

Some of the christians in my family like to take the “let there be light” thing and claim that it’s talking about the big bang, anecdotally.
But that’s probably not even right. In my understanding, the Big Bang wasn’t actually bright, because the first phase of the universe was a superhot but opaque quantum soup. Even the weak nuclear force took time to become distinct from the electromagnetic force. I don’t know if energy packets of a combined electroweak field count as photons exactly.
Regardless, the first light as we know it (in the sense that it could traverse the universe) wasn’t until a few hundred million years after the Big Bang, when the whole mess had cooled enough to become transparent. We now call that initial light the Cosmic Microwave Background radiation.
I dunno, the seas haven’t overtaken us, so I have to question the extent of Poseidon’s power. That is the god you meant, I’m sure.