Why is cosmic background radiation used as evidence of the big bang theory of the origin of the universe?
A.
It corresponds to the temperature predicted by the big bang theory.
B.
It is emitted from a black hole at the center of the universe.
C.
Its wavelength is getting shorter, so it must be very old.
D.
It is not very common, so it must be running out.
A. It corresponds to the temperature predicted by the big bang theory.
The correct answer is A. It corresponds to the temperature predicted by the big bang theory. Cosmic background radiation is the afterglow of the "Big Bang," which occurred approximately 13.8 billion years ago. This radiation permeates the entire universe and has a temperature of around 2.7 Kelvin, which aligns with predictions made by the big bang theory.
The correct answer is A. Cosmic background radiation is used as evidence of the big bang theory because it corresponds to the temperature predicted by the theory.
To understand why this is the case, let's break it down step by step:
1. The big bang theory states that the universe originated from a highly dense and hot state approximately 13.8 billion years ago. As the universe expanded and cooled down, it gave rise to the formation of galaxies and other celestial objects.
2. According to the theory, the initial state of the universe was so hot that it was filled with thermal radiation, which is electromagnetic radiation emitted by matter due to its heat. As the universe expanded, this radiation gradually cooled down.
3. Today, this cooled-down radiation is observed as the cosmic microwave background (CMB) radiation. It is characterized by its relatively uniform distribution and its temperature of around 2.7 Kelvin or -270.45 degrees Celsius.
So, based on the big bang theory, the cosmic background radiation is expected to have a specific temperature. This is exactly what is observed - the temperature of the CMB matches the predicted temperature, providing strong evidence in support of the theory.
Now, let's briefly discuss why the other answer choices are not correct:
B. Cosmic background radiation is not emitted from a black hole at the center of the universe. In fact, the concept of a central black hole is not a part of the big bang theory.
C. The wavelength of cosmic background radiation is not getting shorter. In fact, it is observed in the microwave range, which corresponds to longer wavelengths.
D. Cosmic background radiation is not uncommon, and it is not running out. It is present throughout the universe and is detected from all directions in the sky, suggesting its widespread nature.
In conclusion, the consistent temperature of cosmic background radiation with the predictions of the big bang theory provides strong evidence supporting the theory of the origin of the universe.