- #1
Timvanhoomissen
If the cosmic microwave background occurred at the moment that electrons and protons joined together and photons were now free to travel across the universe, then why haven't those photons already passed it. I'm having a hard time understanding why we can see the CMB forever if it was simply a moment in space time. For instance, if we look far enough back into space and time and observe the formation of a supernova, can't we only see that for a finite amount of time because there are only a certain amount of photons that emit the light of the supernova and travel to Earth? But with regards to the CMB photons in the microwave wavelength are constantly detectable, and I need some help understanding this concept.