What's Black Hole? (ブラックホールって?)

Do you know what black holes made of? I don't know. In general relativity, a black hole is a region of space in which the gravitational field is so powerful that nothing, not even light, can escape...Umm, so what? The following video also shows that they don't answer the question.

What are black holes made of? (BBC, 3 November 2009)


ブラックホールは何で出来ている? (BBC, 3 November 2009)