation must have shifted through the visible portion of the spectrum, it raised the following questions:
If a human eye somehow existed when the cosmic background radiation was within the visible range, what would it see? Would space itself appear to have a colour, and if so, what exactly would it look like? This of course assumes that the intensity of radiation is great enough to be detected by the eye.
Thanks in advance :)
I understand that itβs remnant energy from the Big Bang, and that it accounts for the temperature of the universe (right?).
In chemistry class, we define temperature as the kinetic energy of particles in a system, but how can space have a temperature when there are no particles for energy to move?
Also how is CMB just everywhere? From what I understand, energy is usually in the form of electromagnetic waves, which travel infinitely in a vacuum until they are absorbed by something. What exactly is CMB if not a traveling wave?
