Originally Posted by rowan

Think about it, by definition, it would not be a black swan event, if there's signs of it approaching...

I was reading about a physicist who did some fancy math and predicted the GFC, before it happened, and regressively, prior crashes such as the late 90s tech crash, and the 1990s housing crash in Japan. Can't remember details but it was some sort of oscillation that is usually related to physics data. Even these "black swans" have clear indicators.