A black hole really is an object with very rich structure, just like Earth has a rich structure of mountains, valleys, oceans, and so forth. Its warped space whirls around the central singularity like air in a tornado.

When gravitational waves reach the earth, the waves stretch and squeeze space. This is a tiny stretch and squeeze. Far too small to detect with ordinary human senses.

Gravitational waves will bring us exquisitely accurate maps of black holes - maps of their space-time. Those maps will make it crystal clear whether or not what we're dealing with are black holes as described by general relativity.

Kip Thorne Quotes