What Are "Black Holes?"

New videos DAILY

Join Big Think Edge for exclusive video lessons from top thinkers and doers

----------------------------------------------------------------------------------

There's more than one way to make a black hole, says NASA's Michelle Thaller. They're not always formed from dead stars. For example, there are teeny tiny black holes all around us, the result of high-energy cosmic rays slamming into our atmosphere with enough force to cram matter together so densely that no light can escape.CERN is trying to create artificial black holes right now, but don't worry, it's not dangerous. Scientists there are attempting to smash two particles together with such intensity that it creates a black hole that would live for just a millionth of a second.Thaller uses a brilliant analogy involving a rubber sheet, a marble, and an elephant to explain why different black holes have varying densities. Watch and learn!Bonus fact: If the Earth became a black hole, it would be crushed to the size of a ping-pong ball.

----------------------------------------------------------------------------------

MICHELLE THALLER

Dr. Michelle Thaller is an astronomer who studies binary stars and the life cycles of stars. She is Assistant Director of Science Communication at NASA. She went to college at Harvard University, completed a post-doctoral research fellowship at the California Institute of Technology (Caltech) in Pasadena, Calif. then started working for the Jet Propulsion Laboratory's (JPL) Spitzer Space Telescope. After a hugely successful mission, she moved on to NASA's Goddard Space Flight Center (GSFC), in the Washington D.C. area. In her off-hours often puts on about 30lbs of Elizabethan garb and performs intricate Renaissance dances. For more information, visit

NASA.

----------------------------------------------------------------------------------

TRANSCRIPT:

MICHELLE THALLER: So Mark, you have a great question about black holes: Is there a minimum mass needed for a black hole to form and does a black hole form whenever a stellar object gets that dense?

To begin with, let's talk about the definition of a black hole. Now, most commonly people talk about black holes as being a consequence of a giant star dying. And the idea is that a star has this huge mass and that's a lot of gravity crushing the star together. Now, when the star is alive and there are fusion reactions going on inside the core, that crush of gravity is actually held up. But once the star dies and the fusion reactions go away the gravity crushes inward and there's nothing to support it anymore. So basically gravity becomes so strong in that object that not even light can escape and therefore we call it a black hole. That's probably the most classic way to make a black hole, is you actually make it from the core of a dead star that's collapsing.

But you might be surprised to learn that we actually think there are other ways to make a black hole. And the real answer to your question is that there is no minimum mass needed for a black hole, you just need to have the right density for an object's gravity to be so intense that light can't escape. The universe is very good at making black holes that are about the size of stars; it's an easy way to get them. But the universe makes black holes in other ways too. We actually think there are black holes being generated all around us on very, very small scales. There are things called high-energy cosmic rays — very, very energetic particles that slam into our atmosphere from space. These slam in with enough energy that we think they actually create tiny black holes, black holes that have the mass only a couple of atoms. There's enough energy to cram that matter together so much they form little black holes.

One of the things that we're doing at CERN, which is actually the largest particle accelerator on the earth right now, is trying to get up to those densities. CERN actually does want to make artificial black holes. Actually have two particles collide so intensely that they pop off a little black hole. And before you ask the question — no this is not dangerous. CERN does not get up to energies anywhere near what's happening in the natural world. These high-energy particles from space are much more energetic than CERN could ever do. So if anything dangerous was going to happen, it would already have happened. These tiny little black holes we think don't live very long, maybe even a millionth of a second. The whole point will be to detect them at all. All you need is a certain amount of mass and a certain amount of volume. It doesn't matter how much mass and you'll get a black hole. For example, if you could actually crush the entire Earth into the size of a pi...

For the full transcript, check out