Not all of it. But parts of it really are due to the cosmic microwave background radiation. Light from the moment the universe was transparent enough to let light spread. It’s from about 300,000 years after the big bang if I recall correctly. It’s the earliest image of the universe we have. And it’s more or less everywhere.
Not all of it. But parts of it really are due to the cosmic microwave background radiation. Light from the moment the universe was transparent enough to let light spread. It’s from about 300,000 years after the big bang if I recall correctly. It’s the earliest image of the universe we have. And it’s more or less everywhere.