Dark Matter

There is nothing in Big Bang theory to rule out the notion of artifacts lingering from before the Big Bang. Cosmologists are in the habit of using the term "everything" here, but that's out of semantic convention rather than scientific necessity.

It is possible, though extremely improbable, that dark matter is an artifact from pre-big bang. There is nothing to support this, but there's nothing (to my knowledge or a chatbot's) to disqualify it, either.

It's impossible to imagine how anything could escape the singularity and the bang. But at this point, whatever dark matter is will be extremely unimaginable, because it doesn't seem to fit at all into anything we know (we've been working hard at it for decades, with literally no advance). Whatever it turns out to be will be highly unlikely and probably tear some big chunk of our understanding.

So if it's not as I suggest (and it almost surely isn't), it will be something equally outrageous. And once you pass a certain point of improbability, strange things happen. I wrote a paper on this (PDF link).

When there are no logical alternatives, moons really might be made of green cheese (to paraphrase the old logician's phrase). Past a certain threshold, it's most logical to ask "cheddar or stilton?"