Indeed. There's a Catch-22 here. We would need to identify something that HAS been created ex-nihilo (or at least how it would be done) so it can be studied to determine what properties distinguish it from that which has NOT been created ex-nihilo. If we can't explain the difference in scientific terms, how are we going to test for it? Yet once we've scientifically described ex-nihilo and/or found said ex-nihilo object ... well ... there it is.
What I suspect
@Kylie wants to establish is that ex-nihilo is not possible. Let's call that the
strong case. I maintain the strong case can't be successfully argued. However, one of two
weak cases probably could be successfully argued: 1) ex-nihilo is possible, but this specific apple wasn't formed that way, or 2) it is unknown by us whether the apple was created ex-nihilo.
For case 2, Kylie's example introduces a witness who is claiming an ex-nihilo apple. While we don't know, the witness does. The believer accepts the witness as credible. The skeptic does not. What, then, matters to the believer? If it is only his faith in the witness, it doesn't matter whether the skeptic agrees or not. However, if the believer wants the skeptic to accept the witness, we've most likely entered a game of infinite turtles that only the witness himself can resolve.
FWIW, rather than apples, I would say the
quantum foam is a much better prospect for a study of ex-nihilo possibilities.