It's not that ChatGPT is knowledgable, it's that it's presenting knowledge.
It's mathematically choosing an order of words to present knowledge we've encoded it with/trained it on.
The choice of the words itself isn't really knowledge (depending on how you define knowledge).
There is a related thought experiment that addresses this idea https://en.wikipedia.org/wiki/Chinese_room
It's not that ChatGPT is knowledgable, it's that it's presenting knowledge.
It's mathematically choosing an order of words to present knowledge we've encoded it with/trained it on.
The choice of the words itself isn't really knowledge (depending on how you define knowledge).
There is a related thought experiment that addresses this idea https://en.wikipedia.org/wiki/Chinese_room