Based on the last link, I think he means that advanced civilizations will (almost always, almost completely) live very near black holes. It’s very unlikely we would notice that with current technology, if they make an effort not to be very obvious.
Based on the last link, I think he means that advanced civilizations will (almost always, almost completely) live very near black holes. It’s very unlikely we would notice that with current technology, if they make an effort not to be very obvious.