This is true but irrelevant. In fact, it's
very likely that space-time becomes significantly different right at 'start' (if there was one), but it doesn't matter.
This is just wrong. The premises of
@PureX's 'argument', effectively claim knowledge about the beginning, which, as you have pointed out, we don't have. The whole basis of the 'argument' is that this list:
- Infinite past,
- 'poofing' from nothing, for no reason, or
- magic,
is exhaustive. Given the uncertainty that you are pointing out, and the nature of space-time we observe today, there are many more options.
And the nature of space-time today
is relevant because in implies eternalism, rather than presentism, which is also implicit in the list.