Final answer:
The idea that everything in the universe came from a single dense ball is named the Big Bang theory. Space is full of cosmic microwave background radiation. The Doppler effect refers to the change in observed frequency of a wave due to motion.
Step-by-step explanation:
The idea that everything in the universe came from a single dense ball 10 to 20 billion years ago has been named the Big Bang theory.
Radiotelescopes reveal that space is full of cosmic microwave background radiation. This radiation is considered as one of the key evidences supporting the Big Bang theory.
The Doppler effect is a phenomenon where the observed frequency of a wave changes due to the relative motion between the source of the wave and the observer.
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