BLACK HOLES: Basics: The Pulse of the Planet daily radio program offers free legal online mp3 downloads, exploring the world of sound in nature, culture and science, with audio adventures, world music, extraordinary sound portraits, science diaries, and nature ring-tones; an amazing sonic experience.

Airdate: Dec 10, 1997
Scientist: Neil DeGrasse Tyson


The dense cosmic objects known as black holes have some extraordinary properties.

The rhythms of the cosmos are on a scale much bigger than our current ability to detect them. At the very edge of our understanding of the pulse of the universe are some extraordinary objects known as black holes. I'm Jim Metzner, and this is the Pulse of the Planet, presented by the American Museum of Natural History.

Some Black Holes started out as massive stars. When the star runs out of fuel, it begins to collapse, and it just keeps on collapsing until it's just a point in space with the same mass it had as a star. An object that dense has some special properties.

"Black holes are one of the most fascinating objects in the universe, primarily because they live at the limits of our imagination of what can happen to the structure of matter and to space."

Dr. Neil de Grasse Tyson is the Frederick P. Rose Director of New York's Hayden Planetarium.

"A black hole is actually quite easy to understand. If you're standing on Earth, and you toss something up, obviously it comes back. We all know this because, what goes up must come down. But there's a speed with which you can throw something from Earth where it will never come back."

That speed is known as the escape velocity. Now, Earth's escape velocity is seven miles per second, which means that if you were somehow able to throw a baseball up at seven miles per second, it wouldn't come back down. And to launch a baseball from a black hole, you'd need some serious firepower.

"For a black hole the escape velocity is the speed of light itself. And in fact, the speed of light is not even high enough to escape a black hole. So if you try to send up a beam of light, it'll just come right on back. Since light is the fastest thing we know, once you fall into a black hole, you're never coming out. Ever."

Pulse of the Planet is presented by the American Museum of Natural History. I'm Jim Metzner.