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