Question

Which evidence supports the idea that Cosmic Microwave Background radiation is a remnant of the Big Bang?
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2 points
Its mass is uniform.
Its temperature is uniform.
Its mass fluctuates greatly.
Its temperature fluctuates greatly.

Answer 1

The evidence that supports the idea that Cosmic Microwave Background (CMB) radiation is a remnant of the Big Bang is the uniformity of its temperature.

The Big Bang theory predicts that the universe originated from a singularity, an extremely hot and dense point. As the universe expanded, it cooled down, eventually leading to the formation of atoms and the release of photons. These photons, which make up the CMB radiation, have been traveling through space ever since.

One of the key predictions of the Big Bang theory is that the CMB radiation should have a uniform temperature. This prediction has been confirmed by measurements made by various satellite missions, including the Cosmic Background Explorer (COBE) and the Planck satellite. These measurements have shown that the CMB radiation has a nearly perfect blackbody spectrum with a temperature of about 2.7 Kelvin, which is extremely uniform across the entire observable universe.

On the other hand, the mass of the CMB radiation is not relevant in determining its nature as a remnant of the Big Bang. The CMB radiation consists of massless photons, and while it does contribute to the overall mass-energy density of the universe, the uniformity or fluctuations in its mass do not have a direct bearing on its origin as a remnant of the Big Bang.