I didn't say anything about civilizations or suggest that planets might be hollow. I did say that scientists are exploring the idea of life inside a planet or a star.

I'm not enough a scientist to explain thoroughly but it has something to do with dust clouds being vented to the Earth's crust from carbon deposits deep inside the Earth. It is thought that this may have been the beginning of life on Earth as we know it. If it happens here, it can also happen in space. In other words, we are exploring the surface of planets when the life forms may, in fact, be deep within.

I'm still searching for a transcript of the story I heard on CBC radio about a week ago.

btw - I don't read science fiction.