I had an argument with a friend about a situation. Let's say in real time you have your cold Bitcoin wallet with all the passwords. You find yourself in the past, buying Bitcoins at a low price and sending them to this address, which does not yet exist but will appear in due time in the future. The question is: will the Bitcoins appear at this address in the future when it is generated? I say they will, but my friend says they won't, although I would say he knows more about blockchain.