Which of the following is not an observed characteristic of the cosmic microwave background?
A) It contains prominent spectral lines of hydrogen, the primary chemical ingredient of the universe.
B) It has a perfect thermal radiation spectrum.
C) Its temperature is the same everywhere, except for small variations at the level of 1 part in 100,000.
D) Its temperature is a little less than 3 Kelvin (3 degrees above absolute zero).

Question

Quizplus · Accepted Answer

The cosmic microwave background does not contain prominent spectral lines of hydrogen, as it is a perfect thermal radiation spectrum that has been smoothed out over time due to the expansion of the universe. The other characteristics listed are observed and accepted features of the cosmic microwave background.

Which of the Following Is Not an Observed Characteristic of the Cosmic