Cosmic death beams: Understanding gamma ray bursts | Michelle Thaller | Big Think

Cosmic death beams: Understanding gamma ray bursts

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In a single night, astronomers are able to detect about 20 supernova explosions.

Gamma-ray bursts are even more energetic — in a single flash of radiation they can outshine the rest of the known universe. If a gamma burst went off anywhere in our galaxy, it could be disastrous. The radiation would be beamed far and wide.

However, as long as you're not in the way of one of those beams — or very far the site of the initial explosion — then you're probably safe.

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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.

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TRANSCRIPT:

MICHELLE THALLER: Walter, you've asked a question about how explosions propagate through space. And of course, the amazing thing is that there are incredibly violent explosions going on all around us. I remember I spent one night at Mount Palomar. And there is a specific telescope up there it was called the Palomar Transient Factory that scans the sky for supernova explosions. And the amazing thing was that in a single night-- just one night being up on top of this mountain in Southern California they detected about 20 supernova explosions. And that's an entire solar system ripping itself apart. In a single night, you see 20 of them. And there are actually more violent explosions still, more energetic explosions called gamma ray bursts. And gamma ray bursts are almost sort of unbelievably violent. In a single flash of radiation, one little object can outshine literally the rest of the known universe, billions of galaxies. It becomes so bright that, quite honestly, we had a lot of trouble explaining where all that energy could possibly come from.

Now, a gamma ray burst, you think, wow, something outshines the entire universe, that must not happen very often. Well, incredibly, with our satellites, we detect about one a day. So all around us, there are these mind-blowingly violent events. By and large, they don't affect us much. And that's because of the distance. You see, the main amount of radiation that comes out of these is in the form of light. And I don't mean just visible light. Gamma ray bursts, as the name suggests, have a lot of gamma rays. Now, gamma rays are very high-energy form of light. And gamma rays are produced when conditions the gas around the object reach the many, many billions of degrees. When you're a billion degrees hot, you actually shine, naturally, in gamma rays. Things like supernova explosions, you get a lot of x-rays, things that are millions of degrees hot. But it's still light gamma rays, X-rays, ultraviolet light, the light that we see, visible light, and then there's lower-energy light, too, like microwaves and radio.

The amazing thing is that there's so many different kinds of light, and we are really blind almost all of them. We see a tiny little bit of light that's available. But life is made of photons, and light travels through space. But there's a wonderful thing called the inverse square law, and that describes how the intensity of light drops as you move farther and farther away. And really what it has to do with is the area of a sphere. If you have a light source, and light is coming away, say, from the sun. The sun is shining in all directions. There's a sphere of photons coming away from the light. As those photons move out into space, they're covering a larger and larger area as they move away. And the area of a sphere is related to the square of the distance away that you are from the object. So the square of the radius, the inverse square law. So if you move twice as far away from the sun as we are now, the light from the sun would drop by a factor of four. We've gone twice as far away, it's four times as faint. These objects are so far away from us that that light is spread over an incredibly large area, and it's really lost any sort of i...

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