Question

Why do we expect the cosmic background radiation to be almost, but not quite, the same in all directions?

A) The overall structure of the universe is very uniform, but the universe must have contained some regions of higher density in order for galaxies to form.
B) The temperature of the universe can be found by taking an average over the entire sky, but individual stars will create peaks in the spectrum over small angles.
C) Dark matter consisting of WIMPs greatly smooths out the spectrum, but the small patches of ""light"" matter create peaks in the spectrum.
D) The overall structure of the universe is very uniform, but the synthesis of different elements produces varying signatures within the background spectrum.
E) The overall structure of the universe is very uniform, but intervening gas between us and the era of nuclei absorbs wavelengths depending on the composition and redshift of the gas.

Answer 1

The overall structure of the universe is very uniform, but it must have contained regions of higher density for galaxies to form. Dark matter and the synthesis of different elements contribute to the smoothness and variations in the cosmic background radiation spectrum.

Step-by-step explanation:

The overall structure of the universe is very uniform, but the universe must have contained some regions of higher density for galaxies to form. This explains why we expect the cosmic background radiation to be almost, but not quite, the same in all directions. The particles in the universe at the time of decoupling were not distributed evenly, which led to the formation of large-scale structures such as galaxies. However, the cosmic background radiation is not perfectly smooth, only extremely smooth when observed closely.

Dark matter consisting of WIMPs smooths out the spectrum, but the small patches of "light" matter create peaks in the spectrum. The synthesis of different elements also produces varying signatures within the background spectrum. Intervening gas between us and the era of nuclei can absorb wavelengths depending on the composition and redshift of the gas.