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or is it that the definition of infinity used here excludes such events like there are an infinite number of odd numbers but 2 isn't in that set?

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  • $\begingroup$ Types of infinity: math.stackexchange.com/questions/5378/types-of-infinity $\endgroup$ Mar 14 at 17:04
  • $\begingroup$ How can you tell that there aren't already an infinite number of "universe ending events", and it's just that none of them have yet reached our (possibly) infinitesimal little pocket of the cosmos in the ridiculously brief 13.8 billion years since the BB? Conversely, what makes you think there's even such a thing as a "universe ending event"? Only a universe-sized singularity could do that. $\endgroup$ Mar 15 at 7:12
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The universe has a finite age, about 13.7 billion years. So there has not been time enough for infinite events in our past light-cone.

There are rather few events in mainstream physics that are universe ending. Closed universes eventually implode, and if certain forms of dark energy exist they can cause a Big Rip where the universe expands to infinity in a finite time. But obviously observers cannot look back on them in their past. This is also true for other local disasters like false vacuum decay.

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  • $\begingroup$ If our Big Bang is what follows a Big Rip or implosion, then the universe might be older than 13.7 billion years old, it's just that no evidence survives from back then. $\endgroup$
    – Ryan_L
    Mar 13 at 22:41
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    $\begingroup$ @Ryan_L - You can always add hypothetical, undetectable pasts to any model. After all, the universe could be 10 minutes old with fake memories. But it doesn't make for good physics to assume it. Also, I interpret universe-ending as actually ending the universe. $\endgroup$ Mar 14 at 9:43

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