Question

The cosmic background is 4K. Where are the other photons? A 4K photon produced at the big bang is detected by our detector. Time stops for the photon and hence we are seeing the big bang. Shouldn't we also see the other photons from the big bang?

A) No, as the cosmic background photons are continuously redshifting due to the expansion of the universe, causing their energy to decrease and wavelength to increase over time, making them undetectable in the microwave range.
B) Yes, but the other photons are beyond the observable universe, and their effects are too weak to be detected by current technology.
C) No, because the expansion of the universe causes the other photons to be trapped in regions that are unreachable due to the accelerated cosmic expansion.
D) Yes, but the cosmic microwave background radiation consists of photons that were emitted when the universe cooled enough for atoms to form, and the detection is limited to this specific period due to the recombination era.

Answer 1

The cosmic background radiation, or CMB, represents the afterglow of the hot, early universe. The other photons from the Big Bang have redshifted due to the expansion of the universe and are undetectable in the microwave range where the CMB is visible.

Step-by-step explanation:

The cosmic background radiation, also known as the cosmic microwave background (CMB), is evidence of the Big Bang and represents the afterglow of the hot, early universe. This background radiation is detected in the microwave range and has a temperature of approximately 4K.

While the question asks about the other photons from the Big Bang, it is important to note that the CMB represents the photons emitted when the universe cooled enough for atoms to form, during the recombination era.

As for the other photons from the Big Bang, they have undergone continuous redshifting due to the expansion of the universe. This means their energy has decreased over time while their wavelength has increased, making them undetectable in the microwave range where the CMB is visible. Therefore, option A is correct: the cosmic background photons are continuously redshifting and become undetectable.