Occasionally on the radio I hear a cosmologist say something about how information has to be preserved, even in black holes. What are they talking about? Is this something to do with entropy? Likewise I watched someone on YouTube say he did not think we were living in a simulation, partly because if he himself were to design a simulation of the universe, he'd throw away the bits. I assume he talking about information again, and that by bits he's talking about unavailable energy.