Neil deGrasse Tyson declares the number of possible persons by the number of possible combinations of DNA. This would make twins and clones the same person. In fact the number of possible persons is infinite.
Borges added to Nietzsche’s notion of Eternal Return a Library in which all texts return infinitely, but with variation. But if the library is infinite, all texts also return infinitely without variation. All commas are forever where they belong. And if the universe is structured like the library, then not just all texts but all lives return eternally with and without variation. Every mistake you ever make you make eternally. But you also avoid it eternally. Everyone you ever could have married, you marry. Every life you could have lived, you live. Every mistake you could make, you make. Every mistake you could avoid, you avoid. Everything that can happen happens, happens forever in infinite repetition. And this helps us understand the great emptiness of the universe, an argument against the existence of God. Most of the universe is empty. Most of the library is nonsense. Pockets of meaning are infinite and infinitely rare at the same time, at every time, at all times and in all times. That’s the structure of the library. But it also means that the books we write which are fictions here are realities elsewhere, providing they are possible anywhere. Is there a universe in which flying carpets are real? If there is, there are flying carpets there and Persians who fly on them. If not, not. But Silas Lapham exists with his paint in a universe somewhere. And somewhere he doesn’t gamble on the stock market and somewhere he does.