What Is the Ratio of Cosmic Microwave Background Photons to Hydrogen

question 182

Multiple Choice

What is the ratio of cosmic microwave background photons to hydrogen atoms, on average, in the universe?

• A) about 1 billion to 1
• B) about 1 million to 1
• C) about 1 to 100-very few microwave photons
• D) about 1 to 1-equal numbers of photons and hydrogen atoms

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