What do scientists believe provides for the Big Bang theory

Cosmic microwave Background Radiation.

Explanation: Big Bang theory describes the beginning of the universe. Initially all the matter was confined into a single point. During the big bang, the universe started expanding and cooling down. For the first phase of time , the universe was opaque. C M B radiation is the remnant radiation of Big Bang after the initial stage when the universe became transparent. It is detected all around in the sky and has an average temperature of about 3 K. The detection of C M B radiation provides evidence for the Big Bang Theory.

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