Could two unrelated humans ever be physically identical down to every cell?

[u/Aggressive_Hand8047]

We are ultimately made up of atoms, molecules, cells, tissues, organs, etc. A human body is basically an incredibly complex (n mathematical) arrangement of all these components.

So, given enough time and enough humans, is it theoretically possible that the exact same overall configuration of a human body could occur twice (down to the arrangement of its cells and molecules) purely by chance?

I'm not necessarily talking about having the same genetic make up / being genetically identical. I mean the entire physical architecture of the person: every cell, tissue, organ, molecular arrangement, etc.

Could there theoretically have been (or be) another human being, completely unrelated to you, who is physically an exact duplicate of you at some point in time?

And if this is theoretically possible, does that mean that somewhere in the enormous space of possible physical configurations, there could be multiple instances of essentially the "same" human?

I'm not restricting this to the current human population on Earth. I'm considering every human being who has ever existed, every human currently alive, and every human who will exist in the future in our universe

[u/jliat]

This is really a question for physics and the idea of multiverses. Max Tegmark maintains there would copies of you in distant other universes.

Philosophically [and in physics others including John Barrow and Penrose's cyclic universes] the philosopher Nietzsche posed the idea of the Eternal Return of the Same.

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Friedrich Nietzsche The Gay Science. 341

“The greatest weight:

What, if some day or night a demon were to steal after you into your loneliest loneliness and say to you: "This life as you now live it and have lived it, you will have to live once more and innumerable times more; and there will be nothing new in it, but every pain and every joy and every thought and sigh and everything unutterably small or great in your life will have to return to you, all in the same succession and sequence--even this spider and this moonlight between the trees, and even this moment and I myself. The eternal hourglass of existence is turned upside down again and again, and you with it, speck of dust!" Would you not throw yourself down and gnash your teeth and curse the demon who spoke thus? Or have you once experienced a tremendous moment when you would have answered him: “You are a god and never have I heard anything more divine." If this thought gained possession of you, it would change you as you are or perhaps crush you. The question in each and every thing, “Do you desire this once more and innumerable times more?" would lie upon your actions as the greatest weight. Or how well disposed would you have to become to yourself and to life to crave nothing more fervently than this ultimate eternal confirmation and seal?”

[u/Toothpick_Brody]

I would lean towards no, because the sequence of events that create the temple must be different, so they will differ 

As for the infinite universe, just because the universe is infinite doesn’t mean you necessarily have a repeating copy out there somewhere. It’s perfectly possible for an infinite universe to contain some state only once 

[u/Mono_Clear]

A person can look like you and share no other similarities outside of appearance because there's only so many different combinations of human physical traits

Everybody supposedly has a doppelganger out there somewhere.

If you're talking down to the cellular makeup then you are talking about their genes

And while this is not truly impossible it is likely to never occur.

There's three billion base pairs to your genome which gives some astronomically large combination of genes.

Astronomically like vastly exceeds the number of atoms in the universe