what percent of events are non repeatable

they say a boltzmann brain is expected to occur every 100 trillion years or whatever.   What portion of events don't repeat or repeat very rarely.

wtf is a boltzmann brain

random quantum fluctuations should randomly create brains in space for a couple moments over a long enough time scale, and one of associated problems is boltzmann brains and boltzmann brains should far outnumber human brains and earths on a long enough timescale.

4%

4.1%

Quantum tunneling and fluctuations should lead to a new big bang leading to a universe similar to our own somewhere on the scale of years, so I'd say that's pretty unrepeatable

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I feel like this question has been asked before.