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#### djscan

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I am watching Mega Disasters right now and they are discussing Gama Ray Bursts. They are saying that right before the burst happen a Black Hole is created. Can someone explain to me how we would be able to see any light since a Black Hole allows nothing to escape itâ€™s grip?

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#### origin

##### Guest
As matter falls into the black hole it heats up to the poin that it emits gamma rays. Isn't the 'burst' along the axis of spin of the black hole? I think it is.<br /><br />Once anything is past the event horizon, like light, you are right that it will not be emitted from the black hole.<br /> <div class="Discussion_UserSignature"> </div>

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#### djscan

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But I have learned that nothing can approach the Black Hole for being sucked in to the event horizon. <br /><br />Are you saying that we could approach one from the side and live to tell about it. That is of course if we knew where the side of it was?<br /><br />Sean

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#### billslugg

##### Guest
There are three issues when approaching a black hole. <br /><br />First is the large amount of power you must use to thrust in opposition to the gravitational force. Now if you don't care about ever coming back, that issue is moot. <br /><br />Second is tidal force. As you fall closer, the gravitational gradient is so high, that the difference in pull on your head and feet would be enough force to pull you apart. As it turns out, as the black hole gets larger, the tidal force at the event horizon is less and less. For very massive black holes, it is less than 100 lbs at the event horizon. This is survivable.<br /><br />Thirdly is the extreme flux of gamma rays. You are going to need some heavy duty shielding. Maybe 500 feet of lead.<br /><br />So, yes, you could pass an event horizon and live to tell about it. Unfortunately you would be inside the black hole and you would not be able to tell any of us. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

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#### thebigcat

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djscan: <i>I am watching Mega Disasters right now</i><br /><br />Me: Got better things to do at night than sleep soundly?<br /><br />From Wikipedia - Mega Disasters (TV Show)<br /><br />Season 2, Episode 2: Gamma Ray Bursts<br /><br /><i>Every few seconds, a supernova emits jets of deadly gamma rays somewhere in the galaxy. If one of these gamma ray bursts should happen sufficiently close to the solar system, all life would perish.</i><br /><br />If there were a supernova anywhere in the area we would know it. In fact, if there were a supernova anywhere in the galaxy we would know it without needing astronomers to tell us about it.<br /><br />In fact, all observed gamma ray bursts come from outside of our own galaxy and the currently accepted theory for this is that our own galaxy is too metal-rich.<br /><br />As for how gamma ray bursts could escape from a black hole, short answer is that they don't. The bursts are actually generated <i>outside</i> the black hole in the region surrounding the the event horizon and are believed to be the result of matter falling into the singularity. <div class="Discussion_UserSignature"> </div>

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#### djscan

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djscan: I am watching Mega Disasters right now <br /><br />Me: Got better things to do at night than sleep soundly? <br /><br /><b>Sean: If all your going to do is insult then your input is not needed...</b><br /><br />From Wikipedia - Mega Disasters (TV Show) <br /><br />Season 2, Episode 2: Gamma Ray Bursts <br /><br />Every few seconds, a supernova emits jets of deadly gamma rays somewhere in the galaxy. If one of these gamma ray bursts should happen sufficiently close to the solar system, all life would perish. <br /><br />If there were a supernova anywhere in the area we would know it. In fact, if there were a supernova anywhere in the galaxy we would know it without needing astronomers to tell us about it. <br /><br />In fact, all observed gamma ray bursts come from outside of our own galaxy and the currently accepted theory for this is that our own galaxy is too metal-rich. <br /><br />As for how gamma ray bursts could escape from a black hole, short answer is that they don't. The bursts are actually generated outside the black hole in the region surrounding the the event horizon and are believed to be the result of matter falling into the singularity. <br /><br /><b>Sean: So the GRB's are emitted ony during the infant stages of the BH? These are legit questions and all Insults are unwanted. </b>

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#### origin

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<font color="yellow">But I have learned that nothing can approach the Black Hole for being sucked in to the event horizon.</font><br /><br />Just to add to what some others have said. To escape the graviation of any body you must reach escape velocity. For the surface of the earth that is ~25,000 mph. The higher the gravity the higher the escape velocity.<br />The same escape velocity idea is true for a black hole. The closer you get to the black hole the higher your escape velocity must be to get away from it. At the event horizon the escape velocity is equal to the speed of light. So of course any light on the otherside of the event horizon will never leave the black hole.<br /><br />So the space shuttle could theoretically orbit a black hole and then leave the orbit. Realilistically, tidal forces would probably break it appart but I think you get the point. <div class="Discussion_UserSignature"> </div>

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#### heyscottie

##### Guest
I'm not sure your answer was ever satisfactorily answered in a direct way.<br /><br />There are many misconceptions about black holes. One, for instance, is that they are some kind of cosmic vacuum cleaner that will suck everything in. People are surprised to hear that if the sun suddenly became a black hole that the earth would NOT fall into it, but would continue orbiting as it always has.<br /><br />Black holes are only special because of the great DENSITY they pack their mass into.<br /><br />For instance, if we could theoretically begin compressing the earth, we would start to find escape velocity getting higher and higher at the surface. Once the surface shrinks enough that escape velocity is />= c, we have made a black hole. But something placed where the old surface of the earth was before it was compressed would still have the same old escape velocity we've always needed to launch rockets.<br /><br />It all has to do with the amount of mass and the distance we are from the center of that mass. As objects compress, we can get closer to the center.<br /><br />We think that Gamma ray bursts occur during the collapse. And for us to see them, they must obviously be generated from OUTSIDE of the event horizon if one has formed yet.

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#### themage

##### Guest
I hope this helps a bit.<br /><br />If the sun were to be replaced with a black hole of the same amount of mass, then everything that is in the solar system <i>should</i> be the same. What I mean is that all orbiting bodies should continue to orbit said black hole and no it won't suck everything up.<br /><br />A black hole is nothing more then a lot of mass packed really tight! Sure it has some special properties but for our purposes, just think of a BH as another celestial body.<br />

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#### dragon04

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<font color="yellow">I am watching Mega Disasters right now and they are discussing Gama Ray Bursts. They are saying that right before the burst happen a Black Hole is created. Can someone explain to me how we would be able to see any light since a Black Hole allows nothing to escape itâ€™s grip?</font><br /><br />A GRB has not so much to do about the bright light we might see as it does about the energy (that's very bad for us) that we can't see.<br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

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#### djscan

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Ok I understand what your all saying, thank you all for the constructive discussion.

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