Alastair Wilson attempts to explain:
The ouroboros of the one cyclic universe is majestic indeed. It contains within its belly our own universe, as well as every one of the weird and wonderful alternative possible universes allowed by quantum physics – and at the point where its head meets its tail, it is completely empty yet also coursing with energy at temperatures of a hundred thousand million billion trillion degrees Celsius. Even Loki, the shapeshifter, would be impressed.Alastair Wilson, “How could the Big Bang arise from nothing?” at The Conversation (January 3, 2022)
Wait. There is a simpler explanation: In the beginning, the Lord created the heavens and the earth.