GAMMA RAYS: Clues: 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: Apr 29, 1998
Scientist: Neil DeGrasse Tyson


They generate more energy than virtually any other known phenomena in the universe - but how?

Astronomers have been monitoring far distant bursts of light energy called Gamma Rays for the past thirty -five years. They still don't know what's producing these high energy bursts, but like any good detective, they've been following clues. I'm Jim Metzner, and this is the Pulse of the Planet, presented by the American Museum of Natural History.

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

"The duration of Gamma Ray bursts have been observed to be from anywhere from a few hundredths of a second up to a few thousand seconds. And, you can actually get some physics from that information. You can recognize that if something brightens and dims within a fraction of a second, you have a pretty good idea that the object that produced the burst can be no bigger than the time it takes light to cross its own diameter. So in other words, if you see an object brighten and dim in a tenth of a second, that object can be no bigger than a tenth of a light second across. If it took a hundred seconds to brighten and dim, it can be no bigger than a hundred light seconds in diameter. The time it takes light to go from one side of the object to the other. If it were much bigger than that, then you'd be seeing different parts of the object brighten and dim at different times, thereby confusing your ability to interpret the size of the object. So, because Gamma Ray bursts come and go so quickly, that is our first indication that we're dealing with a very small object. And in our toolbox of explanatory phenomenon, a black hole is something that can pack a lot of energy in a very small region of space. Hence, the prevalence for invoking black hole solutions to what would be giving you these bursts of high energy Gamma Rays."

More on Gamma Ray bursts on future programs. Pulse of the Planet is presented by the American Museum of Natural History. I'm Jim Metzner.