Guest Posted October 14, 2005 Share Posted October 14, 2005 A few days ago I went to an IoP lecture about "The Extreme Physics of Gamma Ray Bursts". Basically, these Gamma Ray bursts were detected during the Cold War when the Americans and Russians sent up satellites which were used to look for Gamma Rays (which suggests the testing of nuclear weapons). Instead of sustained bursts of Gamma Rays which are characteristcal to Nuclear weapons testing, short bursts (ie. 2 seconds to 1 minute long) were discovered. After a lot of dilly dallying about they found out these were coming from thousands upon millions of light years away. Only 1/500th's of these rays were visible to the naked eye, yet the energy contained in these short bursts alone was TEN TIMES that of the TOTAL output of our Sun... in its entire Life! Which means... that if we were to have a Gamma Ray Burst in our galaxy (Up to about 5,000 lightyears away as there is the I = k/d^2 relationship), we would all die instantly (well, when they were to reach us). But to reassure you, we have never (to our knowledge) had one anywhere near us. The nearest is thought to be have been well over 1,000,000,000 light years away I just thought this was interesting! Link to comment Share on other sites More sharing options...
vincent Posted October 14, 2005 Share Posted October 14, 2005 A GRB close enough would definatley spell doom for Earth, Now from what i've read the source of these burts are from stars going supernova, am i right? Link to comment Share on other sites More sharing options...
Guest Posted October 14, 2005 Share Posted October 14, 2005 There are several theories. One is the collapse of large stars (and hence, supernova), the other is comets colliding into neutron stars (releasing bursts of energy). There are several more but they seem a bit ridiculous - for example, anti-matter comets colloding with matter commits, and the creation of White Holes (sort of an inverse Black Hole) The actual energy released in these Gamma Ray Bursts is in the order of 10^46 Joules. Link to comment Share on other sites More sharing options...
Guest Posted October 14, 2005 Share Posted October 14, 2005 1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 = 10^46 Joules :) Link to comment Share on other sites More sharing options...
vincent Posted October 14, 2005 Share Posted October 14, 2005 10^46... i dont have time to do the maths right now, but i'm thinking that is around 4million or 4 billion. Link to comment Share on other sites More sharing options...
SaguratuS Posted October 14, 2005 Share Posted October 14, 2005 10^46... i dont have time to do the maths right now, but i'm thinking that is around 4million or 4 billion. 586671157[/snapback] :blink: Anyways... Yeah, a nearby GRB will spell doom for everything living on the earth, but not for the earth itself. (Minus the roaches of course.) Link to comment Share on other sites More sharing options...
GoogleNinja Posted October 14, 2005 Share Posted October 14, 2005 10^46... i dont have time to do the maths right now, but i'm thinking that is around 4million or 4 billion. 586671157[/snapback] Please tell me you were joking... :pinch: Link to comment Share on other sites More sharing options...
vincent Posted October 14, 2005 Share Posted October 14, 2005 Please tell me you were joking... :pinch: 586671584[/snapback] no, i suck at math right now. Link to comment Share on other sites More sharing options...
raid517 Posted October 14, 2005 Share Posted October 14, 2005 (edited) Well anyway it's much more than 4 billion rigput. 10^46 is a 10 with 46 zeros after it. We don't even have a name for a number as large as that. What interests me though is that these bursts are relatively common. I don't think it tells the whole story, but I have always been facinated by the process of star formation. I mean what happens when enough matter is gathered to allow for the gravitational collapse (although not as powerful as the kind of collapse that occurs when a blackhole is formed) that initiates the process of actually igniting the nuclear fires within a star? Or inother words, what happens when the light initally get switched on? Wouldn't we see bursts of exactly this nature? I guess it would depend on how big the star was and how fast the process occurs. But it would be interesting to try to work out just how much energy a star the size of our sun would give off at the exact instant that the nuclear fusion processes within it first turned on - and then maybe scale this up to what we actually see in terms of mass for other stars in the universe. Ufortunately I don't have access to any scientific modeling equipment that would allow me to calculate this. I guess it can only ever be speculative anyway, as we can never really know how stars are formed (unless of course we can actually witness the exact instant of a star's formation). Maybe the process of star formation is quite gradual and quite sedate? But somehow I doubt this, as in my bones I supect that the process of star formation is likely to be anything but gradual or sedate. Indeed you would imagine that a large proportion of a stars initial mass almost certainly would be ejected at the exact point that a star comes to life. It is an interesting question though. GJ Edited October 14, 2005 by raid517 Link to comment Share on other sites More sharing options...
GoogleNinja Posted October 14, 2005 Share Posted October 14, 2005 no, i suck at math right now. 586671628[/snapback] :p PS: raid517 - I'm sure there is a name for 10^46, it's just not very well known. Link to comment Share on other sites More sharing options...
comk Posted October 15, 2005 Share Posted October 15, 2005 wouldn't the earth's magnetic field deflect it?? Link to comment Share on other sites More sharing options...
Pox Posted October 15, 2005 Share Posted October 15, 2005 wouldn't the earth's magnetic field deflect it?? nothing of this size. supposedly a huge gamma ray burst could be caused by a binary neutron star system collapsing... take out the atmosphere of most planets in the galaxy. (no i didnt get that from a certain greg egan book :ninja: ) Link to comment Share on other sites More sharing options...
[Damien] Posted October 15, 2005 Share Posted October 15, 2005 I remember watching a documentary on this subject. Scientists were stumped at the level of energy being detected, and that if it had come from an explosion then it was bigger than human comprehension, and would seem to violate the laws of physics. In the end they concluded that it was a star being devoured by a black hole, I can't remember which star but they showed a computer model of it being sucked into the black hole, and with the energy being spat out from either side (imagine the black hole as a paper disc, and the energy as a pencil stuck though the middle of it. The energy was shooting outwards from the centre along the same line as the pencil) I may be wrong though, as I'm recalling from memory. Here's some links that seem to be on about the same thing. http://www.msnbc.msn.com/id/9600394/ http://www.newscientist.com/article.ns?id=dn4699 http://edition.cnn.com/2004/TECH/space/02/...blackhole.star/ Link to comment Share on other sites More sharing options...
raid517 Posted October 16, 2005 Share Posted October 16, 2005 Nothing defies the laws of physics - even if we don't know what all those laws are yet. GJ Link to comment Share on other sites More sharing options...
[Damien] Posted October 16, 2005 Share Posted October 16, 2005 Nothing defies the laws of physics - even if we don't know what all those laws are yet.GJ 586678925[/snapback] Exactly, which is why they came to the conclusion that the impossibly high levels of radiation was due to it being focused in a single direction by the black hole rather than scattered in all directions like it would with an exploding star. Link to comment Share on other sites More sharing options...
Guest Posted October 16, 2005 Share Posted October 16, 2005 Yes you're right, there are theories which suggest the energy is scattered in one direction. The GRB would have to be pointing in the Earth's direction for it to have an effect. Apparently we are meant to experience one GRB in our galaxy once every few billion years... I believe we're overdue. Phwoar. Link to comment Share on other sites More sharing options...
[Damien] Posted October 17, 2005 Share Posted October 17, 2005 Bring it on, I got sunblock! :) Link to comment Share on other sites More sharing options...
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